U.S. patent application number 12/837504 was filed with the patent office on 2010-12-16 for system and method.
Invention is credited to Steven M. Hoffberg.
Application Number | 20100317420 12/837504 |
Document ID | / |
Family ID | 43306884 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100317420 |
Kind Code |
A1 |
Hoffberg; Steven M. |
December 16, 2010 |
SYSTEM AND METHOD
Abstract
A system and method providing for communication and reolution of
utility functions between participants, wherein the utility
function is evaluated based on local information at the recipient
to determine a cost value thereof. A user interface having express
representation of both information elements, and associated
reliability of the information. An automated system for optimally
conveying information based on relevance and reliability.
Inventors: |
Hoffberg; Steven M.; (West
Harrison, NY) |
Correspondence
Address: |
Hoffberg & Associates
10 Bank Street, Suite 460
White Plains
NY
10606
US
|
Family ID: |
43306884 |
Appl. No.: |
12/837504 |
Filed: |
July 16, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10771182 |
Feb 3, 2004 |
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12837504 |
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60445346 |
Feb 5, 2003 |
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Current U.S.
Class: |
463/1 |
Current CPC
Class: |
G07F 17/323 20130101;
G07F 17/3237 20130101; G06Q 30/0207 20130101; G06Q 30/08 20130101;
G07F 17/32 20130101; G06Q 30/0282 20130101 |
Class at
Publication: |
463/1 |
International
Class: |
A63F 9/24 20060101
A63F009/24 |
Claims
1. A method of determining a subjective profile of a person,
comprising: presenting a game for play by the person, wherein the
payoff of the game is real and beneficial to the person;
sufficiently observing the game play involving the person to
comprehend a risk aversion profile of the person; employing the
comprehended risk aversion profile to modify a rationality
expectation for the person.
2. The method according to claim 1, wherein the modified
rationality expectation is applied to optimize an interaction with
the person outside of the game play environment.
3. The method according to claim 1, wherein the risk aversion
profile is employed to normalize a system in which rationality is
presumed.
4. The method according to claim 1, further comprising normalizing
a system to compensate for the risk aversion profile.
5. The method according to claim 1, wherein the game is conducted
by an automated processor.
6. The method according to claim 1, wherein the game comprises
stakes similar to a non-game situation, and wherein the risk
aversion profile derived from play of ther game by the person is
employed to modify a rationality expectation for the person in the
non-game situation.
7. The method according to claim 1, wherein the risk aversion
profile is employed in a user-agent which acts on behalf of the
user.
8. The method according to claim 1, wherein the risk aversion
profile is employed to subjectivize a presentation of risk data to
a user.
9. The method according to claim 1, wherein the risk aversion
profile is employed to optimize a presentation of objects
associated with different risks to a user.
10. The method according to claim 1, wherein the risk aversion
profile is employed to match the person with another person or
process, based on a presumed compatibility.
11. A system configured to determine a subjective profile of a
person, comprising: an interactive interface configured for use by
a person to play a game, the game comprising a risk and a payoff
beneficial to the person; an automated processor configured to
monitor sufficient play of the game to derive a risk aversion
profile of the person; a memory configured to store the risk
aversion profile; and an output port configured to communicate a
signal in dependence on the risk aversion profile.
12. The system according to claim 11, wherein the automated
processor is further configured to employ the derived risk aversion
profile to modify a rationality expectation for the person.
13. The system according to claim 12, wherein the modified
rationality expectation is applied with respect to a circumstance
outside of the game, to optimize an interaction with the person
outside of the game play environment, wherein the game comprises a
beneficial payoff to the person.
14. The sytem according to claim 11, wherein the game represents a
model of an interaction involving a plurality of people, and
wherein the risk aversion profile derived from play of ther game by
the person is employed to modify a rationality expectation for the
person in the interaction.
15. The system according to claim 11, wherein the automated
processor is configured to employ the risk aversion profile to
provide a user-agent which acts on behalf of the user.
16. The system according to claim 11, wherein the automated
processor is configured to employ the risk aversion profile to
optimize a presentation of objects associated with different risks
to a user.
17. The system according to claim 11, wherein the automated
processor is configured to employ the risk aversion profile to
match the person with another person or process, based on a
presumed compatibility.
18. A method of generating a user subjective risk aversion profile,
comprising: repeatedly playing a game between an automated
processor and the user, the game comprising a range of statistical
risks and rewards; sufficiently observing the game play involving
the person to generate a predictive risk aversion profile for the
user; employing the predicted risk aversion profile to normalize an
expectation for the person outside of the game.
19. The method according to claim 18, wherein the game is an
auction, and wherein an automated processor employs the predicted
risk aversion profile to bid in an auction on behalf of the
user.
20. The method according to claim 19, wherein the auction comprises
a multi-part auction.
Description
BACKGROUND OF THE INVENTION
[0001] A number of fields of endeavor are relevant to the present
invention, and exemplary prior art, incorporated herein by
reference, are disclosed below. The references disclosed provide a
skilled artisan with embodiments of elements of the present
invention, and the teachings therein may be combined and
subcombined in various manners in accordance with the present
teachings. The topical headings are advisory only, and are not
intended to limit the applicability of any reference. While some
embodiments are discussed as being preferred, it should be
understood that all embodiments discussed, in any portion of this
documents, whether stated as having advantages or not, form a part
of the invention and may be combined and/or subcombined in a
consistent manner in accordance with the teachings hereof.
[0002] Internet
[0003] The Internet is structured such various networks are
interconnected, with communications effected by addressed packets
conforming to a common protocol. Based on the packet addressing,
information is routed from source to destination, often through a
set of networks having multiple potential pathways. The
communications medium is shared between all users. Statistically,
some proportion of the packets are extraordinarily delayed, or
simply lost. Therefore, protocols involving communications using
these packets include error detection schemes that request a
retransmit of required data not received within a time window. In
the even that the network nears capacity or is otherwise subject to
limiting constraint, the incidence of delayed or lost packets
increases, thereby increasing requests for retransmission and
retransmission. Therefore, as the network approaches available
bandwidth, the load increases, ultimately leading to failure. In
instances where a minimum quality of service must be guaranteed,
special Internet technologies are required, to reserve bandwidth or
to specify network pathways. End-to-end quality of service
guarantees, however, may exceed the cost of circuit switched
technologies, such as dialup modems, especially where the high
quality needs are intermittent.
[0004] Internet usage typically involves an Internet server, an
automated system capable of responding to communications received
through the Internet, and often communicating with other systems
not directly connected to the Internet. The server typically has
relatively large bandwidth to the Internet, allowing multiple
simultaneous communications sessions, and usually supports the
hypertext transport protocol (HTTP), which provides, in conjunction
with a so-called web browser on a remote client system, a human
readable interface which facilitates navigation of various
resources available in the Internet. The client systems are
typically human user interfaces, which employ a browser to display
HTTP "web pages". The browser typically does not provide
intelligence. Bandwidth between the client and Internet is
typically relatively small, and various communications and display
rendering considered normal. Typically, both client and server are
connected to the Internet through Internet service providers, each
having its own router.
[0005] It is also known to provide so-called proxy servers and
firewalls, which are automated systems that insulate the client
system from the Internet. Further, so-called Internet applications
and applets are known which provide local intelligence at the
client system. Further, it is known to provide a local server
within the client system for locally processing a portion of the
information. These local servers, applications and applets are
non-standard, and thus require special software to be available
locally for execution.
[0006] Thus, the Internet poses a number of advantages for
commercial use, including low cost and ubiquitous connectivity.
Therefore, it is desirable to employ standard Internet technologies
while achieving sufficient quality communications to effect an
efficient transaction.
[0007] Market Economy Systems
[0008] In modern retail transactions, predetermined price
transactions are common, with market transactions, i.e., commerce
conducted in a setting which allows the transaction price to float
based on the respective valuation allocated by the buyer(s) and
seller(s), often left to specialized fields. While interpersonal
negotiation is often used to set a transfer price, this price is
often different from a transfer price that might result from a
best-efforts attempt at establishing a market price. Assuming that
the market price is optimal, it is therefore assumed that
alternatives are sub optimal. Therefore, the establishment of a
market price is desirable over simple negotiations.
[0009] One particular problem with market-based commerce is that
both seller optimization and market efficiency depend on the fact
that representative participants of a preselected class are invited
to participate, and are able to promptly communicate, on a relevant
timescale, in order to accurately value the goods or services and
make an offer. Thus, in traditional market-based system, all
participants are in the same room, or connected by a high quality
telecommunications link. Alternately, the market valuation process
is prolonged over an extended period, allowing non-real time
communications of market information and bids. Thus, attempts at
ascertaining a market price for non-commodity goods can be subject
to substantial inefficiencies, which reduce any potential gains by
market pricing. Further, while market pricing might be considered
"fair", it also imposes an element of risk, reducing the ability of
parties to predict future pricing and revenues. Addressing this
risk may also reduce efficiency of a market-based system.
[0010] Auction Systems
[0011] When a single party seeks to sell goods to the highest
valued purchaser(s), to establish a market price, the rules of
conduct typically define an auction. Typically, known auctions
provide an ascending price or descending price over time, with
bidders making offers or ceasing to make offers, in the descending
price or ascending price models, respectively, to define the market
price. After determining the winner of the auction, the pricing
rules define uniform price auctions, wherein all successful bidders
pay the lowest successful bid, second price auctions wherein the
winning bidder pays the amount bid by the next highest bidder, and
pay-what-you-bid auctions. The pay-what-you-bid auction is also
known as a discriminative auction while the uniform price auction
is known as a non-discriminative auction. In a second-price
auction, also known as a Vickrey auction, the policy seeks to
create a disincentive for speculation and to encourage bidders to
submit bids reflecting their true value for the good. In the
uniform price and second price schemes, the bidder is encourages to
disclose the actual private value to the bidder of the good or
service, since at any price below this amount, there is an excess
gain to the buyer, whereas by withholding this amount the bid may
be unsuccessful, resulting in a loss of the presumably desirable
opportunity. In the pay-what-you-bid auction, on the other hand,
the buyer need not disclose the maximum private valuation, and
those bidders with lower risk tolerance will bid higher prices.
See, www.isoc.org/inet98/proceedings/3b/3b.sub.--3.html;
www.ibm.com/iac/reports-technical/reports-bus-neg-internet.html.
[0012] Two common types of auction are the English auction, which
sells a single good to the highest bidder in an ascending price
auction, and the Dutch auction, in which multiple units are
available for sale, and in which a starting price is selected by
the auctioneer, which is successively reduced, until the supply is
exhausted by bidders (or the minimum price/final time is reached),
with the buyer(s) paying the lowest successful bid. The term Dutch
auction is also applied to a type of sealed bid auction. In a
multi-unit live Dutch auction, each participant is provided with
the current price, the quantity on hand and the time remaining in
the auction. This type of auction, typically takes place over a
very short period of time and there is a flurry of activity in the
last portion of the auction process. The actual auction terminates
when there is no more product to be sold or the time period
expires.
[0013] In selecting the optimal type of auction, a number of
factors are considered. In order to sell large quantities of a
perishable commodity in a short period of time, the descending
price auctions are often preferred. For example, the produce and
flower markets in Holland routinely use the Dutch auction (hence
the derivation of the name), while the U.S. Government uses this
form to sell its financial instruments. The format of a traditional
Dutch auction encourages early bidders to bid up to their "private
value", hoping to pay some price below the "private value". In
making a bid, the "private value" becomes known, helping to
establish a published market value and demand curve for the goods,
thus allowing both buyers and sellers to define strategies for
future auctions.
[0014] In an auction, typically a seller retains an auctioneer to
conduct an auction with multiple buyers. (In a reverse auction, a
buyer solicits the lowest price from multiple competing vendors for
a desired purchase). Since the seller retains the auctioneer, the
seller essentially defines the rules of the auction. These rules
are typically defined to maximize the revenues or profit to the
seller, while providing an inviting forum to encourage a maximum
number of high valued buyers. If the rules discourage high
valuations of the goods or services, or discourage participation by
an important set of potential bidders, then the rules are not
optimum. A rule may also be imposed to account for the valuation of
the good or service applied by the seller, in the form of a reserve
price. It is noted that these rules typically seek to allocate to
the seller a portion of the economic benefit that would normally
inure to the buyer, creating an economic inefficiency. However,
since the auction is to benefit the seller, not society as a whole,
this potential inefficiency is tolerated. An optimum auction thus
seeks to produce a maximum profit (or net revenues) for the seller.
An efficient auction, on the other hand, maximizes the sum of he
utilities for the buyer and seller. It remains a subject of
academic debate as to which auction rules are most optimum in given
circumstances; however, in practice, simplicity of implementation
may be a paramount concern, and simple auctions may result in
highest revenues; complex auctions, while theoretically more
optimal, may discourage bidders from participating or from applying
their true and full private valuation in the auction process.
[0015] Typically, the rules of the auction are predefined and
invariant. Further, for a number of reasons, auctions typically
apply the same rules to all bidders, even though, with a priori
knowledge of the private values assigned by each bidder to the
goods, or a prediction of the private value, an optimization rule
may be applied to extract the full value assigned by each bidder,
while selling above the sellers reserve.
[0016] In a known ascending price auction, each participant must be
made aware of the status of the auction, e.g., open, closed, and
the contemporaneous price. A bid is indicated by the identification
of the bidder at the contemporaneous price, or occasionally at any
price above the minimum bid increment plus the previous price. The
bids are asynchronous, and therefore each bidder must be
immediately informed of the particulars of each bid by other
bidders.
[0017] In a known descending price auction, the process
traditionally entails a common clock, which corresponds to a
decrementing price at each decrement interval, with an ending time
(and price). Therefore, once each participant is made aware of the
auction parameters, e.g., starting price, price decrement, ending
price/time, before the start of the auction, the only information
that must be transmitted is auction status (e.g., inventory
remaining).
[0018] As stated above, an auction is traditionally considered an
efficient manner of liquidating goods at a market price. The theory
of an auction is that either the buyer will not resell, and thus
has an internal or private valuation of the goods regardless of
other's perceived values, or that the winner will resell, either to
gain economic efficiency or as a part of the buyers regular
business. In the later case, it is a general presumption that the
resale buyers are not in attendance at the auction or are otherwise
precluded from bidding, and therefore that, after the auction,
there will remain demand for the goods at a price in excess of the
price paid during the auction. Extinction of this residual demand
results in the so-called "winner's curse", in which the buyer can
make no profit from the transaction during the auction. Since this
detracts from the value of the auction as a means of conducting
profitable commerce, it is of concern to both buyer and seller. In
fact, experience with initial public offerings (IPOs) of stock
through various means has demonstrated that by making stock
available directly to all classes of potential purchasers, latent
demand for a new issue is extinguished, and the stock price is
likely to decline after issuance, resulting in an IPO which is
characterized as "unsuccessful". This potential for post IPO
decline tempers even initial interest in the issue, resulting in a
paradoxical decline in revenues from the vehicle. In other words,
the "money on the table" resulting from immediate retrading of IPO
shares is deemed a required aspect of the IPO process. Thus,
methods that retain latent demand after IPO shares result in post
IPO increases, and therefore a "successful" IPO. Therefore, where
the transaction scheme anticipates demand for resale after the
initial distribution, it is often important to assure a reasonable
margin for resellers and limitations on direct sale to ultimate
consumers.
[0019] Research into auction theory (game theory) shows that in an
auction, the goal of the seller is to optimize the auction by
allocating the goods inefficiently, and thus to appropriate to
himself an excess gain. This inefficiency manifests itself by
either withholding goods from the market or placing the goods in
the wrong hands. In order to assure for the seller a maximum gain
from a misallocation of the goods, restrictions on resale are
imposed; otherwise, post auction trading will tend to undue the
misallocation, and the anticipation of this trading will tend to
control the auction pricing. The misallocation of goods imposed by
the seller through restrictions allow the seller to achieve greater
revenues than if free resale were permitted. It is believed that in
an auction followed by perfect resale, that any mis-assignment of
the goods lowers the seller's revenues below the optimum and
likewise, in an auction market followed by perfect resale, it is
optimal for the seller to allocate the goods to those with the
highest value. Therefore, if post-auction trading is permitted, the
seller will not benefit from these later gains, and the seller will
obtain sub optimal revenues.
[0020] These studies, however, typically do not consider
transaction costs and internal inefficiencies of the resellers, as
well as the possibility of multiple classes of purchasers, or even
multiple channels of distribution, which may be subject to varying
controls or restrictions, and thus in a real market, such
theoretical optimal allocation is unlikely. In fact, in real
markets the transaction costs involved in transfer of ownership are
often critical in determining a method of sale and distribution of
goods. For example, it is the efficiency of sale that motivates the
auction in the first place. Yet, the auction process itself may
consume a substantial margin, for example 1-15% of the transaction
value. To presume, even without externally imposed restrictions on
resale, that all of the efficiencies of the market may be extracted
by free reallocation, ignores that the motivation of the buyer is a
profitable transaction, and the buyer may have fixed and variable
costs on the order of magnitude of the margin. Thus, there are
substantial opportunities for the seller to gain enhanced revenues
by defining rules of the auction, strategically allocating
inventory amount and setting reserve pricing.
[0021] Therefore, perfect resale is but a fiction created in
auction (game) theory. Given this deviation from the ideal
presumptions, auction theory may be interpreted to provide the
seller with a motivation to misallocate or withhold based on the
deviation of practice from theory, likely based on the respective
transaction costs, seller's utility of the goods, and other factors
not considered by the simple analyses.
[0022] A number of proposals have been made for effecting auction
systems using the Internet. These systems include
consumer-to-consumer, business-to-consumer, and
business-to-business types. Generally, these auctions, of various
types and implementations discussed further below, are conducted
through Internet browsers using hypertext markup language (HTML)
"web pages", using HTTP. In some instances, such as BIDWATCH,
discussed further below, an application with associated applets is
provided to define a user interface instead of HTML.
[0023] As stated above, the information packets from the
transaction server to client systems associated with respective
bidders communicate various information regarding the status of an
interactive auction during the progress thereof. The network
traffic from the client systems to the transaction server is often
limited to the placement of bids; however, the amount of
information required to be transmitted can vary greatly, and may
involve a complex dialogue of communications to complete the
auction offer. Typically, Internet based auction systems have
scalability issues, wherein economies of scale are not completely
apparent, leading to implementation of relatively large transaction
server systems to handle peak loads. When the processing power of
the transaction server system is exceeded, entire system outages
may occur, resulting in lost sales or diminished profits, and
diminished goodwill.
[0024] In most Internet auction system implementations, there are a
large quantity of simultaneous auctions, with each auction
accepting tens or hundreds of bids over a timescale of hours to
days. In systems where the transaction volume exceeds these scales,
for example in stock and commodity exchanges, which can accommodate
large numbers of transactions per second involving the same issue,
a private network, or even a local area network, is employed, and
the public Internet is not used as a direct communications system
with the transaction server. Thus, while infrastructures are
available to allow successful handling of massive transaction per
second volumes, these systems typically avoid direct public
Internet communications or use of some of its limiting
technologies. The transaction processing limitations are often due
to the finite time required to handle, e.g., open, update, and
close, database records.
[0025] In business-to-business auctions, buyers seek to ensure that
the population of ultimate consumers for the good or services are
not present at the auction, in order to avoid the "winner's curse",
where the highest bidder in the auction cannot liquidate or work
the asset at a profit. Thus, business-to-business auctions are
distinct from business-to-consumer auctions. In the former, the
optimization by the seller must account for the desire or directive
of the seller to avoid direct retail distribution, and instead to
rely on a distribution tier represented in the auction. In the
latter, the seller seeks maximum revenues and to exhaust the
possibilities for downstream trade in the goods or services. In
fact, these types of auctions may be distinguished by various
implementing rules, such as requiring sales tax resale
certificates, minimum lot size quantities, preregistration or
qualification, support or associated services, or limitations on
the title to the goods themselves. The conduct of these auctions
may also differ, in that consumer involvement typically is
permissive of mistake or indecision, while in a pure business
environment professionalism and decisiveness are mandated.
[0026] In many instances, psychology plays an important role in the
conduct of the auction. In a live auction, bidders can see each
other, and judge the tempo of the auction. In addition, multiple
auctions are often conducted sequentially, so that each bidder can
begin to understand the other bidder's patterns, including
hesitation, bluffing, facial gestures or mannerisms. Thus, bidders
often prefer live auctions to remote or automated auctions if the
bidding is to be conducted strategically.
[0027] Internet Auctions
[0028] On-line electronic auction systems which allow efficient
sales of products and services are well known, for example,
EBAY.COM, ONSALE.COM, UBID.COM, and the like. Inverse auctions that
allow efficient purchases of product are also known, establishing a
market price by competition between sellers. The Internet holds the
promise of further improving efficiency of auctions by reducing
transaction costs and freeing the "same time-same place"
limitations of traditional auctions. This is especially appropriate
where the goods may be adequately described by text or images, and
thus a physical examination of the goods is not required prior to
bidding.
[0029] In existing Internet systems, the technological focus has
been in providing an auction system that, over the course of hours
to days, allow a large number of simultaneous auctions, between a
large number of bidders to occur. These systems must be scalable
and have high transaction throughput, while assuring database
consistency and overall system reliability. Even so, certain users
may selectively exploit known technological limitations and
artifacts of the auction system, including non-real time updating
of bidding information, especially in the final stages of an
auction.
[0030] Because of existing bandwidth and technological hurdles,
Internet auctions are quite different from live auctions with
respect to psychological factors. Live auctions are often monitored
closely by bidders, who strategically make bids, based not only on
the "value" of the goods, but also on an assessment of the
competition, timing, psychology, and progress of the auction. It is
for this reason that so-called proxy bidding, wherein the bidder
creates a preprogrammed "strategy", usually limited to a maximum
price, are disfavored. A maximum price proxy bidding system is
somewhat inefficient, in that other bidders may test the proxy,
seeking to increase the bid price, without actually intending to
purchase, or contrarily, after testing the proxy, a bidder might
give up, even below a price he might have been willing to pay.
Thus, the proxy imposes inefficiency in the system that effectively
increases the transaction cost.
[0031] In order to address a flurry of activity that often occurs
at the end of an auction, an auction may be held open until no
further bids are cleared for a period of time, even if advertised
to end at a certain time. This is common to both live and automated
auctions. However, this lack of determinism may upset coordinated
schedules, thus impairing efficient business use of the auction
system.
[0032] In order to facilitate management of bids and bidding, some
of the Internet auction sites have provided non-Hypertext Markup
Language (HTML) browser based software "applet" to track auctions.
For example, ONSALE.COM has made available a Marimba Castanet.RTM.
applet called Bidwatch to track auction progress for particular
items or classes of items, and to facilitate bidding thereon. This
system, however, lacks real-time performance under many
circumstances, having a stated refresh period of 10 seconds, with a
long latency for confirmation of a bid, due to constraints on
software execution, quality of service in communications streams,
and bid confirmation dialogue. Thus, it is possible to lose a bid
even if an attempt was made prior to another bidder. The need to
quickly enter the bid, at risk of being too late, makes the process
potentially error prone.
[0033] Proxy bidding, as discussed above, is a known technique for
overcoming the constraints of Internet communications and client
processing limitations, since it bypasses the client and
telecommunications links and may execute solely on the host system
or local thereto. However, proxy bidding undermines some of the
efficiencies gained by a live market.
[0034] U.S. Pat. No. 5,890,138 to Godin, et al. (Mar. 30, 1999),
expressly incorporated herein by reference in its entirety, relates
to an Internet auction system. The system implements a declining
price auction process, removing a user from the auction process
once an indication to purchase has been received. See, Rockoff, T.
E., Groves, M.; "Design of an Internet-based System for Remote
Dutch Auctions", Internet Research, v 5, n 4, pp. 10-16, MCB
University Press, Jan. 1, 1995.
[0035] A known computer site for auctioning a product on-line
comprises at least one web server computer designed for serving a
host of computer browsers and providing the browsers with the
capability to participate in various auctions, where each auction
is of a single product, at a specified time, with a specified
number of the product available for sale. The web server cooperates
with a separate database computer, separated from the web server
computer by a firewall. The database computer is accessible to the
web computer server computer to allow selective retrieval of
product information, which includes a product description, the
quantity of the product to be auctioned, a start price of the
product, and an image of the product. The web server computer
displays, updated during an auction, the current price of the
product, the quantity of the product remaining available for
purchase and the measure of the time remaining in the auction. The
current price is decreased in a predetermined manner during the
auction. Each user is provided with an input instructing the system
to purchase the product at a displayed current price, transmitting
an identification and required financial authorization for the
purchase of the product, which must be confirmed within a
predetermined time. In the known system, a certain fall-out rate in
the actual purchase confirmation may be assumed, and therefore some
overselling allowed. Further, after a purchase is indicate, the
user's screen is not updated, obscuring the ultimate lowest selling
price from the user. However, if the user maintains a second
browser, he can continue to monitor the auction to determine
whether the product could have been purchased at a lower price, and
if so, fail to confirm the committed purchase and purchase the same
goods at a lower price while reserving the goods to avoid risk of
loss. Thus, the system is flawed, and may fail to produce an
efficient transaction or optimal price.
[0036] An Internet declining price auction system may provide the
ability to track the price demand curve, providing valuable
marketing information. For example, in trying to determine the
response at different prices, companies normally have to conduct
market surveys. In contrast, with a declining price auction,
substantial information regarding price and demand is immediately
known. The relationship between participating bidders and average
purchasers can then be applied to provide a conventional price
demand curve for the particular product.
[0037] U.S. Pat. No. 5,835,896, Fisher, et al., issued Nov. 10,
1998, expressly incorporated herein by reference in its entirety,
provides method and system for processing and transmitting
electronic auction information over the Internet, between a central
transaction server system and remote bidder terminals. Those bids
are recorded by the system and the bidders are updated with the
current auction status information. When appropriate, the system
closes the auction from further bidding and notifies the winning
bidders and losers as to the auction outcome. The transaction
server posts information from a database describing a lot available
for purchase, receives a plurality of bids, stored in a bid
database, in response to the information, and automatically
categorizes the bids as successful or unsuccessful. Each bid is
validated, and an electronic mail message is sent informing the
bidder of the bid status. This system employs HTTP, and thus does
not automatically update remote terminal screens, requiring the
e-mail notification feature.
[0038] The auction rules may be flexible, for example including
Dutch-type auctions, for example by implementing a price markdown
feature with scheduled price adjustments, and English-type
(progressive) auctions, with price increases corresponding to
successively higher bids. In the Dutch type auction, the price
markdown feature may be responsive to bidding activity over time,
amount of bids received, and number of items bid for. Likewise, in
the progressive auction, the award price may be dependent on the
quantity desired, and typically implements a lowest successful bid
price rule. Bids that are below a preset maximum posted selling
price are maintained in reserve by the system. If a certain sales
volume is not achieved in a specified period of time, the price is
reduced to liquidate demand above the price point, with the new
price becoming the posted price. On the other hand, if a certain
sales volume is exceeded in a specified period of time, the system
may automatically increase the price. These automatic price changes
allow the seller to respond quickly to market conditions while
keeping the price of the merchandise as high as possible, to the
seller's benefit. A "Proxy Bidding" feature allows a bidder to
place a bid for the maximum amount they are willing to pay, keeping
this value a secret, displaying only the amount necessary to win
the item up to the amount of the currently high bids or proxy bids
of other bidders. This feature allows bidders to participate in the
electronic auction without revealing to the other bidders the
extent to which they are willing to increase their bids, while
maintaining control of their maximum bid without closely monitoring
the bidding. The feature assures proxy bidders the lowest possible
price up to a specified maximum without requiring frequent
inquiries as to the state of the bidding.
[0039] A "Floating Closing Time" feature may also be implemented
whereby the auction for a particular item is automatically closed
if no new bids are received within a predetermined time interval,
assuming an increasing price auction. Bidders thus have an
incentive to place bids expeditiously, rather than waiting until
near the anticipated close of the auction.
[0040] U.S. Pat. No. 5,905,975, Ausubel, issued May 18, 1999,
expressly incorporated herein by reference in its entirety, relates
to computer implemented methods and apparatus for auctions. The
proposed system provides intelligent systems for the auctioneer and
for the user. The auctioneer's system contains information from a
user system based on bid information entered by the user. With this
information, the auctioneer's system determines whether the auction
can be concluded or not and appropriate messages are transmitted.
At any point in the auction, bidders are provided the opportunity
to submit not only their current bids, but also to enter future
bids, or bidding rules which may have the opportunity to become
relevant at future times or prices, into the auction system's
database. Participants may revise their executory bids, by entering
updated bids. Thus, at one extreme, a bidder who wishes to
economize on his time may choose to enter his entire set of bidding
rules into the computerized system at the start of the auction,
effectively treating this as a sealed-bid auction. At the opposite
extreme, a bidder who wishes to closely participate in the auction
may choose to constantly monitor the auction's progress and to
submit all of his bids in real time. See also, U.S. patent
application Ser. No. 08/582,901 filed Jan. 4, 1996, which provides
a method for auctioning multiple, identical objects and close
substitutes.
[0041] Secure Networks
[0042] A number of references relate to secure networks, which are
an aspect of various embodiments of the present invention. These
references are incorporated herein by reference in their entirety,
including U.S. Pat. Nos. 5,933,498 (Schneck, et al., Aug. 3, 1999);
5,978,918 (Scholnick, et al., Nov. 2, 1999); 6,005,943 (Cohen, et
al., Dec. 21, 1999); 6,009,526 (Choi, Dec. 28, 1999); 6,021,202
(Anderson, et al., Feb. 1, 2000); 6,021,491 (Renaud, Feb. 1, 2000);
6,021,497 (Bouthillier, et al., Feb. 1, 2000); 6,023,762 (Dean, et
al., Feb. 8, 2000); 6,029,245 (Scanlan, Feb. 22, 2000); 6,049,875
(Suzuki, et al., Apr. 11, 2000); 6,055,508 (Naor, et al., Apr. 25,
2000); 6,065,119 (Sandford, II, et al., May 16, 2000); 6,073,240
(Kurtzberg, et al., Jun. 6, 2000); 6,075,860 (Ketcham, Jun. 13,
2000); and 6,075,861 (Miller, II, Jun. 13, 2000).
[0043] Cryptographic Technology
[0044] U.S. Pat. No. 5,956,408 (Arnold, Sep. 21, 1999), expressly
incorporated herein by reference, relates to an apparatus and
method for secure distribution of data. Data, including program and
software updates, is encrypted by a public key encryption system
using the private key of the data sender. The sender also digitally
signs the data. The receiver decrypts the encrypted data, using the
public key of the sender, and verifies the digital signature on the
transmitted data. The program interacts with basic information
stored within the confines of the receiver. As result of the
interaction, the software updates are installed within the confines
of the user, and the basic information stored within the confines
of the user is changed.
[0045] U.S. Pat. Nos. 5,982,891 (Ginter, et al., Nov. 9, 1999);
5,949,876 (Ginter, et al., Sep. 7, 1999); and 5,892,900 (Ginter, et
al., Apr. 6, 1999), expressly incorporated herein by reference,
relate to systems and methods for secure transaction management and
electronic rights protection. Electronic appliances, such as
computers, help to ensure that information is accessed and used
only in authorized ways, and maintain the integrity, availability,
and/or confidentiality of the information. Such electronic
appliances provide a distributed virtual distribution environment
(VDE) that may enforce a secure chain of handling and control, for
example, to control and/or meter or otherwise monitor use of
electronically stored or disseminated information. Such a virtual
distribution environment may be used to protect rights of various
participants in electronic commerce and other electronic or
electronic-facilitated transactions. Distributed and other
operating systems, environments and architectures, such as, for
example, those using tamper-resistant hardware-based processors,
may establish security at each node. These techniques may be used
to support an all-electronic information distribution, for example,
utilizing the "electronic highway."
[0046] U.S. Pat. No. 6,009,177 (Sudia, Dec. 28, 1999), expressly
incorporated herein by reference, relates to a cryptographic system
and method with a key escrow feature that uses a method for
verifiably splitting users' private encryption keys into components
and for sending those components to trusted agents chosen by the
particular users, and provides a system that uses modern public key
certificate management, enforced by a chip device that also
self-certifies. The methods for key escrow and receiving an escrow
certificate are also applied herein to a more generalized case of
registering a trusted device with a trusted third party and
receiving authorization from that party enabling the device to
communicate with other trusted devices. Further preferred
embodiments provide for rekeying and upgrading of device firmware
using a certificate system, and encryption of stream-oriented
data.
[0047] U.S. Pat. No. 6,052,467 (Brands, Apr. 18, 2000), expressly
incorporated herein by reference, relates to a system for ensuring
that the blinding of secret-key certificates is restricted, even if
the issuing protocol is performed in parallel mode. A cryptographic
method is disclosed that enables the issuer in a secret-key
certificate issuing protocol to issue triples consisting of a
secret key, a corresponding public key, and a secret-key
certificate of the issuer on the public key, in such a way that
receiving parties can blind the public key and the certificate, but
cannot blind a predetermined non-trivial predicate of the secret
key even when executions of the issuing protocol are performed in
parallel.
[0048] U.S. Pat. No. 6,052,780 (Glover, Apr. 18, 2000), expressly
incorporated herein by reference, relates to a computer system and
process for accessing an encrypted and self-decrypting digital
information product while restricting access to decrypted digital
information. Some of these problems with digital information
protection systems may be overcome by providing a mechanism that
allows a content provider to encrypt digital information without
requiring either a hardware or platform manufacturer or a content
consumer to provide support for the specific form of corresponding
decryption. This mechanism can be provided in a manner that allows
the digital information to be copied easily for back-up purposes
and to be transferred easily for distribution, but which should not
permit copying of the digital information in decrypted form. In
particular, the encrypted digital information is stored as an
executable computer program that includes a decryption program that
decrypts the encrypted information to provide the desired digital
information, upon successful completion of an authorization
procedure by the user. In combination with other mechanisms that
track distribution, enforce royalty payments and control access to
decryption keys, an improved method is provided for identifying and
detecting sources of unauthorized copies. Suitable authorization
procedures also enable the digital information to be distributed
for a limited number of uses and/or users, thus enabling per-use
fees to be charged for the digital information.
[0049] See also, U.S. Pat. Nos. 4,200,770 (Cryptographic apparatus
and method); 4,218,582 (Public key cryptographic apparatus and
method); 4,264,782 (Method and apparatus for transaction and
identity verification); 4,306,111 (Simple and effective public-key
cryptosystem); 4,309,569 (Method of providing digital signatures);
4,326,098 (High security system for electronic signature
verification); 4,351,982 (RSA Public-key data encryption system
having large random prime number generating microprocessor or the
like); 4,365,110 (Multiple-destinational cryptosystem for broadcast
networks); 4,386,233 (Crytographic key notarization methods and
apparatus); 4,393,269 (Method and apparatus incorporating a one-way
sequence for transaction and identity verification); 4,399,323
(Fast real-time public key cryptography); 4,405,829 (Cryptographic
communications system and method); 4,438,824 (Apparatus and method
for cryptographic identity verification); 4,453,074 (Protection
system for intelligent cards); 4,458,109 (Method and apparatus
providing registered mail features in an electronic communication
system); 4,471,164 (Stream cipher operation using public key
cryptosystem); 4,514,592 (Cryptosystem); 4,528,588 (Method and
apparatus for marking the information content of an information
carrying signal); 4,529,870 (Cryptographic identification,
financial transaction, and credential device); 4,558,176 (Computer
systems to inhibit unauthorized copying, unauthorized usage, and
automated cracking of protected software); 4,567,600 (Method and
apparatus for maintaining the privacy of digital messages conveyed
by public transmission); 4,575,621 (Portable electronic transaction
device and system therefor); 4,578,531 (Encryption system key
distribution method and apparatus); 4,590,470 (User authentication
system employing encryption functions); 4,595,950 (Method and
apparatus for marking the information content of an information
carrying signal); 4,625,076 (Signed document transmission system);
4,633,036 (Method and apparatus for use in public-key data
encryption system); 5,991,406 (System and method for data
recovery); 6,026,379 (System, method and article of manufacture for
managing transactions in a high availability system); 6,026,490
(Configurable cryptographic processing engine and method);
6,028,932 (Copy prevention method and apparatus for digital video
system); 6,028,933 (Encrypting method and apparatus enabling
multiple access for multiple services and multiple transmission
modes over a broadband communication network); 6,028,936 (Method
and apparatus for authenticating recorded media); 6,028,937
(Communication device which performs two-way encryption
authentication in challenge response format); 6,028,939 (Data
security system and method); 6,029,150 (Payment and transactions in
electronic commerce system); 6,029,195 (System for customized
electronic identification of desirable objects); 6,029,247 (Method
and apparatus for transmitting secured data); 6,031,913 (Apparatus
and method for secure communication based on channel
characteristics); 6,031,914 (Method and apparatus for embedding
data, including watermarks, in human perceptible images); 6,034,618
(Device authentication system which allows the authentication
function to be changed); 6,035,041 (Optimal-resilience, proactive,
public-key cryptographic system and method); 6,035,398
(Cryptographic key generation using biometric data); 6,035,402
(Virtual certificate authority); 6,038,315 (Method and system for
normalizing biometric variations to authenticate users from a
public database and that ensures individual biometric data
privacy); 6,038,316 (Method and system for protection of digital
information); 6,038,322 (Group key distribution); 6,038,581 (Scheme
for arithmetic operations in finite field and group operations over
elliptic curves realizing improved computational speed); 6,038,665
(System and method for backing up computer files over a wide area
computer network); 6,038,666 (Remote identity verification
technique using a personal identification device); 6,041,122
(Method and apparatus for hiding cryptographic keys utilizing
autocorrelation timing encoding and computation); 6,041,123
(Centralized secure communications system); 6,041,357 (Common
session token system and protocol); 6,041,408 (Key distribution
method and system in secure broadcast communication); 6,041,410
(Personal identification fob); 6,044,131 (Secure digital x-ray
image authentication method); 6,044,155 (Method and system for
securely archiving core data secrets); 6,044,157 (Microprocessor
suitable for reproducing AV data while protecting the AV data from
illegal copy and image information processing system using the
microprocessor); 6,044,205 (Communications system for transferring
information between memories according to processes transferred
with the information); 6,044,349 (Secure and convenient information
storage and retrieval method and apparatus); 6,044,350 (Certificate
meter with selectable indemnification provisions); 6,044,388
(Pseudorandom number generator); 6,044,462 (Method and apparatus
for managing key revocation); 6,044,463 (Method and system for
message delivery utilizing zero knowledge interactive proof
protocol); 6,044,464 (Method of protecting broadcast data by
fingerprinting a common decryption function); 6,044,466 (Flexible
and dynamic derivation of permissions); 6,044,468 (Secure
transmission using an ordinarily insecure network communication
protocol such as SNMP); 6,047,051 (Implementation of charging in a
telecommunications system); 6,047,066 (Communication method and
device); 6,047,067 (Electronic-monetary system); 6,047,072 (Method
for secure key distribution over a nonsecure communications
network); 6,047,242 (Computer system for protecting software and a
method for protecting software); 6,047,268 (Method and apparatus
for billing for transactions conducted over the internet);
6,047,269 (Self-contained payment system with circulating digital
vouchers); 6,047,374 (Method and apparatus for embedding
authentication information within digital data); 6,047,887 (System
and method for connecting money modules); 6,049,610 (Method and
apparatus for digital signature authentication); 6,049,612 (File
encryption method and system); 6,049,613 (Method and apparatus for
encrypting, decrypting, and providing privacy for data values);
6,049,671 (Method for identifying and obtaining computer software
from a network computer); 6,049,785 (Open network payment system
for providing for authentication of payment orders based on a
confirmation electronic mail message); 6,049,786 (Electronic bill
presentment and payment system which deters cheating by employing
hashes and digital signatures); 6,049,787 (Electronic business
transaction system with notarization database and means for
conducting a notarization procedure); 6,049,838 (Persistent
distributed capabilities); 6,049,872 (Method for authenticating a
channel in large-scale distributed systems); 6,049,874 (System and
method for backing up computer files over a wide area computer
network); 6,052,466 (Encryption of data packets using a sequence of
private keys generated from a public key exchange); 6,052,467
(System for ensuring that the blinding of secret-key certificates
is restricted, even if the issuing protocol is performed in
parallel mode); 6,052,469 (Interoperable cryptographic key recovery
system with verification by comparison); 6,055,314 (System and
method for secure purchase and delivery of video content programs);
6,055,321 (System and method for hiding and extracting message data
in multimedia data); 6,055,508 (Method for secure accounting and
auditing on a communications network); 6,055,512 (Networked
personal customized information and facility services); 6,055,636
(Method and apparatus for centralizing processing of key and
certificate life cycle management); 6,055,639 (Synchronous message
control system in a Kerberos domain); 6,056,199 (Method and
apparatus for storing and reading data); 6,057,872 (Digital coupons
for pay televisions); 6,058,187 (Secure telecommunications data
transmission); 6,058,188 (Method and apparatus for interoperable
validation of key recovery information in a cryptographic system);
6,058,189 (Method and system for performing secure electronic
monetary transactions); 6,058,193 (System and method of verifying
cryptographic postage evidencing using a fixed key set); 6,058,381
(Many-to-many payments system for network content materials);
6,058,383 (Computationally efficient method for trusted and dynamic
digital objects dissemination); 6,061,448 (Method and system for
dynamic server document encryption); 6,061,454 (System, method, and
computer program for communicating a key recovery block to enable
third party monitoring without modification to the intended
receiver); 6,061,692 (System and method for administering a meta
database as an integral component of an information server);
6,061,789 (Secure anonymous information exchange in a network);
6,061,790 (Network computer system with remote user data encipher
methodology); 6,061,791 (Initial secret key establishment including
facilities for verification of identity); 6,061,792 (System and
method for fair exchange of time-independent information goods over
a network); 6,061,794 (System and method for performing secure
device communications in a peer-to-peer bus architecture);
6,061,796 (Multi-access virtual private network); 6,061,799
(Removable media for password based authentication in a distributed
system); 6,064,723 (Network-based multimedia communications and
directory system and method of operation); 6,064,738 (Method for
encrypting and decrypting data using chaotic maps); 6,064,740
(Method and apparatus for masking modulo exponentiation
calculations in an integrated circuit); 6,064,741 (Method for the
computer-aided exchange of cryptographic keys between a user
computer unit U and a network computer unit N); 6,064,764 (Fragile
watermarks for detecting tampering in images); 6,064,878 (Method
for separately permissioned communication); 6,065,008 (System and
method for secure font subset distribution); 6,067,620 (Stand alone
security device for computer networks); 6,069,647 (Conditional
access and content security method); 6,069,952 (Data copyright
management system); 6,069,954 (Cryptographic data integrity with
serial bit processing and pseudo-random generators); 6,069,955
(System for protection of goods against counterfeiting); 6,069,969
(Apparatus and method for electronically acquiring fingerprint
images); 6,069,970 (Fingerprint sensor and token reader and
associated methods); 6,070,239 (System and method for executing
verifiable programs with facility for using non-verifiable programs
from trusted sources); 6,072,870 (System, method and article of
manufacture for a gateway payment architecture utilizing a
multichannel, extensible, flexible architecture); 6,072,874
(Signing method and apparatus using the same); 6,072,876 (Method
and system for depositing private key used in RSA cryptosystem);
6,073,125 (Token key distribution system controlled acceptance mail
payment and evidencing system); 6,073,160 (Document communications
controller); 6,073,172 (Initializing and reconfiguring a secure
network interface); 6,073,234 (Device for authenticating user's
access rights to resources and method); 6,073,236 (Authentication
method, communication method, and information processing
apparatus); 6,073,237 (Tamper resistant method and apparatus);
6,073,238 (Method of securely loading commands in a smart card);
6,073,242 (Electronic authority server); 6,075,864 (Method of
establishing secure, digitally signed communications using an
encryption key based on a blocking set cryptosystem); 6,075,865
(Cryptographic communication process and apparatus); 6,076,078
(Anonymous certified delivery); 6,076,162 (Certification of
cryptographic keys for chipcards); 6,076,163 (Secure user
identification based on constrained polynomials); 6,076,164
(Authentication method and system using IC card); 6,076,167 (Method
and system for improving security in network applications);
6,078,663 (Communication apparatus and a communication system);
6,078,665 (Electronic encryption device and method); 6,078,667
(Generating unique and unpredictable values); 6,078,909 (Method and
apparatus for licensing computer programs using a DSA signature);
6,079,018 (System and method for generating unique secure values
for digitally signing documents); 6,079,047 (Unwrapping system and
method for multiple files of a container); 6,081,597 (Public key
cryptosystem method and apparatus); 6,081,598 (Cryptographic system
and method with fast decryption); 6,081,610 (System and method for
verifying signatures on documents); 6,081,790 (System and method
for secure presentment and payment over open networks); 6,081,893
(System for supporting secured log-in of multiple users into a
plurality of computers using combined presentation of memorized
password and transportable passport record), 6,192,473 (System and
method for mutual authentication and secure communications between
a postage security device and a meter server), each of which is
expressly incorporated herein by reference.
[0050] See, also, U.S. Pat. Nos. 6,028,937 (Tatebayashi et al.),
6,026,167 (Aziz), 6,009,171 (Ciacelli et al.) (Content Scrambling
System, or "CSS"), 5,991,399 (Graunke et al.), 5,948,136 (Smyers)
(IEEE 1394-1995), and 5,915,018 (Aucsmith), expressly incorporated
herein by reference, and Jim Wright and Jeff Robillard (Philsar
Semiconductor), "Adding Security to Portable Designs", Portable
Design, March 2000, pp. 16-20.
[0051] See also, Stefik, U.S. Pat. Nos. 5,715,403 (System for
controlling the distribution and use of digital works having
attached usage rights where the usage rights are defined by a usage
rights grammar); 5,638,443 (System for controlling the distribution
and use of composite digital works); 5,634,012 (System for
controlling the distribution and use of digital works having a fee
reporting mechanism); and 5,629,980 (System for controlling the
distribution and use of digital works), expressly incorporated
herein by reference.
[0052] Watermarking
[0053] U.S. Pat. No. 5,699,427 (Chow, et al., Dec. 16, 1997),
expressly incorporated herein by reference, relates to a method to
deter document and intellectual property piracy through
individualization, and a system for identifying the authorized
receiver of any particular copy of a document. More specifically,
each particular copy of a document is fingerprinted by applying a
set of variations to a document, where each variation is a change
in data contents, but does not change the meaning or perusal
experience of the document. A database associating a set of
variants to a receiver is maintained. Thus any variant or copy of
that variant can be traced to an authorized receiver.
[0054] See also, U.S. Pat. Nos. 4,734,564 (Transaction system with
off-line risk assessment); 4,812,628 (Transaction system with
off-line risk assessment); 4,926,325 (Apparatus for carrying out
financial transactions via a facsimile machine); 5,235,166 (Data
verification method and magnetic media therefor); 5,254,843
(Securing magnetically encoded data using timing variations in
encoded data); 5,341,429 (Transformation of ephemeral material);
5,428,683 (Method and apparatus for fingerprinting and
authenticating magnetic media); 5,430,279 (Data verification method
and magnetic media therefor); 5,521,722 (Image handling
facilitating computer aided design and manufacture of documents);
5,546,462 (Method and apparatus for fingerprinting and
authenticating various magnetic media); 5,606,609 (Electronic
document verification system and method); 5,613,004 (Steganographic
method and device); 5,616,904 (Data verification method and
magnetic media therefor); 5,636,292 (Steganography methods
employing embedded calibration data); 5,646,997 (Method and
apparatus for embedding authentication information within digital
data); 5,659,726 (Data embedding); 5,664,018 (Watermarking process
resilient to collusion attacks); 5,687,236 (Steganographic method
and device); 5,710,834 (Method and apparatus responsive to a code
signal conveyed through a graphic image); 5,727,092 (Compression
embedding); 5,734,752 (Digital watermarking using stochastic screen
patterns); 5,740,244 (Method and apparatus for improved
fingerprinting and authenticating various magnetic media);
5,745,569 (Method for stega-cipher protection of computer code);
5,745,604 (Identification/authentication system using robust,
distributed coding); 5,748,763 (Image steganography system
featuring perceptually adaptive and globally scalable signal
embedding); 5,748,783 (Method and apparatus for robust information
coding); 5,761,686 (Embedding encoded information in an iconic
version of a text image); 5,765,152 (System and method for managing
copyrighted electronic media); 5,768,426 (Graphics processing
system employing embedded code signals); 5,778,102 (Compression
embedding); 5,790,703 (Digital watermarking using conjugate
halftone screens); 5,819,289 (Data embedding employing degenerate
clusters of data having differences less than noise value);
5,822,432 (Method for human-assisted random key generation and
application for digital watermark system); 5,822,436 (Photographic
products and methods employing embedded information); 5,832,119
(Methods for controlling systems using control signals embedded in
empirical data); 5,841,886 (Security system for photographic
identification); 5,841,978 (Network linking method using
steganographically embedded data objects); 5,848,155 (Spread
spectrum watermark for embedded signalling); 5,850,481
(Steganographic system); 5,862,260 (Methods for surveying
dissemination of proprietary empirical data); 5,878,137 (Method for
obtaining authenticity identification devices for using services in
general, and device obtained thereby); 5,889,868 (Optimization
methods for the insertion, protection, and detection of digital
watermarks in digitized data); 5,892,900 (Systems and methods for
secure transaction management and electronic rights protection);
5,905,505 (Method and system for copy protection of on-screen
display of text); 5,905,800 (Method and system for digital
watermarking); 5,915,027 (Digital watermarking); 5,920,628 (Method
and apparatus for fingerprinting and authenticating various
magnetic media); 5,930,369 (Secure spread spectrum watermarking for
multimedia data); 5,933,498 (System for controlling access and
distribution of digital property); 5,943,422 (Steganographic
techniques for securely delivering electronic digital rights
management control information over insecure communication
channels); 5,946,414 (Encoding data in color images using patterned
color modulated image regions); 5,949,885 (Method for protecting
content using watermarking); 5,974,548 (Media-independent document
security method and apparatus); 5,995,625 (Electronic cryptographic
packing); 6,002,772 (Data management system); 6,004,276 (Open
architecture cardiology information system); 6,006,328 (Computer
software authentication, protection, and security system);
6,006,332 (Rights management system for digital media); 6,018,801
(Method for authenticating electronic documents on a computer
network); 6,026,193 (Video steganography); 6,044,464 (Method of
protecting broadcast data by fingerprinting a common decryption
function); 6,047,374 (Method and apparatus for embedding
authentication information within digital data); 6,049,627 (Covert
digital identifying indicia for digital image); 6,061,451
(Apparatus and method for receiving and decrypting encrypted data
and protecting decrypted data from illegal use); 6,064,737
(Anti-piracy system for wireless telephony); 6,064,764 (Fragile
watermarks for detecting tampering in images); 6,069,914
(Watermarking of image data using MPEG/JPEG coefficients);
6,076,077 (Data management system); 6,081,793 (Method and system
for secure computer moderated voting), each of which is expressly
incorporated herein by reference.
[0055] Role-Based Access
[0056] U.S. Pat. No. 6,023,765 (Kuhn, Feb. 8, 2000; Implementation
of role-based access control in multi-level secure systems),
expressly incorporated herein by reference, relates to a system and
method for implementation of role-based access control in
multi-level secure systems. Role-based access control (RBAC) is
implemented on a multi-level secure (MLS) system by establishing a
relationship between privileges within the RBAC system and pairs of
levels and compartments within the MLS system. The advantages
provided by RBAC, that is, reducing the overall number of
connections that must be maintained, and, for example, greatly
simplifying the process required in response to a change of job
status of individuals within an organization, are then realized
without loss of the security provided by MLS. A trusted interface
function is developed to ensure that the RBAC rules permitting
individual's access to objects are followed rigorously, and
provides a proper mapping of the roles to corresponding pairs of
levels and compartments. No other modifications are necessary.
Access requests from subjects are mapped by the interface function
to pairs of levels and compartments, after which access is
controlled entirely by the rules of the MLS system.
[0057] See also, U.S. Pat. Nos. 6,073,242 (Electronic authority
server); 6,073,240 (Method and apparatus for realizing computer
security); 6,064,977 (Web server with integrated scheduling and
calendaring); 6,055,637 (System and method for accessing
enterprise-wide resources by presenting to the resource a temporary
credential); 6,044,466 (Flexible and dynamic derivation of
permissions); 6,041,349 (System management/network correspondence
display method and system therefore); 6,014,666 (Declarative and
programmatic access control of component-based server applications
using roles); 5,991,877 (Object-oriented trusted application
framework); 5,978,475 (Event auditing system); 5,949,866
(Communications system for establishing a communication channel on
the basis of a functional role or task); 5,925,126 (Method for
security shield implementation in computer system's software);
5,911,143 (Method and system for advanced role-based access control
in distributed and centralized computer systems); 5,797,128 (System
and method for implementing a hierarchical policy for computer
system administration); 5,761,288 (Service context sensitive
features and applications); 5,751,909 (Database system with methods
for controlling object interaction by establishing database
contracts between objects); 5,748,890 (Method and system for
authenticating and auditing access by a user to non-natively
secured applications); 5,621,889 (Facility for detecting intruders
and suspect callers in a computer installation and a security
system including such a facility); 5,535,383 (Database system with
methods for controlling object interaction by establishing database
contracts between objects); 5,528,516 (Apparatus and method for
event correlation and problem reporting); 5,481,613 (Computer
network cryptographic key distribution system); 5,347,578 (Computer
system security); 5,265,221 (Access restriction facility method and
apparatus), each of which is expressly incorporated herein by
reference.
[0058] Computer System Security
[0059] A number of references relate to computer system security,
which is a part of various embodiment of the invention. The
following references relevant to this issue are incorporated herein
by reference: U.S. Pat. Nos. 5,881,225 (Worth, Mar. 9, 1999);
5,937,068 (Audebert, Aug. 10, 1999); 5,949,882 (Angelo, Sep. 7,
1999); 5,953,419 (Lohstroh, et al., Sep. 14, 1999); 5,956,400
(Chaum, et al., Sep. 21, 1999); 5,958,050 (Griffin, et al., Sep.
28, 1999); 5,978,475 (Schneier, et al., Nov. 2, 1999); 5,991,878
(McDonough, et al., Nov. 23, 1999); 6,070,239 (McManis, May 30,
2000); and 6,079,021 (Abadi, et al., Jun. 20, 2000).
[0060] Computer Security Devices
[0061] A number of references relate to computer security devices,
which is a part of various embodiment of the invention. The
following references relevant to this issue are incorporated herein
by reference: U.S. Pat. Nos. 5,982,520 (Weiser, et al., Nov. 9,
1999); 5,991,519 (Benhammou, et al., Nov. 23, 1999); 5,999,629
(Heer, et al., Dec. 7, 1999); 6,034,618 (Tatebayashi, et al., Mar.
7, 2000); 6,041,412 (Timson, et al., Mar. 21, 2000); 6,061,451
(Muratani, et al., May 9, 2000); and 6,069,647 (Sullivan, et al.,
May 30, 2000).
[0062] Virtual Private Network
[0063] A number of references relate to virtual private networks,
which is a part of various embodiment of the invention. The
following references relevant to this issue are incorporated herein
by reference: U.S. Pat. Nos. 6,079,020 (Liu, Jun. 20, 2000);
6,081,900 (Secure intranet access); 6,081,533 (Method and apparatus
for an application interface module in a subscriber terminal unit);
6,079,020 (Method and apparatus for managing a virtual private
network); 6,078,946 (System and method for management of connection
oriented networks); 6,078,586 (ATM virtual private networks);
6,075,854 (Fully flexible routing service for an advanced
intelligent network); 6,075,852 (Telecommunications system and
method for processing call-independent signalling transactions);
6,073,172 (Initializing and reconfiguring a secure network
interface); 6,061,796 (Multi-access virtual private network);
6,061,729 (Method and system for communicating service information
in an advanced intelligent network); 6,058,303 (System and method
for subscriber activity supervision); 6,055,575 (Virtual private
network system and method); 6,052,788 (Firewall providing enhanced
network security and user transparency); 6,047,325 (Network device
for supporting construction of virtual local area networks on
arbitrary local and wide area computer networks); 6,032,118
(Virtual private network service provider for asynchronous transfer
mode network); 6,029,067 (Virtual private network for mobile
subscribers); 6,016,318 (Virtual private network system over public
mobile data network and virtual LAN); 6,009,430 (Method and system
for provisioning databases in an advanced intelligent network);
6,005,859 (Proxy VAT-PSTN origination); 6,002,767 (System, method
and article of manufacture for a modular gateway server
architecture); 6,002,756 (Method and system for implementing
intelligent telecommunication services utilizing self-sustaining,
fault-tolerant object oriented architecture), each of which is
expressly incorporated herein by reference.
See also, U.S. Pat. Nos. 6,081,900 (Secure intranet access);
6,081,750 (Ergonomic man-machine interface incorporating adaptive
pattern recognition based control system); 6,081,199 (Locking
device for systems access to which is time-restricted); 6,079,621
(Secure card for E-commerce and identification); 6,078,265
(Fingerprint identification security system); 6,076,167 (Method and
system for improving security in network applications); 6,075,455
(Biometric time and attendance system with epidermal topographical
updating capability); 6,072,894 (Biometric face recognition for
applicant screening); 6,070,141 (System and method of assessing the
quality of an identification transaction using an identification
quality score); 6,068,184 (Security card and system for use
thereof); 6,064,751 (Document and signature data capture system and
method); 6,056,197 (Information recording method for preventing
alteration, information recording apparatus, and information
recording medium); 6,052,468 (Method of securing a cryptographic
key); 6,045,039 (Cardless automated teller transactions); 6,044,349
(Secure and convenient information storage and retrieval method and
apparatus); 6,044,155 (Method and system for securely archiving
core data secrets); 6,041,410 (Personal identification fob);
6,040,783 (System and method for remote, wireless positive identity
verification); 6,038,666 (Remote identity verification technique
using a personal identification device); 6,038,337 (Method and
apparatus for object recognition); 6,038,315 (Method and system for
normalizing biometric variations to authenticate users from a
public database and that ensures individual biometric data
privacy); 6,037,870 (Detector system for access control, and a
detector assembly for implementing such a system); 6,035,406
(Plurality-factor security system); 6,035,402 (Virtual certificate
authority); 6,035,398 (Cryptographic key generation using biometric
data); 6,031,910 (Method and system for the secure transmission and
storage of protectable information); 6,026,166 (Digitally
certifying a user identity and a computer system in combination);
6,018,739 (Biometric personnel identification system); 6,016,476
(Portable information and transaction processing system and method
utilizing biometric authorization and digital certificate
security); 6,012,049 (System for performing financial transactions
using a smartcard); 6,012,039 (Tokenless biometric electronic
rewards system); 6,011,858 (Memory card having a biometric template
stored thereon and system for using same); 6,009,177 (Enhanced
cryptographic system and method with key escrow feature); 6,006,328
(Computer software authentication, protection, and security
system); 6,003,135 (Modular security device); 6,002,770 (Method for
secure data transmission between remote stations); 5,999,637
(Individual identification apparatus for selectively recording a
reference pattern based on a correlation with comparative
patterns); 5,999,095 (Electronic security system); 5,995,630
(Biometric input with encryption); 5,991,431 (Mouse adapted to scan
biometric data); 5,991,429 (Facial recognition system for security
access and identification); 5,991,408 (Identification and security
using biometric measurements); 5,987,155 (Biometric input device
with peripheral port); 5,987,153 (Automated verification and
prevention of spoofing for biometric data); 5,986,746
(Topographical object detection system); 5,984,366 (Unalterable
self-verifying articles); 5,982,894 (System including separable
protected components and associated methods); 5,979,773 (Dual smart
card access control electronic data storage and retrieval system
and methods); 5,978,494 (Method of selecting the best enroll image
for personal identification); 5,974,146 (Real time bank-centric
universal payment system); 5,970,143 (Remote-auditing of computer
generated outcomes, authenticated billing and access control, and
software metering system using cryptographic and other protocols);
5,966,446 (Time-bracketing infrastructure implementation);
5,963,908 (Secure logon to notebook or desktop computers);
5,963,657 (Economical skin-pattern-acquisition and analysis
apparatus for access control; systems controlled thereby);
5,954,583 (Secure access control system); 5,952,641 (Security
device for controlling the access to a personal computer or to a
computer terminal); 5,951,055 (Security document containing encoded
data block); 5,949,881 (Apparatus and method for cryptographic
companion imprinting); 5,949,879 (Auditable security system for the
generation of cryptographically protected digital data); 5,949,046
(Apparatus for issuing integrated circuit cards); 5,943,423 (Smart
token system for secure electronic transactions and
identification); 5,935,071 (Ultrasonic biometric imaging and
identity verification system); 5,933,515 (User identification
through sequential input of fingerprints); 5,933,498 (System for
controlling access and distribution of digital property); 5,930,804
(Web-based biometric authentication system and method); 5,923,763
(Method and apparatus for secure document timestamping); 5,920,477
(Human factored interface incorporating adaptive pattern
recognition based controller apparatus); 5,920,384 (Optical imaging
device); 5,920,058 (Holographic labeling and reading machine for
authentication and security applications); 5,915,973 (System for
administration of remotely-proctored, secure examinations and
methods therefor); 5,913,196 (System and method for establishing
identity of a speaker); 5,913,025 (Method and apparatus for proxy
authentication); 5,912,974 (Apparatus and method for authentication
of printed documents); 5,912,818 (System for tracking and
dispensing medical items); 5,910,988 (Remote image capture with
centralized processing and storage); 5,907,149 (Identification card
with delimited usage); 5,901,246 (Ergonomic min-machine interface
incorporating adaptive pattern recognition based control system);
5,898,154 (System and method for updating security information in a
time-based electronic monetary system); 5,897,616 (Apparatus and
methods for speaker verification/identification/classification
employing non-acoustic and/or acoustic models and databases);
5,892,902 (Intelligent token protected system with network
authentication); 5,892,838 (Biometric recognition using a
classification neural network); 5,892,824 (Signature
capture/verification systems and methods); 5,890,152 (Personal
feedback browser for obtaining media files); 5,889,474 (Method and
apparatus for transmitting subject status information over a
wireless communications network); 5,881,226 (Computer security
system); 5,878,144 (Digital certificates containing multimedia data
extensions); 5,876,926 (Method, apparatus and system for
verification of human medical data); 5,875,108 (Ergonomic
man-machine interface incorporating adaptive pattern recognition
based control system); 5,872,849 (Enhanced cryptographic system and
method with key escrow feature); 5,872,848 (Method and apparatus
for witnessed authentication of electronic documents); 5,872,834
(Telephone with biometric sensing device); 5,870,723 (Tokenless
biometric transaction authorization method and system); 5,869,822
(Automated fingerprint identification system); 5,867,802
(Biometrically secured control system for preventing the
unauthorized use of a vehicle); 5,867,795 (Portable electronic
device with transceiver and visual image display); 5,867,578
(Adaptive multi-step digital signature system and method of
operation thereof); 5,862,260 (Methods for surveying dissemination
of proprietary empirical data); 5,862,246 (Knuckle profile identity
verification system); 5,862,223 (Method and apparatus for a
cryptographically-assisted commercial network system designed to
facilitate and support expert-based commerce); 5,857,022 (Enhanced
cryptographic system and method with key escrow feature); 5,850,451
(Enhanced cryptographic system and method with key escrow feature);
5,850,442 (Secure world wide electronic commerce over an open
network); 5,848,231 (System configuration contingent upon secure
input); 5,844,244 (Portable identification carrier); 5,841,907
(Spatial integrating optical correlator for verifying the
authenticity of a person, product or thing); 5,841,886 (Security
system for photographic identification); 5,841,865 (Enhanced
cryptographic system and method with key escrow feature); 5,841,122
(Security structure with electronic smart card access thereto with
transmission of power and data between the smart card and the smart
card reader performed capacitively or inductively); 5,838,812
(Tokenless biometric transaction authorization system); 5,832,464
(System and method for efficiently processing payments via check
and electronic funds transfer); 5,832,119 (Methods for controlling
systems using control signals embedded in empirical data);
5,828,751 (Method and apparatus for secure measurement
certification); 5,825,880 (Multi-step digital signature method and
system); 5,825,871 (Information storage device for storing personal
identification information); 5,815,577 (Methods and apparatus for
securely encrypting data in conjunction with a personal computer);
5,815,252 (Biometric identification process and system utilizing
multiple parameters scans for reduction of false negatives);
5,805,719 (Tokenless identification of individuals); 5,802,199 (Use
sensitive identification system); 5,799,088 (Non-deterministic
public key encryption system); 5,799,086 (Enhanced cryptographic
system and method with key escrow feature); 5,799,083 (Event
verification system); 5,790,674 (System and method of providing
system integrity and positive audit capabilities to a positive
identification system); 5,790,668 (Method and apparatus for
securely handling data in a database of biometrics and associated
data); 5,789,733 (Smart card with contactless optical interface);
5,787,187 (Systems and methods for biometric identification using
the acoustic properties of the ear canal); 5,784,566 (System and
method for negotiating security services and algorithms for
communication across a computer network); 5,784,461 (Security
system for controlling access to images and image related
services); 5,774,551 (Pluggable account management interface with
unified login and logout and multiple user authentication
services); 5,771,071 (Apparatus for coupling multiple data sources
onto a printed document); 5,770,849 (Smart card device with pager
and visual image display); 5,768,382 (Remote-auditing of computer
generated outcomes and authenticated billing and access control
system using cryptographic and other protocols); 5,767,496
(Apparatus for processing symbol-encoded credit card information);
5,764,789 (Tokenless biometric ATM access system); 5,763,862 (Dual
card smart card reader); 5,761,298 (Communications headset with
universally adaptable receiver and voice transmitter); 5,757,916
(Method and apparatus for authenticating the location of remote
users of networked computing systems); 5,757,431 (Apparatus for
coupling multiple data sources onto a printed document); 5,751,836
(Automated, non-invasive iris recognition system and method);
5,751,809 (Apparatus and method for securing captured data
transmitted between two sources); 5,748,738 (System and method for
electronic transmission, storage and retrieval of authenticated
documents); 5,745,573 (System and method for controlling access to
a user secret); 5,745,555 (System and method using personal
identification numbers and associated prompts for controlling
unauthorized use of a security device and unauthorized access to a
resource); 5,742,685 (Method for verifying an identification card
and recording verification of same); 5,742,683 (System and method
for managing multiple users with different privileges in an open
metering system); 5,737,420 (Method for secure data transmission
between remote stations); 5,734,154 (Smart card with integrated
reader and visual image display); 5,719,950 (Biometric, personal
authentication system); 5,712,914 (Digital certificates containing
multimedia data extensions); 5,712,912 (Method and apparatus for
securely handling a personal identification number or cryptographic
key using biometric techniques); 5,706,427 (Authentication method
for networks); 5,703,562 (Method for transferring data from an
unsecured computer to a secured computer); 5,696,827 (Secure
cryptographic methods for electronic transfer of information);
5,682,142 (Electronic control system/network); 5,682,032
(Capacitively coupled identity verification and escort memory
apparatus); 5,680,460 (Biometric controlled key generation);
5,668,878 (Secure cryptographic methods for electronic transfer of
information); 5,666,400 (Intelligent recognition); 5,659,616
(Method for securely using digital signatures in a commercial
cryptographic system); 5,647,364 (Ultrasonic biometric imaging and
identity verification system); 5,647,017 (Method and system for the
verification of handwritten signatures); 5,646,839 (Telephone-based
personnel tracking system); 5,636,282 (Method for dial-in access
security using a multimedia modem); 5,633,932 (Apparatus and method
for preventing disclosure through user-authentication at a printing
node); 5,615,277 (Tokenless security system for authorizing access
to a secured computer system); 5,613,012 (Tokenless identification
system for authorization of electronic transactions and electronic
transmissions); 5,608,387 (Personal identification devices and
access control systems); 5,594,806 (Knuckle profile identity
verification system); 5,592,408 (Identification card and access
control device); 5,588,059 (Computer system and method for secure
remote communication sessions); 5,586,171 (Selection of a voice
recognition data base responsive to video data); 5,583,950 (Method
and apparatus for flash correlation); 5,583,933 (Method and
apparatus for the secure communication of data); 5,578,808 (Data
card that can be used for transactions involving separate card
issuers); 5,572,596 (Automated, non-invasive iris recognition
system and method); 5,561,718 (Classifying faces); 5,559,885 (Two
stage read-write method for transaction cards); 5,557,765 (System
and method for data recovery); 5,553,155 (Low cost method employing
time slots for thwarting fraud in the periodic issuance of food
stamps, unemployment benefits or other governmental human
services); 5,544,255 (Method and system for the capture, storage,
transport and authentication of handwritten signatures); 5,534,855
(Method and system for certificate based alias detection);
5,533,123 (Programmable distributed personal security); 5,526,428
(Access control apparatus and method); 5,523,739 (Metal detector
for control of access combined in an integrated form with a
transponder detector); 5,497,430 (Method and apparatus for image
recognition using invariant feature signals); 5,485,519 (Enhanced
security for a secure token code); 5,485,312 (Optical pattern
recognition system and method for verifying the authenticity of a
person, product or thing); 5,483,601 (Apparatus and method for
biometric identification using silhouette and displacement images
of a portion of a person's hand); 5,478,993 (Process as safety
concept against unauthorized use of a payment instrument in
cashless payment at payment sites); 5,475,839 (Method and structure
for securing access to a computer system); 5,469,506 (Apparatus for
verifying an identification card and identifying a person by means
of a biometric characteristic); 5,457,747 (Anti-fraud verification
system using a data card); 5,455,407 (Electronic-monetary system);
5,453,601 (Electronic-monetary system); 5,448,045 (System for
protecting computers via intelligent tokens or smart cards);
5,432,864 (Identification card verification system); 5,414,755
(System and method for passive voice verification in a telephone
network); 5,412,727 (Anti-fraud voter registration and voting
system using a data card); 5,363,453 (Non-minutiae automatic
fingerprint identification system and methods); 5,347,580
(Authentication method and system with a smartcard); 5,345,549
(Multimedia based security systems); 5,341,428 (Multiple
cross-check document verification system); 5,335,288 (Apparatus and
method for biometric identification); 5,291,560 (Biometric personal
identification system based on iris analysis); 5,283,431 (Optical
key security access system); 5,280,527 (Biometric token for
authorizing access to a host system); 5,272,754 (Secure computer
interface); 5,245,329 (Access control system with mechanical keys
which store data); 5,229,764 (Continuous biometric authentication
matrix); 5,228,094 (Process of identifying and authenticating data
characterizing an individual); 5,224,173 (Method of reducing fraud
in connection with employment, public license applications, social
security, food stamps, welfare or other government benefits);
5,208,858 (Method for allocating useful data to a specific
originator); 5,204,670 (Adaptable electric monitoring and
identification system); 5,191,611 (Method and apparatus for
protecting material on storage media and for transferring material
on storage media to various recipients); 5,163,094 (Method for
identifying individuals from analysis of elemental shapes derived
from biosensor data); 5,155,680 (Billing system for computing
software); 5,131,038 (Portable authentification system); 5,073,950
(Finger profile identification system); 5,067,162
(Method and apparatus for verifying identity using image
correlation); 5,065,429 (Method and apparatus for protecting
material on storage media); 5,056,147 (Recognition procedure and an
apparatus for carrying out the recognition procedure); 5,056,141
(Method and apparatus for the identification of personnel);
5,036,461 (Two-way authentication system between user's smart card
and issuer-specific plug-in application modules in multi-issued
transaction device); 5,020,105 (Field initialized authentication
system for protective security of electronic information networks);
4,993,068 (Unforgettable personal identification system); 4,972,476
(Counterfeit proof ID card having a scrambled facial image);
4,961,142 (Multi-issuer transaction device with individual
identification verification plug-in application modules for each
issuer); 4,952,928 (Adaptable electronic monitoring and
identification system); 4,941,173 (Device and method to render
secure the transfer of data between a videotex terminal and a
server); 4,926,480 (Card-computer moderated systems); 4,896,363
(Apparatus and method for matching image characteristics such as
fingerprint minutiae); 4,890,323 (Data communication systems and
methods); 4,868,376 (Intelligent portable interactive personal data
system); 4,827,518 (Speaker verification system using integrated
circuit cards); 4,819,267 (Solid state key for controlling access
to computer systems and to computer software and/or for secure
communications); 4,752,676 (Reliable secure, updatable [0064]"cash"
card system); 4,736,203 (3D hand profile identification apparatus);
4,731,841 (Field initialized authentication system for protective
security of electronic information networks); 4,564,018 (Ultrasonic
system for obtaining ocular measurements), each of which is
expressly incorporated herein by reference.
[0065] Content-Based Query Servers
[0066] U.S. Pat. No. 5,987,459 (Swanson, et al. Nov. 16, 1999),
expressly incorporated herein by reference, relates to an image and
document management system for content-based retrieval support
directly into the compressed files. The system minimizes a weighted
sum of the expected size of the compressed files and the expected
query response time. Object searching of documents stored by the
system is possible on a scalable resolution basis. The system
includes a novel object representation based on embedded prototypes
that provides for high-quality browsing of retrieval images at low
bit rates.
[0067] U.S. Pat. No. 6,038,560 (Wical, Mar. 14, 2000), expressly
incorporated herein by reference, relates to a concept knowledge
base search and retrieval system, which includes factual knowledge
base queries and concept knowledge base queries, is disclosed. A
knowledge base stores associations among terminology/categories
that have a lexical, semantic or usage association. Document theme
vectors identify the content of documents through themes as well as
through classification of the documents in categories that reflects
what the documents are primarily about. The factual knowledge base
queries identify, in response to an input query, documents relevant
to the input query through expansion of the query terms as well as
through expansion of themes. The concept knowledge base query does
not identify specific documents in response to a query, but
specifies terminology that identifies the potential existence of
documents in a particular area.
[0068] U.S. Pat. No. 6,067,466 (Selker, et al., May 23, 2000),
expressly incorporated herein by reference, relates to a diagnostic
tool using a predictive instrument. A method is provided for
evaluating a medical condition of a patient including the steps of
monitoring one or more clinical features of a patient; based on the
monitored features, computing a primary probability of a medical
outcome or diagnosis; computing a plurality of conditional
probabilities for a selected diagnostic test, the computed
conditional probabilities including a first probability of the
medical outcome or diagnosis assuming the selected diagnostic test
produces a first outcome and a second probability of the medical
outcome or diagnosis assuming the selected diagnostic test produces
a second outcome; and displaying the computed primary probability
as well as the plurality of computed conditional probabilities to a
user as an aid to determining whether to administer the selected
diagnostic test to the patient.
[0069] E-Commerce Systems
[0070] U.S. Pat. No. 5,946,669 (Polk, Aug. 31, 1999), expressly
incorporated herein by reference, relates to a method and apparatus
for payment processing using debit-based electronic funds transfer
and disbursement processing using addendum-based electronic data
interchange. This disclosure describes a payment and disbursement
system, wherein an initiator authorizes a payment and disbursement
to a collector and the collector processes the payment and
disbursement through an accumulator agency. The accumulator agency
processes the payment as a debit-based transaction and processes
the disbursement as an addendum-based transaction. The processing
of a debit-based transaction generally occurs by electronic funds
transfer (EFT) or by financial electronic data interchange (FEDI).
The processing of an addendum-based transaction generally occurs by
electronic data interchange (EDI).
[0071] U.S. Pat. No. 6,005,939 (Fortenberry, et al., Dec. 21,
1999), expressly incorporated herein by reference, relates to a
method and apparatus for storing an Internet user's identity and
access rights to World Wide Web resources. A method and apparatus
for obtaining user information to conduct secure transactions on
the Internet without having to re-enter the information multiple
times is described. The method and apparatus can also provide a
technique by which secured access to the data can be achieved over
the Internet. A passport containing user-defined information at
various security levels is stored in a secure server apparatus, or
passport agent, connected to computer network. A user process
instructs the passport agent to release all or portions of the
passport to a recipient node and forwards a key to the recipient
node to unlock the passport information.
[0072] U.S. Pat. No. 6,016,484 (Williams, et al., Jan. 18, 2000),
expressly incorporated herein by reference, relates to a system,
method and apparatus for network electronic payment instrument and
certification of payment and credit collection utilizing a payment.
An electronic monetary system provides for transactions utilizing
an electronic-monetary system that emulates a wallet or a purse
that is customarily used for keeping money, credit cards and other
forms of payment organized. Access to the instruments in the wallet
or purse is restricted by a password to avoid unauthorized
payments. A certificate form must be completed in order to obtain
an instrument. The certificate form obtains the information
necessary for creating a certificate granting authority to utilize
an instrument, a payment holder and a complete electronic wallet.
Electronic approval results in the generation of an electronic
transaction to complete the order. If a user selects a particular
certificate, a particular payment instrument holder will be
generated based on the selected certificate. In addition, the
issuing agent for the certificate defines a default bitmap for the
instrument associated with a particular certificate, and the
default bitmap will be displayed when the certificate definition is
completed. Finally, the number associated with a particular
certificate will be utilized to determine if a particular party can
issue a certificate.
[0073] U.S. Pat. No. 6,029,150 (Kravitz, Feb. 22, 2000), expressly
incorporated herein by reference, relates to a system and method of
payment in an electronic payment system wherein a plurality of
customers have accounts with an agent. A customer obtains an
authenticated quote from a specific merchant, the quote including a
specification of goods and a payment amount for those goods. The
customer sends to the agent a single communication including a
request for payment of the payment amount to the specific merchant
and a unique identification of the customer. The agent issues to
the customer an authenticated payment advice based only on the
single communication and secret shared between the customer and the
agent and status information, which the agent knows about the
merchant, and/or the customer. The customer forwards a portion of
the payment advice to the specific merchant. The specific merchant
provides the goods to the customer in response to receiving the
portion of the payment advice.
[0074] U.S. Pat. No. 6,047,269 (Biffar, Apr. 4, 2000), expressly
incorporated herein by reference, relates to a self-contained
payment system with creating and facilitating transfer of
circulating digital vouchers representing value. A digital voucher
has an identifying element and a dynamic log. The identifying
element includes information such as the transferable value, a
serial number and a digital signature. The dynamic log records the
movement of the voucher through the system and accordingly grows
over time. This allows the system operator to not only reconcile
the vouchers before redeeming them, but also to recreate the
history of movement of a voucher should an irregularity like a
duplicate voucher be detected. These vouchers are used within a
self-contained system including a large number of remote devices
that are linked to a central system. The central system can e
linked to an external system. The external system, as well as the
remote devices, is connected to the central system by any one or a
combination of networks. The networks must be able to transport
digital information, for example the Internet, cellular networks,
telecommunication networks, cable networks or proprietary networks.
Vouchers can also be transferred from one remote device to another
remote device. These remote devices can communicate through a
number of methods with each other. For example, for a
non-face-to-face transaction the Internet is a choice, for a
face-to-face or close proximity transactions tone signals or light
signals are likely methods. In addition, at the time of a
transaction a digital receipt can be created which will facilitate
a fast replacement of vouchers stored in a lost remote device.
[0075] Micropayments
[0076] U.S. Pat. No. 5,999,919 (Jarecki, et al., Dec. 7, 1999),
expressly incorporated herein by reference, relates to an efficient
micropayment system. Existing software proposals for electronic
payments can be divided into "on-line" schemes which require
participation of a trusted party (the bank) in every transaction
and are secure against overspending, and "off-line" schemes which
do not require a third party and guarantee only that overspending
is detected when vendors submit their transaction records to the
bank (usually at the end of the day). A new "hybrid" scheme is
proposed which combines the advantages of both "on-line" and
"off-line" electronic payment schemes. It allows for control of
overspending at a cost of only a modest increase in communication
compared to the off-line schemes. The protocol is based on
probabilistic polling. During each transaction, with some small
probability, the vendor forwards information about this transaction
to the bank. This enables the bank to maintain an accurate
approximation of a customer's spending. The frequency of polling
messages is related to the monetary value of transactions and the
amount of overspending the bank is willing to risk. For
transactions of high monetary value, the cost of polling approaches
that of the on-line schemes, but for micropayments, the cost of
polling is a small increase over the traffic incurred by the
off-line schemes.
[0077] Micropayments are often preferred where the amount of the
transaction does not justify the costs of complete financial
security. In the micropayment scheme, typically a direct
communication between creditor and debtor is not required; rather,
the transaction produces a result which eventually results in an
economic transfer, but which may remain outstanding subsequent to
transfer of the underlying goods or services. The theory underlying
this micropayment scheme is that the monetary units are small
enough such that risks of failure in transaction closure is
relatively insignificant for both parties, but that a user gets few
chances to default before credit is withdrawn. On the other hand,
the transaction costs of a non-real time transactions of small
monetary units are substantially less than those of secure,
unlimited or potentially high value, real time verified
transactions, allowing and facilitating such types of commerce.
Thus, the rights management system may employ applets local to the
client system, which communicate with other applets and/or the
server and/or a vendor/rights-holder to validate a transaction, at
low transactional costs.
[0078] The following U.S. patents, expressly incorporated herein by
reference, define aspects of micropayment, digital certificate, and
on-line payment systems: U.S. Pat. No. 5,930,777 (Barber, Jul. 27,
1999, Method of charging for pay-per-access information over a
network); U.S. Pat. No. 5,857,023 (Jan. 5, 1999, Derners et al.,
Space efficient method of redeeming electronic payments); U.S. Pat.
No. 5,815,657 (Sep. 29, 1998, Williams, System, method and article
of manufacture for network electronic authorization utilizing an
authorization instrument); U.S. Pat. No. 5,793,868 (Aug. 11, 1998,
Micali, Certificate revocation system), U.S. Pat. No. 5,717,757
(Feb. 10, 1998, Micali, Certificate issue lists); U.S. Pat. No.
5,666,416 (Sep. 9, 1997, Micali, Certificate revocation system);
U.S. Pat. No. 5,677,955 (Doggett et al., Electronic funds transfer
instruments); U.S. Pat. No. 5,839,119 (Nov. 17, 1998, Krsul; et
al., Method of electronic payments that prevents double-spending);
U.S. Pat. No. 5,915,093 (Berlin et al.); U.S. Pat. No. 5,937,394
(Wong, et al.); U.S. Pat. No. 5,933,498 (Schneck et al.); U.S. Pat.
No. 5,903,880 (Biffar); U.S. Pat. No. 5,903,651 (Kocher); U.S. Pat.
No. 5,884,277 (Khosla); U.S. Pat. No. 5,960,083 (Sep. 28, 1999,
Micali, Certificate revocation system); U.S. Pat. No. 5,963,924
(Oct. 5, 1999, Williams et al., System, method and article of
manufacture for the use of payment instrument holders and payment
instruments in network electronic commerce); U.S. Pat. No.
5,996,076 (Rowney et al., System, method and article of manufacture
for secure digital certification of electronic commerce); U.S. Pat.
No. 6,016,484 (Jan. 18, 2000, Williams et al., System, method and
article of manufacture for network electronic payment instrument
and certification of payment and credit collection utilizing a
payment); U.S. Pat. No. 6,018,724 (Arent); U.S. Pat. No. 6,021,202
(Anderson et al., Method and system for processing electronic
documents); U.S. Pat. No. 6,035,402 (Vaeth et al.); U.S. Pat. No.
6,049,786 (Smorodinsky); U.S. Pat. No. 6,049,787 (Takahashi, et
al.); U.S. Pat. No. 6,058,381 (Nelson, Many-to-many payments system
for network content materials); U.S. Pat. No. 6,061,448 (Smith, et
al.); U.S. Pat. No. 5,987,132 (Nov. 16, 1999, Rowney, System,
method and article of manufacture for conditionally accepting a
payment method utilizing an extensible, flexible architecture);
U.S. Pat. No. 6,057,872 (Candelore); and U.S. Pat. No. 6,061,665
(May 9, 2000, Bahreman, System, method and article of manufacture
for dynamic negotiation of a network payment framework). See also,
Rivest and Shamir, "PayWord and MicroMint: Two Simple Micropayment
Schemes" (May 7, 1996); Micro PAYMENT transfer Protocol (MPTP)
Version 0.1 (22 Nov. 95) et seq.,
http://www.w3.org/pub/WWW/TR/WD-mptp; Common Markup for web
Micropayment Systems, http://www.w3.org/TR/WD-Micropayment-Markup
(9 Jun. 99); "Distributing Intellectual Property: a Model of
Microtransaction Based Upon Metadata and Digital Signatures",
Olivia, Maurizio,
http://olivia.modlang.denison.edu/.about.olivia/RFC/09/, all of
which are expressly incorporated herein by reference.
[0079] See, also: U.S. Pat. No. 4,977,595 (Dec. 11, 1990, Method
and apparatus for implementing electronic cash); U.S. Pat. No.
5,224,162 (Jun. 29, 1993, Electronic cash system); U.S. Pat. No.
5,237,159 (Aug. 17, 1993, Electronic check presentment system);
U.S. Pat. No. 5,392,353 (February 1995, Morales, TV Answer, Inc.
Interactive satellite broadcast network); U.S. Pat. No. 5,511,121
(Apr. 23, 1996, Efficient electronic money); U.S. Pat. No.
5,621,201 (April 1997, Langhans et al., Visa International
Automated purchasing control system); U.S. Pat. No. 5,623,547 (Apr.
22, 1997, Value transfer system); U.S. Pat. No. 5,679,940 (October
1997, Templeton et al., TeleCheck International, Inc. Transaction
system with on/off line risk assessment); U.S. Pat. No. 5,696,908
(December 1997, Muehlberger et al., Southeast Phonecard, Inc.
Telephone debit card dispenser and method); U.S. Pat. No. 5,754,939
(May 1998, Herz et al., System for generation of user profiles for
a system for customized electronic identification of desirable
objects); U.S. Pat. No. 5,768,385 (Jun. 16, 1998, Untraceable
electronic cash); U.S. Pat. No. 5,799,087 (Aug. 25, 1998,
Electronic-monetary system); U.S. Pat. No. 5,812,668 (Sep. 22,
1998, System, method and article of manufacture for verifying the
operation of a remote transaction clearance system utilizing a
multichannel, extensible, flexible architecture); U.S. Pat. No.
5,828,840 (Oct. 27, 1998, Server for starting client application on
client if client is network terminal and initiating client
application on server if client is non network terminal); U.S. Pat.
No. 5,832,089 (Nov. 3, 1998, Off-line compatible electronic cash
method and system); U.S. Pat. No. 5,850,446 (Dec. 15, 1998, System,
method and article of manufacture for virtual point of sale
processing utilizing an extensible, flexible architecture); U.S.
Pat. No. 5,889,862 (Mar. 30, 1999, Method and apparatus for
implementing traceable electronic cash); U.S. Pat. No. 5,889,863
(Mar. 30, 1999, System, method and article of manufacture for
remote virtual point of sale processing utilizing a multichannel,
extensible, flexible architecture); U.S. Pat. No. 5,898,154 (Apr.
27, 1999, System and method for updating security information in a
time-based electronic monetary system); U.S. Pat. No. 5,901,229
(May 4, 1999, Electronic cash implementing method using a trustee);
U.S. Pat. No. 5,920,629 (Jul. 6, 1999, Electronic-monetary system);
U.S. Pat. No. 5,926,548 (Jul. 20, 1999, Method and apparatus for
implementing hierarchical electronic cash); U.S. Pat. No. 5,943,424
(Aug. 24, 1999, System, method and article of manufacture for
processing a plurality of transactions from a single initiation
point on a multichannel, extensible, flexible architecture); U.S.
Pat. No. 5,949,045 (Sep. 7, 1999, Micro-dynamic simulation of
electronic cash transactions); U.S. Pat. No. 5,952,638 (Sep. 14,
1999, Space efficient method of electronic payments); U.S. Pat. No.
5,963,648 (Oct. 5, 1999, Electronic-monetary system); U.S. Pat. No.
5,978,840 (System, method and article of manufacture for a payment
gateway system architecture for processing encrypted payment
transactions utilizing a multichannel, extensible, flexible
architecture); U.S. Pat. No. 5,983,208 (Nov. 9, 1999, System,
method and article of manufacture for handling transaction results
in a gateway payment architecture utilizing a multichannel,
extensible, flexible architecture); U.S. Pat. No. 5,987,140 (Nov.
16, 1999, System, method and article of manufacture for secure
network electronic payment and credit collection); U.S. Pat. No.
6,002,767 (Dec. 14, 1999, System, method and article of manufacture
for a modular gateway server architecture); U.S. Pat. No. 6,003,765
(Dec. 21, 1999, Electronic cash implementing method with a
surveillance institution, and user apparatus and surveillance
institution apparatus for implementing the same); U.S. Pat. No.
6,021,399 (Feb. 1, 2000, Space efficient method of verifying
electronic payments); U.S. Pat. No. 6,026,379 (Feb. 15, 2000,
System, method and article of manufacture for managing transactions
in a high availability system); U.S. Pat. No. 6,029,150 (Feb. 22,
2000, Payment and transactions in electronic commerce system); U.S.
Pat. No. 6,029,151 (Feb. 22, 2000, Method and system for performing
electronic money transactions); U.S. Pat. No. 6,047,067 (Apr. 4,
2000, Electronic-monetary system); U.S. Pat. No. 6,047,887 (Apr.
11, 2000, System and method for connecting money modules); U.S.
Pat. No. 6,055,508 (Apr. 25, 2000, Method for secure accounting and
auditing on a communications network); U.S. Pat. No. 6,065,675 (May
23, 2000, Processing system and method for a heterogeneous
electronic cash environment); U.S. Pat. No. 6,072,870 (Jun. 6,
2000, System, method and article of manufacture for a gateway
payment architecture utilizing a multichannel, extensible, flexible
architecture), each of which is expressly incorporated herein by
reference.
[0080] Neural Networks
[0081] The resources relating to Neural Networks, listed in the
Neural Networks References Appendix, each of which is expressly
incorporated herein by reference, provides a sound basis for
understanding the field of neural networks (and the subset called
artifical neural networks, which distinguish biolofical systems)
and how these might be used to solve problems. A review of these
references will provide a state of knowledge appropriate for an
understanding of aspects of the invention which rely on Neural
Networks, and to avoid a prolix discussion of no benefit to those
already possessing an appropriate state of knowledge.
[0082] Wavelets
[0083] The following resources listed in the Wavelets References
Appendix relate to Wavelets and wavelet based analysis, each of
which is expressly incorporated herein by reference, provides a
sound basis for understanding the mathematical basis for wavelet
theory and analysis using wavelet transforms and decomposition, and
how these might be used to solve problems or extract useful
information from a signal. A review of these references will assure
a background in this field for an understanding of aspects of the
invention which rely on wavelet theory.
[0084] Telematics
[0085] The resources relating to telematics listed in the
Telematics Appendix, each of which is expressly incorporated herein
by reference, provides a background in the theory and practice of
telematics, as well as some of the underlying technologies. A
review of these references is therefore useful in inderstanding
practical issues and the context of functions and technologies
which may be used in conjunction with the advances set forth
herein.
[0086] Game Theory
[0087] The following resources listed in the Game Theory References
Appendix, relating to Game Theory, each of which is expressly
incorporated herein by reference, provides a basis for
understanding Game Theory and its implications for the design,
control, and analysis of systems and networks. A review of these
references will assure a background in this field for an
understanding of aspects of the invention which relate to game
Theory.
[0088] Use of Game Theory to Control Ad Hoc Networks
[0089] The resources relating to ad hoc networks and game theory
listed in the Game Theory and Ad Hoc Networks References Appendix,
each of which is expressly incorporated herein by reference,
provides a sound basis for understanding the implications of game
theory for the design, control and analysis of communications
networks, and in particular, ad hoc networks. A review of these
references will assure a background in this field for an
understanding of aspects of the invention which rely on these
topics.
[0090] The following patents are expressly incorporated herein by
reference: U.S. Pat. Nos. 6,640,145, 6,418,424, 6,400,996,
6,081,750, 5,920,477, 5,903,454, 5,901,246, 5,875,108, 5,867,386,
5,774,357, 6,429,812, and 6,252,544.
BRIEF DESCRIPTION OF THE DRAWINGS
[0091] The drawings show:
[0092] FIG. 1 shows a Bayesian Network;
[0093] FIG. 2 shows a Markov chain;
[0094] FIG. 3 shows a model of the output of a Markov chain as a
mixture of Gaussians;
[0095] FIGS. 4A-4C show an input-output, a factorial, and a coupled
Hidden Markov Model (HMM), respectively;
[0096] FIG. 5 shows a predictor corrector algorithm of the discrete
Kalman filter cycle;
[0097] FIG. 6 shows aspects of the discrete Kalman filter cycle
algorithm;
[0098] FIG. 7 shows aspects of the extended Kalman filter
cycle;
[0099] FIG. 8 shows a block diagram of a preferred embodiment of a
communications system according to the present invention;
[0100] FIG. 9 is a schematic diagram showing the prioritization
scheme; and
[0101] FIG. 10 is a block diagram representing a message
format.
[0102] This patent builds upon and extends aspects of U.S. Pat. No.
6,252,544 (Hoffberg), Jun. 26, 2001, and U.S. Pat. No. 6,429,812,
Aug. 6, 2002, which are expressly incorporated herein by reference
in its entirety. See, also, U.S. Pat. No. 6,397,141 (Binnig, May
28, 2002, Method and device for signalling local traffic delays),
expressly incorporated herein by reference, which relates to a
method and an apparatus for signalling local traffic disturbances
wherein a decentralised communication between vehicles, which is
performed by exchanging their respective vehicle data. Through
repeated evaluation of these individual vehicle data, each
reference vehicle may determine a group of vehicles having
relevance for itself from within a maximum group of vehicles and
compare the group behavior of the relevant group with its own
behavior. The results of this comparison are indicated in the
reference vehicle, whereby a homogeneous flow of traffic may be
generated, and the occurrence of accidents is reduced. See, also
U.S. Pat. Nos. 4,706,086 (November, 1987 Panizza 340/902), and
5,428,544 (June, 1995 Shyu 701/117), 6,473,688 (Kohno, et al., Oct.
29, 2002, Traffic information transmitting system, traffic
information collecting and distributing system and traffic
information collecting and distributing method), 6,304,758
(October, 2001, Iierbig et al., 701/117); 6,411,221 (January, 2002,
Horber, 701/117); 6,384,739 (May, 2002, Robert, Jr., 701/117);
6,401,027 (June, 2002, Xa et al., 701/117); 6,411,889 (June, 2002,
Mizunuma et al., 701/117), 6,359,571 (Endo, et al., Mar. 19, 2002,
Broadcasting type information providing system and travel
environment information collecting device); 6,338,011 (Furst, et
al., Jan. 8, 2002, Method and apparatus for sharing vehicle
telemetry data among a plurality of users over a communications
network); 5,131,020 (July, 1992, Liebesny et al., 455/422);
5,164,904 (November, 1992, Sumner, 701/117); 5,539,645 (July, 1996,
Mandhyan et al., 701/119); 5,594,779 (January, 1997, Goodman,
455/4); 5,689,252 (November, 1997, Ayanoglu et al., 340/991);
5,699,056 (December, 1997, Yoshida, 340/905); 5,864,305 (January,
1999, Rosenquist, 340/905); 5,889,473 (March, 1999, Wicks,
340/825); 5,919,246 (July, 1999, Waizmann et al., 701/209);
5,982,298 (November, 1999, Lappenbusch et al., 340/905); 4,860,216
(August, 1989, Linsenmayer, 342/159); 5,302,955 (April, 1994,
Schutte et al., 342/59); 5,809,437 (September, 1998, Breed,
701/29); 6,115,654 (September, 2000, Eid et al., 701/34); 6,173,159
(January, 2001, Wright et al., 455/66); and Japanese Patent
Document Nos. JP 9-236650 (September, 1997); 10-84430 (March,
1998); 5-151496 (June, 1993); and 11-183184 (July, 1999), each of
which is expressly incorporated herein by reference. See also:
Martin E. Liggins, II, et al., "Distributed Fusion Architectures
and Algorithms for Target Tracking", Proceedings of the IEEE, vol.
85, No. 1, (XP-002166088) January, 1997, pp. 95-106.; D. M. Hosmer,
"Data-Linked Associate Systems", 1994 IEEE International Conference
on Systems, Man, and Cybernetics. Humans, Information and
Technology (Cat. No. 94CH3571-5), Proceedings of IEEE International
Conference on Systems, Man and Cybernetics, San Antonio, Tex., vol.
3, (XP-002166089) (1994), pp. 2075-2079.
[0103] One aspect of the invention provides a communications
system, method and infrastructure. According to one preferred
embodiment, an ad hoc, self organizing, cellular radio system
(sometimes known as a "mesh network") is provided. Advantageously,
high gain antennas are employed, preferably electronically
steerable antennas, to provide efficient communications and to
increase communications bandwidth, both between nodes and for the
system comprising a plurality of nodes communicating with each
other. See, U.S. Pat. No. 6,507,739 (Gross, et al., Jan. 14, 2003),
expressly incorporated herein by reference.
[0104] In general, time-critical, e.g., voice communications
require tight routing to control communications latency. On the
other hand, non-time critical communications generally are afforded
more leeway in terms of communications pathways, including a number
of "hops", retransmission latency, and out-of-order packet
communication tolerance, between the source and destination or
fixed infrastructure, and quality of communication pathway.
Further, it is possible to establish redundant pathways, especially
where communications bandwidth is available, multiple paths
possible, and no single available path meets the entire
communications requirements or preferences.
[0105] Technologies for determining a position of a mobile device
are also well known. Most popular are radio triangulation
techniques, including artificial satellite and terrestrial
transmitters or receivers, dead reckoning and inertial techniques.
Advantageously, a satellite-based or augmented satellite system,
although other suitable geolocation systems are applicable.
[0106] Navigation systems are also well known. These systems
generally combine a position sensing technology with a geographic
information system (GIS), e.g., a mapping database, to assist
navigation functions. Systems which integrate GPS, GLONASS, LORAN
or other positioning systems into vehicular guidance systems are
well known, and indeed navigational purposes were prime motivators
for the creation of these systems.
[0107] Environmental sensors are well known. For example, sensing
technologies for temperature, weather, object proximity, location
and identification, vehicular traffic and the like are well
developed. In particular, known systems for analyzing vehicular
traffic patterns include both stationary and mobile sensors, and
networks thereof. Most often, such networks provide a stationary or
centralized system for analyzing traffic information, which is then
broadcast to vehicles.
[0108] Encryption technologies are well known and highly developed.
These are generally classified as being symmetric key, for example
the Data Encryption Standard (DES), and the more recent Advanced
Encryption Standard (AES), in which the same key is used for
encryption as decryption, and asymmetric key cryptography, in which
different and complementary keys are used to encrypt and decrypt,
in which the former and the latter are not derivable from each
other (or one from the other) and therefore can be used for
authentication and digital signatures. The use of asymmetric keys
allows a so-called public key infrastructure, in which one of the
keys is published, to allow communications to be directed to a
possessor of a complementary key, and/or the identity of the sender
of a message to be verified. Typical asymmetric encryption systems
include the Rivest-Shamir-Adelman algorithm (RSA), the
Diffie-Hellman algorithm (DH), elliptic curve encryption
algorithms, and the so-called Pretty Good Privacy (PGP)
algorithm.
[0109] One embodiment of the invention provides a system that
analyzes both a risk and an associated reliability. Another
embodiment of the invention communicates the risk and associated
reliability in a manner for efficient human comprehension,
especially in a distracting environment. See, U.S. Pat. Nos.
6,201,493; 5,977,884; 6,118,403; 5,982,325; 5,485,161; WO0077539,
each of which is expressly incorporated herein by reference, and
the Uniden GPSRD (see Uniden GPSRD User's Manual, expressly
incorporated herein by reference). See, also U.S. Pat. Nos.
5,650,770; 5,450,329; 5,504,482; 5,504,491; 5,539,645; 5,929,753;
5,983,161; 6,084,510; 6,255,942; 6,225,901; 5,959,529; 5,752,976;
5,748,103; 5,720,770; 6,005,517; 5,805,055; 6,147,598; 5,687,215;
5,838,237; 6,044,257; 6,144,336; 6,285,867; 6,340,928; 6,356,822;
6,353,679 each of which is expressly incorporated herein by
reference.
[0110] Statistical Analysis
[0111] It is understood that the below analysis and analytical
tools, as well as those known in the art, may be used individually,
in sub-combination, or in appropriate combination, to achieve the
goals of the invention. These techniques may be implemented in
dedicated or reprogrammable/general purpose hardware, and may be
employed for low level processing of signals, such as in digital
signal processors, within an operating system or dynamic linked
libraries, or within application software. Likewise, these
techniques may be applicable, for example, to low level data
processing, system-level data processing, or user interface data
processing.
[0112] A risk and reliability communication system may be useful,
for example, to allow a user to evaluate a set of events in
statistical context. Most indicators present data by means of a
logical indicator or magnitude, as a single value. Scientific
displays may provide a two-dimensional display of a distribution,
but these typically require significant user focus to comprehend,
especially where a multimodal distribution is represented. User
displays of a magnitude or binary value typically do not provide
any information about a likelihood of error. Thus, while a recent
positive warning of the existence of an event may be a reliable
indicator of the actual existence of the event, the failure to warn
of an event does not necessarily mean that the event does not
exist. Further, as events age, their reliability often
decreases.
[0113] A Bayesian network is a representation of the probabilistic
relationships among distinctions about the world. Each distinction,
sometimes called a variable, can take on one of a mutually
exclusive and exhaustive set of possible states. Associated with
each variable in a Bayesian network is a set of probability
distributions. Using conditional probability notation, the set of
probability distributions for a variable can be denoted by
p(x.sub.i|.pi..sub.i, .chi.), where "p" refers to the probability
distribution, where ".pi..sub.i" denotes the parents of variable
X.sub.i and where ".chi." denotes the knowledge of the expert. The
Greek letter ".chi." indicates that the Bayesian network reflects
the knowledge of an expert in a given field. Thus, this expression
reads as follows: the probability distribution for variable X.sub.i
given the parents of X.sub.i and the knowledge of the expert. For
example, X.sub.1 is the parent of X.sub.2. The probability
distributions specify the strength of the relationships between
variables. For instance, if X.sub.1 has two states (true and
false), then associated with X.sub.1 is a single probability
distribution p(x.sub.1|.chi.)p and associated with X.sub.2 are two
probability distributions p(x.sub.i|X.sub.1=t,.chi.) and
p(X.sub.2|X.sub.1=f, .chi.).
[0114] A Bayesian network is expressed as an acyclic-directed graph
where the variables correspond to nodes and the relationships
between the nodes correspond to arcs. The arcs in a Bayesian
network convey dependence between nodes. When there is an arc
between two nodes, the probability distribution of the first node
depends upon the value of the second node when the direction of the
arc points from the second node to the first node. Missing arcs in
a Bayesian network convey conditional independencies. However, two
variables indirectly connected through intermediate variables are
conditionally dependent given lack of knowledge of the values
("states") of the intermediate variables. In other words, sets of
variables X and Y are said to be conditionally independent, given a
set of variables Z, if the probability distribution for X given Z
does not depend on Y. If Z is empty, however, X and Y are said to
be "independent" as opposed to conditionally independent. If X and
Y are not conditionally independent, given Z, then X and Y are said
to be conditionally dependent given Z.
[0115] The variables used for each node may be of different types.
Specifically, variables may be of two types: discrete or
continuous. A discrete variable is a variable that has a finite or
countable number of states, whereas a continuous variable is a
variable that has an effectively infinite number of states. An
example of a discrete variable is a Boolean variable. Such a
variable can assume only one of two states: "true" or "false." An
example of a continuous variable is a variable that may assume any
real value between -1 and 1. Discrete variables have an associated
probability distribution. Continuous variables, however, have an
associated probability density function ("density"). Where an event
is a set of possible outcomes, the density p(x) for a variable "x"
and events "a" and "b" is defined as:
p ( x ) = Lim a .fwdarw. b [ p ( a .ltoreq. x .ltoreq. b ) ( a - b
) ] ##EQU00001##
[0116] where p(a.ltoreq.x.ltoreq.b) is the probability that x lies
between a and b. Conventional systems for generating Bayesian
networks cannot use continuous variables in their nodes.
[0117] There are two conventional approaches for constructing
Bayesian networks. Using the first approach ("the knowledge-based
approach"), first the distinctions of the world that are important
for decision making are determined. These distinctions correspond
to the variables of the domain of the Bayesian network. The
"domain" of a Bayesian network is the set of all variables in the
Bayesian network. Next the dependencies among the variables (the
arcs) and the probability distributions that quantify the strengths
of the dependencies are determined.
[0118] In the second approach ("called the data-based approach"),
the variables of the domain are first determined. Next, data is
accumulated for those variables, and an algorithm is applied that
creates a Bayesian network from this data. The accumulated data
comes from real world instances of the domain. That is, real world
instances of decision making in a given field. Conventionally, this
second approach exists for domains containing only discrete
variables.
[0119] U.S. application Ser. No. 08/240,019 filed May 9, 1994
entitled "Generating Improved Belief Networks" describes a system
and method for generating Bayesian networks (also known as "belief
networks") that utilize both expert data received from an expert
("expert knowledge") and data received from real world instances of
decisions made ("empirical data"). By utilizing both expert
knowledge and empirical data, the network generator provides an
improved Bayesian network that may be more accurate than
conventional Bayesian networks or provide other advantages, e.g.,
ease of implementation and lower reliance on "expert" estimations
of probabilities. Likewise, it is known to initiate a network using
estimations of the probabilities (and often the relevant
variables), and subsequently use accumulated data to refine the
network to increase its accuracy and precision.
[0120] Expert knowledge consists of two components: an equivalent
sample size or sizes ("sample size"), and the prior probabilities
of all possible Bayesian-network structures ("priors on
structures"). The effective sample size is the effective number of
times that the expert has rendered a specific decision. For
example, a doctor with 20 years of experience diagnosing a specific
illness may have an effective sample size in the hundreds. The
priors on structures refers to the confidence of the expert that
there is a relationship between variables (e.g., the expert is 70%
sure that two variables are related). The priors on structures can
be decomposed for each variable-parent pair known as the "prior
probability" of the variable-parent pair. Empirical data is
typically stored in a database. The database may contain a list of
the observed state of some or all of the variables in the Bayesian
network. Each data entry constitutes a case. When one or more
variables are unobserved in a case, the case containing the
unobserved variable is said to have "missing data." Thus, missing
data refers to when there are cases in the empirical data database
that contain no observed value for one or more of the variables in
the domain. An assignment of one state to each variable in a set of
variables is called an "instance" of that set of variables. Thus, a
"case" is an instance of the domain. The "database" is the
collection of all cases.
[0121] Therefore, it is seen that Bayesian networks can be used to
probabilistically model a problem, in a mathematical form. This
model may then be analyzed to produce one or more outputs
representative of the probability that a given fact is true, or a
probability density distribution that a variable is at a certain
value.
[0122] A review of certain statistical methods is provided below
for the convenience of the reader, and is not intended to limit the
scope of methods, of statistical of other type, which may be
employed in conjunction with the system and method according to the
present invention. It is understood that these mathematical models
and methods may be implemented in known manner on general purpose
computing platforms, for example as a compiled application in a
real-time operating system such as RT Linux, QNX, versions of
Microsoft Windows, or the like. Further, these techniques may be
implemented as applets operating under Matlab or other scientific
computing platform. Alternately, the functions may be implemented
natively in an embedded control system or on a microcontroller.
[0123] It is also understood that, while the mathematical methods
are capable of producing precise and accurate results, various
simplyfying presumptions and truncations may be employed to
increase the tractability of the problem to be solved. Further, the
outputs generally provided according to preferred embodiments of
the present invention are relatively low precision, and therefore
higher order approximation of the analytic solution, in the case of
a rapidly convergent calculation, will often be sufficient.
[0124] A time domain process demonstrates a Markov property if the
conditional probability density of the current event, given all
present and past events, depends only on the jth most recent
events. If the current event depends solely on the most recent past
event, then the process is a first order Markov process. There are
three key problems in HMM use: evaluation, estimation, and
decoding. The evaluation problem is that given an observation
sequence and a model, what is the probability that the observed
sequence was generated by the model (Pr(O|.lamda.)). If this can be
evaluated for all competing models for an observation sequence,
then the model with the highest probability can be chosen for
recognition.
[0125] Pr(O|.lamda.) can be calculated several ways. The naive way
is to sum the probability over all the possible state sequences in
a model for the observation sequence:
Pr ( O | .lamda. ) = ? ? T a ? b ? ( O ? ) ##EQU00002## ? indicates
text missing or illegible when filed ##EQU00002.2##
[0126] However, this method is exponential in time, so the more
efficient forward-backward algorithm is used in practice. The
following algorithm defines the forward variable .alpha. and uses
it to generate Pr(O|.lamda.) (.pi. are the initial state
probabilities, a are the state transition probabilities, and b are
the output probabilites). [0127]
.alpha..sub.1(i)=.pi..sub.ib.sub.i(O.sub.1), for all states i
(if
[0127] i .di-elect cons. S I , .pi. i = L ? ; ##EQU00003## ?
indicates text missing or illegible when filed ##EQU00003.2##
otherwise .pi..sub.i=0) [0128] Calculating .alpha.( ) along the
time axis, for t=2, . . . , T, and all states j, compute
[0128] a ? ( j ) = [ i a ? - 1 ( i ) ? ij ] b j ( O ? )
##EQU00004## ? indicates text missing or illegible when filed
##EQU00004.2## [0129] Final probability is given by
[0129] Pr ( O | .lamda. ) = i ? p ? T ( i ) ##EQU00005## ?
indicates text missing or illegible when filed ##EQU00005.2##
[0130] The first step initializes the forward variable with the
initial probability for all states, while the second step
inductively steps the forward variable through time. The final step
gives the desired result Pr(O|.lamda.), and it can be shown by
constructing a lattice of states and transitions through time that
the computation is only order O(N.sup.2T). The backward algorithm,
using a process similar to the above, can also be used to compute
Pr(O|.lamda.) and defines the convenience variable .beta..
[0131] The estimation problem concerns how to adjust .lamda. to
maximize Pr(O|.lamda.) given an observation sequence O. Given an
initial model, which can have flat probabilities, the
forward-backward algorithm allows us to evaluate this probability.
All that remains is to find a method to improve the initial model.
Unfortunately, an analytical solution is not known, but an
iterative technique can be employed.
[0132] Using the actual evidence from the training data, a new
estimate for the respective output probability can be assigned:
b _ j ( k ) = ? .gamma. ? ( j ) ? T .gamma. ? ( j ) ##EQU00006## ?
indicates text missing or illegible when filed ##EQU00006.2##
[0133] where .gamma..sub.i(i) is defined as the posterior
probability of being in state i at time t given the observation
sequence and the model. Similarly, the evidence can be used to
develop a new estimate of the probability of a state transition
(a.sub.i,j) and initial state probabilities (.pi..sub.i).
[0134] Thus all the components of model (.lamda.) can be
re-estimated. Since either the forward or backward algorithm can be
used to evaluate Pr(O.cndot.|.lamda.) versus the previous
estimation, the above technique can be used iteratively to converge
the model to some limit. While the technique described only handles
a single observation sequence, it is easy to extend to a set of
observation sequences.
[0135] The Hidden Markov Model is a finite set of states, each of
which is associated with a (generally multidimensional) probability
distribution
http://jedlik.phy.bme.hu/.about.gerjanos/HMM/node4.html--r4#r4.
Transitions among the states are governed by a set of probabilities
called transition probabilities. In a particular state an outcome
or observation can be generated, according to the associated
probability distribution. It is only the outcome, not the state
visible to an external observer and therefore states are "hidden"
to the outside; hence the name Hidden Markov Model.
[0136] In order to define an HMM completely, following elements are
needed. [0137] The number of states of the model, N. [0138] The
number of observation symbols in the alphabet, M. If the
observations are continuous then M is infinite. [0139] A set of
state transition probabilities A={a.sub.ij}
a.sub.ij=p{q.sub.i+1=j|q.sub.t=i}, 2.ltoreq.i,j.ltoreq.N, [0140]
where q.sub.t denotes the current state. Transition probabilities
should satisfy the normal stochastic constraints,
[0140] a ij .gtoreq. 0 , 1 .ltoreq. i , j .ltoreq. N ##EQU00007##
and ##EQU00007.2## j = 1 N a ij = 1 , 1 .ltoreq. i .ltoreq. N
##EQU00007.3## B={b.sub.j(k)} [0141] A probability distribution in
each of the states,
[0141] b.sub.j(k)=p{o.sub.t=v.sub.k|q.sub.t=j},
1.ltoreq.j.ltoreq.N, 1.ltoreq.k.ltoreq.M where v.sub.k denotes the
k.sup.th observation symbol in the alphabet, and o.sub.t the
current parameter vector. Following stochastic constraints must be
satisfied.
b j ( k ) .gtoreq. 0 , 1 .ltoreq. j .ltoreq. N , 1 .ltoreq. k
.ltoreq. M ##EQU00008## and ##EQU00008.2## k = 1 M b j ( k ) = 1 ,
1 .ltoreq. j .ltoreq. N ##EQU00008.3##
[0142] If the observations are continuous then we will have to use
a continuous probability density function, instead of a set of
discrete probabilities. In this case we specify the parameters of
the probability density function. Usually the probability density
is approximated by a weighted sum of M Gaussian distributions
b j ( o t ) = m = 1 M c jm ( .mu. jm , .SIGMA. jm , o t )
##EQU00009##
[0143] where, [0144] c.sub.jm=weighting coefficients [0145]
.mu..sub.jm=mean vectors [0146] .SIGMA..sub.jm=Covariance
matrices
[0147] c.sub.jm should satisfy the stochastic constrains,
c jm .gtoreq. 0 , 1 .ltoreq. j .ltoreq. N , 1 .ltoreq. m .ltoreq. M
##EQU00010## and ##EQU00010.2## m = 1 M c jm = 1 , 1 .ltoreq. j
.ltoreq. N ##EQU00010.3## .pi.={.pi..sub.i} [0148] The initial
state distribution,
[0148] where, .pi..sub.i=p{q.sub.1=i}, 1.ltoreq.i.ltoreq.N
[0149] Therefore we can use the compact notation .lamda.=(.LAMBDA.,
B, .pi.)
[0150] to denote an HMM with discrete probability distributions,
while
.lamda.=(.LAMBDA..sub.ic.sub.jm,.mu..sub.jm,.SIGMA..sub.jm,.pi.)
[0151] to denote one with continuous densities.
[0152] For the sake of mathematical and computational tractability,
following assumptions are made in the theory of HMMs.
[0153] (1) The Markov assumption
[0154] As given in the definition of HMMs, transition probabilities
are defined as,
a.sub.ij=p{q.sub.t+1=j|q.sub.t=i}.
[0155] In other words it is assumed that the next state is
dependent only upon the current state. This is called the Markov
assumption and the resulting model becomes actually a first order
HMM.
[0156] However generally the next state may depend on past k states
and it is possible to obtain a such model, called an k.sup.th order
HMM by defining the transition probabilities as follows.
a.sub.i.sub.1.sub.i.sub.2.sub.. . .
i.sub.k.sub.j=p{q.sub.t+1=j|q.sub.t=i.sub.1,q.sub.t-1=i.sub.2, . .
. , q.sub.t-k+1=i.sub.k}, 1.ltoreq.i.sub.1,i.sub.2, . . . ,
i.sub.k,j.ltoreq.N.
[0157] But it is seen that a higher order HMM will have a higher
complexity. Even though the first order HMMs are the most common,
some attempts have been made to use the higher order HMMs too.
[0158] (2) The Stationarity Assumption
[0159] Here it is assumed that state transition probabilities are
independent of the actual time at which the transitions takes
place. Mathematically,
p{q.sub.t.sub.1.sub.+1=j|q.sub.t.sub.1=i}=p{q.sub.t.sub.2.sub.+1=j|q.sub.-
t.sub.2=i},
[0160] for any t.sub.1 and t.sub.2.
[0161] (3) The output Independence Assumption
[0162] This is the assumption that current output (observation) is
statistically independent of the previous outputs (observations).
We can formulate this assumption mathematically, by considering a
sequence of observations,
O=o.sub.1,o.sub.2, . . . , o.sub.T.
[0163] Then according to the assumption for an HMM .lamda.,
p { O q 1 , q 2 , , q T , .lamda. } = t = 1 T p ( o t q t , .lamda.
) . ##EQU00011##
[0164] However unlike the other two, this assumption has a very
limited validity. In some cases this assumption may not be fair
enough and therefore becomes a severe weakness of the HMMs.
[0165] A Hidden Markov Model (HMM) is a Markov chain, where each
state generates an observation. You only see the observations, and
the goal is to infer the hidden state sequence. HMMs are very
useful for time-series modeling, since the discrete state-space can
be used to approximate many non-linear, non-Gaussian systems.
[0166] HMMs and some common variants (e.g., input-output HMMs) can
be concisely explained using the language of Bayesian Networks, as
we now demonstrate.
[0167] Consider the Bayesian network in FIG. 1, which represents a
hidden Markov model (HMM). (Circles denote continuous-valued random
variables, squares denote discrete-valued, clear means hidden,
shaded means observed.) This encodes the joint distribution
P(Q,Y)=P(Q.sub.1)P(Y.sub.1|Q.sub.1)P(Q.sub.2|Q.sub.1)P(Y.sub.2|Q.sub.2)
[0168] For a sequence of length T, we simply "unroll" the model for
T time steps. In general, such a dynamic Bayesian network (DBN) can
be specified by just drawing two time slices (this is sometimes
called a 2TBN)--the structure (and parameters) are assumed to
repeat.
[0169] The Markov property states that the future is independent of
the past given the present, i.e., Q.sub.(t+1)\indep
Q.sub.(t-1)|Q.sub.1. We can parameterize this Markov chain using a
transition matrix, M.sub.(ij)=P(Q.sub.(t+1)=j|Q.sub.1=i), and a
prior distribution, .pi..sub.i=P(Q.sub.1=i).
[0170] We have assumed that this is a homogeneous Markov chain,
i.e., the parameters do not vary with time. This assumption can be
made explicit by representing the parameters as nodes: see FIG. 2:
P1 represents .pi., P2 represents the transition matrix, and P3
represents the parameters for the observation model. If we think of
these parameters as random variables (as in the Bayesian approach),
parameter estimation becomes equivalent to inference. If we think
of the parameters as fixed, but unknown, quantities, parameter
estimation requires a separate learning procedure (usually EM). In
the latter case, we typically do not represent the parameters in
the graph; shared parameters (as in this example) are implemented
by specifying that the corresponding CPDs are "tied".
[0171] An HMM is a hidden Markov model because we don't see the
states of the Markov chain, Q.sub.t, but just a function of them,
namely Y.sub.t. For example, if Y.sub.t is a vector, we might
define P(Y.sub.t=y|Q.sub.t=i)=N(y; .mu..sub.i, o.sub.i). A richer
model, widely used in speech recognition, is to model the output
(conditioned on the hidden state) as a mixture of Gaussians. This
is shown in FIG. 3.
[0172] Some popular variations on the basic HMM theme are
illustrated in FIGS. 4A, 4B and 4C, which represent, respectively,
an input-output HMM, a factorial HMM, and a coupled HMM. (In the
input-output model, the CPD P(Q|U) could be a softmax function, or
a neural network.) Software is available to handle inference and
learning in general Bayesian networks, making all of these models
trivial to implement.
[0173] It is noted that the parameters may also vary with time.
This does not violate the presumptions inherent in an HMM, but
rather merely complicates the analysis since a static simplifying
presumption may not be made.
[0174] A discrete-time, discrete-space dynamical system governed by
a Markov chain emits a sequence of observable outputs: one output
(observation) for each state in a trajectory of such states. From
the observable sequence of outputs, we may infer the most likely
dynamical system. The result is a model for the underlying process.
Alternatively, given a sequence of outputs, we can infer the most
likely sequence of states. We might also use the model to predict
the next observation or more generally a continuation of the
sequence of observations.
[0175] The Evaluation Problem and the Forward Algorithm
[0176] We have a model .lamda.=(.LAMBDA., B, .pi.) and a sequence
of observations O=o.sub.1, o.sub.2, . . . , o.sub.T, and
p{O|.lamda.} must be found. We can calculate this quantity using
simple probabilistic arguments. But this calculation involves
number of operations in the order of N.sup.T. This is very large
even if the length of the sequence, T is moderate. Therefore we
have to look for an other method for this calculation. Fortunately
there exists one which has a considerably low complexity and makes
use an auxiliary variable, .alpha..sub.t(i) called forward
variable.
[0177] The forward variable is defined as the probability of the
partial observation sequence o.sub.1, o.sub.2, . . . , o.sub.T,
when it terminates at the state i. Mathematically,
.alpha..sub.t(i)=p{o.sub.1,o.sub.2, . . . ,
o.sub.t,q.sub.t=i|.lamda.} (1.1)
[0178] Then it is easy to see that following recursive relationship
holds.
a t + 1 ( j ) = b j ( o t + 1 ) i = 1 N .alpha. t ( i ) a ij , 1
.ltoreq. j .ltoreq. N , 1 .ltoreq. t .ltoreq. T - 1 ( 1.2 )
##EQU00012##
[0179] where, .alpha..sub.1(j)=.pi..sub.jb.sub.j(o.sub.1),
1.ltoreq.j.ltoreq.N
[0180] Using this recursion we can calculate .alpha..sub.T(i),
1.ltoreq.i.ltoreq.N
[0181] and then the required probability is given by,
p { O .lamda. } = i = 1 N .alpha. T ( i ) ( 1.3 ) ##EQU00013##
[0182] The complexity of this method, known as the forward
algorithm is proportional to N.sup.2T, which is linear with respect
to T whereas the direct calculation mentioned earlier, had an
exponential complexity.
[0183] In a similar way we can define the backward variable
.beta..sub.t(i) as the probability of the partial observation
sequence o.sub.t+1, o.sub.t+2, . . . , o.sub.T, given that the
current state is i. Mathematically,
.beta..sub.t(i)=p{o.sub.t+1,o.sub.t+2, . . . ,
o.sub.T|q.sub.t=i,.lamda.} (1.4)
[0184] As in the case of .alpha..sub.t(i) there is a recursive
relationship which can be used to calculate .beta..sub.t(i)
efficiently.
.beta. t ( i ) = i = 1 N .beta. t + 1 ( j ) a ij b j ( o t + 1 ) ,
1 .ltoreq. i .ltoreq. N , 1 .ltoreq. t .ltoreq. T - 1 ( 1.5 )
##EQU00014##
[0185] where, .beta..sub.T(i)=1, 1.ltoreq.i.ltoreq.N
[0186] Further we can see that,
.alpha..sub.t(i).beta..sub.t(i)=p{O,q.sub.t=i|.lamda.},
1.ltoreq.i.ltoreq.N, 1.ltoreq.t.ltoreq.T (1.6)
[0187] Therefore this gives another way to calculate p{O|.lamda.},
by using both forward and backward variables as given in eqn. 1.7.
See, http://jedlik.phy.bme.hu/.about.gerjanos/HMM/, expressly
incorporated herein by reference.
p { O .lamda. } = i = 1 N p { O , q t = i .lamda. } = i = 1 N
.alpha. t ( i ) .beta. t ( i ) ( 1.7 ) ##EQU00015##
[0188] Eqn. 1.7 is very useful, specially in deriving the formulas
required for gradient based training.
[0189] The Decoding Problem and the Viterbi Algorithm
[0190] While the estimation and evaluation processes described
above are sufficient for the development of an HMM system, the
Viterbi algorithm provides a quick means of evaluating a set of
HMM's in practice as well as providing a solution for the decoding
problem. In decoding, the goal is to recover the state sequence
given an observation sequence. The Viterbi algorithm can be viewed
as a special form of the forward-backward algorithm where only the
maximum path at each time step is taken instead of all paths. This
optimization reduces computational load and allows the recovery of
the most likely state sequence. The steps to the Viterbi are [0191]
Initialization. For all states i,
.delta..sub.1(i)=.pi..sub.ib.sub.i(O.sub.1); .psi..sub.i(i)=0
[0192] Recursion. From t=2 to T and for all states j,
.delta..sub.1(j)=Max.sub.i[.delta..sub.i-1(i)a.sub.ij]b.sub.j(O.sub.1);
.psi..sub.i(j)=argmax.sub.i[.delta..sub.i-1(i)a.sub.ij] [0193]
Termination. P=Max.sub.ms.sub.p[.delta..sub.T(a)];
s.sub.T=argmax.sub.ms.sub.p[.delta..sub.T(s)] [0194] Recovering the
state sequence. From t=T-1 to 1,
s.sub.i=.psi..sub.i+1(s.sub.i+1)
[0195] In many HMM system implementations, the Viterbi algorithm is
used for evaluation at recognition time. Note that since Viterbi
only guarantees the maximum of Pr(O,S|.lamda.) over all state
sequences S (as a result of the first order Markov assumption)
instead of the sum over all possible state sequences, the resultant
scores are only an approximation.
[0196] So far the discussion has assumed some method of
quantization of feature vectors into classes. However, instead of
using vector quantization, the actual probability densities for the
features may be used. Baum-Welch, Viterbi, and the forward-backward
algorithms can be modified to handle a variety of characteristic
densities. In this context, however, the densities will be assumed
to be Gaussian. Specifically,
b j ( O ? ) = 1 ( 2 .pi. ) ? .sigma. j 1 2 ( O t - .mu. j ) ?
.sigma. j - 1 ( O t - .mu. j ) ##EQU00016## ? indicates text
missing or illegible when filed ##EQU00016.2##
[0197] Initial estimations of .mu. and .sigma. may be calculated by
dividing the evidence evenly among the states of the model and
calculating the mean and variance in the normal way. Whereas flat
densities were used for the initialization step before, the
evidence is used here. Now all that is needed is a way to provide
new estimates for the output probability. We wish to weight the
influence of a particular observation for each state based on the
likelihood of that observation occurring in that state. Adapting
the solution from the discrete case yields
.mu. _ j = ? = 1 T .gamma. ? ( j ) O ? ? = 1 T .gamma. ? ( j )
##EQU00017## and ##EQU00017.2## .sigma. _ j = ? = 1 T .gamma. ? ( j
) ( O ? ? = 1 T .gamma. ? ( j ) ##EQU00017.3## ? indicates text
missing or illegible when filed ##EQU00017.4##
[0198] For convenience, .sub..mu.j is used to calculate .sub..mu.j
instead of the re-estimated .sub..mu.j. While this is not strictly
proper, the values are approximately equal in contiguous iterations
and seem not to make an empirical difference. See,
http://www-white.media.mit.edu/.about.testarne/asl/asl-tr375,
expressly incorporated herein by reference. Since only one stream
of data is being used and only one mixture (Gaussian density) is
being assumed, the algorithms above can proceed normally,
incorporating these changes for the continuous density case.
[0199] We want to find the most likely state sequence for a given
sequence of observations, O=o.sub.1, o.sub.2, . . . , o.sub.T and a
model, .lamda.=(.LAMBDA., B, .pi.).
[0200] The solution to this problem depends upon the way "most
likely state sequence" is defined. One approach is to find the most
likely state q.sub.t at t=t and to concatenate all such q.sub.t's.
But sometimes, this method does not give a physically meaningful
state sequence. Therefore we would seek another method which has no
such problems.
In this method, commonly known as Viterbi algorithm, the whole
state sequence with the maximum likelihood is found. In order to
facilitate the computation we define an auxiliary variable,
.delta. t ( i ) = max q 1 q 2 q ? - 1 p { q 1 , q 2 , , q t - 1 , q
t = i , o 1 , o 2 , , o t - 1 | .lamda. } , ? indicates text
missing or illegible when filed ##EQU00018##
[0201] which gives the highest probability that partial observation
sequence and state sequence up to t=t can have, when the current
state is i.
It is easy to observe that the following recursive relationship
holds.
.delta. t + 1 ( j ) = b j ( o t + 1 ) [ max 1 .ltoreq. i .ltoreq. N
.delta. t ( i ) a ij ] , 1 .ltoreq. i .ltoreq. N , 1 .ltoreq. t
.ltoreq. T - 1 ( 1.8 ) ##EQU00019##
[0202] where, .delta..sub.1(j)=.pi..sub.jb.sub.j(o.sub.1),
1.ltoreq.j.ltoreq.N
[0203] So the procedure to find the most likely state sequence
starts from calculation of .delta..sub.T(j), 1.ltoreq.j.ltoreq.N
using recursion in 1.8, while always keeping a pointer to the
"winning state" in the maximum finding operation. Finally the state
j*, is found where
j * = arg max 1 .ltoreq. j .ltoreq. N .delta. T ( j ) ,
##EQU00020##
[0204] and starting from this state, the sequence of states is
back-tracked as the pointer in each state indicates. This gives the
required set of states.
[0205] This whole algorithm can be interpreted as a search in a
graph whose nodes are formed by the states of the HMM in each of
the time instant t, 1.ltoreq.t.ltoreq.T.
[0206] The Learning Problem
[0207] Generally, the learning problem is how to adjust the HMM
parameters, so that the given set of observations (called the
training set) is represented by the model in the best way for the
intended application. Thus it would be clear that the "quantity" we
wish to optimize during the learning process can be different from
application to application. In other words there may be several
optimization criteria for learning, out of which a suitable one is
selected depending on the application.
[0208] There are two main optimization criteria found in ASR
literature; Maximum Likelihood (ML) and Maximum Mutual Information
(MMI). The solutions to the learning problem under each of those
criteria is described below.
[0209] Maximum Likelihood (ML) Criterion
[0210] In ML we try to maximize the probability of a given sequence
of observations O.sup.W, belonging to a given class w, given the
HMM .lamda..sub.w of the class w, with respect to the parameters of
the model .lamda..sub.w. This probability is the total likelihood
of the observations and can be expressed mathematically as
L.sub.tot=p{O.sup.W|.lamda..sub.w}
[0211] However since we consider only one class w at a time we can
drop the subscript and superscript `w`s. Then the ML criterion can
be given as,
L.sub.tot=p{O|.lamda.} (1.9)
[0212] However there is no known way to analytically solve for the
model .lamda.=(.LAMBDA., B, .pi.), which maximize the quantity
L.sub.tot. But we can choose model parameters such that it is
locally maximized, using an iterative procedure, like Baum-Welch
method or a gradient based method, which are described below.
[0213] Baum-Welch Algorithm
[0214] This method can be derived using simple "occurrence
counting" arguments or using calculus to maximize the auxiliary
quantity
Q ( .lamda. , .lamda. _ ) = q p { q O , .lamda. } log [ p { O , q ,
.lamda. _ } ] ##EQU00021##
[0215] over
.lamda.[http://jedlik.phy.bme.hu/.about.gerjanos/HMM/node11.html--r4#r4],-
[http://jedlik.phy.bme.hu/.about.gerjanos/HMM/node11.html--r21#r21,
p 344-346]. A special feature of the algorithm is the guaranteed
convergence.
To describe the Baum-Welch algorithm, (also known as
Forward-Backward algorithm), we need to define two more auxiliary
variables, in addition to the forward and backward variables
defined in a previous section. These variables can however be
expressed in terms of the forward and backward variables.
[0216] First one of those variables is defined as the probability
of being in state i at t=t and in state j at t=t+1. Formally,
.xi..sub.t(i,j)=p{q.sub.t=i,q.sub.t+1=j|O,.lamda.} (1.10)
[0217] This is the same as,
.xi. t ( i , j ) = p { q t = i , q t + 1 = j , O .lamda. } p { O
.lamda. } ( 1.11 ) ##EQU00022##
[0218] Using forward and backward variables this can be expressed
as,
.xi. t ( i , j ) = .alpha. t ( i ) .alpha. i , j .beta. t + 1 ( j )
b j ( o t + 1 ) i = 1 N j = 1 N .alpha. t ( i ) .alpha. i , j
.beta. t + 1 ( j ) b j ( o t + 1 ) ( 1.12 ) ##EQU00023##
[0219] The second variable is the a posteriori probability,
.gamma..sub.t(i)=p{q.sub.t=i|O,.lamda.} (1.13)
[0220] that is the probability of being in state i at t=t, given
the observation sequence and the model. In forward and backward
variables this can be expressed by,
.gamma. t ( i ) = [ .alpha. t ( i ) .beta. t ( i ) i = 1 N .alpha.
t ( i ) .beta. t ( i ) ] ( 1.14 ) ##EQU00024##
[0221] One can see that the relationship between .gamma..sub.t(i)
and .xi..sub.t(i,j) is given by,
.gamma. t ( i ) = j = 1 N .xi. t ( i , j ) , 1 .ltoreq. i .ltoreq.
N , 1 .ltoreq. t .ltoreq. M ( 1.15 ) ##EQU00025##
[0222] Now it is possible to describe the Baum-Welch learning
process, where parameters of the HMM is updated in such a way to
maximize the quantity, p{O|.lamda.}. Assuming a starting model
.lamda.=(.LAMBDA., B, .pi.), we calculate the `.alpha.`s and
`.beta.`s using the recursions 1.5 and 1.2, and then `.xi.`s and
`.gamma.`s using 1.12 and 1.15. Next step is to update the HMM
parameters according to eqns 1.16 to 1.18, known as re-estimation
formulas.
.pi. _ i = .gamma. 1 ( i ) , 1 .ltoreq. i .ltoreq. N ( 1.16 ) a _
ij = t = 1 T - 1 .xi. t ( i , j ) t = 1 T - 1 .gamma. t ( i ) , 1
.ltoreq. i .ltoreq. N , 1 .ltoreq. j .ltoreq. N ( 1.17 ) b _ j ( k
) = ? = 1 O t = v k T .gamma. t ( j ) t = 1 T .gamma. t ( j ) , 1
.ltoreq. j .ltoreq. N , 1 .ltoreq. k .ltoreq. M ? indicates text
missing or illegible when filed ( 1.18 ) ##EQU00026##
[0223] These reestimation formulas can easily be modified to deal
with the continuous density case too.
[0224] Gradient Based Method
[0225] In the gradient based method, any parameter .theta. of the
HMM .lamda. is updated according to the standard formula,
.THETA. new = .THETA. old - .eta. [ .differential. J .differential.
.THETA. ] .THETA. = .THETA. old ( 1.19 ) ##EQU00027##
[0226] where J is a quantity to be minimized. We define in this
case,
J=E.sub.ML=-log(p{O|.lamda.})=-log(L.sub.tot) (1.20)
[0227] Since the minimization of J=E.sub.ML is equivalent to the
maximization of L.sub.tot, eqn. 1.19 yields the required
optimization criterion, ML. But the problem is to find the
derivative
.differential. J .differential. .THETA. ##EQU00028##
for any parameter .THETA. of the model. This can be easily done by
relating J to model parameters via L.sub.tot. As a key step to do
so, using the eqns. 1.7 and 1.9 we can obtain,
L tot = i = 1 N p { O , q t = i .lamda. } = i = 1 N .alpha. t ( i )
.beta. t ( i ) ( 1.21 ) ##EQU00029##
[0228] Differentiating the last equality in eqn. 1.20 with respect
to an arbitrary parameter .THETA.,
.differential. J .differential. .THETA. = - 1 L tot .differential.
L tot .differential. .THETA. ( 1.22 ) ##EQU00030##
[0229] Eqn. 1.22 gives
.differential. J .differential. , ##EQU00031##
if we know
.differential. L tot .differential. ##EQU00032##
which can be found using eqn. 1.21. However this derivative is
specific to the actual parameter concerned. Since there are two
main parameter sets in the HMM, namely transition probabilities
.alpha..sub.ij, 1.ltoreq.i,j.ltoreq.N and observation probabilities
b.sub.j(k), 1.ltoreq.j.ltoreq.N, 1.ltoreq.k.ltoreq.M, we can find
the derivative
.differential. L tot .differential. ##EQU00033##
for each of the parameter sets and hence the gradient,
.differential. J .differential. . ##EQU00034##
[0230] Gradient with Respect to Transition Probabilities
[0231] Using the chain rule,
.differential. L tot .differential. .alpha. ij = t = 1 T
.differential. L tot .differential. .alpha. t ( j ) .differential.
.alpha. t ( j ) .differential. .alpha. ij ( 1.23 ) ##EQU00035##
[0232] By differentiating eqn. 1.21 with respect to
.alpha..sub.t(j) we get,
.differential. L tot .differential. .alpha. t ( j ) = .beta. t ( j
) , ( 1.24 ) ##EQU00036##
[0233] and differentiating (a time shifted version of) eqn 1.2 with
respect to .alpha..sub.ij
.differential. .alpha. t ( j ) .differential. .alpha. ij = b j ( o
t ) .alpha. t - 1 ( i ) ( 1.25 ) ##EQU00037##
[0234] Eqns. 1.23, 1.24 and 1.25 give,
.differential. L tot .differential. .alpha. ij , ##EQU00038##
and substituting this quantity in eqn. 1.22 (keeping in mind that
.THETA.=.alpha..sub.ij in this case), we get the required
result,
.differential. J .differential. .alpha. ij = - 1 L tot t = 1 T
.beta. t ( j ) b j ( o t ) a t - 1 ( i ) ( 1.26 ) ##EQU00039##
[0235] Gradient with Respect to Observation Probabilities
[0236] Using the chain rule,
.differential. L tot .differential. b j ( o t ) = .differential. L
tot .differential. .alpha. t ( j ) .differential. a t ( j )
.differential. b j ( o t ) ( 1.27 ) ##EQU00040##
[0237] Differentiating (a time shifted version of) the eqn. 1.2
with respect to b.sub.j(O.sub.t)
.differential. a t ( j ) .differential. b j ( o t ) = a t ( j ) b j
( o t ) ( 1.28 ) ##EQU00041##
[0238] Finally we get the required probability, by substituting
for
.differential. L tot .differential. b j ( o t ) ##EQU00042##
in eqn. 1.22 (keeping in mind that .THETA.=b.sub.j(o.sub.t) in this
case), which is obtained by substituting eqns. 1.28 and 1.24 in
eqn. 1.27.
.differential. J .differential. b j ( o t ) = - 1 L tot a t ( j )
.beta. t ( j ) b j ( o t ) , ( 1.29 ) ##EQU00043##
[0239] Usually this is given the following form, by first
substituting for L.sub.tot, from eqn. 1.21 and then substituting
from eqn. 1.14.
.differential. J .differential. b j ( o t ) = - .gamma. t ( j ) b j
( o t ) , ( 1.30 ) ##EQU00044##
[0240] If the continuous densities are used then
.differential. J .differential. c j m , .differential. J
.differential. .mu. j m and .differential. J .differential. .SIGMA.
j m ##EQU00045##
can be found by further propagating the derivative
.differential. J .differential. b j ( O i ) ##EQU00046##
using the chain rule. The same method can be used to propagate the
derivative (if necessary) to a front end processor of the HMM. This
will be discussed in detail later.
[0241] Maximum Mutual Information (MMI) Criterion
[0242] In ML we optimize an HMM of only one class at a time, and do
not touch the HMMs for other classes at that time. This procedure
does not involve the concept "discrimination" which is of great
interest in Pattern Recognition. Thus the ML learning procedure
gives a poor discrimination ability to the HMM system, specially
when the estimated parameters (in the training phase) of the HMM
system do not match with the inputs used in the recognition phase.
This type of mismatches can arise due to two reasons. One is that
the training and recognition data may have considerably different
statistical properties, and the other is the difficulties of
obtaining reliable parameter estimates in the training.
[0243] The MMI criterion on the other hand consider HMMs of all the
classes simultaneously, during training. Parameters of the correct
model are updated to enhance it's contribution to the observations,
while parameters of the alternative models are updated to reduce
their contributions. This procedure gives a high discriminative
ability to the system and thus MMI belongs to the so called
"discriminative training" category.
[0244] In order to have a closer look at the MMI criterion,
consider a set of HMMs
.LAMBDA.={.lamda..sub.v,1.ltoreq.v.ltoreq.V}.
[0245] The task is to minimize the conditional uncertainty of a
class v of utterances given an observation sequence O* of that
class. This is equivalent minimize the conditional information,
I(v|O*,.LAMBDA.)=-log p{v|O*,.LAMBDA.} (1.31)
[0246] with respect to .LAMBDA..
[0247] In an information theoretical frame work this leads to the
minimization of conditional entropy, defined as the expectation
(E(.cndot.)) of the conditional information I,
H(V|O)=E[I(v|O*)]. (1.32)
[0248] where V represents all the classes and O represents all the
observation sequences. Then the mutual information between the
classes and observations,
H(V,O)=H(V)-H(V|O) (1.33)
[0249] become maximized; provided H(V) is constant. This is the
reason for calling it Maximum Mutual Information (MMI) criterion.
The other name of the method, Maximum A Posteriori (MAP) has the
roots in eqn. 1.31 where the a posteriori probability
p{v|O*,.LAMBDA.} is maximized.
[0250] Even though the eqn. 1.31 defines the MMI criterion, it can
be rearranged using the Bayes theorem to obtain a better insight,
as in eqn. 1.34.
E MMI = - log p { v | O ^ , A } = - log p { v , O ^ | A } p { O ^ |
A } = - log p { v , O ^ | A } w p { w , O ^ | A } ( 1.34 )
##EQU00047##
[0251] where w represents an arbitrary class.
[0252] If we use an analogous notation as in eqn. 1.9, we can write
the likelihoods,
L tot clamped = p { v , O ^ | .lamda. } ( 1.35 ) L tot free = w p {
w , O ^ | .lamda. } ( 1.36 ) ##EQU00048##
[0253] In the above equations the superscripts clamped and free are
used to imply the correct class and all the other classes
respectively.
[0254] If we substitute eqns. 1.35 and 1.36 in the eqn. 1.34, we
get,
E MMI = - log L tot clamped L tot free ( 1.37 ) ##EQU00049##
[0255] As in the case of ML re-estimation .quadrature. or gradient
methods can be used to minimize the quantity E.sub.MMI. In the
following a gradient based method, which again makes use of the
eqn. 1.19, is described.
[0256] Since E.sub.MMI is to be minimized, in this case
J=E.sub.MMI,
[0257] and therefore J is directly given by eqn. 1.37. The problem
then simplifies to the calculation of gradients
.differential. J .differential. .THETA. , ##EQU00050##
where .THETA. is an arbitrary parameter of the whole set of HMMs,
.LAMBDA.. This can be done by differentiating 1.37 with respect to
.THETA.,
.differential. J .differential. .THETA. = 1 L tot free
.differential. L tot free .differential. .THETA. - 1 L tot clamped
.differential. L tot clamped .differential. .THETA. ( 1.38 )
##EQU00051##
[0258] The same technique, as in the case of ML, can be used to
compute the gradients of the likelihoods with respect to the
parameters. As a first step likelihoods from eqns. 1.35 and 1.36,
are expressed in terms of forward and backward variables using the
form as in eqn. 1.7.
L tot clamped = i .di-elect cons. class v .alpha. t ( i ) .beta. t
( i ) ( 1.39 ) L tot free = w i .di-elect cons. class w .alpha. t (
i ) .beta. t ( i ) ( 1.40 ) ##EQU00052##
[0259] Then the required gradients can be found by differentiating
eqns. 1.39 and 1.40. But we consider two cases; one for the
transition probabilities and another for the observation
probabilities, similar to the case of ML.
[0260] Maximum Mutual Information (MMI) Criterion
[0261] The MMI criterion considers HMMs of all the classes
simultaneously, during training. Parameters of the correct model
are updated to enhance it's contribution to the observations, while
parameters of the alternative models are updated to reduce their
contributions. This procedure gives a high discriminative ability
to the system and thus MMI belongs to the so called "discriminative
training" category.
[0262] In order to have a closer look at the MMI criterion,
consider a set of HMMs
.LAMBDA.={.lamda..sub.v,1.ltoreq.v.ltoreq.V}.
[0263] The task is to minimize the conditional uncertainty of a
class v of utterances given an observation sequence O* of that
class. This is equivalent minimize the conditional information,
I(v|O*,.LAMBDA.)=-log p{v|O*,.LAMBDA.} (1.31)
[0264] with respect to .LAMBDA..
In an information theoretical frame work this leads to the
minimization of conditional entropy, defined as the expectation
(E(.cndot.)) of the conditional information I,
H(V|O)=E[I(v|O*)] (1.32)
[0265] where V represents all the classes and O represents all the
observation sequences. Then the mutual information between the
classes and observations,
H(V,O)=H(V)-H(V|O) (1.33)
[0266] become maximized; provided H(V) is constant. This is the
reason for calling it Maximum Mutual Information (MMI) criterion.
The other name of the method, Maximum A Posteriori (MAP) has the
roots in eqn. 1.31 where the a posteriori probability
p{v|O*,.LAMBDA.} is maximized.
[0267] Even though the eqn. 1.31 defines the MMI criterion, it can
be rearranged using the Bayes theorem to obtain a better insight,
as in eqn. 1.34.
E MMI = - log p { v | O ^ , A } = - log p { v , O ^ | A } p { O ^ |
A } = - log p { v , O ^ | A } w p { w , O ^ | A } ( 1.34 )
##EQU00053##
[0268] where w represents an arbitrary class.
[0269] If we use an analogous notation as in eqn. 1.9, we can write
the likelihoods,
L tot clamped = p { v , O ^ | .lamda. } ( 1.35 ) L tot free = w p {
w , O ^ | .lamda. } ( 1.36 ) ##EQU00054##
[0270] In the above equations the superscripts clamped and free are
used to imply the correct class and all the other classes
respectively.
[0271] If we substitute eqns. 1.35 and 1.36 in the eqn. 1.34, we
get,
E MMI = - log L tot clamped L tot free ( 1.37 ) ##EQU00055##
[0272] As in the case of ML re-estimation .quadrature. or gradient
methods can be used to minimize the quantity E.sub.MMI. In the
following a gradient based method, which again makes use of the
eqn. 1.19, is described.
[0273] Since E.sub.MMI is to be minimized, in this case
J=E.sub.MMI,
[0274] and therefore J is directly given by eqn. 1.37. The problem
then simplifies to the calculation of gradients
.differential. J .differential. .THETA. , ##EQU00056##
where .THETA. is an arbitrary parameter of the whole set of HMMs,
.LAMBDA.. This can be done by differentiating 1.37 with respect to
.THETA.,
.differential. J .differential. .THETA. = 1 L tot free
.differential. L tot free .differential. .THETA. - 1 L tot clamped
.differential. L tot clamped .differential. .THETA. ( 1.38 )
##EQU00057##
[0275] The same technique, as in the case of ML, can be used to
compute the gradients of the likelihoods with respect to the
parameters. As a first step likelihoods from eqns. 1.35 and 1.36,
are expressed in terms of forward and backward variables using the
form as in eqn. 1.7.
L tot clamped = i .di-elect cons. class v .alpha. t ( i ) .beta. t
( i ) ( 1.39 ) L tot free = w i .di-elect cons. class w .alpha. t (
i ) .beta. t ( i ) ( 1.40 ) ##EQU00058##
[0276] Then the required gradients can be found by differentiating
eqns. 1.39 and 1.40. But we consider two cases; one for the
transition probabilities and another for the observation
probabilities, similar to the case of ML.
[0277] Gradient with Respect to Transition Probabilities
[0278] Using the chain rule for any of the likelihoods, free or
clamped,
.differential. L tot ( ) .differential. a i j = t = 1 T
.differential. L tot ( ) .differential. .alpha. t ( j )
.differential. .alpha. t ( j ) .differential. a i j ( 1.41 )
##EQU00059##
[0279] Differentiating eqns. 1.39 and 1.40 with respect to
.alpha..sub.t(j), to get two results for free and clamped cases and
using the common result in eqn. 1.25, we get substitutions for both
terms on the right hand side of eqn. 1.41. This substitution yields
two separate results for free and clamped cases.
.differential. L tot clamped .differential. a i j = .delta. k v t =
1 T .beta. t ( j ) b j ( o t ) .alpha. t - 1 ( i ) , i .di-elect
cons. class k ( 1.42 ) ##EQU00060##
[0280] where .delta..sub.kv is a Kronecker delta.
.differential. L tot free .differential. a i j = t = 1 T .beta. t (
j ) b j ( o t ) .alpha. t - 1 ( i ) ( 1.43 ) ##EQU00061##
[0281] Substitution of eqns. 1.42 and 1.43 in the eqn. 1.38
(keeping in mind that .THETA.=.alpha..sub.ij in this case) gives
the required result,
.differential. J .differential. a i j = [ 1 L tot free - .delta. k
v L tot clamped ] t = 1 T .beta. t ( j ) b j ( o t ) .alpha. t - 1
( i ) , i .di-elect cons. class k ( 1.44 ) ##EQU00062##
[0282] Gradient with Respect to Observation Probabilities
[0283] Using the chain rule for any of the likelihoods, free or
clamped,
.differential. L tot ( ) .differential. b j ( o t = .differential.
L tot ( ) .differential. .alpha. t ( j ) .differential. .alpha. t (
j ) .differential. b j ( o t ( 1.45 ) ##EQU00063##
[0284] Differentiating eqns. 1.39 and 1.40 with respect to
.alpha..sub.t(j), to get two results for free and clamped cases,
and using the common result in eqn. 1.28, we get substitutions for
both terms on the right hand side of eqn. 1.45. This substitution
yields two separate results for free and clamped cases.
.differential. L tot clamped .differential. b j ( o t ) = .delta. k
v .alpha. t ( j ) .beta. t ( j ) b j ( o t ) , j .di-elect cons.
class k ( 1.46 ) ##EQU00064##
[0285] where .delta..sub.kv is a Kronecker delta. And
.differential. L tot free .differential. b j ( o t ) = .alpha. t (
j ) .beta. t ( j ) b j ( o t ) ( 1.47 ) ##EQU00065##
[0286] Substitution of eqns. 1.46 and 1.47 in eqn. 1.38 we get the
required result,
.differential. J .differential. b j ( o t ) = [ 1 L tot free -
.delta. kv L tot clamped ] .alpha. t ( j ) .beta. t ( j ) b j ( o t
) , j .di-elect cons. class k ( 1.48 ) ##EQU00066##
[0287] This equation can be given a more aesthetic form by
defining,
.gamma. t ( j ) clamped = .delta. k v .alpha. t ( j ) .beta. t ( j
) L tot clamped , j .di-elect cons. class k ( 1.49 )
##EQU00067##
[0288] where .delta..sub.kv is a Kronecker delta, and
.gamma. t ( j ) free = .alpha. t ( j ) .beta. t ( j ) L tot clamped
. ( 1.50 ) ##EQU00068##
[0289] With these variables we express the eqn. 1.48 in the
following form.
.differential. J .differential. b j ( o t ) = 1 b j ( o t ) [
.gamma. t ( j ) free - .gamma. t ( j ) clamped ] ( 1.51 )
##EQU00069##
[0290] This equation completely defines the update of observation
probabilities. If however continuous densities are used then we can
further propagate this derivative using the chain rule, in exactly
the same way as mentioned in the case ML. A similar comments are
valid also for preprocessors.
[0291] Training
[0292] We assume that the preprocessing part of the system gives
out a sequence of observation vectors
O={o.sub.1,o.sub.2, . . . , o.sub.N}.
[0293] Starting from a certain set of values, parameters of each of
the HMMs
.lamda..sub.i,1.ltoreq.i.ltoreq.N
[0294] can be updated as given by the eqn. 1.19, while the required
gradients will be given by eqns. 1.44 and 1.48. However for this
particular case, isolated recognition, likelihoods in the last two
equations are calculated in a peculiar way.
First consider the clamped case. Since we have an HMM for each
class of units in isolated recognition, we can select the model
.lamda..sub.t of the class I to which the current observation
sequence O.sup.1 belongs. Then starting from eqn. 1.39,
L tot clamped = L l l = i .di-elect cons. .lamda. t .alpha. t ( i )
.beta. t ( i ) = i .di-elect cons. .lamda. t .alpha. T ( i ) ( 1.52
) ##EQU00070##
[0295] where the second line follows from eqn. 1.3.
[0296] Similarly for the free case, starting from eqn. 1.40,
L tot free = m = 1 N L m l = m = 1 N [ i .di-elect cons. .lamda. m
.alpha. t ( i ) .beta. t ( i ) ] = m = 1 N i .di-elect cons.
.lamda. m .alpha. T ( i ) ( 1.53 ) ##EQU00071##
[0297] where L.sub.m.sup.I represents the likelihood of the current
observation sequence belonging to class I, in the model
.lamda..sub.m. With those likelihoods defined in eqns. 1.52 and
1.53, the gradient giving equations 1.44 and 1.48 will take the
forms,
.differential. J .differential. a i j = [ 1 m = 1 N L m l - .delta.
k l L l l ] t = 1 T .beta. t ( j ) b j ( o t ) .alpha. t - 1 ( i )
, i , j .di-elect cons. .lamda. k ( 1.54 ) .differential. J
.differential. b j ( o t ) = [ 1 m = 1 N L m l - .delta. k l L l l
] .alpha. t ( j ) .beta. t ( j ) b j ( o t ) , j .di-elect cons.
.lamda. k ( 1.55 ) ##EQU00072##
[0298] Now we can summarize the training procedure as follows.
[0299] (1) Initialize the each HMM, .lamda..sub.i=(.LAMBDA..sub.i,
B.sub.i, .pi..sub.i), 1.ltoreq.i.ltoreq.N with values generated
randomly or using an initialization algorithm like segmental K
means
[http://jedlik.phy.bme.hu/.about.gerjanos/HMM/node19.html--r4#r4].
[0300] (2) Take an observation sequence and [0301] Calculate the
forward and backward probabilities for each HMM, using the
recursions 1.5 and 1.2. [0302] Using the equations 1.52 and 1.53
calculate the likelihoods [0303] Using the equations 1.54 and 1.55
calculate the gradients with respect to parameters for each model
[0304] Update parameters in each of the models using the eqn.
1.19.
[0305] (3) Go to step (2), unless all the observation sequences are
considered.
[0306] (4) Repeat step (2) to (3) until a convergence criterion is
satisfied.
[0307] This procedure can easily be modified if the continuous
density HMMs are used, by propagating the gradients via chain rule
to the parameters of the continuous probability distributions.
Further it is worth to mention that preprocessors can also be
trained simultaneously, with such a further back propagation.
[0308] Recognition
[0309] Comparative to the training, recognition is much simpler and
the procedure is given below.
[0310] (1) Take an observation sequence to be recognized and [0311]
Calculate the forward and backward probabilities for each HMM,
using the recursions 1.5 and 1.2. [0312] As in the equation 1.53
calculate the likelihoods, L.sub.m.sup.t, 1.ltoreq.m.ltoreq.N
[0313] The recognized class l*, to which the observation sequence
belongs, is given by
[0313] l * = arg max 1 .ltoreq. m .ltoreq. N L m l .
##EQU00073##
[0314] (3) Go to step (2), unless all the observation sequences to
be recognized are considered.
[0315] The recognition rate in this case can be calculated as the
ratio between number of correctly recognized speech units and total
number of speech units (observation sequences) to be
recognized.
[0316] Use of Fourier Transform in Pre-Processing
[0317] The Hartley Transform is an integral transform which shares
some features with the Fourier Transform, but which (in the
discrete case), multiplies the kernel by
cos ( 2 .pi. k n N ) - sin ( 2 .pi. k n N ) 1 ) ##EQU00074##
[0318] instead of
- 2 .pi. i k n = cos ( 2 .pi. k n N ) - i sin ( 2 .pi. k n N ) . 2
) ##EQU00075##
[0319] The Hartley transform produces real output for a real input,
and is its own inverse. It therefore can have computational
advantages over the discrete Fourier transform, although analytic
expressions are usually more complicated for the Hartley
transform.
[0320] The discrete version of the Hartley transform can be written
explicitly as
[ a ] : 1 N n = 0 N - 1 a n [ cos ( 2 .pi. k n N ) - sin ( 2 .pi. k
n N ) ] 3 ) : [ a ] - [ a ] , 4 ) ##EQU00076##
[0321] where denotes the Fourier Transform. The Hartley transform
obeys the convolution property
[ a * b ] k = 1 2 ( A k B k - A _ k B _ k + A k B _ k + A _ k B k )
, 5 ) ##EQU00077##
[0322] where
.sub.0.ident.a.sub.0 6)
.sub.n/2.ident.a.sub.n/2 7)
.sub.k.ident.a.sub.n-k 8)
(Arndt). Like the fast Fourier Transform algorithm, there is a
"fast" version of the Hartley transform algorithm. A decimation in
time algorithm makes use of
.sub.n.sup.left[a]=.sub.n/2[a.sup.even]+X.sub.n/2[a.sup.odd] 9)
.sub.n.sup.right[a]=.sub.n/2[a.sup.even]-X.sub.n/2[a.sup.odd],
10)
[0323] where X denotes the sequence with elements
a n cos ( .pi. n N ) - a _ n sin ( .pi. n N ) . 11 )
##EQU00078##
[0324] A decimation in frequency algorithm makes use of
.sub.n.sup.even[a]=.sub.n/2[a.sup.left+a.sup.right], 12)
.sub.n.sup.odd[a]=.sub.n/2[X(a.sup.left-a.sup.right)]. 13)
[0325] The discrete Fourier transform
A k .ident. [ a ] = n = 0 N - 1 - 2 .pi. i k n / N a n 14 )
##EQU00079##
[0326] can be written
[ A k A - l n = 0 N - 1 [ - 2 .pi. i k n / N 0 0 2 .pi. i k n / N ]
F [ a n a n ] 15 ) n = 0 N - 1 1 2 [ 1 - i 1 + i 1 + i 1 - i ] T -
1 [ cos ( 2 .pi. k n N ) sin ( 2 .pi. k n N ) - sin ( 2 .pi. k n N
) cos ( 2 .pi. k n N ) ] H 1 2 [ 1 + i 1 - i 1 - i 1 + i ] T [ a n
a n ] , so F = T - 1 H T . 16 ) ##EQU00080##
[0327] See, http://mathworld.wolfram.com/HartleyTransform.html.
[0328] A Hartley transform based fixed pre-processing may be
considered, on some bases, inferior to that based on Fourier
transform. One explanation for this is based on the respective
symmetries and shift invariance properties. Therefore we expect
improved performances from Fourier transform even when the
pre-processing is adaptive. However a training procedure which
preserves the symmetries of weight distributions must be used. Main
argument of the use of Hartley transform is to avoid the complex
weights. A Fourier transform, however, can be implemented as a
neural network containing real weights, but with a slightly
modified network structure than the usual MLP. We can easily derive
the equations which give the forward and backward pass.
[0329] Forward pass is given by,
[ i = 0 N - 1 x t ( i ) cos ( 2 .pi. i j N ) ] 2 + [ i = 0 N - 1 x
t ( i ) sin ( 2 .pi. i j N ) ] 2 = X ~ t 2 ( j ) ( 2.1 )
##EQU00081##
[0330] where N denotes the window length, and
X.sub.t(j)=|X.sub.t(j)|
[0331] If we use the notation
.theta. i j = 2 .pi. i j N , ##EQU00082##
[0332] and error is denoted by J, then we can find
.differential. J .differential. .theta. i j ##EQU00083##
simply by using the chain rule,
.differential. J .differential. .theta. i j = t = 1 T
.differential. J .differential. X ~ t 2 ( j ) .differential. X ~ t
2 ( j ) .differential. .theta. i j ( 2.2 ) ##EQU00084##
[0333] We assume that
.differential. J .differential. X ~ t 2 ( j ) ##EQU00085##
is known and
.differential. X ~ t 2 ( j ) .differential. .theta. i j
##EQU00086##
can simply be found by differentiating eqn. 2.1 with respect to
.theta..sub.ij. Thus we get,
.differential. X ~ t 2 ( j ) .differential. .theta. i j = 2 x t ( i
) cos ( .theta. i j ) k = 1 N - 1 x t ( k ) sin ( .theta. k j ) - 2
x t ( i ) sin ( .theta. i j ) k = 1 N - 1 x t ( k ) cos ( .theta. k
j ) ( 2.3 ) ##EQU00087##
[0334] Eqns. 2.2 and 2.3 define the backward pass. Note that
.theta..sub.ij can be further back propagated as usual.
[0335] Training Procedure which Preserves Symmetry
[0336] We can use a training procedure which preserves symmetrical
distribution of weights in the Hartley or Fourier transform stages.
In addition to the improved shift invariance, this approach can
lead to parameter reduction. The procedure starts by noting the
equal weights at initialization. Then the forward and backward
passes are performed as usual. But in updating we use the same
weight update for all the equal weights, namely the average value
of all the weight updates corresponding to the equal weights. In
this way we can preserve any existing symmetry in the initial
weight distributions. At the same time number of parameters is
reduced because only one parameter is needed to represent the whole
class of equal weights.
[0337] See, "A Hybrid ANN-HMM ASR system with NN based adaptive
preprocessing", Narada Dilp Warakagoda, M. Sc. thesis (Norges
Tekniske Hogskole, Institutt for Teleteknikk Transmisjonsteknikk),
http://jedlik.phy.bme.hu/.about.gerjanos/HMM/hoved.html.
[0338] As al alternate to the Hartley transform, a Wavelet
transform may be applied.
[0339] The fast Fourier transform (FFT) and the discrete wavelet
transform (DWT) are both linear operations that generate a data
structure that contains segments of various lengths, usually
filling and transforming it into a different data vector of
length.
[0340] The mathematical properties of the matrices involved in the
transforms are similar as well. The inverse transform matrix for
both the FFT and the DWT is the transpose of the original. As a
result, both transforms can be viewed as a rotation in function
space to a different domain. For the FFT, this new domain contains
basis functions that are sines and cosines. For the wavelet
transform, this new domain contains more complicated basis
functions called wavelets, mother wavelets, or analyzing
wavelets.
[0341] Both transforms have another similarity. The basis functions
are localized in frequency, making mathematical tools such as power
spectra (how much power is contained in a frequency interval) and
scalegrams (to be defined later) useful at picking out frequencies
and calculating power distributions.
[0342] The most interesting dissimilarity between these two kinds
of transforms is that individual wavelet functions are localized in
space. Fourier sine and cosine functions are not. This localization
feature, along with wavelets' localization of frequency, makes many
functions and operators using wavelets "sparse" when transformed
into the wavelet domain. This sparseness, in turn, results in a
number of useful applications such as data compression, detecting
features in images, and removing noise from time series.
[0343] One way to see the time-frequency resolution differences
between the Fourier transform and the wavelet transform is to look
at the basis function coverage of the time-frequency plane.
[0344] In a windowed Fourier transform, where the window is simply
a square wave, the square wave window truncates the sine or cosine
function to fit a window of a particular width. Because a single
window is used for all frequencies in the WFT, the resolution of
the analysis is the same at all locations in the time-frequency
plane.
[0345] An advantage of wavelet transforms is that the windows vary.
In order to isolate signal discontinuities, one would like to have
some very short basis functions. At the same time, in order to
obtain detailed frequency analysis, one would like to have some
very long basis functions. A way to achieve this is to have short
high-frequency basis functions and long low-frequency ones. This
happy medium is exactly what you get with wavelet transforms.
[0346] One thing to remember is that wavelet transforms do not have
a single set of basis functions like the Fourier transform, which
utilizes just the sine and cosine functions. Instead, wavelet
transforms have an infinite set of possible basis functions. Thus
wavelet analysis provides immediate access to information that can
be obscured by other time-frequency methods such as Fourier
analysis.
[0347] Wavelet transforms comprise an infinite set. The different
wavelet families make different trade-offs between how compactly
the basis functions are localized in space and how smooth they
are.
[0348] Some of the wavelet bases have fractal structure. The
Daubechies wavelet family is one example.
[0349] Within each family of wavelets (such as the Daubechies
family) are wavelet subclasses distinguished by the number of
coefficients and by the level of iteration. Wavelets are classified
within a family most often by the number of vanishing moments. This
is an extra set of mathematical relationships for the coefficients
that must be satisfied, and is directly related to the number of
coefficients. For example, within the Coiflet wavelet family are
Coiflets with two vanishing moments, and Coiflets with three
vanishing moments.
[0350] The Discrete Wavelet Transform
[0351] Dilations and translations of the "Mother function," or
"analyzing wavelet" .PHI.(x) define an orthogonal basis, our
wavelet basis:
.PHI. ( s l ) ( x ) = 2 - s 2 .PHI. ( 2 - s x - l ) ( 3 )
##EQU00088##
[0352] The variables s and l are integers that scale and dilate the
mother function .PHI.(x) to generate wavelets, such as a Daubechies
wavelet family. The scale index s indicates the wavelet's width,
and the location index l gives its position. Notice that the mother
functions are rescaled, or "dilated" by powers of two, and
translated by integers. What makes wavelet bases especially
interesting is the self-similarity caused by the scales and
dilations. Once we know about the mother functions, we know
everything about the basis. Note that the scaling-by-two is a
feature of the Discrete Wavelet Transform (DWT), and is not,
itself, compelled by Wavelet theory. That is, while it is
computationally convenient to employ a binary tree, in theory, if
one could define a precise wavelet that corresponds to a feature of
a data set to be processed, this wavelet could be directly
extracted. Clearly, the utility of the DWT is its ability to handle
general cases without detailed pattern searching, and therefore the
more theoretical wavelet transform techniques based on precise
wavelet matching are often reserved for special cases. On the other
hand, by carefully selecting wavelet basis functions, or
combinations of basis functions, a very sparse representation of a
complex and multidimensional data space may be obtained. The
utility, however, may depend on being able to operate in the
wavelet transform domain (or subsequent transforms of the sparse
representation coefficients) for subsequent analysis. Note that,
while wavelets are generally represented as two dimensional
functions of amplitude and time, it is clear that wavelet theory
extends into n-dimensional space.
[0353] Thus, the advantageous application of wavelet theory is in
cases where a modest number of events, for example having
associated limited time and space parameters, are represented in a
large data space. If the events could be extracted with fair
accuracy, the data space could be replaced with a vector quantized
model (VQM), wherein the extracted events correspond to real
events, and wherein the VQM is highly compressed as compared to the
raw data space. Further, while there may be some data loss as a
result of the VQM expression, if the real data corresponds to the
wavelet used to model it, then the VQM may actually serve as a form
of error correction. Clearly, in some cases, especially where
events are overlapping, the possibility for error occurs. Further,
while the DWT is often useful in denoising data, in some cases,
noise may be inaccurately represented as an event, while in the raw
data space, it might have been distinguished. Thus, one aspect of a
denoised DWT representation is that there is an implicit
presumption that all remaining elements of the representation
matrix are signal.
[0354] A particular advantage of a DWT approach is that it
facilitates a multiresolution analysis of data sets. That is, if
decomposition of the raw data set with the basis function,
transformed according to a regular progressions, e.g., powers of 2,
then at each level of decomnposition, a level of scale is revealed
and presented. It is noted that the transform need not be a simple
power of two, and itself may be a function or complex and/or
multidimensional function. Typically, non-standard analyses are
reserved for instances where there is, or is believed to be, a
physical basis for the application of such functions instead of
binary splitting of the data space.
[0355] Proceeding with the DWT analysis, we span our data domain at
different resolutions, see
www.eso.org/projects/esomidas/doc/user/98NOV/volb/node308.html,
using the analyzing wavelet in a scaling equation:
W ( x ) = k = - 1 N - 2 ( - 1 ) k c k + 1 .PHI. ( 2 x + k ) ( 4 )
##EQU00089##
[0356] where W(x) is the scaling function for the mother function
.PHI.(x), and c.sub.k are the wavelet coefficients. The wavelet
coefficients must satisfy linear and quadratic constraints of the
form
k = 0 N - 1 c k = 2 , k = 0 N - 1 c k c k + 2 l = 2 .delta. l , 0
##EQU00090##
[0357] where .delta. is the delta function and l is the location
index.
[0358] One of the most useful features of wavelets is the ease with
which one can choose the defining coefficients for a given wavelet
system to be adapted for a given problem. In Daubechies' original
paper, I. Daubechies, "Orthonormal Bases of Compactly Supported
Wavelets," Comm. Pure Appl. Math., Vol 41, 1988, pp. 906-966, she
developed specific families of wavelet systems that were very good
for representing polynomial behavior. The Haar wavelet is even
simpler, and it is often used for educational purposes. (That is,
while it may be limited to certain classes of problems, the Haar
wavelet often produces comprehensible output which can be generated
into graphically pleasing results).
[0359] It is helpful to think of the coefficients {c.sub.0, . . . ,
c.sub.n} as a filter. The filter or coefficients are placed in a
transformation matrix, which is applied to a raw data vector. The
coefficients are ordered using two dominant patterns, one that
works as a smoothing filter (like a moving average), and one
pattern that works to bring out the data's "detail" information.
These two orderings of the coefficients are called a quadrature
mirror filter pair in signal processing parlance. A more detailed
description of the transformation matrix can be found in W. Press
et al., Numerical Recipes in Fortran, Cambridge University Press,
New York, 1992, pp. 498-499, 584-602.
[0360] To complete our discussion of the DWT, let's look at how the
wavelet coefficient matrix is applied to the data vector. The
matrix is applied in a hierarchical algorithm, sometimes called a
pyramidal algorithm. The wavelet coefficients are arranged so that
odd rows contain an ordering of wavelet coefficients that act as
the smoothing filter, and the even rows contain an ordering of
wavelet coefficient with different signs that act to bring out the
data's detail. The matrix is first applied to the original,
full-length vector. Then the vector is smoothed and decimated by
half and the matrix is applied again. Then the smoothed, halved
vector is smoothed, and halved again, and the matrix applied once
more. This process continues until a trivial number of
"smooth-smooth-smooth . . . " data remain. That is, each matrix
application brings out a higher resolution of the data while at the
same time smoothing the remaining data. The output of the DWT
consists of the remaining "smooth (etc.)" components, and all of
the accumulated "detail" components.
[0361] The Fast Wavelet Transform
[0362] If the DWT matrix is not sparse, so we face the same
complexity issues that we had previously faced for the discrete
Fourier transform. Wickerhauser, Adapted Wavelet Analysis from
Theory to Software, A K Peters, Boston, 1994, pp. 213-214, 237,
273-274, 387. We solve it as we did for the FFT, by factoring the
DWT into a product of a few sparse matrices using self-similarity
properties. The result is an algorithm that requires only order n
operations to transform an n-sample vector. This is the "fast" DWT
of Mallat and Daubechies.
[0363] Wavelet Packets
[0364] The wavelet transform is actually a subset of a far more
versatile transform, the wavelet packet transform. M. A. Cody, "The
Wavelet Packet Transform," Dr. Dobb's Journal, Vol 19, April 1994,
pp. 44-46, 50-54.
[0365] Wavelet packets are particular linear combinations of
wavelets. V. Wickerhauser, Adapted Wavelet Analysis from Theory to
Software, A K Peters, Boston, 1994, pp. 213-214, 237, 273-274, 387.
They form bases which retain many of the orthogonality, smoothness,
and localization properties of their parent wavelets. The
coefficients in the linear combinations are computed by a recursive
algorithm making each newly computed wavelet packet coefficient
sequence the root of its own analysis tree.
[0366] Adapted Waveforms
[0367] Because we have a choice among an infinite set of basis
functions, we may wish to find the best basis function for a given
representation of a signal. Wickerhauser, Id. A basis of adapted
waveform is the best basis function for a given signal
representation. The chosen basis carries substantial information
about the signal, and if the basis description is efficient (that
is, very few terms in the expansion are needed to represent the
signal), then that signal information has been compressed.
[0368] According to Wickerhauser, Id., some desirable properties
for adapted wavelet bases are
[0369] 1. speedy computation of inner products with the other basis
functions;
[0370] 2. speedy superposition of the basis functions;
[0371] 3. good spatial localization, so researchers can identify
the position of a signal that is contributing a large
component;
[0372] 4. good frequency localization, so researchers can identify
signal oscillations; and
[0373] 5. independence, so that not too many basis elements match
the same portion of the signal.
[0374] For adapted waveform analysis, researchers seek a basis in
which the coefficients, when rearranged in decreasing order,
decrease as rapidly as possible. to measure rates of decrease, they
use tools from classical harmonic analysis including calculation of
information cost functions. This is defined as the expense of
storing the chosen representation. Examples of such functions
include the number above a threshold, concentration, entropy,
logarithm of energy, Gauss-Markov calculations, and the theoretical
dimension of a sequence.
[0375] Multiresolution analysis results from the embedded subsets
generated by the interpolations at different scales.
[0376] A function f(x) is projected at each step j onto the subset
V.sub.j. This projection is defined by the scalar product
c.sub.j(k) of f(x) with the scaling function .phi.(x) which is
dilated and translated:
c.sub.j(k)=<f(x),2.sup.-j.phi.(2.sup.-jx-k)>
[0377] As .phi.(x) is a scaling function which has the
property:
1 2 .phi. ( x 2 ) = n h ( n ) .phi. ( x - n ) or .phi. ^ ( 2 v ) =
h ^ ( v ) .phi. ^ ( v ) ##EQU00091##
[0378] where h(v) is the Fourier transform of the function
.SIGMA..sub.nh(n).delta.(x-n). We get:
h ^ ( v ) = n h ( n ) - 2 .pi. n v ##EQU00092##
[0379] The property of the scaling function of .phi.(x) is that it
permits us to compute directly the set c.sub.j+1(k) from
c.sub.j(k). If we start from the set c.sub.0(k) we compute all the
sets c.sub.j(k), with j>0, without directly computing any other
scalar product:
c j + 1 ( k ) = n h ( n - 2 k ) c j ( n ) ##EQU00093##
[0380] At each step, the number of scalar products is divided by 2.
Step by step the signal is smoothed and information is lost. The
remaining information can be restored using the complementary
subspace W.sub.j+1 of V.sub.j+1 in V.sub.j. This subspace can be
generated by a suitable wavelet function .psi.(x) with translation
and dilation.
1 2 .psi. ( x 2 ) = n g ( n ) .phi. ( x - n ) or .psi. ^ ( 2 v ) =
g ^ ( v ) .phi. ^ ( v ) ##EQU00094##
[0381] We compute the scalar products <f(x),
2.sup.-(j+1).psi.(2.sup.-(j+1)x-k)> with:
w j + 1 ( k ) = n g ( n - 2 k ) c j ( n ) ##EQU00095##
[0382] With this analysis, we have built the first part of a filter
bank. In order to restore the original data, Mallat uses the
properties of orthogonal wavelets, but the theory has been
generalized to a large class of filters by introducing two other
filters {tilde over (h)} and {tilde over (g)} named conjugated to h
and g.
[0383] The restoration, that is, the inverse transform after
filtering in the transform domanin, is performed with:
c j ( k ) = 2 l [ c j + 1 ( l ) h ~ ( k + 2 l ) + w j + 1 ( l ) g ~
( k + 2 l ) ] ##EQU00096##
[0384] In order to get an exact restoration, two conditions are
required for the conjugate filters: [0385] Dealiasing
condition:
[0385] h ~ ( v + 1 2 ) h ~ ^ ( v ) + g ^ ( v + 1 2 ) g ~ ^ ( v ) =
0 ##EQU00097## [0386] Exact restoration:
[0386] h(v){tilde over (h)}(v)+ (v){tilde over ( )}(v)=1
[0387] In the decomposition, the function is successively convolved
with the two filters H (low frequencies) and G (high frequencies).
Each resulting function is decimated by suppression of one sample
out of two. The high frequency signal is left, and we iterate with
the low frequency signal. In the reconstruction, we restore the
sampling by inserting a 0 between each sample, then we convolve
with the conjugate filters {tilde over (H)} and {tilde over (G)},
we add the resulting functions and we multiply the result by 2. We
iterate up to the smallest scale.
[0388] Orthogonal wavelets correspond to the restricted case
where:
g ^ ( v ) = - 2 .pi. v h ^ * ( v + 1 2 ) ##EQU00098## h ~ ^ ( v ) =
h ^ * ( v ) ##EQU00098.2## g ~ ^ ( v ) = g ^ * ( v ) ##EQU00098.3##
and ##EQU00098.4## h ^ ( v ) 2 + h ^ ( v + 1 2 2 = 1
##EQU00098.5##
[0389] We can easily see that this set satisfies the dealiasing
condition and exact restoration condition. Daubechies wavelets are
the only compact solutions. For biorthogonal wavelets we have the
relations:
g ^ ( v ) = - 2 .pi. v h ~ ^ * ( v + 1 2 ) ##EQU00099## g ~ ^ ( v )
= 2 .pi. v h ^ * ( v + 1 2 ) ##EQU00099.2## and ##EQU00099.3## h ^
( v ) h ~ ^ ( v ) + h ^ * ( v + 1 2 ) h ~ ^ * ( v + 1 2 ) = 1
##EQU00099.4##
[0390] Which also satisfy the dealiasing condition and exact
restoration condition. A large class of compact wavelet functions
can be derived. Many sets of filters were proposed, especially for
coding. The choice of these filters must be guided by the
regularity of the scaling and the wavelet functions. The complexity
is proportional to N. The algorithm provides a pyramid of N
elements.
[0391] The 2D algorithm is based on separate variables leading to
prioritizing of x and y directions. The scaling function is defined
by:
.phi.(x,y)=.phi.(x).phi.(y)
[0392] The passage from a resolution to the next one is done
by:
f j + 1 ( k x , k y ) = l x = - .varies. + .varies. l y = -
.varies. + .varies. h ( l x - 2 k x ) h ( l y - 2 k y ) f i ( l x ,
l y ) ##EQU00100##
[0393] The detail signal is obtained from three wavelets:
[0394] a vertical wavelet: .psi..sup.1(x,y)=.phi.(x).psi.(y)
[0395] a horizontal wavelet: .psi..sup.2(x,y)=.psi.(x).phi.(y)
[0396] a diagonal wavelet: .psi..sup.3(x,y)=.psi.(x).psi.(y)
[0397] which leads to three sub-images:
C j + 1 1 ( k x , k y ) = l x = - .varies. + .varies. l y = -
.varies. + .varies. g ( l x - 2 k x ) h ( l y - 2 k y ) f j ( l x ,
l y ) C j + 1 2 ( k x , k y ) = l x = - .varies. + .varies. l y = -
.varies. + .varies. h ( l x - 2 k x ) g ( l y - 2 k y ) f j ( l x ,
l y ) C j + 1 3 ( k x , k y ) = l x = - .varies. + .varies. l y = -
.varies. + .varies. g ( l x - 2 k x ) g ( l y - 2 k y ) f j ( l x ,
l y ) ##EQU00101##
TABLE-US-00001 TABLE 1 Wavelet transform representation of an image
(two dimensional matrix) f.sup.(2) H.D. Horiz. Det. Horizontal
Details j = 2 j = 1 j = 0 V.D. D.D. j = 2 j = 2 Vert. Det. Diag.
Det. j = 1 j = 1 Vertical Details Diagonal Details j = 0 j = 0
[0398] The wavelet transform can be interpreted as the
decomposition on frequency sets with a spatial orientation.
[0399] The a Trous Algorithm
[0400] The discrete approach of the wavelet transform can be done
with the special version of the so-called a trous algorithm (with
holes). One assumes that the sampled data {c.sub.0(k)} are the
scalar products at pixels k of the function f(x) with a scaling
function .phi.(x) which corresponds to a low pass filter.
[0401] The first filtering is then performed by a twice magnified
scale leading to the {c.sub.1(k)} set. The signal difference
{c.sub.0(k)}-{c.sub.1(k)} contains the information between these
two scales and is the discrete set associated with the wavelet
transform corresponding to .phi.(x). The associated wavelet is
therefore .psi.(x).
1 2 .psi. ( x 2 ) = .phi. ( x ) - 1 2 .phi. ( x 2 )
##EQU00102##
[0402] The distance between samples increasing by a factor 2 from
the scale (i-1) (i>0) to the next one, c.sub.i(k) is given
by:
c i ( k ) = l h ( l ) c i - 1 ( k + 2 i - 1 l ) ##EQU00103##
[0403] and the discrete wavelet transform w.sub.i(k) by:
w.sub.i(k)=c.sub.i-1(k)-c.sub.i(k)
[0404] The coefficients {h(k)} derive from the scaling function
.phi.(x):
1 2 .phi. ( x 2 ) = l h ( l ) .phi. ( x - l ) ##EQU00104##
[0405] The algorithm allowing one to rebuild the data frame is
evident: the last smoothed array c.sub.mp is added to all the
differences w.sub.i.
c 0 ( k ) = c n p ( k ) j = 1 n p w j ( k ) ##EQU00105##
[0406] If we choose the linear interpolation for the scaling
function .phi.:
.phi.(x)=1-|x| if x.di-elect cons.[-1,1]
.phi.(x)=0 if x[-1,1]
[0407] we have:
1 2 .phi. ( x 2 ) = 1 4 .phi. ( x + 1 ) + 1 2 .phi. ( x ) + 1 4
.phi. ( x - 1 ) ##EQU00106##
[0408] c.sub.1 is obtained by:
c 1 ( k ) = 1 4 c 0 ( k - 1 ) + 1 2 c 0 ( k ) + 1 4 c 0 ( k + 1 )
##EQU00107##
[0409] and c.sub.j+1 is obtained from c.sub.j by:
c j + 1 ( k ) = 1 4 c j ( k - 2 j ) + 1 2 c j ( k ) + 1 4 c j ( k +
2 j ) ##EQU00108##
[0410] The wavelet coefficients at the scale j are:
C j + 1 ( k ) = - 1 4 c j ( k - 2 j ) + 1 2 c j ( k ) - 1 4 c j ( k
+ 2 j ) ##EQU00109##
[0411] The above a trous algorithm is easily extensible to the two
dimensional space. This leads to a convolution with a mask of
3.times.3. [0412] pixels for the wavelet connected to linear
interpolation. The coefficents of the mask are:
[0412] ( 1 16 1 8 1 16 1 8 1 4 1 8 1 16 1 8 1 16 ) ##EQU00110##
[0413] At each scale j, we obtain a set {w.sub.j(k,l)} (we will
call it wavelet plane in the following), which has the same number
of pixels as the image.
[0414] If we choose a B.sub.3-spline for the scaling function, the
coefficients of the convolution mask in one dimension are ( 1/16,
1/4, 3/8, 1/4, 1/16), and in two dimensions:
( 1 256 1 64 3 128 1 64 1 256 1 64 1 16 3 32 1 16 1 64 3 128 3 32 9
64 3 32 3 128 1 64 1 16 3 32 1 16 1 64 1 256 1 64 3 128 1 64 1 256
) ##EQU00111##
[0415] The Wavelet Transform Using the Fourier Transform
[0416] We start with the set of scalar products
c.sub.0(k)=<f(x), .phi.(x-k)>. If .phi.(x) has a cut-off
frequency
v c .ltoreq. 1 2 ##EQU00112##
the data are correctly sampled. The data at the resolution j=1
are:
c 1 ( k ) = f ( x ) , 1 2 .phi. ( x 2 - k ) ##EQU00113##
[0417] and we can compute the set c.sub.1(k) from c.sub.0(k) with a
discrete filter h(v):
h ^ ( v ) = { .phi. . ( 2 v ) .phi. ^ ( v ) if v < v c 0 if v c
.ltoreq. v < 1 2 and .A-inverted. v : .A-inverted. n h ^ ( v + n
) = h ^ ( v ) ##EQU00114##
[0418] where n is an integer. So:
c.sub.j+1(v)=c.sub.j(v)h(2.sup.jv)
[0419] The cut-off frequency is reduced by a factor 2 at each step,
allowing a reduction of the number of samples by this factor.
[0420] The wavelet coefficients at the scale j+1 are:
w.sub.j+1(k)=<f(x),2.sup.-(j+1).psi.(2.sup.-(j+1)x-k)>
[0421] and they can be computed directly from c.sub.j(k) by:
w.sub.j+1(v)=c.sub.j(v) (2.sup.jv)
[0422] where g is the following discrete filter:
g ^ ( v ) = { .psi. . ( 2 v ) .phi. ^ ( v ) if v < v c 1 if v c
.ltoreq. v < 1 2 and .A-inverted. v : .A-inverted. n g ^ ( v + n
) = g ^ ( v ) ##EQU00115##
[0423] The frequency band is also reduced by a factor 2 at each
step. Applying the sampling theorem, we can build a pyramid of
N + N 2 + + 1 = 2 N ##EQU00116##
elements. For an image analysis the number of elements is
4 3 N 2 . ##EQU00117##
The overdetermination is not very high.
[0424] The B-spline functions are compact in this directe space.
They correspond to the autoconvolution of a square function. In the
Fourier space we have:
B ^ l ( v ) = sin .pi. v l + 1 .pi. v ##EQU00118##
[0425] B.sub.3(x) is a set of 4 polynomials of degree 3. We choose
the scaling function .phi.(v) which has a B.sub.3(x) profile in the
Fourier space:
.phi. ^ ( v ) = 3 2 B 3 ( 4 v ) ##EQU00119##
[0426] In the direct space we get:
.phi. ( x ) = 3 8 [ sin .pi. x 4 .pi. x 4 ] 4 ##EQU00120##
[0427] This function is quite similar to a Gaussian one and
converges rapidly to 0. For 2-D the scaling function is defined
by
.phi. ^ ( u : v ) = 3 2 B 3 ( 4 r ) , ##EQU00121##
with r= {square root over ( )}(u.sup.2+v.sup.2). It is an isotropic
function.
[0428] The wavelet transform algorithm with n.sub.p scales is the
following one:
[0429] 1. We start with a B3-Spline scaling function and we derive
.psi., h and g numerically.
[0430] 2. We compute the corresponding image FFT. We name T.sub.0
the resulting complex array;
[0431] 3. We set j to 0. We iterate:
[0432] 4. We multiply T.sub.j by (2.sup.ju, 2.sup.jv). We get the
complex array W.sub.j+1. The inverse FFT gives the wavelet
coefficients at the scale 2.sup.j;
[0433] 5. We multiply T.sub.j by h(2.sup.ju, 2.sup.jv). We get the
array T.sub.j+1. Its inverse FFT gives the image at the scale
2.sup.j+1. The frequency band is reduced by a factor 2.
[0434] 6. We increment j
[0435] 7. If j.ltoreq.n.sub.p, we go back to 4.
[0436] 8. The set {w.sub.1, w.sub.2, . . . , w.sub.n.sub.p,
c.sub.n.sub.p} describes the wavelet transform.
[0437] If the wavelet is the difference between two resolutions, we
have:
{circumflex over (.psi.)}(2v)={circumflex over
(.phi.)}(v)-{circumflex over (.phi.)}(2v)
and:
(v)=1-h(v)
[0438] then the wavelet coefficients w.sub.j(v) can be computed by
c.sub.j-1(v)-c.sub.j(v).
[0439] The Reconstruction
[0440] If the wavelet is the difference between two resolutions, an
evident reconstruction for a wavelet transform W={w.sub.1, w.sub.2,
. . . , w.sub.n.sub.p, c.sub.n.sub.p} is:
c ^ 0 ( v ) = c ^ n p ( v ) + j w ^ j ( v ) ##EQU00122##
[0441] But this is a particular case and other wavelet functions
can be chosen. The reconstruction can be done step by step,
starting from the lowest resolution. At each scale, we have the
relations:
c.sub.j+1=h(2.sup.jv)c.sub.j(v)
w.sub.j+1= (2.sup.jv)c.sub.j(v)
[0442] we look for c.sub.j knowing c.sub.j+1, w.sub.j+1, h and g.
We restore c.sub.j(v) with a least mean square estimator:
{circumflex over
(p)}.sub.h(2.sup.jv)|c.sub.j+1(v)-h(2.sup.jv)c.sub.j(v)|.sup.2+{circumfle-
x over (p)}.sub.g(2.sup.jv)|w.sub.j+1(v)- (2.sup.jv)c.sub.j(v)
[0443] is minimum. {circumflex over (p)}.sub.h(v) and {circumflex
over (p)}.sub.g(v) are weight functions which permit a general
solution to the restoration of c.sub.j(v). By c.sub.j(v) derivation
we get:
c.sub.j(v)=c.sub.j+1(v){tilde over
(h)}(2.sup.jv)+w.sub.j+1(v){tilde over ( )}(2.sup.jv)
[0444] where the conjugate filters have the expression:
h ~ ^ ( v ) = p ^ h ( v ) h ^ * ( v ) p ^ h ( v ) h ^ ( v ) 2 + p ^
g ( v ) g ^ ( v ) 2 ##EQU00123## g ~ ^ ( v ) = p ^ g ( v ) g ^ * (
v ) p ^ h ( v ) h ^ ( v ) 2 + p ^ g ( v ) g ^ ( v ) 2
##EQU00123.2##
[0445] It is easy to see that these filters satisfy the exact
reconstruction equation. In fact, above pair of equations give the
general solution to this equation. In this analysis, the Shannon
sampling condition is always respected. No aliasing exists, so that
the dealiasing condition is not necessary (i.e., it is satisfied as
a matter of course).
[0446] The denominator is reduced if we choose:
(v)= {square root over (1-|h(v)|.sup.2)}
[0447] This corresponds to the case where the wavelet is the
difference between the square of two resolutions:
|{circumflex over (.psi.)}(2v)|.sup.2=|{circumflex over
(.phi.)}(v)|.sup.2-|{circumflex over (.phi.)}(2v)|.sup.2
[0448] The reconstruction algorithm is:
[0449] 1. We compute the FFT of the image at the low
resolution.
[0450] 2. We set j to n.sub.p. We iterate:
[0451] 3. We compute the FFT of the wavelet coefficients at the
scale j.
[0452] 4. We multiply the wavelet coefficients w.sub.j by {tilde
over ( )}.
[0453] 5. We multiply the image at the lower resolution c.sub.j by
{tilde over (h)}.
[0454] 6. The inverse Fourier Transform of the addition of
w.sub.j{tilde over ( )} and c.sub.i{tilde over (h)} gives the image
c.sub.j+1.
[0455] 7. j=j-1 and we go back to 3.
[0456] The use of a scaling function with a cut-off frequency
allows a reduction of sampling at each scale, and limits the
computing time and the memory size.
[0457] Thus, it is seen that the DWT is in many respects comparable
to the DFT, and, where convenient, may be employed in place
thereof. While substantial work has been done in the application of
wavelet analysis and filtering to image data, it is noted that the
wavelet transform analysis is not so limited. In particular, one
embodiment of the present invention applies the transform to
describe statistical events represented within a multidimensional
data-space. By understanding the multi-resolution
interrelationships of various events and probabilities of events,
in a time-space representation, a higher level analysis is possible
than with other common techniques. Likewise, because aspects of the
analysis are relatively content dependent, they may be accelerated
by digital signal processing techniques or array processors,
without need to apply artificial intelligence. On the other hand,
the transformed (and possibly filtered) data set, is advantageously
suitable for intelligent analysis, either by machine or human.
[0458] Generally, there will be no need to perform an inverse
transform on the data set. On the other hand, the wavelet analysis
may be useful for characterizing and analyzing only a limited range
of events. Advantageously, if an event is recognized with high
reliability within a transform domain, the event may be extracted
from the data representation and an inverse transform performed to
provide the data set absent the recognized feature or event. This
allows a number of different feature-specific transforms to be
conducted, and analyzed. This analysis may be in series, that is,
having a defined sequence of transforms, feature extractions, and
inverse transforms. On the other hand, the process may be performed
in parallel. That is, the data set is subjected to various "tests",
which are conducted by optimally transforming the data to determine
if a particular feature (event) is present, determined with high
reliability. As each feature is identified, the base data set may
be updated for the remaining "tests", which will likely simplify
the respective analysis, or improve the reliability of the
respective determination. As each event or feature is extracted,
the data set becomes simpler and simpler, until only noise
remains.
[0459] It should be noted that, in some instances, a high
reliability determination of the existence of an event cannot be
concluded. In those cases, it is also possible to perform a
contingent analysis, leading to a plurality of possible results for
each contingency. Thus, a putative feature is extracted or not
extracted from the data set and both results passed on for further
analysis. Where one of the contingencies is inconsistent with a
subsequent high reliability determination, that entire branch of
analysis may be truncated. Ideally, the output consists of a data
representation with probabilistic representation of the existence
of events or features represented within the data set. As discussed
below, this may form the basis for a risk-reliability output space
representation of the data, useable directly by a human (typically
in the form of a visual output) and/or for further automated
analysis.
[0460] It is also noted that the data set is not temporally static,
and therefore the analysis may be conducted in real time based on a
stream of data.
[0461] The Process to be Estimated
[0462] The Kalman filter addresses the general problem of trying to
estimate the state x.di-elect cons..sup.n of a discrete-time
controlled process that is governed by the linear stochastic
difference equation
x.sub.k=Ax.sub.k-1+Bu.sub.k+w.sub.k-1, (3.1)
[0463] with a measurement z.di-elect cons..sup.n that is
z.sub.k=Hx.sub.k+v.sub.k. (3.2)
[0464] The random variables w.sub.k and v.sub.k represent the
process and measurement noise (respectively). They are assumed to
be independent (of each other), white, and with normal probability
distributions
p(w)-N(0,Q), (3.3)
p(v)-N(0,R). (3.4)
[0465] In practice, the process noise covariance Q and measurement
noise covariance R matrices might change with each time step or
measurement, however here we assume they are constant.
[0466] Kalman, Rudolph, Emil, "New Approach to Linear Filtering and
Prediction Problems", Transactions of the ASME--Journal of Basic
Engineering, 82D:35-45 (1960) (describes the namesake Kalman
filter, which is a set of mathematical equations that provides an
efficient computational (recursive) solution of the least-squares
method. The filter is very powerful in several aspects: it supports
estimations of past, present, and even future states, and it can do
so even when the precise nature of the modeled system is
unknown.)
[0467] The n.times.n matrix A in the difference equation (3.1)
relates the state at the previous time step k-1 to the state at the
current step k, in the absence of either a driving function or
process noise. Note that in practice A might change with each time
step, but here we assume it is constant. The n.times.l matrix B
relates the optional control input k.di-elect cons..sup.j to the
state x. The m.times.n matrix H in the measurement equation (3.2)
relates the state to the measurement zk. In practice H might change
with each time step or measurement, but here we assume it is
constant.
[0468] The Computational Origins of the Filter
[0469] We define {circumflex over (x)}.sub.k.sup.-.di-elect
cons..sup.n (note the "super minus") to be our a priori state
estimate at step k given knowledge of the process prior to step k,
and {circumflex over (x)}.sub.k.di-elect cons..sup.n to be our a
posteriori state estimate at step k given measurement z.sub.k. We
can then define a priori and a posteriori estimate errors as
e.sup.-.sub.k.ident.x.sub.k-{circumflex over (x)}.sup.-.sub.k,
and
e.sub.k.ident.x.sub.k-{circumflex over (x)}.sub.k.
[0470] The a priori estimate error covariance is then
P.sup.-.sub.k=E[(e.sup.-.sub.ke.sup.-.sub.k.sup.T], (3.5)
[0471] and the a posteriori estimate error covariance is
P.sub.k=E[e.sub.ke.sub.k.sup.T]. (3.6)
[0472] In deriving the equations for the Kalman filter, we begin
with the goal of finding an equation that computes an a posteriori
state estimate {circumflex over (x)}.sub.k as a linear combination
of an a priori estimate {circumflex over (x)}.sup.-.sub.k and a
weighted difference between an actual measurement z.sub.k and a
measurement prediction H{circumflex over (x)}.sup.-.sub.k as shown
below in (3.7). Some justification for (3.7) is given in "The
Probabilistic Origins of the Filter" found below. See,
http://www.cs.unc.edu/.about.welch/kalman/kalman_filter/kalman-1.htm,
expressly incorporated herein by reference.
{circumflex over (x)}.sub.k={circumflex over
(x)}.sup.-.sub.k+K(z.sub.k-H{circumflex over (x)}.sup.-.sub.k)
(3.7)
[0473] The difference (z.sub.k-H{circumflex over (x)}.sup.-.sub.k)
in (3.7) is called the measurement innovation, or the residual. The
residual reflects the discrepancy between the predicted measurement
H{circumflex over (x)}.sup.-.sub.k and the actual measurement
z.sub.k. A residual of zero means that the two are in complete
agreement.
[0474] The n.times.m matrix K in (3.7) is chosen to be the gain or
blending factor that minimizes the a posteriori error covariance
(3.6). This minimization can be accomplished by first substituting
(3.7) into the above definition for e.sub.k, substituting that into
(3.6), performing the indicated expectations, taking the derivative
of the trace of the result with respect to K, setting that result
equal to zero, and then solving for K. For more details see
[Maybeck79; Brown92; Jacobs93]. One form of the resulting K that
minimizes (3.6) is given by
K k = P k - H T ( HP k - H T + R ) - 1 = P k - H T HP k - H T + R .
( 3.8 ) ##EQU00124##
[0475] Looking at (3.8) we see that as the measurement error
covariance R approaches zero, the gain K weights the residual more
heavily. Specifically,
lim k x .fwdarw. 0 K k = H - 1 . ##EQU00125##
[0476] On the other hand, as the a priori estimate error covariance
P.sup.-.sub.k approaches zero, the gain K weights the residual less
heavily. Specifically,
lim f x .alpha. .fwdarw. 0 K k = 0. ##EQU00126##
[0477] Another way of thinking about the weighting by K is that as
the measurement error covariance R approaches zero, the actual
measurement z.sub.k is "trusted" more and more, while the predicted
measurement H{circumflex over (x)}.sup.-.sub.k trusted less and
less. On the other hand, as the a priori estimate error covariance
P.sup.-.sub.k approaches zero the actual measurement z.sub.k is
trusted less and less, while the predicted measurement H{circumflex
over (x)}.sup.-.sub.k is trusted more and more.
[0478] The Probabilistic Origins of the Filter
[0479] The justification for (3.7) is rooted in the probability of
the a priori estimate {circumflex over (x)}.sup.-.sub.k conditioned
on all prior measurements z.sub.k (Bayes' rule). For now let it
suffice to point out that the Kalman filter maintains the first two
moments of the state distribution,
E[x.sub.k]={circumflex over (x)}.sub.k
E[(x.sub.k-{circumflex over (x)}.sub.k)(x.sub.k-{circumflex over
(x)}.sub.k).sup.T]=P.sub.k
[0480] The a posteriori state estimate (3.7) reflects the mean (the
first moment) of the state distribution--it is normally distributed
if the conditions of (3.3) and (3.4) are met. The a posteriori
estimate error covariance (3.6) reflects the variance of the state
distribution (the second non-central moment). In other words,
p ( x k | z k ) - N ( E [ x k ] , E [ ( x k - x ^ k ) ( x k - x ^ k
) T ] ) = N ( x ^ k P k ) . ##EQU00127##
[0481] For more details on the probabilistic origins of the Kalman
filter, see [Maybeck79; Brown92; Jacobs93].
[0482] The Discrete Kalman Filter Algorithm
[0483] The Kalman filter estimates a process by using a form of
feedback control: the filter estimates the process state at some
time and then obtains feedback in the form of (noisy) measurements.
As such, the equations for the Kalman filter fall into two groups:
time update equations and measurement update equations. The time
update equations are responsible for projecting forward (in time)
the current state and error covariance estimates to obtain the a
priori estimates for the next time step. The measurement update
equations are responsible for the feedback--i.e. for incorporating
a new measurement into the a priori estimate to obtain an improved
a posteriori estimate.
[0484] The time update equations can also be thought of as
predictor equations, while the measurement update equations can be
thought of as corrector equations. Indeed the final estimation
algorithm resembles that of a predictor-corrector algorithm for
solving numerical problems as shown below in FIG. 5, which shows
the ongoing discrete Kalman filter cycle. The time update projects
the current state estimate ahead in time. The measurement update
adjusts the projected estimate by an actual measurement at that
time.
[0485] The specific equations for the time and measurement updates
are presented below:
Discrete Kalman Filter Time Update Equations
[0486] {circumflex over (x)}.sup.-.sub.k=A{circumflex over
(x)}.sub.k-1+Bu.sub.k (3.9)
P.sup.-.sub.k=AP.sub.k-1A.sup.T+Q (3.10)
[0487] Again notice how the time update equations (3.9) and (3.10)
project the state and covariance estimates forward from time step
k-1 to step k. A and B are from (3.1), while Q is from (3.3).
Initial conditions for the filter are discussed in the earlier
references.
Discrete Kalman Filter Measurement Update Equations
[0488] K.sub.k=P.sup.-.sub.kH.sup.T(HP.sup.-.sub.kH.sup.T+R).sup.-1
(3.11)
{circumflex over (x)}.sub.k={circumflex over
(x)}.sup.-.sub.k+K.sub.k(z.sub.k-H{circumflex over
(x)}.sup.-.sub.k) (3.12)
P.sub.k=(1-K.sub.kH)P.sup.-.sub.k (3.13)
[0489] The first task during the measurement update is to compute
the Kalman gain, K.sub.k. Notice that the equation given here as
(3.11) is the same as (3.8). The next step is to actually measure
the process to obtain z.sub.k, and then to generate an a posteriori
state estimate by incorporating the measurement as in (3.12). Again
(3.12) is simply (3.7) repeated here for completeness. The final
step is to obtain an a posteriori error covariance estimate via
(3.13). All of the Kalman filter equations can be algebraically
manipulated into to several forms. Equation (3.8) represents the
Kalman gain in one popular form.
[0490] After each time and measurement update pair, the process is
repeated with the previous a posteriori estimates used to project
or predict the new a priori estimates. This recursive nature is one
of the very appealing features of the Kalman filter--it makes
practical implementations much more feasible than (for example) an
implementation of a Wiener filter [Brown92] which is designed to
operate on all of the data directly for each estimate. The Kalman
filter instead recursively conditions the current estimate on all
of the past measurements. FIG. 6 offers a complete picture of the
operation of the filter, combining the high-level diagram of FIG. 5
with the equations (3.9) to (3.13).
[0491] Filter Parameters and Tuning
[0492] In the actual implementation of the filter, the measurement
noise covariance R is usually measured prior to operation of the
filter. Measuring the measurement error covariance R is generally
practical (possible) because we need to be able to measure the
process anyway (while operating the filter) so we should generally
be able to take some off-line sample measurements in order to
determine the variance of the measurement noise.
[0493] The determination of the process noise covariance Q is
generally more difficult as we typically do not have the ability to
directly observe the process we are estimating. Sometimes a
relatively simple (poor) process model can produce acceptable
results if one "injects" enough uncertainty into the process via
the selection of Q. Certainly in this case one would hope that the
process measurements are reliable.
[0494] In either case, whether or not we have a rational basis for
choosing the parameters, often times superior filter performance
(statistically speaking) can be obtained by tuning the filter
parameters Q and R. The tuning is usually performed off-line,
frequently with the help of another (distinct) Kalman filter in a
process generally referred to as system identification.
[0495] Under conditions where Q and R are in fact constant, both
the estimation error covariance P.sub.k and the Kalman gain K.sub.k
will stabilize quickly and then remain constant (see the filter
update equations in FIG. 6). If this is the case, these parameters
can be pre-computed by either running the filter off-line, or for
example by determining the steady-state value of P.sub.k as
described in [Grewal93].
[0496] It is frequently the case however that the measurement error
(in particular) does not remain constant. For example, observing
like transmitters, the noise in measurements of nearby transmitters
will generally be smaller than that in far-away transmitters. Also,
the process noise Q is sometimes changed dynamically during filter
operation--becoming Q.sub.k--in order to adjust to different
dynamics. For example, in the case of tracking the head of a user
of a 3D virtual environment we might reduce the magnitude of
Q.sub.k if the user seems to be moving slowly, and increase the
magnitude if the dynamics start changing rapidly. In such cases
Q.sub.k might be chosen to account for both uncertainty about the
user's intentions and uncertainty in the model.
[0497] 2 The Extended Kalman Filter (EKF)
[0498] The Process to be Estimated
[0499] As described above, the Kalman filter addresses the general
problem of trying to estimate the state x.di-elect cons..sup.n of a
discrete-time controlled process that is governed by a linear
stochastic difference equation. But what happens if the process to
be estimated and (or) the measurement relationship to the process
is non-linear? Some of the most interesting and successful
applications of Kalman filtering have been such situations. A
Kalman filter that linearizes about the current mean and covariance
is referred to as an extended Kalman filter or EKF.
[0500] In something akin to a Taylor series, we can linearize the
estimation around the current estimate using the partial
derivatives of the process and measurement functions to compute
estimates even in the face of non-linear relationships. To do so,
we must begin by modifying some of the analysis presented above.
Let us assume that our process again has a state vector x.di-elect
cons..sup.n, but that the process is now governed by the non-linear
stochastic difference equation
x.sub.k=f(x.sub.k-1,u.sub.k,w.sub.k-1), (4.1)
[0501] with a measurement z.di-elect cons..sup.n that is
z.sub.k=h(x.sub.k,v.sub.k), (4.2)
[0502] where the random variables w.sub.k and v.sub.k again
represent the process and measurement noise as in (4.3) and (4.4).
In this case the non-linear function f in the difference equation
(4.1) relates the state at the previous time step k-1 to the state
at the current time step k. It includes as parameters any driving
function v.sub.k and the zero-mean process noise w.sub.k. The
non-linear function h in the measurement equation (4.2) relates the
state x.sub.k to the measurement z.sub.k. See,
http://www.cs.unc.edu/.about.welch/kalman/kalman_filter/kalman-2.html,
expressly incorporated herein by reference.
[0503] In practice of course one does not know the individual
values of the noise w.sub.k and v.sub.k at each time step. However,
one can approximate the state and measurement vector without them
as x.sub.k=f({circumflex over (x)}.sub.k-1,u.sub.k,0) (4.3) and
z.sub.k=h( x.sub.k0), (4.4) where {circumflex over (x)}.sub.k is
some a posteriori estimate of the state (from a previous time step
k).
[0504] It is important to note that a fundamental flaw of the EKF
is that the distributions (or densities in the continuous case) of
the various random variables are no longer normal after undergoing
their respective nonlinear transformations. The EKF is simply an ad
hoc state estimator that only approximates the optimality of Bayes'
rule by linearization. Some interesting work has been done by
Julier et al. in developing a variation to the EKF, using methods
that preserve the normal distributions throughout the non-linear
transformations [Julier96].
[0505] The Computational Origins of the Filter
[0506] To estimate a process with non-linear difference and
measurement relationships, we begin by writing new governing
equations that linearize an estimate about (4.3) and (4.4),
x.sub.k= x.sub.k+A(x.sub.k-1-{circumflex over
(x)}.sub.k-1)+ww.sub.k-1, (4.5)
z.sub.k= z.sub.k+H(x.sub.k- x.sub.k)+Vv.sub.k, (4.6)
[0507] where
[0508] x.sub.k and z.sub.k are the actual state and measurement
vectors,
[0509] x.sub.k and z.sub.k are the approximate state and
measurement vectors from (4.3) and (4.4),
[0510] {circumflex over (x)}.sub.k is an a posteriori estimate of
the state at step k,
[0511] the random variables w.sub.k and v.sub.k represent the
process and measurement noise as in (3.3) and (4.4).
[0512] A is the Jacobian matrix of partial derivatives of f with
respect to x, that is
A [ s j , i ] = .differential. f [ s ] .differential. x [ i ] ( x ^
k - 1 , u k 0 ) , ##EQU00128##
[0513] W is the Jacobian matrix of partial derivatives of f with
respect to w,
W [ i , j ] = .differential. f [ i ] .differential. w [ j ] ( x ^ k
- 1 , u k , 0 ) , ##EQU00129##
[0514] H is the Jacobian matrix of partial derivatives of h with
respect to x,
H [ i , j ] = .differential. h [ i ] .differential. x [ j ] ( x _ k
, 0 ) , ##EQU00130##
[0515] V is the Jacobian matrix of partial derivatives of h with
respect to v,
V [ i , j ] = .differential. h [ i ] .differential. v [ j ] ( x _ k
, 0 ) . ##EQU00131##
[0516] Note that for simplicity in the notation we do not use the
time step subscript k with the Jacobians A, W, H, and V, even
though they are in fact different at each time step.
[0517] Now we define a new notation for the prediction error,
.sub.jk.ident.x.sub.k- x.sub.k, (4.7)
[0518] and the measurement residual,
.sub.k.ident.z.sub.k- z.sub.k. (4.8)
[0519] Remember that in practice one does not have access to
x.sub.k in (4.7), it is the actual state vector, i.e. the quantity
one is trying to estimate. On the other hand, one does have access
to z.sub.k in (4.8), it is the actual measurement that one is using
to estimate x.sub.k. Using (4.7) and (4.8) we can write governing
equations for an error process as
.sub.k=A(x.sub.k-1-{circumflex over (x)}.sub.k-1)+.epsilon..sub.k,
(4.9)
.sub.k=H .sub.k+.eta..sub.k, (4.10)
[0520] where .epsilon..sub.k and .eta..sub.k represent new
independent random variables having zero mean and covariance
matrices WQW.sup.T and VRV.sup.T, with Q and R as in (3.3) and
(3.4) respectively.
[0521] Notice that the equations (4.9) and (4.10) are linear, and
that they closely resemble the difference and measurement equations
(3.1) and (3.2) from the discrete Kalman filter. This motivates us
to use the actual measurement residual .sub.k in (4.8) and a second
(hypothetical) Kalman filter to estimate the prediction error
.sub.k given by (4.9). This estimate, call it .sub.k, could then be
used along with (4.7) to obtain the a posteriori state estimates
for the original non-linear process as
{circumflex over (x)}.sub.k= x.sub.k+ .sub.k. (4.11)
[0522] The random variables of (4.9) and (4.10) have approximately
the following probability distributions (see the previous
footnote):
p( .sub.k)-N(0,E[ .sub.k .sub.k.sup.T])
p(.epsilon..sub.k)-N(0,WQ.sub.kW.sup.T)
p(.eta..sub.k)-N(0,VR.sub.kV.sup.T)
[0523] Given these approximations and letting the predicted value
of {tilde over (e)}.sub.k be zero, the Kalman filter equation used
to estimate .sub.k is
.sub.k=K.sub.k .sub.k. (4.12)
[0524] By substituting (4.12) back into (4.11) and making use of
(4.8) we see that we do not actually need the second (hypothetical)
Kalman filter:
x ^ k = x _ k + K k ? = x _ k + K k ( z k - z _ k ) ? indicates
text missing or illegible when filed ( 4.13 ) ##EQU00132##
[0525] Equation (4.13) can now be used for the measurement update
in the extended Kalman filter, with x.sub.k and z.sub.k coming from
(4.3) and (4.4), and the Kalman gain K.sub.k coming from (3.11)
with the appropriate substitution for the measurement error
covariance.
[0526] The complete set of EKF equations is shown below. Note that
we have substituted {circumflex over (x)}.sup.-.sub.k for x.sub.k
to remain consistent with the earlier "super minus" a priori
notation, and that we now attach the subscript k to the Jacobians
A, W, H, and V, to reinforce the notion that they are different at
(and therefore must be recomputed at) each time step.
EKF Time Update Equations
[0527] {circumflex over (x)}.sup.-.sub.k=f({circumflex over
(x)}.sub.k-1,u.sub.k,0) (4.14)
P.sup.-.sub.k=A.sub.kP.sub.k-1A.sub.k.sup.T+W.sub.kQ.sub.k-1W.sub.k.sup.-
T (4.15)
[0528] As with the basic discrete Kalman filter, the time update
equations (4.14) and (4.15) project the state and covariance
estimates from the previous time step k-1 to the current time step
k. Again f in (4.14) comes from (4.3), A.sub.k and W.sub.k are the
process Jacobians at step k, and Q.sub.k is the process noise
covariance (3.3) at step k.
EKF Measurement Update Equations
[0529]
K.sub.k=P.sup.-.sub.kH.sub.k.sup.T(H.sub.kP.sup.-.sub.kH.sub.k.sup-
.T+V.sub.kR.sub.kV.sub.k.sup.T).sup.-1 (4.16)
{circumflex over (x)}.sub.k={circumflex over
(x)}.sup.-.sub.k+K.sub.k(z.sub.k-h({circumflex over
(x)}.sup.-.sub.k,0)) (4.17)
P.sub.k=(I-K.sub.kH.sub.k)P.sup.-.sub.k (4.18)
[0530] As with the basic discrete Kalman filter, the measurement
update equations (4.16), (4.17) and (4.18) correct the state and
covariance estimates with the measurement z.sub.k. Again h in
(4.17) comes from (3.4), H.sub.k and V are the measurement
Jacobians at step k, and R.sub.k is the measurement noise
covariance (3.4) at step k. (Note we now subscript R allowing it to
change with each measurement.)
[0531] The basic operation of the EKF is the same as the linear
discrete Kalman filter as shown in FIG. 5. FIG. 7 offers a complete
picture of the operation of the EKF, combining the high-level
diagram of FIG. 5 with the equations (4.14) through (4.18).
[0532] An important feature of the EKF is that the Jacobian H.sub.k
in the equation for the Kalman gain K.sub.k serves to correctly
propagate or "magnify" only the relevant component of the
measurement information. For example, if there is not a one-to-one
mapping between the measurement z.sub.k and the state via h, the
Jacobian H.sub.k affects the Kalman gain so that it only magnifies
the portion of the residual z.sub.k-h({circumflex over
(x)}.sup.-.sub.k,0) that does affect the state. Of course if over
all measurements there is not a one-to-one mapping between the
measurement z.sub.k and the state via h, then as you might expect
the filter will quickly diverge. In this case the process is
unobservable.
[0533] The Process Model
[0534] In a simple example we attempt to estimate a scalar random
constant, a voltage for example. Let's assume that we have the
ability to take measurements of the constant, but that the
measurements are corrupted by a 0.1 volt RMS white measurement
noise (e.g. our analog to digital converter is not very accurate).
In this example, our process is governed by the linear difference
equation
x k = A x k - 1 + B u k + w k = x k - 1 + w k , ##EQU00133##
[0535] with a measurement z.di-elect cons..sup.1 that is
z k = H x k + v k = x k + v k . ##EQU00134##
[0536] The state does not change from step to step so A=1. There is
no control input so u=0. Our noisy measurement is of the state
directly so H=1. (Notice that we dropped the subscript k in several
places because the respective parameters remain constant in our
simple model.)
[0537] The Filter Equations and Parameters
[0538] Our time update equations are {circumflex over
(x)}.sup.-.sub.k={circumflex over (x)}.sub.k-1,
P.sup.-.sub.k=P.sub.k-1+Q,
[0539] our measurement update equations are
K k = P k - ( P k - + R ) - 1 = P k - P k - + R , x ^ k = x ^ k - +
K k ( z k - x ^ k - ) , P k = ( 1 - K k ) P k - . ( 5.1 )
##EQU00135##
[0540] Presuming a very small process variance, we let Q=1e-5. (We
could certainly let Q=0 but assuming a small but non-zero value
gives us more flexibility in "tuning" the filter as we will
demonstrate below.) Let's assume that from experience we know that
the true value of the random constant has a standard normal
probability distribution, so we will "seed" our filter with the
guess that the constant is 0. In other words, before starting we
let {circumflex over (x)}.sub.k-1=0.
[0541] Similarly we need to choose an initial value for P.sub.k-1,
call it P.sub.0. If we were absolutely certain that our initial
state estimate {circumflex over (x)}.sub.0=0 was correct, we would
let P.sub.0=0. However given the uncertainty in our initial
estimate {circumflex over (x)}.sub.0, choosing P.sub.0=0 would
cause the filter to initially and always believe {circumflex over
(x)}.sub.k=0. As it turns out, the alternative choice is not
critical. We could choose almost any P.sub.0.noteq.0 and the filter
would eventually converge. It is convenient, for example, to start
with P.sub.0=1. [0542] Brown92 Brown, R. G. and P. Y. C. Hwang.
1992. Introduction to Random Signals and Applied Kalman Filtering,
Second Edition, John Wiley & Sons, Inc. [0543] Gelb74 Gelb, A.
1974. Applied Optimal Estimation, MIT Press, Cambridge, Mass.
[0544] Grewal93 Grewal, Mohinder S., and Angus P. Andrews (1993).
Kalman Filtering Theory and Practice. Upper Saddle River, N.J. USA,
Prentice Hall. [0545] Jacobs93 Jacobs, O. L. R. 1993. Introduction
to Control Theory, 2nd Edition. Oxford University Press. [0546]
Julier96 Julier, Simon and Jeffrey Uhlman. "A General Method of
Approximating Nonlinear Transformations of Probability
Distributions," Robotics Research Group, Department of Engineering
Science, University of Oxford [cited 14 Nov. 1995]. Available from
http://www.robots.ox.ac.uk/.about.siju/work/publications/Unscented.zip.
[0547] Kalman60 Kalman, R. E. 1960. "A New Approach to Linear
Filtering and Prediction Problems," Transaction of the
ASME--Journal of Basic Engineering, pp. 35-45 (March 1960). [0548]
Lewis86 Lewis, Richard. 1986. Optimal Estimation with an
Introduction to Stochastic Control Theory, John Wiley & Sons,
Inc. [0549] Maybeck79 Maybeck, Peter S. 1979. Stochastic Models,
Estimation, and Control, Volume 1, Academic Press, Inc. [0550]
Sorenson70 Sorenson, H. W. 1970. "Least-Squares estimation: from
Gauss to Kalman," IEEE Spectrum, vol. 7, pp. 63-68, July 1970.
[0551] See, also: [0552] "A New Approach for Filtering Nonlinear
Systems" by S. J. Julier, J. K. Uhlmann, and H. F. Durrant-Whyte,
Proceedings of the 1995 American Control Conference, Seattle,
Wash., Pages:1628-1632. Available from
http://www.robots.ox.ac.uk/.about.siju/work/publications/ACC95_pr.zip
[0553] Simon Julier's home page at
http://www.robots.ox.ac.uk/.about.siju/. [0554] "Fuzzy Logic
Simplifies Complex Control Problems", Tom Williams, Computer
Design, Mar. 1, 1991. [0555] "Neural Network And Fuzzy Systems--A
Dynamical Systems Approach To Machine Intelligence", Bart Kosko;
Prentice Hall 1992; Englewood Cliffs, N.J.; pp. 13, 18, 19. [0556]
B. Krogh et al., "Integrated Path Planning and Dynamic Steering
Control for Autonomous Vehicles," 1986. [0557] Brockstein, A.,
"GPS-Kalman-Augmented Inertial Navigation System Performance,"
Naecom '76 Record, pp. 864-868, 1976. [0558] Brooks, R., "Solving
the Fine-Path Problem by Good Representation of Free Space," IEEE
Transactions on Systems, Man, and Cybernetics, pp. 190-197,
March-April, 1983. [0559] Brown, R., "Kalman Filtering Study
Guide-A Guided Tour," Iowa State University, pp. 1-19, 1984. [0560]
Brown, R., Random Signal Analysis & Kalman Filtering, Chapter
5, pp. 181-209, no date. [0561] D. Kuan et al., "Model-based
Geometric Reasoning for Autonomous Road Following," pp. 416-423,
1987. [0562] D. Kuan, "Autonomous Robotic Vehicle Road Following,"
IEEE Transactions on Pattern Analysis and Machine Intelligence, pp.
647-658, 1988. [0563] D. Touretzky et al., "What's Hidden in the
Hidden Layers?," Byte, pp. 227-233, August 1989. [0564] Data Fusion
in Pathfinder and Travtek, Roy Sumner, VNIS '91 conference, October
20-23, Dearborn, Mich. [0565] Database Accuracy Effects on Vehicle
Positioning as Measured by the Certainty Factor, R. Borcherts, C.
Collier, E. Koch, R. Bennet, VNIS '91 conference from October
20-23, Dearborn, Mich. [0566] Daum, F., et al., "Decoupled Kalman
Filters for Phased Array Radar Tracking," IEEE Transactions on
Automatic Control, pp. 269-283, March 1983. [0567] Denavit, J. et
al., "A Kinematic Notation for Lower-Pair Mechanisms Bases on
Matrices," pp. 215-221, June, 1955. [0568] Dickmanns, E. et al.,
"Guiding Land Vehicles Along Roadways by Computer Vision", The
Tools for Tomorrow, Oct. 23, 1985. [0569] Edward J. Krakiwsky, "A
Kalman Filter for Integrating Dead Reckoning, Map Matching and GPS
Positioning", IEEE Plans '88 Position Location and Navigation
Symposium Record, Kissemee, Fla. USA, Nov. 29-Dec. 2, 1988, pp.
39-46. [0570] Fuzzy Systems and Applications, United Signals and
Systems, Inc., Bart Kosko with Fred Watkins, Jun. 5-7, 1991. [0571]
IEEE Journal of Robotics & Automation, vol. 4, No. 4, August.
1988, IEEE (New York) J. LeM "Domain-dependent reasoning for visual
navigation of roadways, pp. 419-427 (Nissan) Mar. 24, 1988. [0572]
J. Crowley, "Part 3: Knowledge Based Supervision of Robotics
Systems," 1989 IEEE Conference on Robotics and Automation, pp.
37-42, 1989. [0573] Kaczmarek, K. W., "Cellular Networking: A
Carrier's Perspective", 39th IEEE Vehicular Technology Conference,
May 1, 1989, vol. 1, pp. 1-6. [0574] Knowledge Representation in
Fuzzy Logic, Lotfi A. Zadeh, IEEE Transactions on Knowledge and
Data Engineering, vol. 1, No. 1, March 1989. [0575] Sennott, J. et
al., "A Queuing Model for Analysis of A Bursty Multiple-Access
Communication Channel," IEEE, pp. 317-321, 1981. [0576] Sheridan,
T. "Three Models of Preview Control," IEEE Transactions on Human
Factors in Electronics, pp. 91-102, June 1966. [0577] Sheth, P., et
al., "A Generalized Symbolic Notation for Mechanism," Transactions
of the ASME, pp. 102-112, Febuary 1971. [0578] Sorenson, W.,
"Least-Squares estimation: From Gauss to Kalman," IEEE Spectrum,
pp. 63-68, July 1970. [0579] "Automobile Navigation System Using
Beacon Information" pp. 139-145. [0580] W. Uttal, "Teleoperators,"
Scientific American, pp. 124-129, December 1989. [0581] Wareby,
Jan, "Intelligent Signaling: FAR & SS7", Cellular Business, pp.
58, 60 and 62, July 1990. [0582] Wescon/87 Conference Record, vol.
31, 1987, (Los Angeles, US) M. T. Allison et al "The next
generation navigation system", pp. 941-947. [0583] Ekaterina
L.-Rundblad, Alexei Maidan, Peter Novak, Valeriy Labunets, Fast
Color Wavelet-Haar Hartley-Prometheus Transforms For Image
Processing,
www.prometheus-inc.com/asi/algebra2003/papers/katya2.pdf. [0584]
Richard Tolimieri and Myoung An, Group Filters And Image
Processing,
www.prometheus-inc.com/asi/algebra2003/papers/tolimieri.pdf. [0585]
Daniel N. Rockmore, Recent Progress And Applications In Group FFTs,
http://www.prometheus-inc.com/asi/algebra2003/papers/rockmore.pdf.
[0586] Thomas Theu.beta.l and Robert F. Tobler and Eduard Groller,
"The Multi-Dimensional Hartley Transform as a Basis for Volume
Rendering", citeseer.nj.nec.com/450842.html.
[0587] See also, U.S. patent Nos. (expressly incorporated herein by
reference): [0588] U.S. Pat. Nos. 3,582,926; 4,291,749; 4,314,232;
4,337,821; 4,401,848; 4,407,564; 4,419,730; 4,441,405; 4,451,887;
4,477,874; 4,536,739; 4,582,389; 4,636,782; 4,653,003; 4,707,788;
4,731,769; 4,740,779; 4,740,780; 4,752,824; 4,787,039; 4,795,223;
4,809,180; 4,818,048; 4,827,520; 4,837,551; 4,853,687; 4,876,594;
4,914,705; 4,967,178; 4,988,976; 4,995,258; 4,996,959; 5,006,829;
5,043,736; 5,051,735; 5,070,323; 5,070,931; 5,119,504; 5,198,797;
5,203,499; 5,214,413; 5,214,707; 5,235,633; 5,257,190; 5,274,560;
5,278,532; 5,293,115; 5,299,132; 5,334,974; 5,335,276; 5,335,743;
5,345,817; 5,351,041; 5,361,165; 5,371,510; 5,400,045; 5,404,443;
5,414,439; 5,416,318; 5,422,565; 5,432,904; 5,440,428; 5,442,553;
5,450,321; 5,450,329; 5,450,613; 5,475,399; 5,479,482; 5,483,632;
5,486,840; 5,493,658; 5,494,097; 5,497,271; 5,497,339; 5,504,622;
5,506,595; 5,511,724; 5,519,403; 5,519,410; 5,523,559; 5,525,977;
5,528,248; 5,528,496; 5,534,888; 5,539,869; 5,547,125; 5,553,661;
5,555,172; 5,555,286; 5,555,502; 5,559,520; 5,572,204; 5,576,724;
5,579,535; 5,627,547; 5,638,305; 5,648,769; 5,650,929; 5,653,386;
5,654,715; 5,666,102; 5,670,953; 5,689,252; 5,691,695; 5,702,165;
5,712,625; 5,712,640; 5,714,852; 5,717,387; 5,732,368; 5,734,973;
5,742,226; 5,752,754; 5,758,311; 5,777,394; 5,781,872; 5,919,239;
6,002,326; 6,013,956; 6,078,853; 6,104,101; and 6,449,535. [0589]
M. Krebs, "Cars That Tell You Where To Go," The New York Times,
Dec. 15, 1996, section 11, p. 1. [0590] L Kraar, "Knowledge
Engineering," Fortune, Oct. 28, 1996, pp. 163-164. [0591] S.
Heuchert, "Eyes Forward: An ergonomic solution to driver
information overload," Society of Automobile Engineering, September
1996, pp. 27-31. [0592] J. Braunstein, "Airbag Technology Take
Off," Automotive & Transportation Interiors, August 1996, p.
16. [0593] I. Adcock, "No Longer Square," Automotive &
Transportation Interiors, August 1996, p. 38
[0594] One embodiment of the present invention advances the art by
explicitly communicating reliability or risk information to the
user. Therefore, in addition to communicating an event or predicted
event, the system also computes or determines a reliability of the
information and outputs this information. The reliability referred
to herein generally is unavailable to the original detection
device, though such device may generate its own reliability
information for a sensor reading.
[0595] Therefore, the user interface according to this embodiment
is improved by outputting information relating to both the event
and a reliability or risk with respect to that information.
[0596] According to a preferred embodiment of the invention, a
vehicle travel information system is provided, for example
integrated with a vehicular navigation system. In a symmetric
peer-to-peer model, each vehicle includes both environmental event
sensors and a user interface, but the present invention is not
dependent on both aspects being present in a device. As the vehicle
travels, and as time advances, its context sphere is altered. For
any context sphere, certain events or sensed conditions will be
most relevant. These most relevant events or sensed, to the extent
known by the system, are then output through a user interface.
However, often, the nature or existence of relevant or potentially
relevant event is unreliable, or reliance thereon entails risk.
[0597] In the case of a vehicle traveling along a roadway, there
are two particular risks to analyze: first, that the recorded event
may not exist (false positive), and second, that an absence of
indication of an event is in error (false negative). For example,
the degree of risk may be indicated by an indication of color
(e.g., red, yellow green) or magnitude (e.g., a bar graph or
dial).
[0598] In many cases, the degree of risk is calculable, and thus
may be readily available. For example, if the event sensor is a
detection of police radar, reliability may be inferred from a time
since last recording of an event. If a car is traveling along a
highway, and receives a warning of traffic enforcement radar from a
car one mile ahead, there is a high degree of certainty that the
traffic enforcement radar will actually exist as the vehicle
proceeds along the highway. Further, if the traffic radar is in
fixed location, there is a high degree of certainty that there is
no traffic enforcement radar closer than one mile. On the other
hand, if a warning of traffic radar at a given location is two
hours old, then the risk of reliance on this information is high,
and the warning should be deemed general and advisory of the nature
of risks in the region. Preferably, as such a warning ages, the
temporal proximity of the warning is spread from its original
focus.
[0599] On the contrary, if the warning relates to a pothole in a
certain lane on the highway, the temporal range of risk is much
broader: even a week later, the reliability of the continued
existence at that location remains high. However, over the course
of a year, the reliability wanes. On the other hand, while there
may be a risk of other potholes nearby, the particular detected
pothole would not normally move.
[0600] The algorithm may also be more complex. For example, if a
traffic accident occurs at a particular location, there are
generally acceptable predictions of the effect of the accident on
road traffic for many hours thereafter. These include
rubbernecking, migrations of the traffic pattern, and secondary
accidents. These considerations may be programmed, and the set of
events and datapoints used to predict spatial and temporal effects,
as well as the reliability of the existence of such effects. This,
in turn, may be used to advise a traveler to take a certain route
to a destination.
[0601] Eventually, the reliability of the information is inferred
to be so low as to cause an expiration of the event, although
preferably a statistical database is maintained to indicate
geographic regional issues broadly.
[0602] Therefore, the system and method according to the present
invention provides an output that can be considered "two
dimensional" (or higher dimensional); the nature of the warning,
and the reliability of the warning. In conjunction, the system may
therefore output a reliability of an absence of warning. In order
to conserve communications bandwidth, it is preferred that an
absence of warning is inferred from the existence of a
communications channel with a counterpart, along with a failure of
a detection of an event triggering a warning. Alternately, such
communications may be explicit.
[0603] The present invention can provide a mobile warning system
having a user interface for conveying an event warning and an
associated reliability or risk of reliance on the warning.
[0604] Preferably, the reliability or risk of reliance is assessed
based on a time between original sensing and proximity. The
reliability may also be based on the nature of the event or sensed
condition. An intrinsic reliability of the original sensed event or
condition may also be relayed, as distinct from the reliability or
risk of reliance assuming the event or condition to have been
accurately sensed.
[0605] In order to determine risk, often statistical and
probabilistic techniques may be used. Alternately, non-linear
techniques, such as neural networks, may be employed. In employing
a probabilistic scheme, a sensor reading at time zero, and the
associated intrinsic probability of error are stored. A model is
associated with the sensor reading to determine a decay pattern.
Thus, in the case of traffic enforcement radar, the half-life for a
"radar trap" for K band radar being fixed in one location is, for
example, about 5 minutes. Thereafter, the enforcement officer may
give a ticket, and proceed up the road. Thus, for times less than
three minutes, the probability of the traffic enforcement radar
remaining in fixed position is high. For this same time-period, the
probability that the traffic enforcement officer has moved up the
road against the direction of traffic flow is low. A car following
3 miles behind a reliable sensor at 60 mph would therefore have a
highly reliable indication of prospective conditions. As the time
increases, so does the risk; a car following ten miles behind a
sensor would only have a general warning of hazards, and a general
indication of the lack thereof. However, over time, a general (and
possibly diurnal or other cyclic time-sensitive variation) risk of
travel within a region may be established, to provide a
baseline.
[0606] It is noted that the risks are not limited to traffic
enforcement radar or laser. Rather, the scheme according to the
present invention is generalized to all sorts of risks. For
example, a sensor may detect or predict sun glare. In this case, a
model would be quite accurate for determining changes over time,
and assuming a reliable model is employed, this condition could
generally be accurately predicted.
[0607] Another example is road flooding. This may be detected, for
example, through the use of optical sensors, tire drag sensors,
"splash" sensors, or other known sensors. In this case, the
relevant time-constant for onset and decay will be variable,
although for a given location, the dynamics may be modeled with
some accuracy, based on sensed actual conditions, regional
rainfall, ground saturation, and particular storm pattern.
Therefore, a puddle or hydroplaning risk may be communicated to the
driver in terms of location, likely magnitude, and confidence.
[0608] It is noted that these three independent parameters need not
all be conveyed to the user. For example, the geographic proximity
to an event location may be used to trigger an output. Therefore,
no independent output of location may be necessary in this case. In
some cases, the magnitude of the threat is relevant, in other cases
it is not. In many present systems (e.g., radar detection), threat
magnitude is used as a surrogate for risk. However, it is well
understood that there are high magnitude artifacts, and low
magnitude true threats, and thus this paradigm has limited basis
for use. The use of risk or confidence as an independent factor may
be express or intermediate. Thus, a confidence threshold may be
internally applied before communicating an event to the user. In
determining or predicting risk or confidence, it may be preferred
to provide a central database. Therefore, generally more complex
models may be employed, supported by a richer data set derived from
many measurements over an extended period of time. The central
database may either directly perform the necessary computations, or
convey an appropriate model, preferably limited to the context
(e.g., geography, time, general environmental conditions), for
local calculation of risk.
[0609] The incorporated references relate, for example, to methods
and apparatus which may be used as part of, or in conjunction with
the present invention. Therefore, it is understood that the present
invention may integrate other systems, or be integrated in other
systems, having complementary, synergistic or related in some way.
For example, common sensors, antennas, processors, memory,
communications hardware, subsystems and the like may provide a
basis for combination, even if the functions are separate.
[0610] The techniques according to the present invention may be
applied to other circumstances. Therefore, it is understood that
the present invention has, as an object to provide a user interface
harnessing the power of statistical methods. Therefore, it is seen
that, as an aspect of the present invention, a user interface, a
method of providing a user interface, computer software for
generating a human-computer interface, and a system providing such
a user interface, presents a prediction of a state as well as an
indication of a statistical reliability of the prediction.
[0611] Within a vehicular environment, the statistical analysis
according to the present invention may also be used to improve
performance and the user interface of other systems. In particular,
modern vehicles have a number of indicators and warnings. In most
known systems, warnings are provided at pre-established thresholds.
According to the present invention, a risk analysis may be
performed on sensor and other data to provide further information
for the user, e.g., an indication of the reliability of the sensor
data, or the reliability under the circumstances of the sensor data
as basis for decision. (For example, a temperature sensor alone
does not indicate whether an engine is operating normally.)
EXAMPLE 1
[0612] The present example provides a mobile telecommunications
device having a position detector, which may be absolute, relative,
hybrid, or other type, and preferably a communications device for
communicating information, typically location relevant information.
The device may serve as a transmitter, transmitting information
relevant to the location (or prior locations) of the device, a
receiver, receiving information relevant to the location (or
prospective location) of the device, or a composite.
[0613] In the case of a transmitter device or stand-alone device, a
sensor is provided to determine a condition of or about the device
or its context. This sensor may populate a map or mapping system
with historical map data.
[0614] During use, a receiving device seeks to output location
context-relevant information to the user, and therefore in this
embodiment includes a human user interface. Typically, in a vehicle
having a general linear or highly constrained type path, a position
output is not a critical feature, and may be suppressed in order to
simplify the interface. Rather, a relative position output is more
appropriate, indicating a relative position (distance, time, etc.)
with respect to a potential contextually relevant position. In
addition, especially in systems where a plurality of different
types of sensors or sensed parameters are available, the nature of
the relevant context is also output. Further, as a particular
feature of the present invention, a risk or reliability assessment
is indicated to the user. This risk or reliability assessment is
preferably statistically derived, although it may be derived
through other known means, for example Boolean analysis, fuzzy
logic, or neural networks.
[0615] For example, the device may provide weather information to
the user. Through one or more of meteorological data from standard
reporting infrastructure (e.g., NOAA, Accuweather.RTM., etc.),
mobile reporting nodes (e.g., mobiles devices having weather
sensors), satellite data, and other weather data sources, a local
weather map is created, preferably limited to contextual relevance.
In most cases, this weather map is stored locally; however, if the
quality of service for a communications link may be assured, a
remote database system serving one or more devices may be provided.
For example, a cellular data communications system may be used to
communicate with the Internet or a service provider.
[0616] The mobile unit, in operation, determines its position, and,
though explicit user input and/or inferential analysis, determines
the itinerary or expected path of the device and time sequence. The
device (or associated systems) then determines the available
weather information for the route and anticipated itinerary (which
may itself be dependent on the weather information and/or reaction
thereto). This available information is then modeled, for example
using a statistical model as described hereinabove, to predict the
forthcoming weather conditions for the device or transporting
vehicle.
[0617] The device then determines the anticipated conditions and
relevance sorts them. In this case, both positive and negative
information may be useful, i.e., a warning about bad weather, ice,
freezing road surfaces, fog, sand-storms, rain, snow, sleet, hail,
sun glare, etc., and an indication of dry, warm, well-illuminated
road surfaces may both be useful information.
[0618] In addition, through the analysis, a number of presumptions
and predictions are made, for example using a chain. Therefore,
while the system may predict a most likely state of affairs, this
alone does not provide sufficient information for full reliance
thereon. For example, the present road surface freezing conditions
thirty miles ahead on a road may be a poor indicator of the road
conditions when the device is at that position. In addition to
changes in the weather, human action may be taken, such as road
salt, sand, traffic, etc., which would alter the conditions;
especially in response to a warning. On the other hand, a report of
freezing road conditions one mile ahead would generally have high
predictive value for the actual road conditions when the device is
at that location, assuming that the vehicle is traveling in that
direction.
[0619] In many cases, there is too much raw information to
effectively display to the user all relevant factors in making a
reliability or risk determination. Thus, the device outputs a
composite estimation of the reliability or risk, which may be a
numeric or non-parametric value. This is output in conjunction with
the nature of the alert and its contextual proximity.
[0620] As stated above, there will generally be a plurality of
events, each with an associated risk or reliability and location.
The relevance of an event may be predicted based on the dynamics of
the vehicle in which the device is transported and the nature of
the event. Thus, if the vehicle requires 170 feet to stop from a
speed of 60 MPH, a warning which might trigger a panic stop should
be issued between 170-500 feet in advance. If the warning is
triggered closer than 170 feet, preferably the warning indicates
that the evasive maneuver will be necessary.
[0621] In this case, the risk indicator includes a number of
factors. First, there is the reliability of the data upon which the
warning is based. Second, there is the reliability of the
predictive model which extrapolates from, the time the raw data is
acquired to the conjunction of the device and the location of the
event. Third, there is an assessment of the relative risks of,
responding to a false positive versus failing to respond to a false
negative. Other risks may also be included in the analysis.
Together, the composite risk is output, for example as a color
indicator. Using, for example, a tricolor (red-green-blue) light
emitting diode (LED) or bicolor LED (red-green), a range of colors
may be presented to the user. Likewise, in an audio alert, the
loudness or harmonic composition (e.g., harmonic distortion) of a
tone or alert signal may indicate the risk or reliability. (In the
case of loudness, preferably a microphone measures ambient noise to
determine a minimum loudness necessary to indicate an alert).
[0622] The position detector is preferably a GPS or combined
GPS-GLONASS receiver, although a network position detection system
(e.g., Enhanced 911 type system) may also be employed. Preferably,
the position detector achieves an accuracy of .+-.30 meters 95% of
the time, and preferably provides redundant sensors, e.g., GPS and
inertial sensors, in case of failure or error of one of the
systems. However, for such purposes as pothole reporting,
positional accuracies of 1 to 3 meters are preferred. These may be
obtained through a combination of techniques, and therefore the
inherent accuracy of any one technique need not meet the overall
system requirement.
[0623] The position detector may also be linked to a mapping system
and possibly a dead reckoning system, in order to pinpoint a
position with a geographic landmark. Thus, while precise absolute
coordinate measurements of position may be used, it may also be
possible to obtain useful data at reduced cost by applying certain
presumptions to available data. In an automotive system, steering
angle, compass direction, and wheel revolution information may be
available, thereby giving a rough indication of position from a
known starting point. When this information is applied to a mapping
system, a relatively precise position may be estimated. Therefore,
the required precision of another positioning system used in
conjunction need not be high, in order to provide high reliability
position information. For example, where it is desired to map
potholes, positional accuracy of 10 cm may be desired, far more
precise than might be available from a normal GPS receiver mounted
in a moving automobile. Systems having such accuracy may then be
used as part of an automated repair system. However, when combined
with other data, location and identification of such events is
possible. Further, while the system may include or tolerate
inaccuracies, it is generally desired that the system have high
precision, as compensation for inaccuracies may be applied.
[0624] A typical implementation of the device provides a memory for
storing events and respective locations. Preferably, further
information is also stored, such as a time of the event, its
character or nature, and other quantitative or qualitative aspects
of the information or its source and/or conditions of acquisition.
This memory may be a solid state memory or module (e.g., 64-256 MB
Flash memory), rotating magnetic and/or optical memory devices, or
other known types of memory.
[0625] The events to be stored may be detected locally, such as
through a detector for radar and/or laser emission source, radio
scanner, traffic or road conditions (mechanical vehicle sensors,
visual and/or infrared imaging, radar or LIDAR analysis, acoustic
sensors, or the like), places of interest which may be selectively
identified, itinerary stops, and/or fixed locations. The events may
also be provided by a remote transmitter, with no local event
detection. Therefore, while means for identifying events having
associated locations is a part of the system as a whole, such means
need not be included in every apparatus embodying the
invention.
[0626] Radar detectors typically are employed to detect operating
emitters of X (10.5 GHz), K (25 GHz) and Ka (35 GHz) radar
emissions from traffic control devices or law enforcement personnel
for detecting vehicle speed by the Doppler effect. These systems
typically operate as superheterodyne receivers which sweep one or
more bands, and detect a wave having an energy significantly above
background. As such, these types of devices are subject to numerous
sources of interference, accidental, intentional, and incidental. A
known system, Safety Warning System (SWS) licensed by Safety
Warning System L.C., Englewood Fla., makes use of such radar
detectors to specifically warn motorists of identified road
hazards. In this case, one of a set of particular signals is
modulated within a radar band by a transmitter operated near the
roadway. The receiver decodes the transmission and warns the driver
of the hazard.
[0627] LIDAR devices emit an infrared laser signal, which is then
reflected off a moving vehicle and analyzed for delay, which
relates to distance. Through successive measurements, a sped can be
calculated. A LIDAR detector therefore seeks to detect the
characteristic pulsatile infrared energy.
[0628] Police radios employ certain restricted frequencies, and in
some cases, police vehicles continuously transmit a signal. While
certain laws restrict interception of messages sent on police
bands, it is believed that the mere detection and localization of a
carrier wave is not and may not be legally restricted. These radios
tend to operate below 800 MHz, and thus a receiver may employ
standard radio technologies.
[0629] Potholes and other road obstructions and defects have two
characteristics. First, they adversely effect vehicles which
encounter them. Second, they often cause a secondary effect of
motorists seeking to avoid a direct encounter or damage, by slowing
or executing an evasive maneuver. These obstructions may therefore
be detected in three ways; first, by analyzing the suspension of
the vehicle for unusual shocks indicative of such vents; second, by
analyzing speed and steering patterns of the subject vehicle and
possibly surrounding vehicles; and third, by a visual, ultrasonic,
or other direct sensor for detecting the pothole or other
obstruction. Such direct sensors are known; however, their
effectiveness is limited, and therefore an advance mapping of such
potholes and other road obstructions greatly facilitates avoiding
vehicle damage and executing unsafe or emergency evasive maneuvers.
An advance mapping may also be useful in remediation of such road
hazards, as well.
[0630] Traffic jams occur for a variety of reasons. Typically, the
road carries traffic above a threshold, and for some reason the
normal traffic flow patterns are disrupted. Therefore, there is a
dramatic slowdown in the average vehicle speed, and a reduced
throughput. Because of the reduced throughput, even after the cause
of the disruption has abated, the roadways may take minutes to
hours to return to normal. Therefore, it is typically desired to
have advance warnings of disruptions, which include accidents,
icing, rain, sun glare, lane closures, road debris, police action,
exits and entrances, and the like, in order to allow the driver to
avoid the involved region or plan accordingly. Abnormal traffic
patterns may be detected by comparing a vehicle speed to the speed
limit or a historical average speed, by a visual evaluation of
traffic conditions, or by broadcast road advisories. High traffic
conditions are associated with braking of traffic, which in turn
results in deceleration and the illumination of brake lights. Brake
lights may be determined by both the specific level of illumination
and the center brake light, which is not normally illuminated.
Deceleration may be detected by an optical, radar or LIDAR sensor
for detecting the speed and/or acceleration state of nearby
vehicles.
[0631] While a preferred embodiment of the present invention
employs one or more sensors, broadcast advisories, including those
from systems according to or compatible with the present invention,
provide a valuable source of information relating to road
conditions and information of interest at a particular location.
Therefore, the sensors need not form a part of the core system.
Further, some or all of the required sensors may be integrated with
the vehicle electronics ("vetronics"), and therefore the sensors
may be provided separately or as options. It is therefore an aspect
of an embodiment of the invention to integrate the transceiver, and
event database into a vetronics system, preferably using a digital
vetronics data bus to communicate with existing systems, such as
speed sensors, antilock brake sensors, cruise control, automatic
traction system, suspension, engine, transmission, and other
vehicle systems.
[0632] According to one aspect of the invention, an adaptive wise
control system is provided which, in at least one mode of
operation, seeks to optimize various factors of vehicle operation,
such as fuel efficiency, acceleration, comfort, tire wear, etc. For
example, an automatic acceleration feature is provided which
determines a most fuel-efficient acceleration for a vehicle. Too
slow an acceleration will result in increased time at suboptimal
gear ratios, while too fast acceleration will waste considerable
fuel. Actual operating efficiency may be measured during vehicle
use, allowing an accurate prediction of fuel efficiency under
dynamically changing conditions, such as acceleration. Vehicle
sensors may assist in making a determination that optimum
acceleration is safe; objects both in front and behind the vehicle
may be sensed. If an object is in front of the vehicle, and the
closing speed would predict a collision, then the acceleration is
decreased, or even brakes applied. Ilan object is rapidly advancing
from the rear, the acceleration may be increased in order to avoid
impact or reduce speed differential. See, U.S. Pat. Nos. 6,445,308
(Koike, Sep. 3, 2002, Positional data utilizing inter-vehicle
communication method and traveling control apparatus), 6,436,005
(Bellinger, Aug. 20, 2002, System for controlling drivetrain
components to achieve fuel efficiency goals), 6,418,367 (Toukura,
et al., Jul. 9, 2002, Engine transmission control system),
expressly incorporated herein by reference.
[0633] Likewise, the operation of a vehicle may be optimized
approaching a stop, such as a stop sign, red light, or the like. In
this case, the system optimization may be more complex. In addition
to fuel economy, wear on brakes, engine (especially if compression
braking is employed), transmission, tires, suspension, time,
accident-related risks, and the like, may also be included. In the
case of a stop sign, the issue also arises with respect to a
so-called "rolling stop". Such a practice provides that the vehicle
does not actually stop, but reaches a sufficiently low speed that
the driver could stop if required by circumstances. While this
practice is technically considered a violation, in many instances,
it is both efficient and useful. For example, a stop line is often
located behind an intersection, with impaired visibility. Thus, the
vehicle might come to a complete stop, begin to accelerate, and
then find that the intersection is not clear, and be forced to stop
again. One particular reason for a rolling stop is the storage of
energy in the vehicular suspension during acceleration and
deceleration. As the vehicle comes to a stop, the springs and shock
absorbers of the suspension undergo a clamped oscillation, which is
relatively uncorfortable, and destabilizes the vehicle and its
contents.
[0634] According to one aspect of the present invention, the driver
may locate a deceleration target and/or a target speed. The vehicle
navigation system may assist, recording an exact location of a stop
line, geographic (hills, curves, lane marker locations, etc.),
weather conditions (ice, sand, puddles, etc.) and other
circumstances surrounding the vehicle. Other vehicles and
obstructions or pedestrians, etc. may also be identified and
modeled. Using models of the various components, as well as cost
functions associated with each, as well as subjective factors,
which may include vehicle occupant time-cost and comfort functions,
an optimal acceleration or deceleration profile may be calculated.
The system may therefore express control over throttle, brakes,
transmission shifts, clutch, valve timing, suspension controls,
etc., in order to optimize vehicle performance.
[0635] See US patent Nos. (expressly incorporated herein by
reference): U.S. Pat. Nos. 6,503,170; 6,470,265; 6,445,308;
6,292,743; 6,292,736; 6,233,520; 6,230,098; 6,220,986; 6,202,022;
6,199,001; 6,182,000; 6,178,377; 6,174,262; 6,098,016; 6,092,014;
6,092,005; 6,091,956; 6,070,118; 6,061,003; 6,052,645; 6,034,626;
6,014,605; 5,990,825; 5,983,154; 5,938,707; 5,931,890; 5,924,406;
5,835,881; 5,774,073; 6,442,473; 4,704,610; 5,712,632; 5,973,616;
and 6,008,741.
[0636] The radio used for the communications subsystem can be radio
frequency AM, FM, spread spectrum, microwave, light (infrared,
visible, UV) or laser or maser beam (millimeter wave, infrared,
visible), or for short distance communications, acoustic or other
communications may be employed. The system preferably employs an
intelligent transportation system (ITS) or Industrial, Scientific
and Medical (ISM) allocated band, such as the 915 MHz, 2.4 MHz or
5.8 GHz band. (The 2.350-2.450 GHz band corresponds to the emission
of microwave ovens, and thus the band suffers from potentially
significant interference). The 24.125 GHz band, corresponding to
K-band police radar, may also be available; however, transmit power
in this band is restricted, e.g., less than about 9 mW. The signal
may be transmitted through free space or in paths including fiber
optics, waveguides, cables or the like. The communication may be
short or medium range omnidirectional, line of sight, reflected
(optical, radio frequency, retroreflector designs), satellite,
secure or non-secure, or other modes of communications between two
points, that the application or state-of-the-art may allow. The
particular communications methodology is not critical to the
invention, although a preferred embodiment employs a spread
spectrum microwave transmission.
[0637] A particularly preferred communications scheme employs
steerable high gain antennas, for example a phased array antenna,
which allows a higher spatial reuse of communications bands and
higher signal to noise ratio that an omnidirectional antenna.
[0638] A number of Dedicated Short Range Communications (DSRC)
systems have been proposed or implemented in order to provide
communications between vehicles and roadside systems. These DSRC
systems traditionally operate in the 900 MHz band for toll
collection, while the FCC has recently made available 75 MHz in the
5.850-5.925 GHz range for such purposes, on a co-primary basis with
microwave communications, satellite uplinks, government radar, and
other uses. However, spectrum is also available in the so-called
U-NII band, which encompasses 5.15-5.25 GHz (indoors, 50 mW) and
5.25-5.35 (outdoors, 250 mW). A Japanese ITS ("ETC") proposal
provides a 5.8 GHz full duplex interrogation system with a half
duplex transponder, operating at about 1 megabit per second
transmission rates.
[0639] In August 2001, the DSRC standards committee (ASTM 17.51)
selected 802.11a as the underlying radio technology for DSRC
applications within the 5.850 to 5.925 GHz band. The IEEE 802.11a
standard was modified, in a new standard referred to as 802.11a R/A
(roadside applications) to meet DSRC deployment requirements, and
includes OFDM modulation with a lower data rate, 27 MBS for DSRC
instead of 54 MBS for 802.11a.
[0640] Proposed DSRC applications include:
[0641] Emergency Vehicle Warning--Currently, emergency vehicles
only have sirens and lights to notify of their approach. With DSRC,
the emergency vehicle can have the traffic system change traffic
lights to clear traffic along it's intended route. Also, this route
information can be broadcast to other cars to provide user/vehicle
specific directions to reduce collisions.
[0642] Traffic congestion data can be exchanged between vehicles.
On-coming traffic exchanges information on traffic status ahead so
that vehicle navigation systems can dynamically provide the best
route to a destination.
[0643] An industry standard interoperable tolling platform could
expand the use of toll systems or processing payments at parking
lots, drive-through establishments (food, gas), etc.
[0644] Safety applications could benefit from use of DSRC. The DSRC
automaker consortium (DaimlerChrysler, GM, Ford, Toyota, Nissan,
& VW) are seeking ways to enhance passenger safety with DSRC
communications. For example, in a typical collision, a car has only
10 milliseconds to tighten seatbelts, deploy airbags, etc. If an
additional advance warning of 5 milliseconds was provided, one
could tighten seatbelts, warm-up the airbags, etc. to prepare the
car for collision. Using radar, GPS data, etc. a car can determine
that a collision is imminent, and it can then notify the car about
to be hit to prepare for collision.
[0645] See: ASTM E2213-02--Standard Specification for
Telecommunications and Information Exchange Between Roadside and
Vehicle Systems--5 GHz Band Dedicated Short Range Communications
(DSRC) Medium Access Control (MAC) and Physical Layer (PHY)
Specifications (This standard, ASTM E2213-02--Standard
Specification for Telecommunications and Information Exchange
Between Roadside and Vehicle Systems--5 GHz Band Dedicated Short
Range Communications (DSRC) Medium Access Control (MAC) and
Physical Layer (PHY) Specifications, describes a medium access
control layer (MAC) and physical layer (PHY) specification for
wireless connectivity using dedicated short-range communications
(DSRC) services. This standard is based on and refers to the
Institute of Electrical and Electronics Engineers (IEEE) standard
802.11 (Wireless LAN Medium Access Control and Physical Layer
specifications), and standard 802.11a (Wireless LAN Medium Access
Control and Physical Layer specifications High-Speed Physical Layer
in the 5 GHz band). This standard is an extension of IEEE 802.11
technology into the high-speed vehicle environment. It contains the
information necessary to explain the difference between IEEE 802.11
and IEEE 802.11a operating parameters required to implement a
mostly high-speed data transfer service in the 5.9-GHz Intelligent
Transportation Systems Radio Service (ITS-RS) band or the
Unlicensed National Information Infrastructure (UNII) band, as
appropriate).
[0646] ANSI X3.38-1988 (R1994)--Codes--Identification of States,
the District of Columbia, and the Outlying and Associated Areas of
the United States for Information Interchange
[0647] ASTM PS111-98--Specification for Dedicated Short Range
Communication (DSRC) Physical Layer Using Microwave in the 902 to
928 MHz Band
[0648] ASTM PS105-99--Specification for Dedicated Short Range
Communication (DSRC) Data Link Layer: Medium Access and Logical
Link Control
[0649] CEN Draft Document: prENV278/9/#65 Dedicated Short Range
Communication (DSRC)--Application Layer (Layer 7)
[0650] IEEE Std 1489-1999--Standard for Data Dictionaries for
Intelligent Transportation Systems--Part 1: Functional Area Data
Dictionaries
[0651] GSS Global Specification for Short Range Communication. The
platform for Interoperable Electronic Toll Collection and Access
Control
[0652] ISO 3166-1:1997--Codes for the representation of names of
countries and their subdivisions--Part 1: Country codes
[0653] ISO 3779:1983--Road vehicles--Vehicle identification
numbering (VIN)--Content and structure
[0654] ISO/IEC 7498-1:1994--Information technology--Open Systems
Interconnection--Basic Reference Model: The Basic Model
[0655] ISO 7498-2:1989--Information processing systems--Open
Systems Interconnection--Basic Reference Model--Part 2: Security
Architecture
[0656] ISO/IEC 7498-3:1997--Information technology--Open Systems
Interconnection--Basic Reference Model: Naming and addressing
[0657] ISO/IEC 7498-4:1989--Information processing systems--Open
Systems Interconnection--Basic Reference Model--Part 4: Management
framework
[0658] ISO 3780:1983--Road vehicles--World manufacturer identifier
(WMI) code
[0659] ISO/IEC 8824-1:1995--Information technology--Abstract Syntax
Notation One (ASN.1): Specification of basic notation
[0660] ISO/IEC 8825-2:1996--Information technology--ASN.1 encoding
rules: Specification of Packed Encoding Rules (PER)
[0661] ISO TC204 WG15 Committee Of Japan TICS/DSRC--DSRC
Application Layer High Data Rate mobile environment
[0662] ASTM E2158-01--Standard Specification for Dedicated Short
Range Communication (DSRC) Physical Layer Using Microwave in the
902-928 MHz Band
[0663] ASTM PS105-99--Standard Provisional Specification for
Dedicated Short Range Communication (DSRC) Data Link Layer
[0664] IEEE Std 1455-1999--Standard for Message Sets for
Vehicle/Roadside Communications
[0665] IEEE Std 802.11-1999--Information
Technology--Telecommunications and information exchange between
systems--Local and metropolitan area networks--Specific
requirements--Part 11: Wireless LAN Medium Access Control and
Physical Layer specifications
[0666] IEEE Std 802.11a-1999--Information
Technology--Telecommunications and information exchange between
systems--Local and metropolitan area networks--Specific
requirements--Part 11: Wireless LAN Medium Access Control and
Physical Layer specifications: High Speed Physical Layer in the 5
GHz band
[0667] Each of which is expressly incorporated herein in its
entirety.
[0668] It is noted that the present technology has the capability
for streamlining transportation systems, by communicating traffic
conditions almost immediately and quickly allowing decisions to be
made by drivers to minimize congestion and avoid unnecessary
slowdowns. A particular result of the implementation of this
technology will be a reduction in vehicular air pollution, as a
result of reduced traffic jams and other inefficient driving
patterns. To further the environmental protection aspect of the
invention, integration of the database with cruise control and
driver information systems may reduce inefficient vehicle speed
fluctuations, by communicating to the driver or controlling the
vehicle at an efficient speed. As a part of this system, therefore,
adaptive speed limits and intelligent traffic flow control devices
may be provided. For example, there is no need for fixed time
traffic lights if the intersection is monitored for actual traffic
conditions. By providing intervehicle communications and
identification, such an intelligent system is easier to implement.
Likewise, the 55 miles per hour speed limit that was initially
presented in light of the "oil crisis" in the 1970's, and parts of
which persist today even in light of relatively low petroleum
pricing and evidence that the alleged secondary health and safety
benefit is marginal or non-existent, may be eliminated in favor of
a system which employs intelligence to optimize the traffic flow
patterns based on actual existing conditions, rather than a static
set of rules which are applied universally and without
intelligence.
[0669] The communications device may be a transmitter, receiver or
transceiver, transmitting event information, storing received event
information, or exchanging event information, respectively. Thus,
while the system as a whole typically involves a propagation of
event information between remote databases, each system embodying
the invention need not perform all functions.
[0670] In a retroreflector system design, signal to noise ratio is
improved by spatial specificity, and typically coherent detection.
An interrogation signal is emitted, which is modulated and
redirected back toward its source, within a relatively wide range,
by a receiver. Thus, while the receiver may be "passive", the
return signal has a relatively high amplitude (as compared to
nonretroreflective designs under comparable conditions) and the
interrogator can spatially discriminate and coherently detect the
return signal. Both optical and RF retroreflector systems exist.
This technique may also be used to augment active communications
schemes, for example allowing a scanning or array antenna to
determine an optimal position or spatial sensitivity or gain, or a
phase array or synthetic aperture array to define an optimal
spatial transfer function, even in the presence of multipath and
other types of signal distortion and/or interference.
[0671] According to one embodiment of the invention, a plurality of
antenna elements are provided. These may be, for example, a set of
high gain antennas oriented in different directions, or an array of
antennas, acting together. Accordingly, the antenna structure
permits a spatial division multiplexing to separate channels, even
for signals which are otherwise indistinguishable or overlapping.
For example, this permits a single antenna system to communicate
with a plurality of other antenna systems at the same time, with
reduced mutual interference. Of course, these communications
channels may be coordinated to further avoid overlap. For example,
the communications band may be subdivided into multiple channels,
with respective communications sessions occurring on different
channels. Likewise, a plurality of different bands may be
simultaneously employed, for example 802.11g (2.4 GHz), 802.11a
(5.4 GHz), and 802.11a R/A (5.9 GHz). In another embodiment, a
mechanically scanning high gain antenna may provide directional
discrimination. Such an antenna may be, for example, a cylindrical
waveguide electromagnetically reflective at one end, having a
diameter corresponding to the wavelength of the band, and with a
probe extending about half-way into the cylinder perpendicularly to
its axis, at about a quarter wavelength from the reflective end.
Likewise, a so-called "Pringles Can Antenna", which has been termed
a Yagi design, and known modifications thereof, have been deemed
useful for extending the range of 802.11b communications.
[0672] According to one embodiment, a radome may be provided on the
roof of a vehicle, having therein an antenna array with, for
example, 4-64 separate elements. These elements, are, for example,
simple omnidirectional dipole antennas. The size and spacing of the
antenna elements is generally determined by the wavelength of the
radiation. However, this distance may be reduced by using a
different dielectric than air. For example, see U.S. Pat. No.
6,452,565, expressly incorporated herein by reference. See, also
www.antenova.com (Antenova ltd., Stow-cum-Quy, Cambridge, UK).
[0673] A preferred radome also includes a GPS antenna, as well as
cellular radio antenna (IS-95, PCS, GSM, etc.).
[0674] In a preferred embodiment, the communications device employs
an unlicensed band, such as 900 MHz (902-928 MHz), FRS, 49 MHz, 27
MHz, 2.4-2.5 GHz, 5.4 GHz, 5.8 GHz, etc. Further, in order to
provide noise immunity and band capacity, spread spectrum RF
techniques are preferred.
[0675] In one embodiment, communications devices are installed in
automobiles. Mobile GPS receivers in the vehicles provide location
information to the communications devices. These GPS receivers may
be integral or separate from the communications devices. Event
detectors, such as police radar and laser (LIDAR) speed detectors,
traffic and weather condition detectors, road hazard detectors (pot
holes, debris, accidents, ice, mud and rock slides, drunk drivers,
etc.), traffic speed detectors (speedometer reading, sensors for
detecting speed of other vehicles), speed limits, checkpoints, toll
booths, etc., may be provided as inputs to the system, or
appropriate sensors integrated therein. The system may also serve
as a beacon to good Samaritans, emergency workers and other
motorists in the event of accident, disablement, or other status of
the host vehicle.
[0676] It is noted that at frequencies above about 800 MHz, the
transmitter signal may be used as a part of a traffic radar system.
Therefore, the transmitted signal may serve both as a
communications stream and a sensor emission. Advantageously, an
electronically steerable signal is emitted from an array.
Reflections of the signal are then received and analyzed for both
reflection time coefficients and Doppler shifts. Of course, a radar
may use static antennas and/or mechanically scanning antennas, and
need not completely analyze the return signals.
[0677] Functions similar to those of the Cadillac (GM) On-Star
system may also be implemented, as well as alarm and security
systems, garage door opening and "smart home" integration.
Likewise, the system may also integrate with media and
entertainment systems. See, U.S. Pat. Nos. 6,418,424; 6,400,996;
6,081,750; 5,920,477; 5,903,454; 5,901,246; 5,875,108; 5,867,386;
5,774,357, expressly incorporated herein by reference. These
systems may reside in a fixed location, within the vehicle, or
distributed between fixed and mobile locations. The system may also
integrate with a satellite radio system, and, for example, the
satellite radio antenna may be included in the antenna system for
other communication systems within the vehicle.
[0678] The memory stores information describing the event as well
as the location of the event. Preferably, the memory is not
organized as a matrix of memory addresses corresponding to
locations, e.g., a "map", but rather in a record format having
explicitly describing the event and location, making storage of the
sparse matrix more efficient and facilitating indexing and sorting
on various aspects of each data record. Additional information,
such as the time of the event, importance of the event, expiration
time of the event, source and reliability of the event information,
and commercial and/or advertising information associated with the
event may be stored. The information in the memory is processed to
provide a useful output, which may be a simple alphanumeric, voice
(audible) or graphic output or the telecommunications system. In
any case, the output is preferably presented in a sorted order
according to pertinence, which is a combination of the abstract
importance of the event and proximity, with "proximity" weighted
higher than "importance". Once a communication or output cycle is
initiated, it may continue until the entire memory is output, or
include merely output a portion of the contents.
[0679] Typically, a navigation system includes a raster "map" of
geographic regions, which is further linked to a database of
features, geocoded to the map. Alternately, the map may itself be a
set of geocoded features, without a raster representation. Various
events and features defined by the sensors provided by the present
system, or received through a communications link, may therefore be
overlaid or integrated into the geocoded features. Advantageously,
all of the geocoded features are separately defined from the static
geography, and therefore may be separately managed and processed.
For example, geologic features are persistent, and absent
substantial human activity or natural disaster, are persistent.
Other features, such as roads, attractions, and other conditions,
are subject to change periodically. Each geocoded feature (or
indeed, any feature or event, whether geocoded or not) may be
associated with a timeconstant representing an estimated life; as
the time since last verification increases, the probability of
change also increases. This may be used to provide a user with an
estimation of the reliability of the navigation system, or indeed
any output produced by the system. It is noted that the
timeconstant may also be replaced with an expression or analysis
which is a function of time, that is, to account for diurnal,
weekly, seasonal, annual, etc. changes. Such expression or analysis
need to be repetitive; for example, after an abnormality in traffic
flow, traffic patterns tend to remain distorted for a long period
(e.g., hours) after the abnormality is corrected, or after a driver
passes the abnormality; this distortion is both temporally and
spatially related to the original abnormality, and may be
statistically estimated. Chaos, fractal and/or wavelet theories may
be particularly relevant to this analysis.
[0680] In outputting information directly to a human user,
thresholds are preferably applied to limit output to events which
are of immediate consequence and apparent importance. For example,
if the communications device is installed in a vehicle, and the
information in the memory indicates that a pothole, highway
obstruction, or police radar "trap" is ahead, the user is informed.
Events in the opposite direction (as determined by a path or
velocity record extracted from the position detector) are not
output, nor are such events far away. On the other hand, events
such as road icing, flooding, or the like, are often applicable to
all nearby motorists, and are output regardless of direction of
travel, unless another communications device with event detector
indicates that the event would not affect the local communications
device or the vehicle in which it is installed.
[0681] According to an embodiment of the invention, relevance of
information and information reliability are represented as
orthogonal axes. For each set of facts or interpretation
(hypothesis) thereof, a representation is projected on the plane
defined by these two axes. This representation for each event
generally takes the form of a bell curve, although the statistics
for each curve need not be Gaussian. The area under the superposed
curves, representing the constellation of possible risks or
relevances, are then integrated, starting with relevance=1.00
(100%), proceding toward relevance=0.00 (0%). As the area under a
given peak exceeds a threshold, which need not be constant, and
indeed may be a function of relevance or reliability, and/or
subjective factors, the event is presented as a warning output to
the user. This method ensures that the output includes the most
relevant events before less relevant events, but excluding those
events with low reliability. Using a dynamic threshold, highly
relevant events of low reliability are presented, while low
relevance events of even modest reliability are suppressed. It is
possible for the threshold to exceed 1.0, that is, a complete
suppression of irrelevant events, regardless of reliability.
[0682] Alternately, the event projection into the
relevance-reliability plane may be normalized by a function which
accounts for the desired response function, with a static threshold
applied.
[0683] The reason why the determination employs an integration of a
stochastic distribution, rather than a simple scalar representation
of events, is that this allows certain events with broad
distributions, but a mean value below than of another event with a
narrower distribution, to be ranked ahead, as being more
significant. This has potentially grater impact for events having
decidedly non-normal distributions, for example with significant
kurtosis, skew, multimodality, etc., and in which a mean value has
no readily interpretable meaning.
[0684] The present invention therefore provides a method,
comprising receiving a set of facts or predicates, analyzing the
set of facts or predicates to determine possible events,
determining, from the possible events, a relevance to a user and
associated statistical distribution thereof, and presenting a
ranked set of events, wherein said ranking is dependent on both
relevance and associated statsistical distribution. The associated
statistical distribution, for example, decribes a probability of
existence of an associated event, and the relevance comprises a
value function associated with that event if it exists, wherein
said ranking comprises an analysis of probability-weighted benefits
from each event to an overall utility function for the user. The
ranking may comprises a combinorial analysis of competing sets of
rankings.
[0685] It is therefore apparent that each event, that is, a set of
facts or factual predicates, or conclusions drawn therefrom, are
represented as a distribution proijected into a
relevance-reliability plane. On the abscissa, relevance has a scale
of 0 to 1. At zero relevance, the information is considered not
useful, whereas at a relevance value approaching 1, the information
is considered very relevant. Since the determination of relevance
is generally not exact nor precise, there is an associated
reliability, that is, there is a range of possibilities and their
likelihoods relating to a set of presumed facts. The various
possibilities sum to the whole, which means that the area under the
curve (integral from 0 to 1 of the distribution curve) should sum
to 1, although various mathematical simplifications and intentional
or unintentional perturbations may alter this area. Relevance
requires a determination of context, which may include both
objective and subjective aspects. Relevance typically should be
determined with respect to the requestor, not the requestee,
although in certain circumstances, the requestee (possibly with
adjustmjents) may serve as a proxy for the requestor. There are a
number of methods for weighting higher relevances above lower
relevances. One way is to determine a transfer function which masks
the normalized distribution with a weighting function. This may be
a simple linear ramp, or a more complex function. As discussed
above, a numeric integration from 1 to 0, with a respective
decision made when the integral exceeds a threshold, allowing
multiple decisions to be ranked, is another possibility.
[0686] Using a hierarchal analysis, this process may occur at
multiple levels, until each significant hypothesis is analyzed,
leaving only putative hypothesis which are insignificant, that is,
with sufficient external information to distinguish between the
respective possibilities. In order to simplify the output set,
redundancy is resolved in favor of the most specific significant
hypothesis, while insignificant hypotheses are truncated (not
presented). As the number of signififcant hypotheses becomes in
excess of a reasonable number (which may be an adaptive or
subjective determination), related hypotheses may be grouped.
Relatedness of hypotheses may be determined based on commonality of
factual predicates, resulting user action, or other commonality.
That is, the grouping may be the same as, or different from, the
hierarchy of the analysis.
[0687] It is also noted that the projection need not be in the
relevance-reliability plane. Rather, the analysis is intended to
present useful information: that which which represents information
having a potential materiality to the user, and which has
significance in a statistical sense. Therefore, a data analysis
which does not purely separate relevanmce and reliability, but
nevertheless allows a general banalcing of these issues, may
nevertheless be suitable.
[0688] This type of analysis may also be used to normalize utility
functions between respective bidders. To determine a cost, a local
set of events or factual predicates are analyzed with respect t to
a received context. The various hypotheses are projected onto a
relevance-reliability plane. With respect to each user, the
projection of each event is normalized by that user's conveyed
utility function. It is useful to maintain the stochastic
distribution representation for each event, since this facilitates
application of the user utility function. The winning bidder is the
bidder with the highest normalized integration of the event
representation in the relevance-reliability projection plane.
[0689] Advantageously, according to embodiment of the present
invention, output information is presented to the user using a
statistical and/or probabilistic analysis of both risk and
reliability. Risk is, for example, the estimated quantitative
advantage or disadvantage of an event. In the case of competing
risks, a cost function may be employed to provide a normalized
basis for representation and analysis. While the risk is generally
thought of as a scalar value, there is no particular reason why
this cannot itself be a vector or multiparameter function, such as
a mean and standard deviation or confidence interval. Reliability
is, for example, the probability that the risk is as estimated.
Likewise, the reliability may also be a scalar value, but may also
be a complex variable, vector or multiparameter function.
[0690] Since a preferred use of the risk and reliability estimates
is as part of a user interface, these are preferably represented in
their simplest forms, which will typically take a scalar form, such
as by projection from a high dimensionality space to a low
dimensionality space, or an elimination or truncation of
information which is predicted to be of low significance in a
decision-making process. However, where the risk, or risk profile,
cannot be simply represented, or such representation loses
significant meaning, a higher dimensionality representation may be
employed. For human user interfaces, graphic displays are common,
which generally support two-dimensional graphics, representing
three dimensional distributions, for example, x, y, and brightness
or color. Using a time sequence of graphic elements, one or more
additional dimensions may be represented. Likewise, some graphic
displays are capable of representing depth, and thus support an
additional degree of freedom. Therefore, it can be seen that the
risk and reliability are not intrinsically limited to scalar
representations, and where the quantity and quality of the
information to be presented warrants, a higher dimensionality or
additional degrees of freedom may be presented.
[0691] In a voice output system, a sequence of information may be
output, trading immediacy and semantic complexity for information
content. Complex sounds or other grammars may also be employed,
especially where the relevance has a short time-constant.
[0692] According to one embodiment of the invention, risk and
reliability are separately output to the user. It is understood
that both risk and reliability may be output in an integral or
interrelated form as well. For example, a driver might wish to
employ a radar detector. A traditional radar detector emits a
signal indicative of signal type and signal strength. Based on
these emissions, the driver decides on a course of action. Ideally,
the driver responds immediately (if necessary) to the first
detected signal, even if this is of low signal strength or
potentially an artifact. On the other hand, the system according to
the present invention may analyze the reliability of the detected
signal as an indicator of risk. For example, on a highway, an X
band radar signal directed from in front of the vehicle, which
commences at relatively high signal strength, and which occurs in a
location having a past history of use as a location for monitoring
traffic speeds for enforcement purposes, and which was recently
confirmed (e.g., within the past 5 minutes) as being an active
traffic enforcement site, would be deemed a high reliability
signal. On the other hand, on the same highway, if a continuously
emitted (or half-wave 60 Hz emission) X band signal is detected, in
a location where such a signal is consistently detected by other
drivers, and none is cited for violation of traffic laws, then this
detection would be considered a low reliability detection of a risk
or traffic enforcement radar. While a threshold of reliability may
be applied, and thus a "squelch" applied to the risk output,
preferably, the reliability signal is presented separately. When
risk and reliability are both high, for example, an enhanced alert
may be presented. When risk is high but reliability low, an
indication may be nevertheless presented to the user for his
analysis. This scheme would assist the user in dealing with
statistical aberrations, as well as intentional masking of
conditions. For example, a traffic enforcement radar system may be
intentionally used in an area of normal interference with radar
detectors; the system according to the present invention would
present an alert to the user of this possibility.
[0693] Such analysis is not limited to radar detectors. For
example, a bridge may be likely to freeze (i.e., become slippery)
under certain conditions. Some of these conditions may be detected,
such as local weather, past precipitation, and the like. Indeed,
recent road sand and salt may also be accounted for. However,
uncertainty remains as to the actual road surface conditions, which
may change over the course of a few minutes. Therefore, the system
according to the present invention may determine the risk, i.e.,
slippery road conditions, and the reliability of its determination.
This reliability may be estimated from actual past experience of
the system in question, as well as from other systems including
appropriate sensors, for which data is available.
[0694] According to the present invention, to risk tolerance, or
more properly stated, the reliability-adjusted risk tolerance of a
user may be used to "normalize" or otherwise adjust the outputs of
the system. Thus, for example, an emergency vehicle may take higher
risks than would normally be acceptable. Clearly, if there is a
100% probability that the vehicle will skid on black ice on the
road ahead, this risk would be unacceptable for any rational driver
seeking to continue driving. On the other hand, an ambulance driver
on an urgent call may be willing to undertake a 5% risk that the
road is slippery, while a normal driver might be willing to accept
only a 1% risk. The ambulance driver, in the above example,
generally takes a number of risks, and caution must be balanced to
assure that the goals are met, and indeed that risks are not
increased as a result of undue caution. For example, driving at a
slow speed increases the risk that the vehicle will be rear-ended,
or that the driver will fall asleep during the trip. Even pulling
over the side of the road does not eliminate risk to zero, so it is
important to do a comparative risk analysis.
[0695] The risk/reliability analysis is not limited to driving
condition alerts. For example, the system may be used to advise the
user regarding the need for preventive maintenance or repair. The
system may also be used as part of an entertainment system: What is
the likelihood that a channel will broadcast an undesired
commercial within the next minute? Should a recording stored in
memory be purged in favor of a new recording? What radio station
will be most acceptable to the set of occupants of the vehicle?
[0696] In some cases, therefore, the risk/reliability analysis may
be used by an automated system, and need not be presented directly
to the user; in other instances, the set of information is for
presentation to the user.
[0697] Another aspect of the invention involves a method for
presentation of a multidimensional risk profile to a user.
According to prior systems, a "risk" is presented to a user as a
binary signal, modulated binary signal, and/or a scalar value. A
signal type (e.g., band, SWS code, etc. for a radar detector,
temperature, wind speed, wind direction, barometric pressure and
trend, for a weather gauge) may also be expressed. Accordingly, as
set of orthogonal scalar values is presented representing different
parameters. Certainly, graphic representations of mean and standard
deviation are well known; however, the reliability aspect of the
present invention is not analogous to a simple standard
deviation--it typically represents something qualitatively
different. For example, a determination of the magnitude of the
risk variable carries its own standard deviation, which, though a
possible element of a reliability determination, does not address
the issue of how the measured parameter (with its own statistical
parameters of measurement) relates to the underlying issue. In some
cases, there with be a direct relationship and near 100%
correlation between the measured parameter and risk variable; in
other cases, the measured parameter has poor correlation with the
risk variable, and further analysis is necessary.
[0698] The system preferably ages event data intelligently,
allowing certain types of events to expire or decrease in
importance. A traffic accident event more than 12 hours old is
likely stale, and therefore would not be output, and preferably is
purged; however, locations which are the site of multiple accidents
may be tagged as hazardous, and the hazard event output to the user
as appropriate.
[0699] A temporal analysis may also be applied to the event data,
and therefore diurnal variations and the like accounted for.
Examples of this type of data include rush hour traffic, sun glare
(adjusted for season, etc.), vacation routes, and the like.
[0700] Thus, user outputs may be provided based on proximity,
importance, and optionally other factors, such as direction, speed
(over or under speed limit), time-of-day, date or season (e.g., sun
glare), freshness of event recordation, and the like.
[0701] According to the present invention, a stored event may be
analyzed for reliability. Such reliability may be determined by
express rules or algorithms, statistically, or otherwise, generally
in accordance with particular characteristics of the type of event.
Thus, even where a detected value, at the time of measurement, has
a high reliability for indicating an event or condition, over time
the reliability may change.
[0702] U.S. Pat. No. 6,175,803 (Chowanic, et al., Ford Global
Technologies, Inc.), expressly incorporated herein by reference in
its entirety, relates to a telematics system which employs routing
criteria which include a statistical risk index. The route and
associated risks may be output together, and a risk-minimized route
may be automatically selected.
[0703] According to a preferred embodiment, audio and/or visual
warnings are selectively provided. In this case, a warning of only
a single event is provided at any given time. Typically, a visual
alert indicator illuminates, and an initial tone alert indicates
the nature of an urgent warning. The visual indicator also outputs
a strength or proximity of the alert. Typically, these basic
indicators are illuminated red, because this color is societally
associated with alerts, and this causes less constriction of the
iris of the eye at night. A separate visual indicator, such as a
bar graph, meter, or color coded indicator (e.g., bicolor or
tricolor light emitting diode) provides a separate reliability or
risk of reliance indication. After acoustically indicating the
nature and strength or proximity of the warning, an acoustic
indication of reliability or risk of reliance may be enunciated.
The visual reliability or risk of reliance indicator is constantly
active, while the warning indicator is selectively active when an
alert is present.
[0704] Typically, alerts will be classified by category, and a
separate algorithm applied to determine the appropriate reliability
factor, for example an exponential decay. As updated information is
received or becomes available, this replaces presumably less
reliable older data as a basis for a reliability determination. The
system may also anticipate a geographic change in location of the
event, for example a traffic enforcement officer in motion, or a
traffic jam, along with reliability information for the
prediction.
[0705] When multiple alerts are simultaneously active, low priority
alerts are suppressed, and the active higher-priority alerts
alternate. Priority of alerts, in this case, may be determined
based on the nature of the alert, contextual proximity, the
reliability of the measurement of the alert, the reliability of
reliance on the recorded information, and a comparison of the
respective alerts and potential interaction.
[0706] At any time, there will likely be a number "issues" to be
analyzed. In order to provide an efficient user interface, these
issues are analyzed to determine urgency or importance, and only
those which meet criteria are particularly presented. For example,
the fact that the fuel gauge reads half-full is not normally a
cause for particular alert. However, if the vehicle is passing a
gas station which has a relatively low price, the alert may be
welcome. Without further information, these facts together reach a
sufficient importance to produce an alert. See, U.S. Pat. No.
6,484,088 (Reimer, Nov. 19, 2002, Fuel optimization system with
improved fuel level sensor), expressly incorporated herein by
reference. That is, the risk (need for fuel; capacity to purchase
additional fuel; distance to next gas station and margin of safety
given present fuel supply; etc.), ands the reliability (fuel price
predicted to be cheaper than other fuel along predicted vehicle
path before urgent need for fuel; etc.), together meet a
"threshold" (which, of course, may be particularly dynamic in
nature). Additional information, however, may reduce the importance
of this information below a threshold level; for example, the
present trip is time critical; the same gas station is predicted to
be passed a number of times before the fuel tank is empty; other
stations predicted to be passed have lower prices; pricing is
anticipated to be more advantageous at a later time (e.g., gas sale
on Monday; anticipated trip to another locale with lower gas
prices; etc.), etc. Thus, the set of facts including available
information is analyzed, for example using Bayesian techniques,
Hierarchal Markov Models or other techniques, to predict the
importance to the user. Each of these facts or predicates, or sets
of facts and/or predicates, of course, has its own estimated
reliability, and thus the overall conclusion is thereby limited.
Accordingly, this reliability of the logical conclusion is output
along with the conclusion itself.
[0707] With sufficient facts or predicates available, there may be
competing outputs, both relating to fuel use, conservation, and
refill strategies and otherwise. Thus, the system must compare the
competing prospective outputs to determine which are actually
presented. It may be useful in such circumstances to compute a cost
function for presenting this data. In this way, for example, an
advertiser or other external influence maybe permitted to impact
the overall analysis, e.g., presentation of data though the user
interface. This cost function may also balance driving conditions:
for example, when stopped at a traffic light, less urgent messages
may be presented with lower risk of driver distraction. The user
interface typically supports only a limited amount of information
to be conveyed, and ergonomics may further limit the amount of
information. Thus, there will typically arise the issue of
screening information for presentation to the user.
[0708] The cost function is analogous to a utility function, which
may be perturbed or modified based on subjective factors. As such,
automated negotiations are possible based on bidder and auctioneer
contexts, and predetermined and/or adaptive parameters. By
communicating complex, un-normalized information, and allowing an
ex post facto reduction in dimensionality or degrees of freedom,
greater efficiency may be obtained.
[0709] In choosing which information to present, a preferred
embodiment according to the present invention analyzes the risk and
reliability, to produce a composite weight or cost, which may then
be compared with other weights or costs, as well as a dynamic
threshold, which may be separately analyzed or implemented as a
part of a cost function. Taking a simple case first, information
which is immediately applicable, represents a high degree of risk,
and which is reliable, is presented with a highest weighting. If
the same indication is unreliable, then the presentation is
deweighted. A high risk with a low reliability would compete with a
low risk with high reliability for presentation through the user
interface. As previously discussed, a cost function may be used to
factor in external or artificial considerations as well.
[0710] If the risk or reliability changes as a function of time,
and this is the significant temporal relationship, then these
factors may be changed updated, and the user interface modified
according to a present condition. In some cases, the presentation
relating to an event need not be continuous. That is, as a result
of presentation to the user, the cost function is modified, and the
event is not again represented until the cost function exceeds the
presentation threshold. The change in cost function may indeed be
purely a function of time, or take into consideration dynamically
changing variables. For example, if a traffic jam is ten minutes
ahead on the road (using predicted travel speeds), and there are a
number of opportunities within the path leading toward the traffic
to circumvent it, the urgency of taking a detour is low. As the
time until the traffic decreases, or as the last opportunities for
detour are approaching, any decision by the user become critical.
This required decision is, in this case, the risk. On the other
hand, the traffic may be caused by a traffic light or other
temporary obstruction. Therefore, the reliability of the risk
indication will depend on an analysis of the surrounding
circumstances and the likelihood that the predicted risk will be
the actual risk. Time, in this case, is not clearly independent of
the other factors, and therefore need not represent an independent
output to the user. It is noted that such analysis of risk and
reliability may be facilitated by a wavelet domain transform, which
need not be a discrete wavelet transform (DWT), although the binary
decomposition properties of this transform may prove convenient or
advantageous in various circumstances. In particular, the purpose
of the transform is not necessarily a storage or
computation-efficient representation; rather, the purpose is to
significantly separate degrees of freedom to simplify the
statistical and probabilistic analysis. It is also noted that the
particular wavelets may be complex, high dimensionality, asymmetric
functions, and need not be wavelets of a traditional kind used in
image compression.
[0711] It may also be useful to transform the data into various
domains, such as time, frequency, wavelet, alternate iterated
function system, or the like, for filtering and denoising.
Preferably, adaptive thresholds are employed, although in many
instances the filtering may be performed in a context-independent
manner. On the other hand, where appropriate, the filtering may be
context sensitive, that is, the modifications of the data set
during the filtering are dependent on a calculated risk,
reliability, or relevance, or other parameter. Further analysis may
be performed either in the transform domain, inverse transform to
the original representation, or using a different transform.
[0712] It is also possible to employ a fractal (iterated function
system) analysis and/or transform of the data. In this case, a
function within a space, of any dimensional order, is decomposed
into a representation of a set of components, which may include
continuous functions (wavelet) or discontinuous functions
(geometric shape), each of which may be translated, scaled only any
axis, and amplitude scaled. Indeed, where convenient, the function
within a space may be decomposed into a plurality of separate
representations. Thus, according to one example, a number of
feature-specific decompositions may be applied where appropriate.
In the case of non-linear functions, it may be possible to
decompose the function into a linear component and a non-linear
component, wherein a relatively simplified non-linear component may
be subjected to a type-specific analysis. Thus, it is understood
that even relatively complex and seemingly intractable problems may
be addressed. It is further noted that incalculable aspects of a
fact or predicate net may be represented within the context of a
reliability variable. As such, a network is analyzed, and to the
extent possible, numeric analysis applied to reduce the result to
low-dimensionality terms. The predicted magnitude or potential
magnitude of the residual function or the uncertainty bounds may
then be estimated, resulting in a contribution to the reliability
output. Of course, the reliability estimate need be limited to
unknowns, and may also represent a contribution from an analytical
technique which produces a calculated uncertainty.
[0713] In a typical process, a data set, which may include a
plurality of dimensions, is first processed to reduce noise. For
example, error correction and detection algorithms may be applied
to eliminate spurious data or correct data which has been
corrupted. This process may also include a subprocess for
eliminating intentional spurious data, for example, data
communicated by a malfeasant, or data generated automatically in a
random or pseudorandom manner to make the entire dataset suspect as
a source of incriminating evidence. This is discussed in more
detail, below. The data may also be filtered or denoised using one
or more various algorithms, especially where the data is obtained
continuously from local sensors. Preferably, one or more
model-based algorithms is employed to optimally process data or
portions of data. This later function may be consolidated with a
feature extractor to correlate data with patterns which likely
indicate a known event, to classify the signal. A multidimensional
hidden Markov tree (HMT) analysis may be used to process the data.
A known principal component analysis (PCA) may, for example,
precede the HMT, to reduce the dimensionality of the data matrix by
extracting the linear relationship between the variables and
decorrelating the cross correlation in the data matrix. The hidden
Markov tree is a statistical model governing the wavelet
coefficients, and exploiting its tree structure in the
time-frequency domain. Each wavelet coefficient is modeled as a
Gaussian mixture with a hidden state variable. See, Detection and
Classification of Abnormal Process Situations Using
Multi-dimensional Wavelet Domain Hidden Markov Trees (Nov. 9,
2000), Amid Bakhtazad,
http://www.chem.eng.usyd.edu.au/events/poster.sub.--2000/present6/ppframe-
.htm
[0714] In order to prevent a data transmission from being used as
self-incriminating evidence, steps may be taken to undermine the
reliability of any single piece of data within a data set. In the
former case, a random or pseudorandom process may be used to
corrupt the database. This may take the form of modifications of
existing records and/or generation of phantom records. Typically,
such corruptions are made in such manner that a corresponding
filter in a receiving unit, with high reliability, will be able to
"uncorrupt" tile data. However, without knowledge of the actual
corruption parameters, which are not transmitted, the
reconstruction is statistical and not lossless. Therefore, with
high reliability, the content of the database is communicated, but
not in such manner that anyone could opine that individual data
within the database is real. For example, a database with GPS and
chronology will necessarily include data which may be used to
derive the speed of the vehicle. When that speed is in excess of
the speed limit, a transmission or retention of the data may be
used as an admission of transgression of speed limit laws. Using a
known filter scheme implemented at the receiver, an algorithm at
the transmitter may operate on the data to corrupt that data in
such manner that the receiver will correct the data. By applying a
low parameter at the transmitter, the reliability of the received
data can be controlled. The transmitter may, for example, determine
that 25% of the data is to be corrupted, and 1% corrupted in such
manner that the receive filter does not accurately reconstruct the
data. However, the corrupt 1% may be distributed such that 99% is
flagged as spurious, based on, for example, excess or negative
speeds, non-monotonic travel, etc. Thus, 0.01% of the corrupt data
is conveyed without being caught, a statistic which is likely less
than other, non-intentional corrupting influences. Each of these
parameters may be independently controlled at the transmitter.
Likewise, it is even possible for these corrupting parameters to be
transmitted, alerting the receiver that the data may be suspect.
Again, since these are statistical processes, no single data point
would have evidentiary reliability.
[0715] Using various cryptographic techniques, such as public key
infrastructure (PKI), it may also be possible to secretly
synchronize the internal filters of the communicating devices, to
maintain high reliability of user alerts, while masking the data
itself. Thus, using secure hardware and appropriate software
techniques, all or most of the corruptions may be corrected or
eliminated. For example, the transmitter uses a pseudorandom noise
generator to control a corruption of data to be transmitted.
Information related to the cryptographic key used to initialize the
pseudorandom noise generator is securely conveyed to the receiver,
for example using a Kerberos or other type of cryptographic key
negotiation. The receiver then initializes its own corresponding
pseudorandom noise generator to generate a synchronized stream,
allowing it to decorrupt the data. Clearly, various techniques,
including those known in the art, may be combined to remedy
weaknesses of any given scheme. Preferably, a plurality of
different algorithms are available, should one or more prove
broken.
[0716] See, Matthew Crouse and Robert Nowak and Richard Baraniuk,
"Wavelet-Based Statistical Signal Processing Using Hidden Markov
Models", Proceedings ICASSP-97 (IEEE International Conference on
Acoustics, Speech and Signal Processing), IEEE Transactions on
Signal Processing, 1997, and cited references, expressly
incorporated herein by reference. See, also, B. Vidakovic,
Wavelet-based nonparametric Bayes methods, Technical Report, ISDS,
Duke University., Merlise Clyde, and Heather Desimone and Giovanni
Parmigiani, Prediction Via Orthogonalized Model Mixing, Journal of
the American Statistical Association, 91(435):1197 (1996); Katrin
Keller, Souheil Ben-Yacoub, and Chafic Mokbel, Combining
Wavelet-domain Hidden Markov Trees with Hidden Markov Models,
IDIAP-RR 99-14 (1999), expressly incorporated herein by reference.
See, also, Attoor Sanju Nair, Jyh-Charn Liu, Laurence Rilett and
Saurabh Gupta, "Non-Linear Analysis of Traffic Flow," the 4th
International IEEE conference on Intelligent Transportation
systems, Oakland Calif., Aug. 25-29, 2001, (accepted), expressly
incorporated herein by reference.
[0717] In like manner, additional dimensions of analysis may be
added, resulting in further modifications of a cost function.
[0718] Urgency is a subset of relevance. Relevance may also be
treated as an independent factor; that is, not included within risk
or reliability. For example, a fact representing a risk may be
known with high certainty, for example, a weather condition on a
road: this fact, however, has low relevance if the car is parked in
a covered garage. Thus, according to an aspect of the invention,
the relevance may be considered an independent variable. Typically,
in this case, the risk and reliability are together analyzed to
determine a cost function; the cost function is then filtered using
a relevance criteria (which, for example, produces a modified cost
function), and typically sorted or ranked by weight. This relevance
therefore replaces a simple threshold with respect to making
ultimate decisions regarding information presentation to the user.
Relevancy may be determined by explicit input from the user,
implicit user input, collaborative processes, statistical analysis
of other user under like circumstances, or the like. It is noted
that the cost function may be personalized for each user.
[0719] In some cases, a dimensionless cost function is too
simplistic, and leads to results which fail to convey useful
information to the user; in those cases, sets of outputs may be
presented based on one or more criteria, or an estimated composite
function. Therefore, it is understood that a complex "cost
function" or utility function, resulting in an output having
various degrees of freedom, may be employed.
[0720] Preferably, the system according to the present invention is
integrated with a vehicular telematics system, thus providing
access to various vehicle data, in addition to environmental data.
However, it is not so limited, and may be used in any type of
man-machine interface wherein complex data is to be presented to a
user for human consideration.
[0721] It is noted that, in some instances, a fact or predicate set
may possibly represent a plurality of different events. In this
case, it ma sometimes be useful to group these events together.
This is particularly the case if the nature of the alert and likely
response to the alert by the user is similar, regardless of the
particular event giving rise to the sensor readings. In that case,
the risks, reliabilities, and relevance are aggregated in an
appropriate fashion, for example vector summed or composite
magnitude, and an aggregate cost function output, along with a
generic alert. This generic alert may then be subdivided into its
components, for example in a lower-hierarchal level user interface
output. In this manner, a set of possible events, none of which
would exceed an alert threshold individually, may together exceed
the threshold and indeed receive a high ranking.
[0722] Another way of analyzing this situation is that the system
may analyze the available data at a number of hierarchal levels. At
each level, the risk, reliability and optionally relevance is
determined, and the result stored. The user interface may then
select events based on redundancy and generic alerts, superceding
the particular ranking of events at a homogeneous level of
analysis. For example, data indicating stopped traffic ahead may be
consistent with an accident, stop light, or construction. These may
be divided into normal events (with low risk) (traffic light) and
abnormal events (with high risk)(accident or construction). The
former would not generally issue an alert, unless a suitable bypass
is available that would be efficient. The later, on the other hand,
would likely generate an alert. The available information may not
be able to distinguish between an accident and construction, and
indeed, the individual probabilities of these may be insignificant.
However, together, the probabilities may be significant. Likewise,
since these are two alternative, generally inconsistent
possibilities, the reliability of each will be greatly reduced.
Grouped together, however, their joint reliability is estimated to
be about the remaining likelihood after the traffic light is
accounted for, with high reliability. With respect to relevance,
each of these events would have similar relevance, which would be
high, assuming the stopped traffic is along the itinerary of the
vehicle. Thus, a composite alert of "abnormal stopped traffic 1
mile ahead; reliability 33%" would be a useful compromise to
maintain an efficient user interface while conveying the useful
information. Of course, the underlying system should generally
still compute the probabilities, reliability and relevance for each
possibility, since this analysis may yield more useful information
and provide better guidance to the user.
[0723] The ranking may, for example, employ a combinatorial
analysis of a set of rankings based on a self-consistent
probability-weighted utility of each event within a ranked set.
That is, if various events are mutually inconsistent, then a
ranking is limited by a presumption of the existence of one event,
and competing hypotheses are established as different rankings. In
a rigorous sense, the utility may be determined by a mathematical
integration of the appropriate function, although in many instances
either the data will be represented as a field which can be simply
summed, or simplifying presumptions may be applied to make the
evaluation tractable.
[0724] According to an aspect of the invention, a user transmits a
relevance or cost function to corresponding other users, which then
calculate the most useful information to transmit based on the
circumstances of the intended recipient. Likewise, a plurality of
users may exchange their respective relevance or cost functions.
This relevance or cost function is, for example, a current
position, immediate itinerary, and any other particular relevance
factors. Such other factors might include heavy load, urgent
transit, travel preferences, or the like. Upon receipt, the device
of the other corresponding user then calculates relevance and/or
cost functions using its local data set based on the received
parameters. This calculation is then used as a filter to determine
a priority of data to be transmitted. As the time available for
transmission grows, the amount of information transmitted may be
complete. For example, two cars traveling adjacent on a highway or
parked near each other may conduct a complete data exchange. When
optimizing the broadcast of data based on a plurality of user's
relevance or cost functions, a weighting may be applied which
balances the maximum good for the many with the urgent needs of the
few. Likewise, accommodations may be made for anticipated duration
of communication for the respective users, and the availability of
packet forwarding and secondary retransmission.
[0725] Since all devices share a common transmission medium, it is
generally useful to compute a cost function for use of the shared
medium as well, allowing peers access to the medium after the
marginal utility for the current user has declined. Access to the
shared medium may also be allocated on a round robin basis,
especially when demand is highest. Each device preferably monitors
all local transmissions, since these will likely include data of
some relevance to each device. Likewise, by monitoring such
transmissions, one device may make presumptions as to the state of
the local database of another device (especially given a knowledge
of its present position and path), and therefore avoid redundant
transmissions of data. Likewise, in such a peer to peer network, a
voting scheme may be instituted, allowing the peer with the "best"
data, i.e., the data which is most reliable, most accurate, most
recent, most detail, or other criteria to transmit with higher
priority.
[0726] Known packet data broadcast protocols may be used to convey
the information. Likewise, known peer-to-peer techniques and
protocols may be used to communicate, or control communications,
between peers.
[0727] According to another aspect of the invention, a user may
broadcast or transmit a specific query for information, using as at
least a part of the query a relevance or cost function. Recipients
of the broadcast or transmission then execute a search of their
database based on the received query, and respond accordingly. This
query may be a broad or narrow request for information, and thus
need not result in a complete exchange of data.
[0728] In order to optimally allocate communications bandwidth,
users within an area may engage in a local auction, that is, each
user bids for use of the shared medium, with those deferred and the
supplier of information receiving credits. An accounting for these
credits may, for example, take place each time a device connects
with a central database, for example, using a "hotspot" or other
access to the Internet. These credits may, for example, be
converted into economic values. In like manner, advertisers may
also bid for access to users, with users, for example, receiving
credit for receipt of advertising. Such bidding may be on an
individual or group basis. Typically, advertising will be relevant,
for example as a location-based output, but need not be.
[0729] It is also possible to conduct auctions or otherwise account
for control of the communications medium using a zero-sum temporal
averaging. That is, each user has an a priori equal right to
access. As a user takes advantage of that access, its rights
decrease, until exhausted. Over time, rights are added, and accrued
rights expire. For example, rights may have a half-life of 5
minutes, with a regression to a predetermined value. As more users
compete for control over the medium, cost increases. Suppliers of
information may receive partial credits from the consumer. Value
transmission may take place using a modified micropayment scheme,
for example a variant of Agora Micropayment Protocol, "Agora: A
Minimal Distributed Protocol for Electronic Commerce", Eran Gabber
and Abraham Silberschatz, Bell Laboratories or MPTP, Micro Payment
Transfer Protocol (MPTP) Version 0.1, W3C Working Draft 22 Nov. 95,
www.w3.org/pub/WWW/TR/WD-mptp-951122.
[0730] Thus, within a cell, each user is a primary recipient, a
secondary recipient, a supplier, or undefined. A primary recipient
bids for access and control of the medium, i.e., the communications
band. This bid takes the form of a cell identification (i.e., the
controlling user's location and itinerary), as well as an economic
function representing the required information and valuation
thereof by the user. The bids are broadcast and each recipient
calculates an actual value for the bid using its own database and
the relevance function. The calculated economic values, filtered by
the recipient databases, are then broadcast, and the highest actual
valuation is deemed winner. A negotiation then occurs between the
bidder and the holder of the valued information, for payment for
the transmission, and other bidders receive a lesser value as a
concession. Secondary recipients of the information also pay for
the information, based on their respective bids, with a
redistribution to the other bidders as a concession. Devices which
are not active bidders have no economic effect, although these may
accumulate and use transmitted information from others. Thus, an
economic redistributioh occurs efficiently, while optimally
allocating scarce bandwidth.
[0731] In general, the auction parameters may be too complex for
interactive user entry. Rather, the user cost function itself
represents the user valuation, and therefore is usable as a bidding
function. In the cost function, both subjective and objective
values are observed. With respect to objective values, the
relationship of a user context and an event known by the recipient
provides a relevance, and therefore the objective valuation. This
objective valuation is then warped by user subjective factors. Some
users may be quite willing to pay more for a better quality of
service. At least a portion of this value is distributed to other
users, this system allows even those with low valuation to access
the network, since these deferred users will accumulate credits. In
some cases, the credits may be provided with cash value (i.e., an
ability of a user to extract cash proceeds from the system), while
in other cases, these credits are limited to use with the system,
with no redemption rights. The use of a central authority for the
purchase of usage credits'therefore allows a profit incentive for
the authority responsible for the system. A user may therefore
express a higher valuation by purchasing units from an authority,
or by providing value to other users of the system, which may, for
example, require enhanced hardware purchases to include more and/or
better sensors of various conditions.
[0732] A negotiation or auction may also include external elements,
such as fixed infrastructure. In this case, the scarce resource is,
for example, the right of way. Elements of the fixed infrastructure
which are subject to negotiation include traffic lights, draw
bridges, railroad crossings, etc. Typically, such infrastructure
systems have low intelligence. By employing communications with
interested parties, a more efficient outcome may be predicted as
compared to "fair", though unintelligent decisions. Thus, competing
drivers may bid for a right of way or green light. The traffic
signal may be arbiter of the negotiation, or merely recipient of
the defined result. In some instances, the negotiation is free of
cost, for example, a traffic light with but one car approaching and
no hazards surrounding. In this case, the signal allows the driver
to pass, unobstructed. In another instance, a large amount of
traffic may be present, seeking to pass through an intersection.
All of the vehicles seeking to pass present "bids" for the right,
with bids representing common interests oroutcomes pooled. The
aggregate bids are then compared for action. In this case, the
transaction may have no economic impact, but rather the utility
functions may be relatively non-subjective. For example, emergency
vehicles may have a non-subjectively determined high valuation,
cars driving toward the intersection with a present state of
traffic flow control in their favor at a medium valuation, and
stopped traffic with a low valuation. As the duration of the stop
increases, a delay factor increases the valuation for the stopped
traffic to compensate, allowing or forcing the signal to change.
The objective criteria used in this circumstance (which may, for
example, be defined by a municipality or traffic engineer) may
include optimization of pollution, energy efficiency, effects of
traffic flow on other intersections, speed control, and other
considerations.
[0733] It is noted that, since external elements communicate using
the same communications system, and indeed various communications
systems may share the same band, the concept of bidding for use of
the shared or scarce resource may transcend a given communications
purpose, and, other than communicating using a common protocol for
the bidding and auction process, other users of the band need not
communicate public information.
[0734] A user may also provide a subjective element to a context,
for example, a driver may be in a rush or be late for a meeting.
This may be explicitly input by the user, as a factor which adjusts
the cost function higher, or may be derived implicitly from
observation of user behavior. Likewise, a driver may be in no
particular rush, and therefore place a low relevance to information
which might be of particular benefit to allow him to travel
faster.
[0735] Thus, in a purely fair system, each user is allocated a
"fair" chance for access to the scarce bandwidth resource, and bids
using equally distributed credits to compensate those users
deferred, and particularly those users who provide useful
information. A user bids using a cost function, representing the
maximum value of the resource to that user. Using known auction
theory, for example, the cost to the winning bidder may be the
price bid by the second-highest bidder. Of course, other known
auction types may be employed. The cost function may be
automatically generated by a user based on available funds, likely
future required use of the funds, a relevance or context which
allows for adaptive bidding based on the value of the information
to be provided, and user-subjective factors. The actual normalized
bid is resolved by the respective recipients, which then broadcast
the results. The maximum value bidder then controls the scarce
bandwidth resource until the bid-for communication is completed or
exhausted. In order to avoid inefficient reauction overhead, a
periodic auction may be conducted, with all bidders placed in a
queue.
[0736] Clearly, in real world situations, a number of additional
distortions will take place. Bidders may become unavailable prior
to completion of a communication. Interference may require
retransmission.
[0737] As discussed above, each "limited resource" may be subject
to auction. Preferably, a spatial division multiplexing scheme is
employed, wherein each band has one or more frequency channels.
High gain, directional antennas are employed, such that there is a
high degree of frequency reuse within a local area. However, there
will be a statistical degree of competition for the frequencies. In
addition, there will be competition from other competing uses for
the band, which may also engage in an auction scheme for access.
Typically, by efficiently negotiating an auction between all users
of the resource (i.e., the overhead for negotiation is negligible
as compared to the actual usage), overall throughput and capacity
will be increased.
[0738] For example, each system may include 8-16 transceivers or
the ability to conduct 8-16 communication sessions simultaneously.
In the former case, 8-16 directional antennas having relatively low
overlap are arrayed in different directions, providing a physical
separation. In the later case, a phased array or synthetic aperture
antenna system electronically defines 8-16 independent apertures,
also with low overlap. Each spatial domain aperture and its
associated coverage area represents a different resource which may
be allocated. Therefore, multiple simultaneous negotiations may
occur simultaneously. Each aperture may be a separate radio, with
packets routed there-between, or the radios may be coordinated.
[0739] It is also noted that the communications system may be used
not only for packet data communications between peers, but also as
a real time communication system for data streams, such as voice
communications. In this case, hand-offs may be necessary between
various nodes in order to assure continuous end-to-end
communications. Such hand-offs and multiple hop communications may
be predicted in advance and pre-negotiated. Such communications
predictions may, indeed, involve multiple systems, such as various
cellular carriers and protocols, 802.11 hot spots, and a mobile
ad-hoc network with sporadic links to fixed infrastructure. This,
in turn, allows a balancing of competitive uses for the resources,
quality of service, cost, and For example, by providing a mobile
ad-hoc supplementation for a fixed cellular infrastructure, the
incidence of dropped calls and service unavailability may be
reduced. Likewise, cellular carriers may allocate their
infrastructure build-outs and capital investments where the return
on investment will be maximum. On the other hand, cellular users in
such regions may employ other users to act as repeaters for
extending the effective range of their equipment. In this case, the
compensation and/or negotiation therefore for use of the system may
come, in whole, or in part, from the fixed infrastructure provider.
On the other hand, if the system is sponsored by the fixed
infrastructure carrier, then the repeater services hosted by each
node may be at no incremental cost to the fixed service
provider.
[0740] This later possibility provides an interesting opportunity.
Since the fixed cellular infrastructure providers generally own
licensed spectrum, the implementation of repeater or ad hoc
services between mobile units may be coordinated centrally, with
mobile-to-mobile communications using cellular channels, which may
be time domain (TDMA), frequency domain (FDMA), code division (COMA
and related systems), or other type of band-sharing scheme in
accordance with the more global standards generally established for
these services. Typically, mobile-to-mobile communications use
omnidirectional antennas, and packet data communications may use
excess system capacity, e.g., capacity not presently being used for
voice or other toll or real-time service. The fixed infrastructure
my also provide coordination of information communication services,
local buffering, ad multicast f information of general
interest.
[0741] It is therefore clear that the present invention may
comprise both disruptive and incremental technologies, and the
underlying business model may therefore be modified to suit.
[0742] A particular issue which is advantageously addressed during
the design phase is the ecurity of the system against "hackers" or
malfeasants. This may be dealt with by providing a central database
of authorized users, with peer reporting of accounting and apparent
abuse. If a user is suspected of abuse, its access rights may be
extinguished. This, in turn, will at least prevent the user from
engaging in auctions, and, if transmissions are encrypted or
otherwise secure, may prevent eavesdropping on normal
communications streams. This same result may be imposed on a user
who exhausts his credits, although it is preferred that a user who
is otherwise in compliance with normal regulations be permitted to
receive communications and indeed to gain new credits by
transmitting useful information.
[0743] Since the system is a packet data system, similar to in many
respects, and possibly an extension of, the Internet, various known
Internet security paradigms may be applied and employed.
[0744] While it is often useful to engage in fair auctions or
games, it is also possible to engage in unfair auctions. For
example, since there may be external financial requirements for
maintenance of the system, these may be paid by subscription fees,
or subsidized by advertisers. The advertiser may transmit its own
cost function, and bid for presentation to given users, or engage
in a broadcast for all users. In this case, more valuable users
will gain more credits, and therefore have more control over the
network. This is not "fair", but the distortions implicit in this
technique may be tolerable. Likewise, a bidder may purchase
credits, but typically this purchase will be consumed by the
service operator, and not paid to the users as a whole. However,
presumably, this will on the whole reduce normal service pricing
for all users. Indeed, various promotional techniques may be used
to distort allocation of bandwidth, without departing from the
general scope of the invention.
[0745] It is noted that this implicit auction process, wherein a
user bids a utility function rather than a normalized economic
value, is a distinct part of the invention, applicable to a
plurality of contexts and environments, well beyond telematics.
Likewise, the concept of bidding for quality of service to control
a shared resource, against competing users, is also applicable to
other contexts, notably peer-to-peer networks, other shared
transmission medium networks, and queues.
[0746] In order to define a user's subjective preferences, value
functions, and the like, a number of methods may be employed.
Certainly, express and explicit inputs may be received from a user.
Likewise, a user model may be constructed by observation of the
user. A user may be classified as a member of a group having common
preferences, and then the preferences associated with the group may
serve as a proxy for the user himself. This is called a
collaborative profile, the basis for a collaborative filter. In
order to classify a user into a group, personality tests and/or
common attributes may be employed. According to a particular aspect
of the invention, a user may be classified by game play. By using
game theory, irrational or subjective user biases. By using games,
a user's utility function r valuation may be assessed. Likewise,
risk tolerance and demand for immediate gratification can be
determined. Further, game theory in the form of wagering may also
assist in determining economic normalizations. Games, especially
with the results augmented by collaborative profiling, may through
a limited number of iterations, elicit relatively detailed
information. Indeed, through inter-relation with commercial
sponsorship (or state associated lotteries), the economic
incentives and risks of the game may be made quite real.
[0747] In communicating data to another communications device,
typically it is desired to transmit (or exchange) all of the memory
or all of a "public" portion of the memory, with the received
information sorted and processed by the receiving unit and relevant
information persistently stored in the memory. After exchange,
conflicts may be resolved by a further exchange of information. An
error detection and correction (EDC) protocol may be employed, to
assure accurate data transmission.
[0748] Since the communication bandwidth is necessarily limited,
and the communications channels subject to noise and crowding, it
is often important to prioritize transmissions. It is noted that,
without a complete communication of the memory, it is difficult to
determine which events a communications partner is aware of, so
that an initial communication may include an identification of the
partners as well as recent encounters with other partners, to
eliminate redundant communications, where possible. Vehicles
traveling in the same direction will often be in close proximity
longer than vehicles traveling in opposite directions. Further, the
information of relevance to a vehicle traveling in the same
direction will differ from the information of relevance to a
vehicle traveling in the opposite direction. Thus, in addition to
an identification of the communications device, the recent path and
proposed path and velocity should also be exchanged. Based on this
information, the data is prioritized and sorted, formatted and
transmitted. Since the communications channel will likely vary in
dependence on distance between partners, the communications
protocol may be adaptive, providing increased data rate with
decreasing distance, up to the channel capacity. Further, when the
vehicles are relatively close, a line-of-sight communications
scheme may be implemented, such as infrared (e.g., IRdA), while at
larger distances (and/or for all distances) a spread spectrum 915
MHz, 2.4 GHz or 5.825 GHz RF communications scheme implemented.
[0749] Where multiple communications devices are present within a
common communications region, these may be pooled, allowing
transmissions from one transmitter to many receivers. In addition,
within a band, multiple channels may be allocated, allowing
multiple communications sessions. In this case, a single
arbitration and control channel is provided to identify
communications devices and communications parameters. Preferably, a
communications device has the capability to monitor multiple
channels simultaneously, and optionally to transmit on multiple
channels simultaneously, where channel congestion is low. The
channels are typically frequency division. Where such frequency
division channels are defined, communications may be facilitated by
so-called "repeaters", which may itself be a mobile transceiver
according to the present invention. Preferably, such a repeater
unit itself monitors the data stream, and may even process the data
stream based on its internal parameters before passing it on.
[0750] In order to assure data integrity and optimize data
bandwidth, both forward and retrospective error correction are
applied. Data is preferably packetized, with each packet including
error detection and correction information. Successful receipt of
each packet is acknowledged on a reverse channel, optionally
interspersed with corresponding data packets traveling in the
reverse direction (e.g., full duplex communications). Where the
data error rate (raw or corrected) is unacceptably high, one or
more "fallback" modes may be implemented, such as reduced data
rates, more fault tolerant modulation schemes, and extended error
correction and detection codes. Transmitter power may also be
modulated within acceptable limits.
[0751] A central repository of event data may be provided, such as
on the Internet or an on-line database. In this case, event
information may be administered remotely, and local storage
minimized or eliminated.
[0752] Communications with the central database may be conducted
through cellular infrastructure, wired or wireless local area
network hotspots, or in other communications bands and other
communications schemes.
[0753] Where primary event information storage is remote from the
device, preferably local storage is based on an itinerary (route)
and frequently traveled areas, with less frequently traveled and
not prospectively traveled routes stored remotely. This allows
consolidated update of memory by a large number of sources, with
statistical error detection and correction of errant event
information. The itinerary information may be programmed in
conjunction with a GPS system and mapping/navigation software.
[0754] According to one embodiment of the invention, a plurality of
functions are integrated into a single device, a sensor or detector
for sensor emissions, for example speed control devices, a human
computer interface, a computer system including processor, memory,
and operatiung system, geospational positioning device, and
wireless communication system. Preferably, the system supports
accessory inputs and outputs, which may be through wired or wirless
means. The human computer interface preferably includes both a
graphic display and a natural language (e.g., voice) interface. The
computer system preferably possesses sufficient machine
intelligence to filter outputs based on relevance and context, as
well as interpret inputs as usable commands.
[0755] Data communications over a wireless link, for communicating
between vehicles, preferably is highly compressed and fault
tolerant. For digital data, this typically requires error detection
and correction codes, while for data representing analog
information, the information may be encoded such that more
important information is transmitted in a more robust manner than
less important information. For example, image information may be
communicated in a hierarchally compressed manner, with higher order
information transmitted in a manner less susceptible to
interference and signal fading than lower order information.
[0756] The digital data may be compressed, for example, using a
dictionary lookup, run length encoding, and/or model-based vector
quantization method. Thus, since transceivers will typically be
within 2000 meters from each other, relative position may be
relayed in an offset format, with a grid size based on GPS
precision and required accuracy, e.g., about 50-100 meters. The
encoding may be adaptive, based, for example, on stored map
information, with information representation density highest on
traveled routes and lower in desolate areas. Thus, a sort of
differential-corrected positional coding may be established between
units.
[0757] By integrating functions, efficiencies are achieved. Thus, a
single central processor, memory, program store and user interface
may suffice for all functions. Further, the power supply and
housing are also consolidated. While GPS and telecommunication
antennas may be maintained as distinct elements, other portions of
the system may also be integrated. In a device intended for
vehicular applications, the GPS and other functions may be
available to other vehicular systems, or the required data received
from other systems.
[0758] Communication between communications devices may employ
unlicensed spectrum or licensed spectrum, and may communicate
between mobile units or between mobile and fixed resources. For
example, excess capacity of a traditional cellular system may be
used for inter-vehicle communications. Thus, the system may include
or encompass a typical cellular (AMPS, IS-136, IS-95, CDPD, PCS
and/or GSM) type telecommunications device, or link to an external
telecommunications device.
[0759] Even where the cellular telephony infrastructure is not
involved, mobile hardware may be reused for the present invention.
For example, digital or software defined cellular telephone
handsets may permit programmed use outside the normal cellular
system protocols.
[0760] According to the present invention, messages may be passed
between a network of free roving devices. In order to maintain
network integrity, spurious data should be excluded. Thus, in order
to prevent a "hacker" or miscreant (e.g., overzealous police
official) from intentionally contaminating the dispersed database,
or an innocent person from transmitting corrupted data, the
ultimate source of event data is preferably recorded. When corrupt
or erroneous data is identified, the source may then also be
identified. The identity of the corrupting source is then
transmitted or identified, for example to other radios or to a
central database, whereupon, units in the field may be programmed
to ignore the corrupt unit, or to identify its location as a
possible event to be aware of. Further, assuming the hardware of
the corrupted unit remains operational, a code may be transmitted
to it deactivating it or resetting or reprogramming it.
[0761] Preferably, data is transmitted digitally, and may be
encrypted. Encryption codes may be of a public-key/private key
variety, with key lookup and/or certificate verification, either
before each data exchange, or on a global basis with published
updates. In fact, corrupt or unauthorized units may be deactivated
by normal and authorized units within the network, thus inhibiting
"hacking" of the network. Communications may be metered or
otherwise controlled externally, with charges assessed based on
usage factors. As discussed above, units may bid for control over
the transmission medium, and an accounting may take place either
between corresponding units, with a central database, or both.
Thus, a subscription based system is supported.
[0762] Techniques corresponding to the Firewire (IEEE 1394) copy
protection scheme may be implemented, and indeed the system
according to the present invention may implement or incorporate the
IEEE 1394 interface standard. The IEEE 1394 key management scheme
may be useful for implementing subscription schemes and for
preventing tampering.
[0763] One way to subsidize a subscription-based system is through
advertising revenue. Therefore, the "events" may also include
messages targeted to particular users, either by location,
demographics, origin, time, or other factors. Thus, a motel or
restaurant might solicit customers who are close by (especially in
the evening), or set up transponders along highways at desired
locations. Travelers would then receive messages appropriate to
time and place. While the user of the system according to the
present invention will typically be a frequent motorist or
affluent, the system may also provide demographic codes, which
allow a customized response to each unit. Since demographic
information is personal, and may indicate traveler vulnerability,
this information is preferably not transmitted as an open message
and is preferably not decodable by unauthorized persons. In fact,
the demographic codes may be employed to filter received
information, rather than to broadcast interests.
[0764] Commercial messages may be stored in memory, and therefore
need not be displayed immediately upon receipt. Further, such
information may be provided on a so-called "smart card" or PC Card
device, with messages triggered by location, perceived events, time
and/or other factors. In turn, the presentation of commercial
messages may be stored for verification by an auditing agency, thus
allowing accounting for advertising fees on an "impression"
basis.
[0765] The communications device may also receive data through
broadcasts, such as using FM sidebands, paging channels, satellite
transmission and the like. Thus, locationally or temporally distant
information need not be transmitted between mobile units.
Satrellite radio systems may also be integrated.
[0766] While low power or micropower design is desirable, in an
automobile environment, typically sufficient power is continuously
available to support sophisticated and/or power hungry electronic
devices; thus, significant design freedom is provided to implement
the present invention using available technologies.
[0767] FIG. 8 shows a block diagram of a communications device
embodiment of the present invention. The mobile communications
device 1 includes a location sensing system 2, producing a location
output 3; a memory 4, for example storing a set of locations and
associated events; a telecommunications subsystem 5, for example
communicating event and location information between a remote
system and the memory 4; and a processor 6, for example processing
the location output in conjunction with the stored locations and
associated events in the memory 4, to determine a priority
thereof.
[0768] The location sensing system 2 may include a known GPS
receiver, which produces data that is analyzed by the processor 6.
In an alternate embodiment, the GPS receiver includes its own
processor and outputs coordinate positions, e.g., Cartesian
coordinates, latitude and longitude, to the communications device
processor 6, e.g., through a serial port or data bus, such as PC
card, Universal serial Bus (USB), Firewire (IEEE 1394), peripheral
connect interface (PCI), or other bus, such as that present within
an automobile for communication of signals between subsystems. The
location sensing system may also determine a position based on the
GLONASS system, LORAN, inertial reference, cellular base stations
10',10'', triangulation with fixed radio sources, such as FM radio
and television stations, environmental markers and/or transponders,
or the like. The location system may also be network based, for
example relying on a cellular network to produce georeferenced
positioin information.
[0769] The communications subsystem 5 is, for example, an 802.11g
wireless Ethernet local area network system, having a router and
switch controlling communications between 8 separate spatially
distinct channels, defined by a "smart antenna". These spatially
distinct channels are agile and having an aperture capable of being
steered in real time to adjust for a change in relative position
and orientation. The router and switch permit forwarding of packets
received through one channel to another, as well as local
communications control. The radio transceiver 12, operates in the
unlicensed 2.4 GHz band, according to FCC regulations for this type
of equipment. The system may alternately or additionally
communicate in other unlicensed bands, such as 27 MHz, 49 MHz, FRS
band, 900 MHz, 5.4 GHz, 5.8-5.9 GHz using various known modulation
schemes and data communication protocols. Further, licensed radio
bands may also be used, including FM radio sidebands (88-108 MHz),
television PRO channel, cellular telephony channels, DECT, PCS and
GSM channels, and the like. Likewise, satellite systems 16, 17 may
be used to communicate with the mobile communications device 1.
Thus, for example, instead of direct communication between mobile
units, the existing cellular telephony 10',10'' infrastructure may
be used to provide intercell, local, and/or regional communications
between units, controlled by cellular telephone switching
processors 11', 11''. These communications may be given a lower
priority than voice communications on the cellular telephone
network, and therefore may use otherwise excess bandwidth, thus
allowing reduced costs and reduced user fees or subscription
rates.
[0770] The memory 4 may be of any standard type, for example, one
or more of static random access memory, dynamic random access
memory, ferroelectric memory, magnetic domain memory (e.g.,
diskette, hard disk), non-volatile semiconductor memory (e.g.,
UV-EPROM, EEPROM, Flash, non-standard electrically erasable
programmable non-volatile memory), optically readable memory (e.g.,
R-CDROM, RW-CDROM, R-DVD, DVD-RAM, etc.), holographic memory, and
the like. Preferably, common memory devices, such as EDO, SDRAM,
RIMM, DDR, are employed, at least for a volatile portion of the
memory, allowing simple upgrades and industry standard
compatibility.
[0771] While the preferred embodiment includes a radio frequency
transceiver for transmitting event data and receiving event data,
embodiments are also possible which either transmit or receive the
relevant data, but not both. For example, regulations may limit
certain transmissions or relevant event sensors, e.g., radar
detectors in trucks. In these cases, a receive-only embodiment may
be appropriate. Further, while radio frequency communications are
preferred, due to their range, data capacity and availability,
optical communications systems 13, e.g., infrared LED's and laser
diodes, acoustic communication 15, passive backscatter
communications (employing an RF transceiver such as the spread
spectrum transceiver 12), and the like may also be employed in
conjunction or in substitution of a radio frequency system. Optical
communication systems 13 may employ various detectors, including
optical homodyne detectors, or other coherent optical detectors, or
other types of optical sensors, such as PIDs, CCDs, silicon
photodiodes, and the like.
[0772] Under some circumstances, a wired or dedicated link between
units may be appropriate. For example, a central database 20 may
provide consolidated and reliable data. The relevant portion of the
database 20 may be downloaded by telephone through a modem 21,
either through a physical connection 23 (e.g., POTS or ISDN, line),
through a broadband Internet connect, or other network 24, to a
database server 25. The memory 4 of the mobile unit may also be
uploaded to the central database 20, after processing by the
database server 25, during the same connection or session.
[0773] Thus, according to the present invention, the public
switched telephone network 24 may be involved both during
intermittent mass data communications with a central database 20,
and also using, for example, cellular telephony 14, for the normal
operation of the system (e.g., communications between mobile
units).
[0774] As discussed above, general access to and control over the
communications channel may be arbitrated on a bid and auction
basis, as appropriate to avoid contention.
[0775] The processor 6 analyzes the information stored in memory 4
to provide a prioritized output. Thus, the memory may store
information relating to a relatively large number of events,
without overwhelming the capacity of a human user or communications
partner. Priority may be based on a number of factors, including
proximity of a stored location to a sensed location or a
spatial-temporal proximity of a stored location to a loci of an
itinerary 101, a prospective conjunction 102 of a sensed location
with a stored location, a type of event 103, a type of event and a
sensed condition associated with the mobile communications device
104, or other factors or a combination of factors. Neural networks,
fuzzy logic and/or traditional logic paradigms may also be employed
to prioritize the outputs. These logical paradigms are provided in
known manner, and, especially in the case of neural network-based
systems, a training aspect may be supplied with the system to allow
it to adapt to the preferences and capabilities of the user. Thus,
for a human user, events which are forthcoming and important are
output, while past events and those in the distant future, if at
all, are low priority. On the other hand, for communications with
other devices, the prioritization is primarily in consideration of
the fact that the communication between units may be only short
lived; therefore, the data is communicated in order to priority,
preferably of the recipient device. In an adaptive device, if the
user believes that the information from the device is
inappropriate, a simple input is provided, which is later analyzed
to alter the information presentation algorithm. Likewise, if an
information alert retrospectively turns out to be erroneous is a
predictable manner, i.e., relating to a route not taken, the system
may internally adjust the algorithm without user input.
[0776] In order to sort the priorities, the intended recipient may,
for example, identify itself 201 and communicate its location 202
an itinerary or intended or prospective path 205. High priority
messages 204 and various codes 203 may be interspersed through the
communication string. The transmitting unit then outputs data 206
in order of the computed or predicted importance of the event and
the time before the recipient encounters the event. Static events,
such as fixed location radar emission sources, which may, for
example, indicate a source for interference with a radar detector,
or a speed detection/control device, may be transmitted as well. In
the case where there is contention for the band, the communications
session is limited by the scope of the authorization for use of the
band. Where there is no contention, the duration of the
communications channel will generally control the amount of
information communicated.
[0777] Therefore, it is noted that the present invention provides a
means for mapping events and for analyzing their significance.
Thus, this embodiment does not merely rely on processed sensor
outputs to supply information to the user; rather, sensor outputs
may be filtered based on past experience with the particular
location in question. If a particular user does not have direct
experience with a location, then the experience of others at that
location may be substituted or combined to improve analysis of the
sensor signal. Therefore, the signal analysis from the sensor need
not be subjected to a relatively high threshold to avoid false
alarms. A low threshold is acceptable because other information is
employed to determine the nature of the physical elements that give
rise to the event and sensor activation.
[0778] It is noted that, in the case of "false alarms", the
response of the unit is to detect the event, e.g., radar signal,
correlate it with a stored "false alarm" event, and suppress an
alarm or modify the alarm signal. Thus, information stored in
memory and/or transmitted between units, may signify an important
alarm or a suppression of an erroneous alarm. In this context is
apparent that the integrity of the database structure, especially
from corruption by the very sources of alarms which are intended to
be detected, is important. To the extent that the environment
responds to the existence and deployment of the system according to
the present invention, for example by detecting transmissions
between units to identify and locate units, and thereby alter the
nature of an event to be detected, the present system may also be
adaptive, in terms of its function and signature spectral patterns.
In one aspect, the system may employ a so-called "FLASH" upgradable
memory, which controls system, operation. Therefore, periodically,
the system operation may be altered. The communications may
selectively occur on a plurality of bands, using a plurality of
protocols. Thus, for example, the system may have tri-band
capability, e.g., 900 MHz, 2.4 GHz and 5.8 GHz. The mapping feature
of the present invention may also be used to identify the locations
of such monitoring sites. The system may also mask its
transmissions as other, more common types of transmissions or
environmental sources of emissions. A direct sequence spread
spectrum technique maybe employed that is difficult to detect
without knowing the spread spectrum sequence seed. Of course, an
aspect of the present invention is open communications, which as a
matter of course are not securely encrypted and which would
identify the transponder and its location. This problem may be
addressed, in part, relying on laws which prevent unauthorized
eavesdropping and unauthorized interception and decryption of
communications, unauthorized "copying" of copyright works and
defeating of copy protection schemes thereof, control over
availability of authorized transceivers, and patent protection of
the design and implementation. According to one embodiment of the
invention, channel use and control is established over a first
channel, which may be out of band with respect to the normal tada
communications channel. Preferably, this control channel is
longer-range and more robust than the data communications channel,
permitting control to precede normal communications capability, and
providing enhanced rocover and network reconfiguration
capabilities.
[0779] According to one embodiment, all communications are direct
sequence spread spectrum over a wide band, with medium to high
security codes, e.g., 10 bits or greater length chip sequence and
12 bits or greater data encryption, and more preferably 16 bit or
greater chip sequence and 16 bit or greater data encryption. The
chip sequence of the control and arbitration channel, which should
be available to all compatible units, may be adaptive or changing,
for example following a formula based on time, location, and/or an
arbitrary authorization code provided with a subscription update.
Further, the chip sequence may vary based on selective availability
(SA) deviancies in GPS data, or based on the identity of satellites
in view of the receiver. While such information might be available
to "pirates", miscreants, hackers and scofflaws, the algorithm for
generating the chip sequence might be held as confidential, and
thus the system unusable without specific authorization and
incompatible with equipment without such algorithm. Such systems
employing secure encryption with open access have been employed in
satellite television (General Instrument VideoCipher II) and the
like. It is noted that, in order to mask a message in a spread
spectrum signal, multiple active channels may be employed, one or
more of which transmits the desired data and the remainder
transmitting noise or masking data.
[0780] Employing 2.4 or 5.8 GHz communications bands, data rates of
10 megabits per second (MBPS) are possible, although lower rates,
such as 0.5-1.0 MBPS may be preferred to reduce loss due to
interference or adverse communications conditions and maintain
availability of simultaneous communications on multiple channels
within the band in a small geographic area.
[0781] Where mobile devices are traveling parallel and at similar
speeds, or both are stopped, an extended communications session may
be initiated. In this case, the data prioritization will be
weighted to completely exchange a public portion of the database,
although emphasis will still be placed on immediately forthcoming
events, if anticipated. On the other hand, where computed or
user-input trajectories indicate a likely brief encounter, the
immediate past events are weighted most heavily.
[0782] In order to analyze temporal or spatial relevance, the
memory 4 preferably stores an event identifier 301, a location 302,
a time of detection of an event 303, a source of the event
information 304, an encoding for a likely expiration of the event
305, a reliability indicator for the event 306, and possibly a
message associated with the event 307 including other information.
These data fields may each be transmitted or received to describe
the event, or selectively transmitted based on the nature of the
event or an initial exchange between units specifying the
information which will be communicated. Other types of relevance
may also be accounted for, as discussed above.
[0783] For example, in a radar detector embodiment, mobile police
radar "traps" are often relocated, so that a particular location of
one event should not be perpetuated beyond its anticipated or
actual relevance. In this case, expirations may be stored, or
calculated based on a "type" of event according to a set of rules.
False alarms, due to security systems, traffic control and
monitoring systems, and the like, may also be recorded, to increase
the reliability any warnings provided.
[0784] Likewise, traffic jams often resolve after minutes or hours,
and, while certain road regions may be prone to traffic jams,
especially at certain hours of the day and/or days of the week,
abnormal condition information should not persist indefinitely.
[0785] The preferred embodiment according to the present invention
provides an event detector, which, in turn is preferably a police
radar 18 and LIDAR 19 detector. Other detected events may include
speed of vehicle, traffic conditions, weather conditions, road
conditions, road debris or potholes, site designation, sources of
radio signals or interference or false alarms for other event
detectors, and particular vehicles, such as drunk drivers or
unmarked police cars (possibly by manual event input). The event
detector may include, for example, a sensor. such as a camera 26,
which may analyze traffic control indicia (such as speed limits,
cautions, traffic lights). The event may also include a commercial
message or advertisement, received, for example from a fixed
antenna beside a road, which, for example, is stored as the message
307. Such a commercial message 307 may be presented immediately or
stored for future output. The received message, whether commercial
or not, may be a static or motion graphic image, text or sound
message. The user output of the system 27 may thus be visual, such
as a graphic or alphanumeric (text) display, indicator lights or
LED's 28, audible alerts or spoken voice through an audio
transducer 29.
[0786] The camera is, for example, a color or infrared charge
coupled device (CCD) or complementary metal oxide silicon field
effect transistor (CMOS) imager, having resolution of 0.3 to 6.0
megapixels. Image communication may be, for example H.261 or
H.263+, using H.323 or H.324 protocol, or MPEG-4. The imager may
also be incorporated as part of a mobile videoconferencing system,
although a dual imager system (one for imaging persons and the
other for imaging road conditions) may be implemented. Other ITU
standards, e.g., T.120, may be employed for data communications,
although the particular nature of the data communications
channel(s) may compel other communications protocols.
[0787] In order to maintain the integrity of the database stored in
memory 4, 20, it may be useful to store the originator of a record,
i.e., its source 304. Thus, if event information from that origin
is deemed unreliable, all records from that source may be purged,
and future messages ignored or "flagged". As stated above, even the
proximity of an unreliable or modified unit may be detrimental to
system operation. Therefore, where the location of such a unit is
known, other units in proximity may enter into a silent mode.
Further, normal units may transmit a "kill" message to the
unreliable unit, causing it to cease functioning (at least in a
transmit mode) until the problem is rectified or the unit
reauthorized.
[0788] The unit is preferably tamper-proof, for example, codes
necessary for unit activation and operation are corrupted or erased
if an enclosure to the unit is opened. Thus, techniques such as
employed in the General Instrument VideoCipher II and disclosed in
Kaish et al., U.S. Pat. No. 4,494,114, may be employed.
[0789] The communications subsystem preferably employs an error
correction/error detection protocol, with forward error correction
and confirmation of received data packet. The scheme may be
adaptive to the quality of the communication channel(s), with the
packet length, encoding scheme, transmit power, bandwidth
allocation, data rate and modulation scheme varied in an adaptive
scheme to optimize the communication between units. In many cases,
units engaged in communication will exchange information
bidirectionally. In that case, a full duplex communication protocol
is preferred; on the other hand, where communication is
unidirectional, greater data communication rates may be achieved
employing the available bandwidth and applying it to the single
communication session.
[0790] In some instances, it may be desired to maintain privacy of
communications. In that case, two possibilities are available;
spread spectrum communications, preferably direct sequence spread
spectrum communications is employed, to limit eavesdropping
possibilities. Second, the data itself may be encrypted, using, for
example, a DES, PGP, elliptic keys, or RSA type encryption scheme.
Keys may be supplied or exchanged in advance, negotiated between
partners, or involve a public key-private key encryption algorithm.
For example, the spread spectrum communications chip sequence may
be based on an encrypted code. Ultrawideband (UWB) communications
techniques may also be employed.
[0791] In order to provide flexibility in financing the
communications devices, the commercial messages 307 discussed above
may be employed. Further, by circulating authorization tokens or
codes 203, a subscription service may be provided. Thus, in a
simplest subscription scheme, the communications device has a timer
function, which may be a simple clock or GPS referenced. The user
must input an authorization code periodically in order for the
device to continue operating. Thus, similarly to satellite
television receivers and some addressable cable television
decoders, failure to provide the authorization code, which may be
entered, e.g., by telephone communication or through a keypad 30,
renders the device temporarily or permanently inoperative. In order
to reduce the burden of reauthorizations, the authorization codes
or tokens may be passed through the communications "cloud" 24, so
that devices 1, if used, will eventually receive the authorization
data. Conversely, a code 203 may be circulated which specifically
deactivates a certain device 1, for example for non-payment of the
subscription fee or misuse of the device (e.g., in an attempt to
corrupt other users databases). The authorization process is
preferably integral to the core operation of the system, making
bypassing authorization difficult.
[0792] Where a number of communications devices are in proximity, a
multi-party communication session may be initiated. For example,
the communications subsystem may have simultaneous multi-channel
capability, allowing each unit to transmit on a separate channel or
use a shared channel. Where the number of channels or channel
capacity is insufficient, units may take turns transmitting event
information on the same channel (e.g., according to estimated
priority), or time division multiplex (TDM) the channel(s).
Preferably, the communication scheme involves a number of channels
within a band, e.g., 1 common control channel and 24 data
communications channels. Since some communication sessions may be
relatively short, e.g., limited to a few seconds, a data
communications channel preferably has a maximum capacity of tens of
kilobits per second or higher. In some cases, hundreds of kilobits,
or megabit range bandwidths are achievable, especially with a small
number of channels (e.g., one channel). For example, so-called
third generation (3G) cellular communications protocols may be
employed.
[0793] Thus, for example, a DSSS spread spectrum transceiver
operating in the 2.5 GHz band might have a usable bandwidth of 10
megabits per second, even while sharing the same band with other
transceivers in close proximity. Where necessary, directional
antennas or phased arrays may be employed to provide spatial
discrimination.
[0794] The system preferably has advanced ability to detect channel
conditions. Thus, where communications are interrupted by physical
limitations in the channel, the impairment to the communications
channel is detected and the communications session paused until the
impairment abates. This, in turn, will allow other units, which
might not be subject to the impairment, to use the same channel
during this interval. The channel impairment may be detected by a
feedback protocol between communications partners, or by means of
symmetric antennas and communications systems, by which an
impairment of a received signal may be presumed to affect the
transmitted signal as well. The latter requires a high degree of
standardization of equipment design and installation for
effectiveness.
[0795] It is particularly noted that, where the events to be
detected and the communications subsystem operate in the same band,
structures may be shared between the communications and event
detection systems, but this also increases the possibilities for
interference.
[0796] As one embodiment of the invention, the processor may be
provided as a standard personal digital assistant (PDA) with a PC
Card or PCMCIA slot for receiving a standard GPS receiver and
another standard PC Card slot for receiving an 802.11b/g/a/a R/A
module. The PDA, in turn has memory, which may include random
access memory, flash memory, and rotating magnetic memory (hard
disk), for example. The PDA has a processing system which is
capable of running applications written in general purpose, high
level languages such as C. The PDA may operate under a standard
operating system, such as Microsoft Windows CE, Palm OS, Linux, or
a proprietary operating system. A software application written in a
high level language can normally be ported to run in the PDA
processing system. Thus, the basic elements of the hardware
platform are all available without customization. In a preferred
embodiment, an event sensor is provided, such as a police radar and
laser speed detection equipment system (e.g., "radar detector") is
provided. This may employ a modified commercially available radar
detector, to produce a serial data stream or parallel signal set.
For example, radar detectors providing an alphanumeric display
often transmit data to the display controller by means of a serial
data signal. This signal may be intercepted and interfaced with a
serial port or custom port of the PDA.
[0797] Optionally, the GPS Smart Antenna is "differential-ready" to
apply differential GPS (DGPS) error correction information to
improve accuracy of a GPS determined location. The application
program for the PDA may be provided in a semiconductor memory
cartridge or stored on hard disk.
[0798] The PDA 30 includes the processing system, including a
microprocessor, memory, precoded program instructions and data
stored in memory, a microprocessor bus for addresses, data, and
control, an interrupt bus for interrupt signals, and associated
hardware, operates in a conventional manner to receive digital
signals, process information, and issue digital signals. A user
interface in the PDA includes a visual display or audible output to
present signals received from the processing system to a user, a
user entry system to issue signals from the user to the processing
system. The user interface may include one or more push keys,
toggle switches, proximity switches, trackballs, joysticks or
pressure sensitive keys, a touch-sensitive display screen,
microphones or a combination of any of the above used together or
with other similar type user input methods. The PDA sends digital
signals representing addresses, data, and commands to the memory
device and receives digital signals representing instructions and
data from the memory. A PDA interface electrically connects the
processing system to a GPS Smart Antenna. If the PDA and GPS are
not integrated, a preferred interface comprises a computer standard
low to medium speed serial data interface, such as RS-232, RS-422,
or USB (1.0, 1.1, 2.0), IEEE-1394, Bluetooth (especially if the
communications system operates in another band), through a cabled
interface for connection to the GPS Smart Antenna.
[0799] The GPS Smart Antenna system includes a GPS receiver antenna
to receive GPS satellite signals from GPS satellite transmitters, a
GPS frequency downconverter to downconvert the approximately 1.575
GHz frequency of the L1 GPS satellite signals to a lower frequency
(LF) signal that is suitable for digital processing, and to issue
the LF to a GPS processor. The GPS processor demodulates and
decodes the LF signal and provides location information for at
least one of (i) location of the GPS antenna, (ii), GPS satellite
pseudoranges between the GPS satellites and the GPS antenna, (iii)
rate of change of location of the GPS antenna, (iv) heading of the
GPS antenna, and (v) time to a GPS interface. Optionally, the GPS
Smart Antenna and GPS processor are differential-ready. An optional
input select switch, controlled by the GPS processor upon a request
from the PDA, allows a single serial interface to receive either a
control signal from the PDA or a DGPS error correction signal from
an optional DGPS radiowave receiver. Alternately, a DGPS-type
system may be coordinated between multiple mobile receivers, top
provide high relative position accuracy, even where the absolute
position accuracy is low. Since the event position calculations are
based on the relative position frame, the effect is to accurately
position the events with respect to the vehicle.
[0800] The user device may display, for example, map features
according to a coordinate system such as latitude and longitude.
The display may also include an indication of the location of the
GPS receiver, an itinerary, proposed route, and indications of the
location of various events. By correlating the GPS with a stored
map, the absolute location of the vehicle may be determined by map
matching techniques. In accordance with the present invention,
these events are derived from the event detector or the memory.
Other communications devices may also be located on the
display.
[0801] The user entry system has both touchscreen keys and press
keys in the present embodiment. With a touchscreen, a user enters a
request by touching a designated portion overlying a visual display
with his finger (or soft pointer, such as a plastic pen). The
touchscreen senses the touch and causes a digital signal to be sent
to the processing system indicating where the touch was made.
Switches such as rotary switches, toggle switches, or other
switches can equally well be applied. An advantage of the
touchscreen is that a label or a placement of the touchscreen, and
a corresponding function of the touchscreen, may be changed by the
computer controlling the display any number of times without
changing electrical or mechanical hardware. In the present
embodiment, zoom keys may be employed change scale and resolution
of a map on the display. Zooming in decreases the scale, so that
the map is viewed with greater resolution over a lesser area of the
map. Zooming out increases the scale, so that a greater area of the
map is viewed with lesser resolution. A map orientation key selects
an orientation of a direction on the map with a direction on the
visual display, for example, orientations of north up or current
ground track up. It is noted that these map functions are generally
known, and known techniques may be generally applied for such map
functions. According to the present invention, in addition to
normal map functions, the event data may be overlayed on the map to
provide additional dimensions of display data. Further, by
providing these data, which are dynamic, the map system becomes
useful even to travelers who are well aware of the geography and
layout of the region being traveled.
[0802] One communications scheme, a 900 MHz spread spectrum
communications system, operates as follows. The RF receiver
includes an antenna, low noise amplifier (LNA) with a noise
temperature below 80 degrees Kelvin and a helical bandpass filter
to cancel the image frequency noise. The filtered signal is then
downconverted to an intermediate frequency (IF) of about 70 MHz,
which is the result of mixing the filtered received signal with a
local oscillator signal of between about 832-858 MHz at about 17
dbm. Of course, other tuning frequencies may be selected, for
example, to avoid interference with other equipment. The local
oscillator thus operates at about 850 MHz and is locked to a
reference of 10.625 MHz. The 70 MHz IF frequency is amplified and
filtered by a SAW filter 906 with a bandwidth of 1.5-10 MHz,
depending on the data signal bandwidth. The IF is then demodulated
to baseband, employing a demodulator using an inverse sequence from
the transmitted spread spectrum sequence. Thus, in a frequency
hopping embodiment, the demodulator synthesizes a signal having the
appropriate frequency sequence. In a direct sequence spread
spectrum embodiment, the demodulator provides the appropriate
pseudorandom code sequence to demodulate the received signal. Time
synchronization may be effected by using the timing functions of
the GPS receiver. The demodulated signal is then decoded into
messages, which are typically digital bitstreams.
[0803] In a 2.4 GHz system, the RF semiconductor technology will
typically include gallium arsenide integrated circuits. In a 5.8
GHz system, the RF section semiconductors are preferably silicon
germanium. Once demodulated to below about 1 GHz, standard silicon
technologies may be employed.
[0804] The baseband demodulator may also comprise a digital radio,
employing a digital signal processor, receiving a digitized IF
signal and outputting a data stream. In this case, it may be
preferred to digitize at an IF frequency below 70 MHz. For example,
with a data stream having a bandwidth of 1.5 MHz, the preferred IF
is 3-10 MHz, with quadrature digitization of the analog signal at
that IF. The IF signal may be processed in parallel with a
plurality of demodulators, allowing multiple signals to be received
simultaneously.
[0805] In the 900 MHz embodiment, a PLL, such as a 1.1 gigahertz
PLL frequency synthesizer, Part No. MC145190 available from
Motorola Semiconductors, Phoenix, Ariz., may be used to generate
the first IF. This frequency synthesizer, referenced to the 9.6
megahertz reference frequency, generates a local oscillator signal
of approximately 860 megahertz. This PLL synthesizer chip produces
a locked stable output signal which is low pass filtered to produce
a variable voltage to control voltage control oscillator. VCO is,
for example, Part No. MQC505-900 operating at approximately 860
megahertz and available from Murata of Tokyo, Japan. The feedback
through sense keeps synthesizer chip stable to produce a stable,
fixed course output. A second PLL produces a fine control
frequency. The second PLL includes a synthesizer chip, e.g., Part
No. MC145170 available from Motorola Semiconductor of Phoenix,
Ariz. This PLL frequency synthesizer chip has digital controls for
control by a microcontroller. The output of the fine synthesizer
chip is low pass filtered to produce a variable DC voltage to
control a voltage controlled oscillator, e.g., Part No. MQC309-964,
operating within the 900 megahertz band. The fine adjust frequency
is band pass filtered with an SAW band pass filter with a center
frequency of approximately 38 megahertz. The band pass filter is,
for example, Part No. SAF38.9MZR80Z also available from Murata of
Tokyo, Japan. The output of the second PLL is controlled in
accordance with the output frequency desired based on the frequency
of the hop transmitted at the current time. By adjusting the fine
frequency, which would be mixed with the coarse frequency, the
output frequency in the 900 megahertz band is produced with very
little phase noise, very little phase jitter and extremely narrow
noise skirt. Thus, this double loop system serves to demodulate the
signal to a low IF frequency or to baseband.
EXAMPLE 2
[0806] Ad hoc networks are a good candidate for analysis and
optimization according to game theory. A multihop ad hoc network
requires a communication to be passed through a disinterested node.
The disinterested node incurs a cost, thus leading to a
disincentive to cooperate. Meanwhile, bystander nodes must defer
their own communications. By understanding the decision analysis of
the various nodes in a network, it is possible to define a system
which, in accordance with game theory, provides a benefit or
incentive to promote cooperation and network reliability and
stability. The incentive, in economic form, may be charged to the
node(s) benefiting from the communication, and is preferably based
on a value of the benefit received. This network optimization
employs a modified combinatorial (VCG) auction, which optimally
compensates those burdened by the communication, while charging the
benefiting participants. Equilibrium usage and headroom may be
influenced by deviating from a zero-sum condition. The mechanism
seeks to define fairness in terms of market value, providing
probable participation benefit for all nodes, leading to network
stability.
I. Introduction
[0807] I describe the application of game theory concepts to the
arbitration of access to bandwidth in an ad hoc communications
network, more particularly to network including mobile nodes.
According to applicable elements of game theory, an agent makes a
decision to cooperate with a system having established rules, or to
circumvent it. Likewise, cheating, i.e., adopting behavior contrary
to an expected nor, may be an option, and can be analyzed in the
context of a decision. Therefore, a game theoretic approach
addresses the situation where the operation of an agent which has
freedom of choice, allowing optimization on a high level,
considering the possibility of alternatives to a well designed
system. According to game theory, the best way to ensure that a
system retains compliant agents, is to provide the greatest
anticipated benefit, at the least anticipated cost, compared to the
alternates.
[0808] Mobile ad hoc networks encompass multihop networks, which,
by their nature, require participation of disinterested nodes to
operate. Technically, however, the multihop scenario is not
intrinsic, since it is reasonable to presume that in some networks,
all nodes are within range of each other. Each scenario poses a
classic game theory issue to each node: why defer to other nodes if
no direct benefit is obtained? The multihop network adds the
further issue of: why participate in communications between other
nodes if no direct benefit is obtained? We discuss a set of
mechanisms, incentives and rationales as a framework for analyzing
node behavior and optimization, and seeks to respond to these
issues by proposing appropriate incentives to promote network
efficiency and stability.
[0809] In these sections, we seek to avoid mathematical expression
of the principles, as well as formal proofs. This is for three
reasons: these mathematical expressions and proofs are detailed
elsewhere, the recitation of these formulae and associated
derivation are distracting to the essence presented herein, and
such a presentation might imply that, in practice, complete
information may be available in order to fully evaluate and employ
such expressions. In fact, it is likely that any real and feasible
implementation of will sufficiently deviate from a tractable
theoretical model, and thus require substantial simplifying
presumptions, to make any such presentation misleading.
II. Background
[0810] The application of game theory to ad hoc networks has been
addressed in various forms to date. In general, there is a
divergence between approaches which define a real-world system,
with all of its complexity, and required functionality, and those
which seek to mathematically tractable model having a definite set
of rules and presumptions leading to a comprehensible and useful
result. Each level of complexity and relaxation of limitations on
the system, decreases the ability to accurately model the system
and produce a result directly applicable to a deployable control
system. Construction and evaluation of models lags their
theoretical exposition. Focus is on a theoretical framework for the
arbitration control system, with the modeling and evaluation
remaining as the subject of later work.
[0811] An ad hoc network is a wireless network which does not
require fixed infrastructure or centralized control. The terminals
in the network cooperate and communicate with each other, in a self
organizing network. In a multihop network, communications can
extend beyond the scope of a single node, employing neighboring
nodes within the scope, to forward messages. In a mobile ad hoc
network, constraints are not placed on the mobility of nodes, that
is, they can relocate within a time scale which is short with
respect to the communications, thus requiring consideration of
dynamic changes in network architecture.
[0812] Ad hoc networks pose control issues with respect to
contention, routing and information conveyance. There are typically
tradeoffs involving equipment size, cost and complexity, protocol
complexity, throughput efficiency, energy consumption, and
"fairness" of access arbitration. Other factors may also come into
play.
[0813] Game theory studies the interactions of multiple independent
decision makers, each seeking to fulfill their own objectives. Game
theory encompasses, for example, auction theory and strategic
decision-making. By providing appropriate incentives, a group of
independent actors may be persuaded, according to self-interest, to
act toward the benefit of the group. That is, the selfish
individual interests are aligned with the community interests. In
this way, the community will be both efficient and the network of
actors stable and predictable. Of course, any system wherein the
"incentives" impose too high a cost, themselves encourage
circumvention. In this case, game theory also addresses this
issue.
[0814] We first analyze the issues that give rise to cooperative
problems in ad hoc networks. We then survey game theory in its
traditional forms, followed by a more complete discussion of ad hoc
networks. We then focus on published examples of the application of
game theory to the control and analysis of ad hoc networks, more
particularly on the theoretical costs and benefits applicable to
nodes in ad hoc networks, the behavior of communications nodes, and
apply game theory to define incentives predicted to result in an
efficient ad hoc network. Finally, we provide a new framework for a
real-time telematics information communication network proposed for
deployment.
III. Cooperative Problems in Ad Hoc Networks
[0815] To understand why game theory is applicable the control over
ad hoc networks, consider the analogy of a classroom. The teacher
acts as a central authority and arbitrator to ensure decorum. The
teacher recognizes one student at a time for public communication.
This is an example of centralized control. If there were no teacher
to recognize a student, pandemonium would result, unless a suitable
process of self-organization is established, which obtains
cooperation dictating common rules, adopted according to mutual
incentives.
[0816] Now, suppose one student wishes to send a note across the
room. Presumably, there are multiple paths to the destination. But
how can the student be sure that the note will be forwarded? How
does one know which neighbor to hand-off to? Suppose that
forwarding the note imposes a burden, such as the risk of being
caught and sanctioned? Consider the possibility, after conclusion
of negotiations for forwarding, a student fails to fulfill his
assumed responsibility?
[0817] It is therefore clear that the issues of subjective and
objective costs and benefits, distance, complexity, and
reliability, are therefore interrelated, and there may be practical
restraints on achieving theoretical system capacity.
[0818] The game theoretic solution is to link an incentive or
benefit to the desired behavior, to promote each agent cooperate
with note forwarding, on a rational basis. The ultimate payoff
should be borne by the student receiving the benefit. Thus, by
linking a benefits to costs, a stable society is achieved,
approaching a desirable equilibrium.
[0819] In order to incentivize the intermediaries, a student could
compensate them by taping dimes to the note, instructing each
forwarding student to remove one dime (the packet purse model).
Alternately, the recipient may be expected to pay for the
transmission through an acknowledgement message with attached value
(the packet trade model). However, how do we know that the first
recipient will not remove all the money and throw away the note?
How can the intermediaries ensure, in the packet trade model, that
the recipient will eventually pay? How does the responsible party
know how much must be paid? These models also require stability of
the route during the process, and imply a priori knowledge of the
route. This approach does not permit variations in compensation,
e.g., some students might accept a nickel, and others in a critical
position, might require a quarter. In cases of unreliable routes,
should the originator send two notes by alternate paths, or attempt
to pay more for a single reliable delivery?
[0820] Even with imposition of a traffic sensitive cost, one node
of the network may seek to send an inordinate number of messages,
resulting in congestion. A node in a critical location may become
wealthy, and its fees rise, leading to instability. Likewise, in a
virtual construct, what does one use as currency? We see that
consideration must be given to keeping traffic below capacity,
since highly loaded networks often have decreased efficiency.
IV. Game Theory
[0821] Game theory is the study of the interaction of independent
agents, in an environment where there are rules, decisions, and
outcomes. Game theory defines the theoretical basis for strategy,
as well as providing a framework for analyzing real-world actors.
Game theory may be applied to automated systems, providing a basis
for the analysis and optimization of such systems. Aspects of game
theory have been applied to telecommunications, for example to
optimize network routing, and has quality of service implications.
Communications resources may be treated as utilities, and auctions
have been applied to the optimization of allocation of utility
resources.
[0822] Each game has a set of rules or constraints, under which the
agents operate. "Cheating", if permitted at all, is modeled as an
available decision of an agent to comply with other constraints.
Therefore, the game is valid as a model only for the rules and
constraints considered. Each decision maker pursues a goal, and may
take into account their knowledge or expectations of the other
decision makers' behavior. According to game theory, rationality
leads to optimality, and therefore analyzing the game and acting
logically in accordance with the rules leads to the best
outcome.
[0823] It is conceptually simple for an automated system to act
rationally. That is, given a set of facts and circumstances, the
rational analysis is fixed and obtainable. On the other hand,
humans acting on purely mental consideration may deviate from
rationality. For example, humans exhibit a broad range of risk
tolerance, which is not directly explained by rational analysis. It
is noted that risk tolerance, and other aspects of behavior, have
been modeled, and as such, can themselves be treated scientifically
and rationally. In fact, game theory expressly recognizes that
agents may express private values which are not rationally
explained, and that by understanding these values, a strategic
advantage is obtained. Thus, while rationality is assumed as an
optimum strategy for each entity, real entities have imperfect
estimates of payoff and risk, and indeed may miscalculate or
misconstrue the circumstances. Such perturbations may be
compensated, under certain circumstances, by way of various
parameters added to the modeling equation.
[0824] Game theory is typically encompassed in the study of
economics, since a self-interested node will always try to increase
its wealth, and all other concepts may be considered in terms of
their subjective economic costs and benefits. Game theory can be
used not only to analyze a defined game, but also to define a game
having a desired outcome, i.e., to optimize a set of rules and
constraints. The preferences of a node can be expressed either with
a utility function, or with preference relations, ranking various
consequences.
[0825] Games can be divided into noncooperative and cooperative
games. In cooperative games, the joint actions of groups are
analyzed, i.e. what is the outcome if a group of players cooperate.
In noncooperative games, the actions of the single players are
considered. The cooperative game model may be used to analyze
heterogeneous ad hoc networks. In strategic games, decisions are
made at the commencement of the game. In extensive games, decisions
may be made interactively. The strategic game model is suitable for
representing simple real life events such as a sealed bid auction.
A progressive bid auction may be modeled as an extensive game.
[0826] Games can also be divided according to their payoff
structures. A game is called zero-sum game if the sum of the
utilities is constant in every outcome. Zero-sum games are
considered strictly competitive games. For example, an auction is a
zero sum game, since the buyer pays the seller, with no other gains
or losses incurred. If the players are fully informed about each
other's moves, the game has perfect information. Only extensive
games consider the issue of perfect information. In games with
complete information the utility function of each player is known.
In a game with incomplete information, the privacy of a player's
utility function is held as a strategic advantage.
[0827] Pareto efficiency exists if there is no other outcome that
would make all players better off. An equilibrium is a result of
the optimization of the individual players; but does not imply that
the result is "good" or globally optimum. The solution of a
strategic game is a Nash equilibrium. Every strategic game with
finite number of players, each with a finite set of actions, has an
equilibrium point. This Nash equilibrium is a point from which no
single player wants to deviate unilaterally. When a game is played,
the rationality assumption will force the game into a Nash
equilibrium outcome. If the outcome is not a Nash equilibrium, at
least one player would gain a higher payoff by choosing another
action. If there are multiple equilibriums, more information on the
behavior of the players is needed to determine the outcome of the
game.
[0828] In the strategic and extensive games, the solution of a game
is a complete set of strategies that achieve a Nash equilibrium. In
cooperative games, the solution comprises the subsets of players or
coalitions from which no member has an incentive to break away.
Cooperative games can be divided between games in which the
coalition is free to internally distribute a payoff (transferable
payoff), and those in which the payoff is personal to coalition
members (non-transferable payoff). A dominant strategy is one in
which the same decision is made based on the various different
rational strategies an agent may adopt.
[0829] To better understand game theory, it is useful to consider
simple games. In one game, called the prisoner's dilemma, two
criminals are arrested and charged with a crime. The police do not
have enough evidence to convict the suspects, unless at least one
confesses. They are not able to communicate. If neither confesses,
they will be convicted of a minor crime and sentenced for one
month. If one confesses, and the other does not, the confessing one
will be given immunity and released and the other will be sentenced
for nine months. If both confess, both will be sentenced for six
months.
[0830] Another famous game is the battle of the sexes. A couple is
going to spend an evening out. She wishes to attend the opera and
he wishes to attend a hockey match, but each gains a benefit of the
other's company.
[0831] In the prisoner's dilemma, all the outcomes except (Confess;
Confess) are Pareto efficient. In the battle of the sexes, an
outcome in which husband and wife attend different events are not
Pareto efficient. The outcome (Confess; Confess) is the
equilibrium, while outcome (Don't confess; Don't confess) results
in higher payoff for both the criminals, but it is not an
equilibrium because both the players have an incentive to deviate
from it. In the battle of the sexes, the pure strategy equilibrium
points are (Opera; Opera) and (Hockey; Hockey). There is also a
third Nash equilibrium with mixed strategies, in which both choose
their preferred option with probability 2:3. The prisoner's dilemma
is a good example of a sub-optimal equilibrium. Both players would
gain a higher payoff by playing (Don't confess; Don't confess).
[0832] Another example of game theory is the so-called tragedy of
the commons. In this game, a set of farmers live in a community
with a grass-filled square. Each farmer is confronted with a
decision as to whether to acquire another goat, which eats grass in
the square. So long as the benefit of having the goat is in excess
of the personal detriment of that goat's grass consumption, it is a
dominant strategy to acquire the goat, even though the necessary
result of all farmers acting rationally is the loss, to all, of the
benefits of the square.
[0833] In computer networks, issues arise as the demand for
communications bandwidth approaches the theoretical limit. Under
such circumstances, the behavior of nodes will affect how close to
the theoretical limit the system comes, and also which
communications are permitted. The well known collision sense,
multiple access (CSMA) protocol allows each node to request access
to the network, essentially without cost or penalty, and regardless
of the importance of the communication. While the protocol incurs
relatively low overhead and may provide fully decentralized
control, under congested network conditions, the system may exhibit
instability, that is, a decline in throughput as demand increases,
resulting in ever increasing demand on the system resources and
decreasing throughput. According to game theory, the deficit of the
CSMA protocol is that it is a dominant strategy to be selfish and
hog resources, regardless of the cost to society, resulting in "the
tragedy of the commons."
[0834] Game theory is most readily applied in the optimization of
communications routes through a defined network, to achieve the
best surplus allocation. The problems of determining the network
topology, and conducting the communications themselves, are also
applications of game theory. Since the communications incidental to
the network access arbitration require consideration of some of the
same issues as the underlying communications, elements of game
theory apply correspondingly. Due to various uncertainties, the
operation of the system is stochastic. This presumption, in turn,
allows estimation of optimality within an acceptable margin of
error, permitting simplifying assumptions and facilitating
implementation.
[0835] In an ad hoc network used for conveying real-time
information, as might be the case in a telematics system, there are
potentially unlimited data communication requirements, and network
congestion is almost guaranteed. Therefore, using a CSMA protocol
as the paradigm for basic information conveyance is destined for
failure, unless there is a disincentive to network use. On the
other hand, a system which provides more graceful degradation under
high load, sensitivity to the importance of information to be
communicated, and efficient utilization of the communications
medium would appear more optimal. Such a system is proposed below
in Section VII.
[0836] One way to impose a cost which varies in dependence on the
societal value of the good or service, is to conduct an auction,
which is a mechanism to determine the market value of the good or
service, at least between the auction participants. In an auction,
the bidder seeks to bid the lowest value, up to a value less than
or equal to his own private value (the actual value which the
bidder appraises the good or service, and above which there is no
surplus), that will win the auction. Since competitive bidders can
minimize the gains of another bidder by exploiting knowledge of the
private value attached to the good or service by the bidder, it is
generally a dominant strategy for the bidder to attempt to keep its
private value a secret, at least until the auction is concluded,
thus yielding strategies that result in the largest potential gain.
Auction strategies become more complex when the bidder himself is
not a consumer or collector, but rather a reseller. In this case,
the private value of the bidder is influenced by the perception of
the private value of other bidders, and thus may change over the
course of the auction in a successive price auction. On the other
hand, in certain situations, release or publication of the private
value is a dominant strategy, and can result in substantial
efficiency, that is, honesty in reporting the private value results
in the maximum likelihood of prospective gain.
[0837] A so-called Vickrey-Clarke-Groves, or VCG, auction, is a
type of auction suitable for bidding, in a single auction, for the
goods or services of a plurality of offerors, as a unit. In the
classic case, each bidder bids a value vector for each available
combination of goods or services. The various components and
associated ask price are evaluated combinatorially to achieve the
minimum sum to meet the requirement. The winning bid set is that
which produces the maximum value of the accepted bids, although the
second (Vickrey) price is paid. In the present context, each
offeror submits an ask price (reserve) or evaluatable value
function for a component of the combination. If the minimum
aggregate to meet the bid requirement is not met, the auction
fails. If the auction is successful, then the set of offerors
selected is that with the lowest aggregate bid, and they are
compensated that amount.
[0838] The surplus, i.e., gap between bid and ask, is then
available to compensate the deferred bidders. This surplus is
distributed proportionately to original the bid value for the
bidder, thus further encouraging an honest valuation of control
over the resource.
[0839] The network is such that, if any offeror asks an amount that
is too high, it will be bypassed. Since the bidder pays the second
highest price, honesty in bidding the full private value is
encouraged, with the further incentive of the losing bidder payment
being proportional to the bid. VCG auctions have found application
in providing segment links to route goods, or information in a
network. In defining the goods and services that are the subject of
the auction, it is possible to value the non-interference of a
competitor; that is, a competitor is both a buyer and seller in the
sale multi-good auction, with the purchase and sale being
inconsistent combinations.
[0840] The traditional VCG auction, is postulated as being optimal
for allocation of multiple resources between agents. It is
"strategyproof" and efficient, meaning that it is a dominant
strategy for agents to report their true valuation for a resource,
and the result of the optimization is a network which maximizes the
value of the system to the agents. Game theory also allows an
allocation of cost between various recipients of a broadcast or
multicast. That is, the communication is of value to a plurality of
nodes, and a large set of recipient nodes may efficiently receive
the same information. This allocation from multiple bidders to
multiple sellers is a direct extension of VCG theory, and a similar
algorithm may be used to optimize allocation of costs and
benefit.
V. Ad Hoc Networks
[0841] In an ad hoc network, there is no central authority
controlling network operation, and there is typically a presumption
that some nodes cannot directly communicate with others, leading to
a requirement for communication intermediaries to forward packets,
i.e., a multihop architecture. A mobile ad hoc network adds the
further presumption that nodes are not stationary, and therefore a
route discovery mechanism is required.
[0842] In order to determine the network architecture state, each
node must broadcast its existence, and, for example, a payload of
information including its identity, location, itinerary (navigation
vector) and possibly an "information value function" and/or
"information availability function". Typically, the system operates
in a continuous state, so that, after stabilization, it is
reasonable to estimate of the present state based on the prior
state information. In a system with mobile nodes, the mobility may
be predicted, or updates provided as necessary. Using an in-band or
out-of-band propagation mechanism, this information must propagate
through a sphere of influence or to a network edge, which may be
physically or artificially defined. Nodes may be presumed to
operate with a substantially common estimation of network topology,
and therefore only deviations from previously propagated
information need be propagated. Of course, a mechanism should be
provided for initialization and in case a new node joins the
network. If such estimates were accurate, the network could then be
modeled similarly to a non-mobile network, with certain extensions.
On the other hand, typical implementations will present substantial
deviations between actual network architecture and predicted
network architecture, requiring substantial fault tolerance in the
fundamental operation of the protocol and system.
[0843] If we presume that there is a spatial or temporal limit to
relevance, for example, 5 miles or 10 hops, or 1 to 5 minutes, then
the network state propagation may be so limited. Extending the
network to encompass a large number of nodes, will necessarily
reduce the tractability of the optimization, although this may also
produce substantial benefits, especially if the hop distance is
relatively short with respect to the desired communication range.
Each node may therefore impose a local estimate of relevance as a
filter on communications, especially arbitration communications.
This consideration is accommodated by communicating, from each
node, an update to all other nodes within its network relevance
boundary, and a state variable which represents an estimate of
relevant status beyond the arbitrarily defined boundary. The
boundary estimate is advantageous in order to ensure long range
consistency. On a practical note, assuming a cost is incurred by
employing the ad hoc network, which scales with the number of hops,
then at some point, especially considering the latency and
reliability issues of ad hoc networks with a large number of hops,
it is more efficient to employ cellular communications or the like.
On the other hand, making the ad hoc network suitable and reliable
for 100 hop communications will necessarily impede communications
over a much smaller number of hops, thus disincentivizing the more
reasonable uses of the network.
[0844] For example, the propagation of network state and other
protocol-level information may conveniently occur over a finite
number of hops, for example 5-10, in an outward direction, a
condition which may be assessed by GPS assistance. For each hop, a
relatively simple protocol, such as a collision sense-multiple
access (CSMA) protocol, may be employed, with each node propagating
information according to a set of rules. (It is noted that, since
this communication is not "limitless" in contrast to bulk real-time
sensor data, CSMA may be an appropriate and efficient
protocol).
[0845] An example of the application of game theory to influence
system architecture arises when communications latency is an issue.
A significant factor in latency is the node hop count. Therefore, a
system may seek to reduce node hop count by using an algorithm
other than a nearest neighbor algorithm, bypassing some nodes with
longer distance communications. In analyzing this possibility, one
must not only look at the cost to the nodes involved in the
communication, but also the cost to nodes which are prevented from
simultaneously accessing the network. As a general proposition, the
analysis of the network must include the impact of each action, or
network state, on every node in the system, although simplifying
presumptions may be appropriate where information is unavailable,
or the anticipated impact is trivial.
[0846] There are a number of known and proven routing models
proposed for forwarding of packets in ad hoc networks. These
include Ad Hoc On-Demand Distance Vector (AODV) Routing, Optimized
Link State Routing Protocol (OLSR), Dynamic Source Routing Protocol
(DSR), and Topology Dissemination Based on Reverse-Path Forwarding
(TBRPF). In most systems analyzed to date, the performance metrics
studied were power consumption, end-to-end data throughput and
delay, route acquisition time, percentage out-of-order delivery,
and efficiency. A critical variable considered in many prior
studies is power cost, presuming a battery operated transceiver
with finite available power. There can be significant differences
in optimum routing depending on whether node has a transmit power
control, which in turn controls range, and provides a further
control over network topology. Likewise, steerable antennas,
antenna arrays, and other forms of multiplexing provide further
degrees of control over network topology. Note that the
protocol-level communications are preferably broadcasts, while
information conveyance communications are typically point-to-point.
Prior studies typically presume a single transceiver, with a single
antenna, and thus use an omni-directional antenna, with in-band
protocol data, for all communications. The tradeoff made in
limiting system designs according to these presumptions should be
clear.
[0847] Routing protocols in ad hoc networks typically employ three
strategies: flooding, proactive routing, and reactive routing.
Flooding protocols broadcast packets to all the nodes in the
network, while the remaining protocols do not. In proactive
routing, the protocol maintains route information all the time,
while in reactive routing, a route is discovered only when needed.
All or some of these strategies may be employed simultaneously.
Flooding typically consumes too much bandwidth and energy to be
efficient, as compared to more sophisticated strategies. However,
in cases with very high mobility, the flooding protocols best
ensure that the transmission reaches its destination.
[0848] In proactive routing, each node stores and updates routing
information constantly. The routing tables can be updated based on
perceived changes in the network topology. Therefore, a new
transmission can start immediately without a route discovery delay.
However, the constant exchange of routing information adds overhead
to the protocol. OLSR and TBRPF protocols use proactive routing.
The overhead traffic of a proactive routing protocol increases as
the mobility of the nodes increases, since the routing information
needs to be updated in shorter intervals.
[0849] In reactive routing, when a node wishes to transmit, it
starts a route discovery process in order to find a path to the
receiver. The routes remain valid until the route is no longer
needed. AODV and DSR protocols use reactive routing. In the AODV
protocol, to find a route to a receiver, a terminal broadcasts a
route request message containing the address of the receiver and
the lifespan of the message. Terminals receiving the message add
their address to the packet and forward it if the lifespan is not
exhausted. If a receiver or a terminal knowing the route to the
receiver receives the route request message, it sends a route reply
back to the requester. If the sender does not receive a route reply
before a timeout occurs, it sends another route request with a
longer lifespan. The use of sequential route requests with
incremental increases in timeout allows a mapping of the network by
hop count.
[0850] In order for an ad hoc network to be effective, the nodes
need to cooperate. This cooperation comes at a cost. In power
constrained systems, for example, the cost is battery consumption.
In other scenarios, the network utilization is itself a burden. The
various nodes must cooperate in both arbitration and control, e.g.,
route discovery and optimization, and the information forwarding
itself. In fact, participation in the route discovery, without
notice that the node will fail to forward information packets, has
been shown in studies to be more detrimental to the network than
simply abstaining entirely.
[0851] It is the general self-interest of a node to conserve its
own resources, maintain an opportunity to access resources, while
consuming whatever resource of other nodes as it desires. Clearly,
this represents the "tragedy of the commons", in which selfish
individuals fail to respect the very basis for the community they
enjoy, and a network of rational nodes operating without
significant incentives to cooperate would likely fail. On the other
hand, if donating a node's resources generated an associated
benefit to that node, while consuming network resources imposed a
cost, stability and reliability can be achieved. So long as the
functionality is sufficient to meet the need, and the economic
surplus is "fairly" allocated, that is, the cost incurred is less
than the private value of the benefit, and that cost is transferred
as compensation to those burdened in an amount in excess of their
incremental cost, adoption of the system should increase stability.
In fact, even outside of these bounds, the system may be more
stable than one which does not tax system use nor reward altruistic
behavior. While the system is a zero sum system, and over time, the
economic effects will average out, in any particular instance, the
incentive for selfish behavior by a node will be diminished.
[0852] The concepts of node misbehavior and maliciousness, and
competing networks consuming the same resources, are not addressed
at length herein. However, these issues are also addressed by
aspects of game theory. For example, an ad hoc network may defer to
or compete with an interfering network, and the decision of which
strategy to adopt is within the province of game theory. The
particularities of agent misbehavior or hacking are not completely
addressed herein, although real implementations must necessarily
consider these issues. Sometimes, the solution to these issues is
technological, but in others, the reaction of other nodes to
discovery of misbehavior may be sufficient to discourage it. The
intent is to formulate a system which is sufficiently robust and
advantageous as to disincentivize non-compliance and
non-cooperation, that is, the inherent advantages of compliance
with the system architecture exceed the anticipated benefits of the
alternative.
[0853] One way to remedy selfish behavior is to increase the cost
of acting this way, that is, to impose a cost or tax for access to
the network. In a practical implementation, however, this is
problematic, since under lightly loaded conditions, the "value" of
the communications may not justify a fixed cost which might be
reasonable under other conditions, and likewise, under heavier
loads, critical communications may still be delayed or impeded.
Note that where the network includes more nodes, the throughput may
increase, since there are more potential routes and overall
reliability may be increased, but the increased number of nodes
will likely also increase network demand. A variable cost,
dependent on relative "importance", may be provided, and indeed, as
alluded to above, this cost may be market based, in the manner of
an auction. In a multihop network, such an auction is complicated
by the requirement for a distribution of payments between the chain
of nodes, with each node having potential alternate demands for its
cooperation. The VCG auction mechanism excludes nodes which ask too
high a price, and the auction itself may comprise a value function
encompassing reliability, latency, quality of service, or other
non-economic parameters, in economic terms. The network may further
require compensation to nodes which must defer communications
because of inconsistent states, such as in order to avoid
interference or duplicative use of an intermediary node, and which
take no direct part in the communication. It is noted that the
concept of the winner of an auction paying the losers is relatively
obscure, and itself upsets the normal analysis, since the
possibility of a payment from the winner to the loser alters the
allocation of economic surplus between the bidder, seller, and
others. Likewise, while the cost to the involved nodes may be real,
the cost to the uninvolved nodes may be subjective. Clearly, it
would appear that involved nodes should generally be better
compensated than uninvolved nodes, although a formal analysis
remains to be performed.
[0854] In a more general sense, the underlying presumption is that
the network provides competitive access to the physical transport
medium, and that cooperation with the protocol provides significant
advantages over competition with it. Clearly, the issues of
commercial success and market dominance are much more complex and
not capable of being accurately modeled according to known
paradigms; on the other hand, a system providing rational benefits
will be more likely to succeed than one with irrational benefits or
ill defined explicable benefits. Under normal circumstances, a well
developed ad hoc network system can present as a formidable
coordinated competitor for access to contested bandwidth by other
systems, while within the network, high valued communications may
receive priority. Thus, a node presented with a communications
requirement is presented not with the simple choice of participate
or abstain, but rather whether to participate in an ad hoc network
with predicted stability and mutual benefit, or one with the
possibility of failure due to selfish behavior, and
non-cooperation. Even in the absence of a present communication
requirement, a network which rewards cooperative behavior may be
preferable to one which simply expects altruism.
[0855] After the network architecture is defined, compensation is
paid to those nodes providing value or subjected to a burden
(including foregoing communication opportunity) by those gaining a
benefit. The payment may be a virtual currency, with no specific
true value, although the virtual currency system provides a
convenient method to tax, subsidize, or control the system, and
thus apply a normalized extrinsic value.
[0856] Game theory also encompasses the concept of that each node
may have an associated "reputation" in the community. This
reputation may be evaluated as a parameter in an economic analysis,
or applied separately. This reputation may be anecdotal or
statistical. In either case, if access to resources and payments
are made dependent on reputation, nodes will be incentivized to
maintain a good reputation, and avoid generating a bad reputation.
Therefore, by maintaining and applying the reputation in a manner
consistent with the community goals, the nodes are compelled to
advance those goals in order to benefit from the community. Game
theory distinguishes between good reputation and bad reputation.
Nodes may have a selfish motivation to assert that another node has
a bad reputation, while it would have little selfish motivation,
absent collusion, for undeservedly asserting a good reputation. On
the other hand, a node may have a selfish motivation in failing to
reward behavior with a good reputation.
[0857] The virtual currency and reputation may be considered
orthogonal, since the status of a node's currency account provides
no information about the status of its reputation.
VI. Published Ad Hoc Network Examples
[0858] By no way a comprehensive list of published applications of
game theory to the control of ad hoc networks, below are discussed
a number of prominent examples.
[0859] The Terminodes project includes many of the features
described above. This project proposes a method to encourage
cooperation in ad hoc networks that is based on a virtual currency
called nuglets. Each node contains a tamper-proof hardware module
which handles the nuglets. When a node forwards a packet it
extracts nuglets from the payload. In order to make a transmission,
the sender appends nuglets needed to forward the packet through the
network to its destination. However, a central node probably likely
accumulates excess nuglets, hence it has less value for additional
nuglets, leading to lower incentive for network activity.
Peripheral nodes may possess insufficient nuglets to support their
needs. However, the system appears to achieve a balance over time,
assuming random node movement. The Terminodes project is notable
for the depth and completeness of its analysis, as well as the
progress made toward implementation.
[0860] Crowcroft et al. present a traffic-sensitive pricing model.
Compensation for packet forwarding is responsive to both required
energy consumption and local congestion at a node. This mechanism
both enforces cooperation and balances traffic loads to avoid
congestion. Stabilization of price and node wealth occurs in static
networks.
[0861] The Confidant protocol detects node misbehavior and routes
traffic around the misbehaving nodes, to isolate them from the
network. Misbehavior of neighboring nodes is broadcast to the
network by observing nodes. A trust record is used to evaluate the
validity of a report, thus disincentivizing misbehavior in the
reporting process. The reputation information is applied by a path
manager define a route and rejects access requested by misbehaving
nodes.
[0862] The Core protocol is similar to Confidant; each node
maintains reputation information, which is updated based on both
observation and third party report. A threshold function is applied
to limit access by nodes based on their reputation, resulting in
isolation.
[0863] Michiardi et al. analyze whether it is optimal to join or
defect from an ad hoc network, based on node utility function,
payoff share, cost of cooperation, number of cooperating nodes,
etc.
[0864] Srinivasan et al. apply game theory to model an ad hoc
network at a connection level, providing a complicated extended
game model. Before a user can transmit, all the nodes along the
defined route must accept the relay request. Energy consumption of
terminals is restricted by an expected lifetime of batteries, that
is, the nodes are modeled as being power constrained. A normalized
acceptance rate, a proportion of successful and attempted relays
through a node, as observed by neighboring nodes, is sought to be
maximized.
[0865] Urpi et al. model an ad hoc network at packet level. The
model is based on an estimate of neighboring nodes, the remaining
energy of node, and various packet traffic metrics. The payoff of
the model is simply the access to packet forwarding, weighted by
energy cost, provided to a node.
[0866] Noncooperative game theory offers a basis for analyzing
Internet traffic, wherein each user tries to independently maximize
its quality of service. The network operator focuses on maximizing
network performance as a whole. Thus, in this case, different
players adopt different roles, with different value functions. Game
theory may thus by applied to optimize routing, flow control,
queuing disciplines and traffic pricing. While ad hoc network
routing is similar to the Internet, there are also significant
differences. In an ad hoc network, routes may be inconsistent.
[0867] Nagle studied the concept of fairness in queuing in packet
switches. In a first in-first out queue, a selfish node may
saturate the queue with requests. Nagle proposes, as a solution,
distinct queues for each source with a round-robin scheduler,
providing a fair queuing scheme, which encourages keeping the
user's queue as short as possible.
[0868] Game theory has also been applied on flow control. Each user
tries to maximize its utility, defined by the ratio of average
throughput and average delay. It has been shown that a unique Nash
equilibrium exists in such a system, which converges to an
equilibrium point. The nodes seek to both maximize their own
quality of service, but also the fairness of resource allocation,
resulting in a Pareto efficient solution.
[0869] ALOHA is a wireless CSMA protocol using time division
multiplexing. Transmission probabilities are a design specification
of the system, but if a player uses a higher probability, his
throughput will likely increase, leading to a misbehavior
incentive. The selfish system appears to perform no better than a
centrally controlled (non-CSMA) system, and performance typically
drops by half. A pricing mechanism may be incorporated, thus taxing
users for their bandwidth demands. An extensive analysis of the
subject of the application of game theory to the control of ad hoc
networks, including both an extensive review of the literature, and
new analysis, is provided in the master's Thesis of Juha Leino,
entitled "Applications of Game Theory in Ad Hoc Network", Helsinki
University Of Technology (2003). Leino modeled the interaction
between one node and the rest of the network as an extensive game.
The networks were presumed to be energy constrained, and the nodes
to be selfish, with the result stated as the amount of contribution
the network can request from a node. Leino modeled nodes with power
constrained, power adaptive, omnidirectional transceivers, each of
which have a uniform communication demand on the network.
[0870] When a node connects to an ad hoc network, it gains both
benefits and obligations. The other nodes forward its traffic,
hence it can save energy and reach nodes outside its own
transmission range, as compared to a single hop transmission.
Correspondingly, the node should participate in the network
functions like the route discovery and traffic forwarding that
consume the resources of the node, in addition to the basic
communications themselves. In order to find participation in the
network advantageous, the node has gain greater benefits greater
than the obligations imposed. This, of course, may be modeled as a
game. The node seeks to minimize energy consumption, and the
network seeks to ensure its functionality. The decision of the node
is to cooperate or to defect.
[0871] In one of Leino's models, he requires that reward of
forwarding needs to be proportional to the energy consumed when the
packet is forwarded. He analyzes the situation of both a honest
node and a cheating node, i.e., one that uses the network's
resources without full participation in the network overhead. He
concluded that if a node has an opportunity to cheat, it adversely
affects the network far more than mere defection. Leino also
analyzed whether, under his presumptions, a group of honest nodes
will voluntarily aggregate as an ad hoc network, or would prefer to
remain as a set of independent uncooperative actors, without
benefit of multihop transmissions. He concludes that under his
presumptions, in some networks, there are nodes which have
detrimental involvement in the ad hoc network, and if all such
"loser" nodes refuse to participate, the network may collapse. The
proportion of losers drops with minimum energy routing, since the
average cost is lowered, making gains from participation more
likely. There are also networks with no losers, and these provide
gains to all participants. Loser nodes tend to be in the center of
the network, rather than the periphery.
VII. Real Time Telematics Information Communication
[0872] Mobile, self organizing, ad hoc communications networks have
been proposed for telematics systems, for cellular network
extension, long range (multihop) traffic information communication,
and short range collision avoidance systems.
[0873] Telematics is a recently applied term that now encompasses
radio transmitters or receivers in vehicles. Three basic schemes
exist: wide area broadcast communication, where all relevant nodes
are presumed to be within the same communication zone (e.g.,
satellite radio, RDDS receivers, etc.); cellular communications,
where an array of fixed-position low power transceivers
contiguously blanket a territory, providing various zones which
allow multiplexing within a band; and mesh network communications,
which allow ad hoc formation of a communications infrastructure,
optionally linking to various fixed infrastructure.
[0874] Telematics systems may be used for many purposes, for
example, real time traffic information (RTTI), which in an extreme
case may involve communication of live video streams. In a more
modest system, various sensors may provide road and traffic data,
as well as weather and incident information. In other words, the
appetite of such a system for bandwidth is potentially limitless,
unless constraints are imposed. On the other hand, RTTI is
typically not power constrained, since it is vehicle based rather
than hand-held, and therefore the cost of using the system will
focus more on competition for bandwidth (the limited physical
transport layer (PHY) resource) than power consumed in
communications. Likewise, communications latency is not critical,
unless full duplex voice communications are supported. It is noted
that parked vehicles may also be involved in network
communications, and the frequency band may be shared with portable
communicators with self-contained power sources, making the
economic cost of communications and power consumption a potential
factor for some nodes, leading to split strategies.
[0875] Likewise, especially for voice communications, interfacing
with the fixed infrastructure through cellular telephone towers or
802.11 hotspots may impose additional economic constraints on the
system. Telematics systems typically include a GPS geolocation
system, which may be of great use in mapping nodes for routing
navigation functions. Indeed, the telematics system may be
integrated within a navigation system and/or entertainment system.
This is relevant to the extent that one considers the incremental
cost of the hardware and its market placement.
[0876] The system is designed to operate over a wide range of node
densities, from city rush hour traffic to rural highways. Due to a
perceived incompatibility of a RTTI system with cellular
infrastructure business models, as well as inconsistent
availability of cellular coverage of roadways, the architecture is
designed as a decentralized control, with incidental involvement of
the cellular networks, except for voice communications outside of
the mobile ad hoc network. This decentralized control introduces a
substantial level of complexity, since it must account for rapidly
changing network architecture, various types of channel
impairments, hidden nodes, and temporal and spatial distance
issues, and interference.
[0877] In defining the system, both the available hardware, costs
and purposes for use must be considered. Desirable characteristics
of a telematics system include real time telematics information
communication, multihop voice communication forwarding,
decentralized control, and to the extent possible, user privacy.
The hardware may include multichannel directional smart antennas,
out-of-band signaling and control, complex and sophisticated
computational resources, to provide efficient utilization of an
unlicensed or shared band.
[0878] That is, it is clear that a system that provides an
omnidirectional antenna system with in band signaling and control,
is inefficient as compared to a system which directs its
transmitted energy only in the direction of the intended target,
and does not intrude on a high capacity physical transport medium
with relatively low information content signaling packets.
[0879] In a real time telematics ad hoc network with potentially
unlimited data communication requirements, network congestion is
almost guaranteed, in a continuous network of mobile nodes. RF
interference issues will likely prevent network capacity from
scaling with node density. Therefore, an alternate to CSMA was
sought that provided more graceful degradation under high load,
sensitivity to the importance of information to be communicated,
and efficient utilization of the communications medium.
[0880] In order to optimize the network, additional information is
employed, although this imposes a burden of increased protocol
overhead, complexity, and potential loss privacy. One way to remedy
selfish behavior is to increase the cost of acting this way, that
is, to impose a cost for access to the network. In a practical
implementation, however, this is problematic, since under lightly
loaded conditions, the "value" of the communications may not
justify a fixed cost which might be reasonable under other
conditions, and likewise, under heavier loads, critical
communications may still be delayed or impeded. Therefore, a
variable cost, dependent on relative "importance", may be imposed.
In determining this relative importance, a market evaluation,
requires a comparison, termed an auction, is employed. In a
multihop network, such an auction is complicated by the requirement
for distributing payments among the chain of nodes along the route,
with each node having potential alternate demands for its
cooperation and resources. According to a more sophisticated
analysis, one must also compensate nodes not directly involved in
the communication for their deference.
[0881] In a scenario involving a request for information, the
auction is complicated by the fact that the information resource
content is unknown to the recipient, and therefore the bid is
blind, that is, the value of the information to the recipient is
indeterminate. However, game theory supports the communication of a
value function or utility function, which can then be evaluated at
each node possessing information to be communicated, to normalize
its value. Fortunately, it is a dominant strategy in a VCG auction
to communicate a truthful value. In this case, a value function may
instead be communicated, which can then be evaluated at each node
possessing information to be communicated. In a mere request for
information conveyance, such as the transport nodes in a multihop
network, or in a cellular network infrastructure extension model,
the bid may be a true (resolved) value, since the information
content is not the subject of the bidding; rather it is the value
of the communications per se, and the bidding node can reasonably
value its bid.
[0882] In a cellular network infrastructure extension model, the
bid may represent a resolved value, since the information content
is not the subject of the bidding; rather it is the value of the
communications per se. In the case of voice, however, the
communications are bidirectional and enduring, thus raising quality
of service and handoff issues.
[0883] Game theory is most readily applied in the optimization of
communications routes through a defined network, to achieve the
best economic surplus allocation. That is, the problem of
determining the network topology, and the communications
themselves, are ancillary, though real, applications of game
theory. Since the communications incidental to the arbitration
require consideration of some of the same issues as the underlying
communications, corresponding elements of game theory may apply at
both levels of analysis. Due to various uncertainties, the
operation of the system is stochastic. This presumption, in turn,
allows estimation of optimality within a margin of error,
simplifying implementation as compared to a rigorous analysis
without regard to statistical significance.
[0884] The VCG auction is postulated as being optimal for
allocation of multiple resources between agents. It is
"strategyproof" and efficient, meaning that it is a dominant
strategy for agents to report their true valuation for a resource,
and the result of the optimization is a network which maximizes the
value of the system to the agents.
[0885] Game theory also allows an allocation of cost between
various recipients of a broadcast or multicast. That is, in many
instances, telematic information is of value to a plurality of
nodes, and a large set of recipient nodes may efficiently receive
the same information. This allocation is a direct extension of VCG
theory.
[0886] The preferred method for acquiring an estimate of the state
of the network is through use of a proactive routing protocol.
Thus, in order to determine the network architecture state, each
node must broadcast its existence, and, for example, a payload of
information including its identity, location, itinerary (navigation
vector) and "information value function". Typically, the system
operates in a continuous state, so that it is reasonable to
commence the process with an estimate of the state based on prior
information. Using an in-band or out-of-band propagation mechanism,
this information must propagate to a network edge, which may be
physically or artificially defined. If all nodes operate with a
substantially common estimation of network topology, only
deviations from previously propagated information need be
propagated.
[0887] CSMA is proposed for the protocol-related communications
because it is relatively simple and robust, and well suited for ad
hoc communications in lightly loaded networks. An initial node
transmits using an adaptive power protocol, to achieve an effective
transmit range of somewhat less than about two times the estimated
average inter-nodal distance. This distance therefore promotes
propagation to a set of neighboring nodes, without unnecessarily
interfering with communications of non-neighboring nodes and
therefore allowing this task to be performed in parallel.
Neighboring nodes also transmit in succession, providing sequential
and complete protocol information propagation over a relevance
range.
[0888] If we presume that there is a spatial limit to relevance,
for example, 5 miles or 10 hops, then the network state propagation
may be so limited. Extending the network to encompass a large
number of nodes will necessarily reduce the tractability of the
optimization. Each node has a local estimate of relevance. This
consideration is accommodated, along with a desire to prevent
exponential growth in protocol-related data traffic, by receiving
an update from all nodes within a node's network relevance
boundary, and a state variable which represents an estimate of
relevant status beyond the arbitrarily defined boundary. The
propagation of network state may thus conveniently occur over a
finite number of hops, for example 5-10.
[0889] Under conditions of relatively high nodal densities, the
system may employ a zone strategy, that is, proximate groups of
nodes are is treated as an entity for purposes of external state
estimation, especially with respect to distant nodes or zones. Such
a presumption is realistic, since at extended distances,
geographically proximate nodes may be modeled as being similar or
inter-related, while at close distances, and particularly within a
zone in which all nodes are in direct communication, internode
communications may be subject to mutual interference, and can occur
without substantial external influence. Alternately, it is clear
that to limit latencies and communication risks, it may be prudent
to bypass neighboring nodes, thus trading latency for power
consumption and overall network capacity. Therefore, a hierarchal
scheme may be implemented to geographically organize the network at
higher analytical levels, and geographic cells may cooperate to
appear externally as a single entity.
[0890] A supernode within a zone may be selected for its superior
capability, or perhaps a central location. The zone is defined by a
communication range of the basic data interface for communications,
with the control channel having a longer range, for example at
least double the normal data communications range. Communications
control channel transmitters operate on a number of channels, for
example at least 7, allowing neighboring zones in a hexagonal tiled
array to communicate simultaneously without interference. In a
geographic zone system, alternate zones which would otherwise be
interfering may use an adaptive multiplexing scheme to avoid
interference. All nodes may listen on all control channels,
permitting rapid propagation of control information.
[0891] In order to effective provide decentralized control, either
each node must have a common set of information to allow execution
of an identical control algorithm; or nodes defer to the control
signals of other nodes without internal analysis for optimality. A
model of semi-decentralized control is also known, in which
dispersed "supernodes", are nominated as master, with other
topologically nearby nodes remaining as slave nodes. In the pure
peer network, complete information conveyance to each node is
required, imposing a relatively high overhead. In a master-slave
(or supernode) architecture, increased reliance on a single node
trades-off reliability and robustness (and other advantages of pure
peer-to-peer networks) for efficiency. A supernode within a
cellular zone may be selected for its superior capability, or
perhaps is at a central location or is immobile. Once each control
node (node or supernode) has an estimate of network topology, the
next step is to optimize network channels. According to VCG theory,
each agent has an incentive to broadcast its truthful value or
value function for the scarce resource, which in this case, is
control over communications physical layer, and or access to
information. This communication can be consolidated with the
network discovery transmission. Each control node then performs a
combinatorial solution for the set of simultaneous equations
according to VCG theory (or extensions thereof). This solution
should be consistent between all nodes, and the effects of
inconsistent solutions may be resolved by collision sensing, and
possibly an error/inconsistency detection and correction algorithm
specifically applied to this type of information.
[0892] As part of the network mapping, communications impairment
and interference sources are also mapped. GPS assistance may be
particularly useful in this aspect. Where interference is caused by
interfering communications, the issue is a determination of a
strategy of deference or competition. If the interfering
communication is continuous or unresponsive, then the only
available strategy is competition. On the other hand, when the
competing system uses, for example, a CSMA system, such as 802.11,
competition with such a communication simply leads to
retransmission, and therefore ultimately increased network load,
and deference strategy may be more optimal (dominant), at least and
until it is determined that the competing communication is
incessant. Other communications protocols, however may have a more
or less aggressive strategy. By observation of a system over time,
its strategies may be revealed, and game theory permits composition
of an optimal strategy.
[0893] The optimization process produces a representation of an
optimal network architecture during the succeeding period. That is,
value functions representing bids are broadcast, with the system
then being permitted to determine an optimal real valuation and
distribution of that value. Thus, prior to completion of the
optimization, potentially inconsistent allocations must be
prevented, and each node must communicate its evaluation of other
node's value functions, so that the optimization is performed on a
normalized economic basis. This step may substantially increase the
system overhead, and is generally required for completion of the
auction. This valuation may be inferred, however, for transit nodes
in a multihop network path, since there is little subjectivity for
nodes solely in this role, and the respective value functions may
be persistent. For example, the valuation applied by a node to
forward information is generally content and involved party
independent.
[0894] A particular complication of a traffic information system is
that the nature of the information held by any node is private to
that node (before transmission), and therefore the valuation is not
known until after all bids are evaluated. Thus, prior to completion
of optimization, each node must communicate its evaluation of other
nodes' value functions, so that the optimization is performed on an
economic basis. This required step substantially increases the
system overhead. This valuation may be inferred, however, for
transit nodes in a multihop network path.
[0895] After the network usage is defined, compensation is paid to
those nodes providing value or subjected to a burden (including
foregoing communication opportunity) by those gaining a benefit.
The payment is generally of a virtual currency, with no specific
true value, although the virtual currency system provides a
convenient method to tax the system.
[0896] Exerting external economic influences on the system may have
various effects on the optimization, and may exacerbate differences
in subjective valuations. The application of a monetary value to
the virtual currency substantially also increases the possibility
of misbehavior and external attacks. On the other hand, a virtual
currency with no assessed real value is self-normalizing, while
monetization leads to external and generally irrelevant influences
as well as possible arbitrage. External economic influences may
also lead to benefits, which are discussed in various papers on
non-zero sum games.
[0897] In order to provide fairness, the virtual currency (similar
to the so-called "nuglets" or "nuggets" proposed for use in the
Terminodes project) is self-generated at each node according to a
schedule, and itself may have a time dependent value. For example,
the virtual currency may have a half-life or temporally declining
value. On the other hand, the value may peak at a time after
generation, which would encourage deference and short term savings,
rather than immediate spending, and would allow a recipient node to
benefit from virtual currency transferred before its peak value.
This also means that long term hoarding of the currency is of
little value, since it will eventually decay in value, while the
system presupposes a nominal rate of spending, which is normalized
among nodes. The variation function may also be adaptive, but this
poses a synchronization issue for the network. An external estimate
of node wealth may be used to infer counterfeiting, theft and
failure to pay debts, and to further effect remediation.
[0898] The currency is generated and verified in accordance with
micropayment theory. Micropayment theory generally encompasses the
transfer of secure tokens (e.g., cryptographically endorsed
information) having presumed value, which are intended for
verification, if at all, in a non-real time transaction, after the
transfer to the recipient. The currency is circulated (until
expiration) as a token, and therefore is not subject to immediate
authentication by source. Since these tokens may be communicated
through an insecure network, the issue of forcing allocation of
payment to particular nodes may be dealt with by cryptographic
techniques, in particular public key cryptography, in which the
currency is placed in a cryptographic "envelope" addressed to the
intended recipient, e.g., is encrypted with the recipient's public
key, which must be broadcast and used as, or in conjunction with, a
node identifier. This makes the payment unavailable to other than
the intended recipient. The issue of holding the encrypted token
hostage and extorting a portion of the value to forward the packet
can be dealt with by community pressure, that is, any node
presenting this (or other undesirable) behavior might be
ostracized. The likelihood of this type of misbehavior is also
diminished by avoiding monetization of the virtual currency.
[0899] This currency generation and allocation mechanism generally
encourages equal consumption by the various nodes over the long
term. In order to discourage consumption of bandwidth, an external
tax may be imposed on the system, that is, withdrawing value from
the system base on usage. Clearly, the effects of such a tax must
be carefully weighed, since this will also impose an impediment to
adoption as compared to an untaxed system. On the other hand, a
similar effect use-disincentive may be obtained by rewarding low
consumption, for example by allocating an advertising subsidy
between nodes, or in reward of deference. In a model telematics
system, an audio and/or visual display provides a useful
possibility for advertising and sponsorship; likewise, location
based services may include commercial services.
[0900] Each node computes a value function, based on its own
knowledge state, risk profile and risk tolerance, and wealth,
describing the value to it of additional information, as well as
its own value for participating in the communications of others.
The value function typically includes a past travel history, future
travel itinerary, present location, recent communication partners,
and an estimator of information strength and weakness with respect
to the future itinerary. It may be presumed that each node has a
standard complement of sensors, and accurately acquired descriptive
data for its past travel path. Otherwise, a description of the
available information is required. One advantage of a value
function is that it changes little over time, unless a need is
satisfied or circumstances change, and therefore may be a
persistent attribute.
[0901] Using the protocol communication system, each node transmits
its value function (or change thereof), passes through
communications from neighboring nodes, and may, for example
transmit payment information for the immediate-past bid for
incoming communications.
[0902] Messages are forwarded outward (avoiding redundant
propagation back to the source), with messages appended from the
series of nodes. Propagation continues for a finite number of hops,
until the entire community has an estimate of the state and value
function of each node in the community. Advantageously, the network
beyond a respective community may be modeled in simplified form, to
provide a better estimate of the network as a whole.
[0903] After propagation, each node evaluates the set of value
functions for its community, with respect to its own information
and ability to forward packets. Each node may then make an offer to
supply or forward information, based on the provided information.
In the case of multihop communications, the offers are propagated
to the remainder of the community, for the maximum number of hops,
including the originating node. At this point, each node has a
representation of the state of its community, with community edge
estimates providing consistency for nodes with differing community
scopes, the valuation function each node assigns to control over
portions of the network, as well as a resolved valuation of each
node for supplying the need. Under these circumstances, each node
may then evaluate an optimization for the network architecture, and
come to a conclusion consistent with that of other members of its
community. If supported, node reputation may be updated based on
past performance, and the reputation applied as a factor in the
optimization and/or externally to the optimization. As discussed
above, a VCG-type auction is employed as a basis for optimization.
Since each node receives bid information from all other nodes
within the maximum node count, the VCG auction produces an
optimized result.
[0904] Transmissions are made in frames, with a single bidding
process controlling multiple frames, for example a multiple of the
maximum number of hops. Therefore, the bid encompasses a
frame's-worth of control over the modalities. In the event that the
simultaneous use of, or control over, a modality by various nodes
is not inconsistent, then the value of the respective nodes may be
summed, with the resulting allocation based on, for example, a
ratio of the respective value functions. As a part of the
optimization, nodes are rewarded not only for supporting the
communication, but also for deferring their own respective needs.
As a result, after controlling the resources, a node will be
relatively less wealthy and less able to subsequently control the
resources, while other nodes will be more able to control the
resources. The distribution to deferred nodes also serves to
prevent pure reciprocal communications, since the proposed
mechanism distributes and dilutes the wealth to deferring
nodes.
[0905] Because each node in the model presented above has complete
information, for a range up to the maximum node count, the wealth
of each node can be estimated by its neighbors, and payment
inferred even if not actually consummated. (Failure of payment can
occur for a number of reasons, including both malicious and
accidental). Because each hop adds significant cost, the fact that
nodes beyond the maximum hop distance are essentially incommunicado
is typically of little consequence; since it is very unlikely that
a node more than 5 or 10 hops away will be efficiently included in
any communication, due to the increasing cost with distance, as
well as reduction in reliability and increase in latency. Thus,
large area and scalable networks may exist.
[0906] Typically, cryptography is employed for both authentication
and to preserve privacy. External regulation, in a legal sense at
least, is typically imposed by restrictions on hardware and
software design, as well as voluntary compliance at risk of
detection and legal sanction.
IX. Conclusion
[0907] The use of game theory as a basis for analyzing ad hoc
networks provides a basis for understanding the behavior of complex
networks of independent nodes. By presuming a degree of choice and
decision-making by nodes, we obtain an analysis that is robust with
respect to such considerations.
[0908] The principal issues impeding deployment are the inherent
complexity of the system, as well as the overhead required to
continuously optimize the system. Further work will allow a
determination of a set of simplifying presumptions to reduce
protocol overhead and reduce complexity.
[0909] The ad hoc network does not exist in a vacuum. There are
various competing interests seeking to use the same bandwidth, and
technological superiority alone does not assure dominance and
commercial success. Game theory may also be used as a tool to
analyze the entities which seek to deploy ad hoc networks,
especially where they compete.
[0910] The present invention therefore provides an automated
negotiation for control of a set of resources by competing bidders
and, offerors, comprising receiving, from each of a plurality of
bidders, a utility function representing a value to the bidder to
obtain of a set of resources; receiving, from each of a plurality
of offerors, a utility function representing a value to the offeror
to relinquish a set of resources; computing a set of successful
bids from the plurality of bidders and plurality of offers, a
successful bid comprising a matching of a maximimum aggregate value
of the sets of resources to the bidders and a minimum aggregate
value of the sets of resources to the offerors, wherein the maximum
aggregate value of bids equals or exceeds the minimum aggregate
value of offers; and receiving for each set of resources from a
bidder placing a respective successful bid a Vickrey price, and
paying to for each set of resources to an offeror of a respective
successful bid each its offer price, with any surplus being
allocated to bidders based on a value bid. The bidder utility
function may be evaluated based on private information of an
offeror, and communicated as a normalized value.
EXAMPLE 3
[0911] According to a further aspect of the invention, it is
desired to understand the subjective risk aversion profile of a
person. Risk-aversion is a significant deviation from rationality
which can be quantified and understood, and further a calculus is
available for applying the risk aversion to normalize systems in
which rationality is presumed. Accordingly, the method comprises
presenting a game for play by a person, wherein the payoff of the
game is real and beneficial to the person. That is, the incentive
and risk must be real, with some limits on the ability to
extrapolate beyond the scope of risk presented. The person is then
sufficiently observed during the game play to comprehend a risk
aversion profile of the user. Typically, the game is automated, but
this is not required, and, in fact, a competition between two or
more players is possible. This scenario is generally quite
beneficial where the stakes of the game are identical or similar to
the risk aversion personality attribute sought to be defined. The
comprehended risk aversion profile may then be used to modify a
rationality expectation for the person. The modified rationality
expectation may then be applied to optimize an interaction with the
person outside of the game play environment.
[0912] This process is particularly useful for creating a
user-agent to act on behalf of the user, in a manner commersurate
with a subjective profile of the user, or to subjectivize a
presentation of risk data to a user. For example, in the
probability based user interface discussed above, the
event-probability map may be analyzed based on the subjective risk
tolerance of the user, and the output optimized accordingly. This
method may also be applied for optimally pairing a user with
another person or process, based on compatibility.
[0913] There has thus been shown and described novel communications
devices and systems and methods which fulfill all the objects and
advantages sought therefor. Many changes, modifications,
variations, combinations, subcombinations and other uses and
applications of the subject invention will, however, become
apparent to those skilled in the art after considering this
specification and the accompanying drawings which disclose the
preferred embodiments thereof. All such changes, modifications,
variations and other uses and applications which do not depart from
the spirit and scope of the invention are deemed to be covered by
the invention, which is to be limited only by the claims which
follow.
TELEMATICS REFERENCES APPENDIX
[0914] On the Propagation of Long-Range Dependence in the
Internet--Veres, Kenesi, Molnar . . . (2000)
galahad.elte.hu/.about.vattay/cikkeim/vmkv.pdf [0915] Anthill: A
Framework for the Development of Agent-Based . . . --Babaoglu,
Meling . . . (2002) www.cs.unibo.it/babaoglu/papers/icdcs02.pdf
[0916] Automatic Web Page Categorization by Link and Context . . .
--Attardi, Gulli . . . (1999) [0917]
aure.iei.pi.cnr.it/.about.fabrizio/Publications/THAI99/THAI99.ps
[0918] Distributed Interactive Media--Mauve (2000) [0919]
www.informatik.uni-mannheim.de/informatik/pi4/publications/library/Mauve2-
000d.ps.gz [0920] Weak Bisimulation for Fully Probabilistic
Processes--Baier, Hermanns (1999) [0921]
web.informatik.uni-bonn.de/l/papers/acta_inf.ps [0922] Structured
Multimedia Authoring--Hardman, van Rossum, Bulterman (1993) [0923]
www.cwi.nl/ftp/CWIreports/CST/CS-R9304.ps.Z [0924] Solving the
modeling problems of object-oriented languages . . . --Aksit,
Tekinerdogan (1998)
trese.cs.utwente.nl/aop-ecoop98/papers/Aksit.pdf [0925] Group
Communication in Differentiated Services Networks--Bless, Wehrle
(2001) [0926] www.tm.uka.de/.about.bless/IQ2001-ds_multicast.pdf
[0927] Ad Hoc Relay Wireless Networks over Moving Vehicles on
Highways--Chen, Kung, Vlah (2001)
www.eecs.harvard.edu/.about.htk/publication/2001-mobihoc-ckv.pdf
[0928] A Framework for Generating Network-Based Moving
Objects--Brinkhoff (2002) [0929]
www.fh-wilhelmshaven.de/oow/institute/iapg/personen/brinkhoff/pape-
r/GeoInformatica2002.pdf [0930] The Amsterdam Hypermedia Model:
extending hypertext . . . --Hardman, Bulterman . . . (1993)
www.cwi.nl/ftp/CWIreports/CST/CS-R9306.ps.Z [0931] On functional
equivalence of certain fuzzy controllers and . . . --Koczy, Tikk,
Gedeon (2000) www.mft.hu/publications/tikk/tikk3.pdf [0932]
Specification of a Service Management Architecture . . . --Mayerl,
Nochta . . . (2000) [0933]
www.cooperation-management.de/publikationen/paper/usm2000_mayerl-n-
ochta.pdf [0934] Agent-mediated Electronic Commerce: Scientific and
Technological . . . --Sierra (2001) [0935]
www.iiia.csic.es/.about.sierra/articles/2001/RoadmapAMEC/Roadmap.ps
[0936] On the Integration of IR and Databases--de Vries, Wilschut
(1999) [0937] www.cs.utwente.nl/.about.arjen/Pics/ds8_short.ps.gz
[0938] Towards a Harmonization of UML-Sequence Diagrams and
MSC--Rudolph, Grabowski, Graubmann (1999)
www.itm.mu-luebeck.de/publications/SDL99-Harmonization.ps.gz [0939]
Logarithmic Time Cost Optimal Parallel Sorting is Not Yet Fast in .
. . --Natvig (1996) [0940]
www.idi.ntnu.no/.about.lasse/publics/SC90.ps [0941] CMIFed: A
Presentation Environment for Portable . . . --van Rossum . . .
(1993) [0942] www.cwi.nl/ftp/CWIreports/CST/CS-R9305.ps.Z [0943]
Requirements of Traffic Telematics to Spatial Databases--Brinkhoff
(1999) [0944] www.fh-oldenburg.de/iapg/personen/brinkhof/SSD99.pdf
[0945] A Task-Specific Ontology for the Application and . . .
--Shahar, Miksch, Johnson [0946]
www-smi.stanford.edu/pubs/SMI_Reports/SMI-96-0649.pdf [0947]
Practical Considerations in Building a Multi-Lingual . . .
--Business Letters John acl.ldc.upenn.edu/W/W97/W97-0906.pdf [0948]
BPP: A Protocol for Exchanging Pricing Information . . . --Oberle,
Ritter, Wehrle [0949]
www.tm.uka.de/.about.wehrle/pubs/2001.sub.--07_HPSR01_BPP.pdf
[0950] An Open Architecture for Evaluating Arbitrary Quality of
Service . . . --Wehrle (2001) [0951]
www.tm.uka.de/.about.wehrle/pubs/2001.sub.--06 ICN01_KIDS.pdf
[0952] Improving the performance of TCP on guaranteed bandwidth . .
. --Ritter, Wehrle, Wolf [0953]
www.tm.uka.de/.about.wehrle/pubs/2001.sub.--02_KIVS01_GR_TCP.pdf
[0954] Efficient Image Compression of Medical Images Using the
Wavelet--Transform And Fuzzy
rtsimage.di.uoa.gr/publications/euro00-1.pdf [0955] Advanced
Mechanisms for Available Rate Usage in ATM . . . --Bless,
Holzhausen . . . [0956]
www.tm.uka.de/.about.wehrle/pubs/2001.sub.--04_ICATM01_AvRateUsage.pdf
[0957] An Extensible Agent Architecture for a Competitive . . .
--Hoen, Bohte . . . [0958]
www.cwi.nl/.about.hoen/publications/SEN-R0217.ps [0959] Elements of
an Open Framework for Pricing in the Future . . . --Gerke, Ritter .
. . [0960]
www.tm.uka.de/.about.wehrle/pubs/2000.sub.--09_Qofis00_Pricing.pdf
[0961] Traffic Priorization and Differentiation with Active Queue .
. . --Walter, Wehrle (2002) [0962]
www.tm.uka.de/.about.wehrle/pubs/2002.sub.--09_ICTSM02_AF_AR.pdf
[0963] A Simulation Suite for Internet Nodes with the Ability to .
. . --Wehrle, Reber, Kahmann [0964]
www.tm.uka.de/.about.wehrle/pubs/2001.sub.--01_CNDS01_Sim.pdf
[0965] Image Compression Using the Wavelet Transform--On Textural
Regions of Interest [0966]
rtsimage.di.uoa.gr/publications/euro98.pdf [0967] Towards Better
Support of Transaction Oriented . . . --Bless, Holzhausen . . .
[0968] www.tm.uka.de/.about.bless/QoflS2001-qf-online.pdf [0969]
User feedback on the use of public key certificates--Klobucar
(2001) [0970] www.e5.ijs.si/staff/tomaz/erk2001.pdf [0971] Using
Realistic Internet Topology Data for Large Scale Network . . .
--Bless [0972] www.tm.uka.de/.about.bless/omnet_ws.sub.--2002-1.pdf
[0973] The Trust Factor in the Virtual Enterprise . . . --Mobile
Broadband Service [0974]
paula.oulu.fi/Publications/Submited/ICE2000f.pdf [0975] User and
Session Mobility in a Plug-and-Play Network . . . --Mazen Malek
Shiaa [0976]
www.item.ntnu.no/.about.plugandplay/publications/eunice2002.pdf
[0977] Dynamic Aggregation of Reservations for Internet
Services--Bless [0978] www.tm.uka.de/.about.bless/ictsm10-daris.pdf
[0979] Advanced Service Creation Using--Distributed Object
Technology [0980]
www.ee.surrey.ac.uk/Personal/G.Pavlou/Publicationstournal-papers/Adam-02b-
.pdf [0981] Semantics and Verification of UML Activity Diagrams for
Workflow . . . --Eshuis (2002) [0982]
wwwhome.cs.utwente.nl/.about..eshuis/thesis-hyperlinks.pdf [0983]
be cited as a National Research Council report . . . --The Four Way
[0984] www7.nationalacademies.org/CSTB/wp_geo_armstrong.pdf [0985]
Support Specification and Selection in TAPAS--Aagesen, Anutariya,
Shiaa, Helvik [0986]
www.item.ntnu.no/.about.plugandplay/publications/euniceCap2002.pdf
[0987] Profiling and Internet Connectivity in Automotive . . .
--Cilia, Hasselmeyer . . . [0988]
www.cs.ust.hk/vldb2002/VLDB2002-papers/S33P08.pdf [0989] MIETTA--A
Framework for Uniform and Multilingual Access to--Structured
Database www.xtramind.com/.about.holger/paper/iral00.pdf [0990]
Definition And Utilisation Of OMG IDL TO TTCN-3 MAPPINGS--Ebner,
Yin, Li [0991]
www.itm.mu-luebeck.de/publications/idltottcn3mapping.pdf [0992]
Campiello--New user interface approaches for community . . .
--Antonietta Grasso Michael (1998)
www11.informatik.tu-muenchen.de/publications/pdf/Grasso1998a.pdf
[0993] SDL and MSC Based Test Generation for Distributed . . .
--Grabowski, Koch . . . (1998)
www.itm.mu-luebeck.de/publications/SDL99-DistributedTesting.ps.gz
[0994] Autolink--A Tool for Automatic Test Generation from . . .
--Koch, Grabowski . . . (1998)
www.itm.mu-luebeck.de/publications/A-98-05/Report-A-98-05.ps.gz
[0995] PATROCLOS: A Flexible and High-Performance Transport
Subsystem--Braun (1994)
www.iam.unibe.ch/.about.braun/lit/vanc_p.ps.gz [0996] Multilingual
Generation and Summarization of Job . . . --Somers, Black . . .
(1997) [0997] sskkii.gu.se/Tree/Reports/anlp97/ANLP.paper.ps [0998]
Real-time TTCN for testing real-time and multimedia
systems--Walter, Grabowski (1997)
www.itm.mu-luebeck.de/publications/IWTCS98RT/IWTCS98-RT-TTCN.ps.gz
[0999] Applying SAMSTAG to the B-ISDN protocol SSCOP--Grabowski,
Scheurer, Dai . . . (1997)
www.itm.mu-luebeck.de/publications/IWTCS97SSCOP/IWTCS97-SSCOP.ps.gz
[1000] A Continuously Available and Highly Scalable . . .
--Hvasshovd . . . (1991) [1001]
www.idi.ntnu.no/IDT/grupper/DB-grp/tech_papers/hpts91.ps [1002] A
Modular VLSI Implementation Architecture for . . . --Braun,
Schiller . . . (1994) [1003]
www.iam.unibe.ch/.about.braun/lit/vanc_bsz.ps.gz [1004]
Transportation modelling methods and advanced transport
telematics--Toint (1993)
thales.math.fundp.ac.be/pub/reports/TR92-24.ps [1005] Impact of ATM
ABR Control on the Performance of TCP-Tahoe and . . . --Feng,
Ghosal
networks.cs.ucdavis.edu/.about.ghosal/globecom/globecom_paper.ps
[1006] Detecting Opportunities for Parallel Observations on the . .
. --Michael Lucks Space (1992)
www.stsci.edu/public/sst/poms/poms.ps [1007] Expression Of
Interest--Network Of Excellence [1008]
www.ctit.utwente.nl/internal/info-programmes/IST/Eol-NoE/eHealth.pdf
[1009] Optimisation of trapezoidal membership functions in a fuzzy
rule--System By The [1010]
www.univ-savoie.fr/labos/lamii/Busefal/Documents/85-05.pdf [1011] A
Framework For Video Modelling--Petkovic, Jonker (2000) [1012]
www.cwi.nl/.about.acoi/DMW/documents/./world/innsb.ps [1013] An
Architecture For Reverse Charging In The Internet--Sprenkels,
Parhonyi, Pras, . . . (2000)
wwwsnmp.cs.utwente.nl/nm/research/results/publications/sprenkels/sprenkel-
sram-reverse-charging.pdf [1014] Behavior of a Bayesian Adaptation
Method for . . . --Fredouille, Mariethoz, . . . (2000) [1015]
ftp.idiap.ch/pub/marietho/publications/AdaptICASSP2000_IRR02.ps.gz
[1016] Software Process Modeling and Evolution in EPOS--Jaccheri,
Larsen, Conradi (1992)
www.idt.unit.no/.about.epos/Papers/capri-final.ps [1017] Individual
Management of Personal Reachability in . . . --Reichenbach . . .
(1997) [1018]
www.inf.tu-dresden.de/.about.hf2/publ/1997/RDFR.sub.--971FIPSec.pdf
[1019] A Generic Software Component Framework for Distributed . . .
--Batteram, Idzenga (1997)
www.trc.nl/events/ecscw97oogp/papers/batteram.pdf [1020] Efficient
Partitioning of Sequences--Olstad, Manne (1995)
www.ii.uib.no/.about.fredrikm/fredrik/papers/efficient.ps [1021]
Integrated Video Archive Tools--Hjelsvold, Langorgen, Midtstraum .
. . (1995) [1022]
www.idt.ntnu.no/IDT/grupper/DB-grp/tech_papers/ACM-MM95.ps [1023]
MULINEX: Multilingual Web Search and Navigation--Joanne Capstick
Abdel (1998) speech.ftw.at/.about.gor/pub/twlt98/mulinex-twlt98.pdf
[1024] A Non-Interleaving Semantics for MSC--Heymer (1998) [1025]
www.itm.mu-luebeck.de/publications/ANIS/ANIS.ps.gz [1026] An
Overview Of The Cave Project Research . . . --Bimbot, Hutter . . .
(1998) [1027]
www.ubilab.org/publications/print_versions/pdf/bim98.pdf [1028]
Cross Language Retrieval with the Twenty-One system--Wessel Kraaij
(1998) [1029] trec.nist.gov/pubs/trec6/papers/twentyone.ps [1030]
Verifying Business Processes using SPIN--Janssen, Mateescu, Mauw .
. . (1998) [1031] ftp.win.tue.nl/pub/techreports/sjouke/spin98.ps.Z
[1032] Implementation of a Parallel Transport Subsystem on a . . .
--Braun, Schmidt (1993) [1033]
www.telematik.informatik.uni-karlsruhe.de/.about.schmidt/schmidt_hpdc93.p-
s.gz [1034] Uniform Versioning The Change-Oriented Model--Munch,
Larsen, Gulla . . . (1993) [1035]
www.idt.unit.no/.about.bjornmu/cov-scm4.ps [1036] Architectural
Considerations for Personal Mobility In--The Wireless Internet
[1037] www.item.ntnu.no/.about.plugandplay/publications/PWC2002.pdf
[1038] Synchronization In Ad Hoc Networks Based On UTRA TDD--Ebner,
Rohling, Halfmann, Lott (2002)
www.et2.tu-harburg.de/Mitarbeiter/Ebner/PIMRC02_Ebner.pdf [1039]
Pervasive Privacy with Identity Management--Jendricke, Kreutzer,
Zugenmaier [1040]
www.teco.edu/.about.philip/ubicomp2002ws/organize/identity.pdf
[1041] Formalising Hinting in Tutorial Dialogues--Tsovaltzi,
Matheson (2002) [1042] www.ltg.ed.ac.uk/edilog/papers/185.pdf
[1043] TimedTTCN-3--A Real-Time Extension For TTCN-3-Dai,
Grabowski, Neukirchen [1044]
www.itm.mu-luebeck.de/publications/timedttcn3.pdf [1045] Mapping
CORBA IDL to TTCN-3 based on IDL to TTCN-2 mappings--Ebner (2001)
[1046] www.itm.mu-luebeck.de/publications/FBT2001/fbt2001_ebner.pdf
[1047] Mobile Identity Management--Jendricke, Kreutzer, Zugenmaier
[1048]
ftp.informatik.uni-freiburg.de/documents/reports/report178/report00178.ps-
.gz [1049] Causal Reasoning In A Medical--Knowledge Based System
[1050]
www.newcastle.edu.au/school/design-comm-info/staff/gibbon/ecis98.ps
[1051] A Secure Web-based Medical Digital Library--Architecture
Based On [1052] thalis.cs.unipi.gr/.about.jpap/medical.pdf [1053]
IPv6 Autoconfiguration in Large Scale Mobile Ad-Hoc
Networks--Kilian Weniger Martina
www.iponair.de/publications/Weniger-EuroWireless02.pdf [1054]
Serviceware Framework For Developing 3g Mobile--Services Sahin
Albayrak (2002) [1055] www.ssgrr.it/en/ssgrr2002w/papers/37.pdf
[1056] Traffic Controlmethods For High Speed--Packet Switched
Networks (2002) [1057]
hsnlab.ttt.bme.hu/.about.molnar/files/pch2002.pdf [1058] The Impact
Of Filtering On Spatial Continuous Queries--Brinkhoff (2002) [1059]
www.fh-wilhelmshaven.de/oow/institute/iapg/personen/brinkhoff/paper/SDH20-
02.pdf [1060] On the Generation of Time-Evolving Regional
Data--Tzouramanis . . . (2002) [1061]
delab.csd.auth.gr/papers/GE002tvm.pdf [1062] A dynamic service
delivery framework based on the OSGi model--Vos, Buytaert, Buytaert
(2002) www.ssgrr.it/en/ssgrr2002w/papers/165.pdf [1063] Applying
bacterial algorithm to optimise trapezoidal . . . --Botzheim,
Hamori, Koczy (2001) [1064] www.mft.hu/hallg/200106.pdf [1065]
Deadlock Probability in Unrestricted Wormhole Routing
Networks--Folkestad, Roche (1997)
ftp.cs.ucla.edu/tech-report/1997-reports/970008.ps.Z [1066] The
Infostations Challenge: Balancing Cost and--Ubiquity In Delivering
[1067] www.winlab.rutgers.edu/.about.ryates/papers/ieeepc6b.ps
[1068] A Proposal for a Combination of Compression and
Encryption--Lutz Vorwerk Thomas [1069]
www.informatik.uni-trier.de/.about.vorwerk/publics/perth.ps [1070]
Mobility Management In Plug And Play Network--Architecture Mazen
Malek (2002) [1071]
www.item.ntnu.no/.about.plugandplay/publications/smartnet2002.pdf
[1072] Adaptive Importance Sampling Simulation Of Queueing
Networks--de Boer [1073] www.informs-cs.org/wsc00papers/086.PDF
[1074] Ics--Forth--Erich Leisch Stelios (1999) [1075]
www.ics.forth.gr/ICS/acti/cmi_hta/publications/papers/1999/hector_solutio-
ns/hector_solutions.pdf [1076] Co-Evolution of Bargaining
Strategies in a Decentralized . . . --Eymann (2001) [1077]
www.iig.uni-freiburg.de/.about.eymann/publications/TEymann01.pdf
[1078] VBR Video Source Characterization And A Practical . . .
--Cselenyi, Molnar [1079]
hsnlab.ttt.bme.hu/.about.molnar/files/VBRtelsys.ps.gz [1080] An
approach to dynamic reconfiguration of . . . --Almeida, Wegdam . .
. (2001) [1081]
www.cs.utwente.nl/.about.alme/cvitae/sbrc2001-final-footnote.pdf
[1082] www.ub.utwente.nl/webdocs/ctit/1/0000004f.pdf [1083] A
GSM/GPS Receiver With a Bandpass Sigma-Delta Analog . . . --Muller,
Boehm, Hentschel (1999)
www.ifn.et.tu-dresden.de/MNS/veroeffentlichungen/1999/Mueller_T_EU-
W.sub.--99.pdf [1084] An Intelligent Educational Metadata
Repository--Bassiliades, Kokkoras . . . (2002) [1085]
www.csd.auth.gr/%7Elpis/publications/crc-chapter1.pdf [1086]
Messor: Load-Balancing through a Swarm of Autonomous
Agents--Montresor, Meling, Babaoglu (2002)
www.cs.unibo.it/babaoglu/papers/ap2p02.pdf [1087] Exact trade-off
between approximation accuracy and . . .
--Tikk, Baranyi [1088] www.mft.hu/publications/baranyi/baranyi2.pdf
[1089] On the Queue Tail Asymptotics for General Multifractal
Traffic--Molnar, Dang, Maricza [1090]
hsnlab.ttt.bme.hu/.about.molnar/files/ifipnw02.pdf [1091] Feature
Ranking Based On Interclass Separability For Fuzzy . . . --Tikk,
Gedeon (2000) [1092] www.mft.hu/publications/tikk/tikk8.pdf [1093]
Public Key Certificate Revocation Schemes--Ames (2000) [1094]
www.pvv.ntnu.no/.about.andrearn/certrev/thesis/CertRevThesis.sub.--29Feb2-
000.ps.gz [1095] Competitive market-based allocation of consumer
attention . . . --Bohte, Gerding . . . (2001) [1096]
www.cwi.nl/ftp/CWIreports/SEN/SEN-R0131.ps.Z [1097] Towards
Adaptive, Resilient and Self-Organizing . . . --Montresor, Meling .
. . [1098]
www.elet.polimi.it/Users/DEI/Sections/CompEng/GianPietro.Picco/ntw02-p2p/-
papers/18.pdf [1099] Stability of interpolative fuzzy KH
controllers--Tikk, Joo . . . (2002) [1100]
www.mft.hu/publications/tikk/tikk4.pdf. [1101] Comprehensive
analysis of a new fuzzy rule interpolation method--Tikk, Baranyi
(2000) [1102] www.mft.hu/publications/tikk/tikk2.pdf [1103] Design
and Use of Clinical Ontologies:--Curricular Goals For [1104]
www-smistanford.edu/pubs/SMI_Reports/SMI-1999-0767.pdf [1105]
Toward Standardization of Electronic Guideline . . . --Elkin,
Peleg, Lacson, . . . (2000) [1106]
www-smi.stanford.edu/pubs/SMI_Reports/SMI-2001-0865.pdf [1107]
Extracting Information for Automatic Indexing of Multimedia
Material--Saggion . . . (2002)
parlevink.cs.utwente.nl/projects/mumis/documents/mumis-lrec2002.pdf
[1108] Investigation of a new alpha-cut based fuzzy . . .
--Baranyi, Tikk, Yam . . . [1109]
www.mft.hu/publications/tikk/tikk11.pdf [1110] The Evolution of
Jini" Technology--In Telematics By [1111]
wwws.sun.com/software/jini/whitepapers/PsiNapticTelematics.pdf
[1112] Desktop Synchronous Distance Learning Application--Enhanced
With Efficient [1113] ru6.cti.gr/Publications/645.pdf;
ru6.cti.gr/Publications/904.pdf [1114] Adaptive compression of
DICOM-image data--Hludov, Engel, Meinel [1115]
www.informatik.uni-trier.de/.about.meinel/papers/tes.sub.--2.ps
[1116] Telematic Tools to Support Group Projects in Higher
Education--Jan Van Der [1117]
www.ub.utwente.nl/webdocs/ctit/1/00000004.pdf [1118] A
Receiver-initiated WDM Multicast Tree Construction Protocol . . .
--Ip Dense Mode [1119]
www.ub.utwente.nl/webdocs/ctit/1/00000032.pdf [1120] AUTOLINK--A
Tool for the Automatic and . . . --Schmitt, Koch . . . (1997)
[1121] 141.83.21.121/publications/ALASA/SchmKochGraHog.ps.gz [1122]
The Term Processor Generator Kimwitu--van Eijk, Belinfante, Eertink
. . . (1997) [1123] wwwtios.cs.utwente.nl/kimwitu/tacas97.ps.gz
[1124] Security Engineering of Lattice-Based Policies--Bryce (1997)
[1125] set.gmd.de/.about.kuehnhsr/CWASAR/D06.1.ann5.ps.gz [1126] A
scheme for adaptive biasing in importance sampling--Heegaard (1997)
[1127] www.idt.unit.no/.about.poulh/publications/IS-adaptive.ps
[1128]
www.item.ntnu.no/.about.poulh/publications/adapt-scheme-abstract.ps
[1129] Towards the Industrial Use of Validation . . . --Ek,
Grabowski . . . [1130]
www.itm.mu-luebeck.de/publications/A-97-03/SDL-Forum-97.ps.gz
[1131] A Browser for a Versioned Entity-Relationship
Database--Gulla (1992) [1132]
www.idt.unit.no/.about.epos/Papers/browser.ps [1133] The Eternal
Resource Locator: An Alternative Means of . . . --Vaclav [1134]
www.usenix.org/publications/library/proceedings/ec98/full_papers/anderson-
/anderson.pdf [1135] A Continuously Available and Highly Scalable .
. . --Hvasshovd . . . (1991) [1136]
www.idi.ntnu.no/IDT/grupper/DB-grp/tech_papers/hpts91.ps [1137] A
Parallel Implementation of XTP on Transputers--Braun, Zitterbart
(1991) [1138] www.iam.unibe.ch/.about.braun/lit/lcn16_xtp.ps.gz
[1139] Stublets: A Notion for Mobility-Aware Application
Adaption--Dietmar Kottmann Christian (1996)
ftp.diku.dk/diku/distlab/wmr96/sommer.ps.gz [1140] ATM Traffic
Measurements and Analysis on a Real Testbed--Molnar, Cselenyi, . .
. (1996) [1141] hsnlab.ttt.bme.hu/.about.molnar/files/itc2.ps.gz
[1142] A CORBA Platform for Component Groupware--Hofte, van der
Lugt, Bakker (1996) [1143]
www.telin.nl/publicaties/1996/ozchi96.pdf [1144] The European Web
Index: An Internet Search Service for . . . --Lundberg, Ardo . . .
(1996) [1145]
www.lub.lu.se/desire/radar/reports/D3.12/D3.12.v1.0.ps [1146]
Results Of The CEO Project WWW Management--Hazewinkel, Van
Hengstum, Pras (1996)
wwwsnmp.cs.utwente.nl/nm/research/results/publications/pras/WWW.pdf
[1147] Towards Integrated QoS Management--Schmidt, Zitterbart
(1995) [1148]
www.telematik.informatik.uni-karlsruhe.de/.about.schmidt/schmidt_h-
ipp94.ps.gz [1149] On engineering support for business process
modelling . . . --Franken, de Weger . . . (1996) [1150]
wwwhome.cs.utwente.nl/.about.pires/publications/bpr96.pdf [1151]
Optimization of Spatial Joins Using Filters--Veenhof, Apers,
Houtsma (1995) [1152]
wwwis.cs.utwente.nl:8080/isdoc/confpaper/veenhof.BNCOD95.accepted.ps.gz
[1153] Software Architecture of Ubiquitous Scientific Computing . .
. --Tzvetan Drashansky (1995) [1154]
www.cs.purdue.edu/homes/saw/publications/95/ubiq-pses.ps [1155]
Wavefront implementation of Self Organizing Maps on RENNS--Gaute
Myklebust (1995) www.idt.unit.no/.about.gautemyk/icdsp95.ps [1156]
On the Enterprise Modelling of an--Educational Information . . .
[1157] www.ub.utwente.nl/webdocs/ctit/1/0000002f.pdf [1158] VBR
Video Source Characterization And A Practical . . . --Cselenyi,
Molnar [1159] hsnlab.ttt.bme.hu/.about.molnar/files/VBRtelsys.ps.gz
[1160] Use of the CANTOR system for collaborative learning in . . .
--Hans Andersen Verner [1161] newmedia.colorado.edu/cscl/270.pdf
[1162] Jgroup/ARM: A Distributed Object Group Platform . . .
--Meling, Montresor, . . . [1163]
www.CS.UniBO.it/babaoglu/papers/jgroup-arm.pdf [1164] Validation of
the Open Service Access API for UMTS . . . --Maarten Wegdam
Dirk-Jaap [1165]
arch.cs.utwente.nl/publications/papers/proms01-osa-Incs22130210.pdf
[1166] A Hyperlink-Proposal Mechanism to Exemplify Cognitive . . .
--Haffner, Roth, Meinel [1167]
www.informatik.uni-trier.de/.about.meinel/papers/Paper02.ps [1168]
Digital Signatures For Automobiles?!--Gollan, Meinel [1169]
www.informatik.uni-trier.de/.about.meinel/papers/DigitalSignaturesAuto02.-
pdf [1170] Designing Safe Smart Home Systems for Vulnerable
People--Dewsbury, Taylor [1171]
www.smartthinking.ukideas.com/_DIRC.pdf [1172] Providing
X.509-based user--Access Control To [1173]
ftp.polito.it/pub/security/papers/sec98/sec98.ps.gz [1174] Seeing
Speech In Space And Time: Psychological And . . . --Ruth Campbell
Department [1175] www.asel.udel.edu/icslp/cdrom/vol3/1008/a1008.pdf
[1176] The Process of Designing Appropriate Smart Homes: Including
. . . --Guy Dewsbury Bruce [1177]
www.smartthinking.ukideas.com/Dewsbury_et_al_Appropriate_design_of_smart_-
homes.pdf [1178] Transparent Dynamic Reconfiguration for
CORBA--Almeida, Wegdam, van. (2001) [1179]
www.cs.utwente.nl/.about.alme/cvitae/doa01.pdf [1180] Dissemination
of Mutable Sets of Web Objects--Buchholz, Goebel, Schill, Ziegert
(2001) wwwrn.inf.tu-dresden.de/.about.buchholz/askom/PDCS2001.pdf
[1181] How to Support the Negotiation of Service Level Agreements .
. . --Koppel, Boning, Abeck (1999)
www.cooperation-management.de/publikationen/paper/isas99_Abeck-Boening-Ko-
eppel.pdf [1182] PAMINA: A Certificate Based Privilege Management
System--Nochta, Ebinger, Abeck (2002)
www.isoc.org/isoc/conferences/ndss/02/proceedings/papers/nochta.pdf
[1183] Modeling IT Operations to Derive Provider Accepted
Management . . . --Abeck, Mayerl (1999)
www.cooperation-management.de/publikationen/paper/im99_abeck-mayerl.pdf
[1184] On deriving rules for nativised pronunciation in . . .
--Trancoso, Viana . . . (1999) [1185]
www.l2f.inesc.pt/documents/papers/Trancoso99b.pdf [1186] A CANDLE
to light the way?--Sebastian Abeck Jodok [1187]
www.cooperation-management.de/publikationen/paper/ACandletoLightTheWay.pd-
f [1188] Internet Agents for Telemedicine Services--Mea, Roberto,
Conti, Di . . . (1999) [1189]
www.telemed.uniud.it/papers/VDM-MI99.pdf [1190] Supporting Secure
and Transparent Delegation in the CORBA . . . --Zoltn Nochta Taufiq
(2001)
www.cooperation-management.de/publikationen/paper/pwc2001_nrr_cr.pdf
[1191] The adaptation and use of a WWW-based coursemanagement
system . . . --De Boer, Collis (2000)
www.ub.utwente.nl/webdocs/ctit/1/00000059.pdf [1192] Evaluation of
Mobile Agent Systems with Respect to Failure . . . --Otto Winner
October [1193]
www.item.ntnu.no/.about.ottow/papers/failsemMASreport.pdf [1194]
Proactive Services in a Distributed Traffic Telematics . . .
--Gura, Held, Kaiser [1195]
www.informatik.uni-ulm.de/rs/projekte/core/ProctiveServ.pdf [1196]
TCP over GPRS--Performance Analysis--Manner (1999) [1197]
www.cs.helsinki.fi/u/jmanner/papers/Thesis-Manner.ps [1198] Ip Over
Wavelength-Routed Access Networks--Marcos Rogrio Salvador [1199]
wwwctit.cs.utwente.nl/.about.salvador/Eunice99.pdf [1200]
Increasing Retrievability and Reusability of Learning . . .
--Hiddink Van Der [1201]
www.ub.utwente.nl/webdocs/ctit/1/00000056.pdf [1202] Experiences
from Development of Home Health Care Applications . . . --Leili
Lind Erik [1203] ftp.imt.liu.se/pub/bildb/MIpapers/524_LIND.PDF
[1204] A Review of Parallel Implementations of Backpropagation . .
. --Torresen, Tomita [1205] www.ifi.uio.no/.about.jimtoer/chp2.ps
[1206] ESCORT: Towards Integration in Intersection Control--Andrea
Savigni Filippo (2000) [1207]
www.cs.ucl.ac.uk/staff/A.Savigni/papers/2000_jubilee_escort_roma.pdf
[1208] Usability Field-Test Of A Spoken Data-Entry System--Marcello
Federico And [1209]
poseidon.itc.it:7117/.about.ssi/DITELO/papers/ICASSP99.sub.--1.ps
[1210] FLAMINGO: A Packet-switched IP over WDM Metro Optical
Network--Dey Koonen Geuzebroek (2001)
wwwctit.cs.utwente.nl/.about.salvador/NOC2001.pdf [1211] Real-time
test specification with TTCN-3--Dai, Grabowski, Neukirchen (2001)
[1212]
www.itm.mu-luebeck.de/publications/FBT2001/Abstract_fbt01neukdai.pdf
[1213] A System for Uniform and Multilingual Access to Structured .
. . --Xu, Netter, Stenzhorn (2000)
www.cs.ust.hk/acl2000/Demo/04_xu.pdf [1214] Corpus-driven learning
of Event Recognition Rules--Roberto Basili Maria [1215]
www.dcs.shetac.uk/.about.fabio/ML4IE/2.PS.gz [1216] Web-Support for
Activating Use of Theory in Group-Based Learning--Jan Van Der
[1217] www.ub.utwente.nl/webdocs/ctit/1/0000005a.pdf [1218]
Automated Generation of Category-Specific Thesauri for . . .
--Attardi, Di Marco . . . (1998) [1219]
faure.iei.pi.cnr.it/.about.fabrizio/Publications/TRO698.ps [1220]
The use of CMC in applied social science training--Interim Report
Merja [1221] www.stir.ac.uk/schema/deliverables/D5.3.pdf [1222] The
IT-Potential Of Haptics--Touch access for people with . . .
--Sjostrom (1999) [1223]
www.certec.lth.se/doc/touchaccess/TouchAccess.pdf [1224] An
All-Optical WDM Packet-Switched Network Architecture . . . --Marcos
Rogrio Salvador (2001)
wwwctit.cs.utwente.nl/.about.salvador/ICN2001.pdf [1225] An
Adaptive, Collaborative Environment to Develop . . . --Vizcano . .
. [1226] oreto.inf-cr.uclm.es/personas/avizcaino/itsenv.ps [1227]
The HyperMuseum Theme Generator System: Ontology based . . .
--Stuer, Meersman, De . . . (2001)
www.archimuse.com/mw2001/papers/stuer/stuer.html [1228]
http://wise.vub.ac.be/Download/Papers/stuerMW2001.pdf [1229]
Failure Semantics of Mobile Agent Systems Involved in . . . --Otto
Wittner Carsten (1999) [1230]
www.item.ntnu.no/.about.ottow/papers/failsemNIK99.pdf [1231]
Cross-Entropy Guided Mobile Agents Finding Cyclic Paths in . . .
--Wittner, Helvik (2002) [1232]
www.item.ntnu.no/.about.wittner/aamas2002_submitted.pdf [1233]
Cross Entropy Guided Ant-like Agents Finding Dependable . . .
--Wittner, Helvik (2002) [1234]
www.item.ntnu.no/.about.wittner/cec2002.pdf [1235] Using
Information Flow Control to Evaluate Access . . . --Mantel,
Schairer, . . . [1236]
www.dfki.de/.about.schairer/publications/report00159.ps.gz [1237]
Network Architecture of a Packet-switched WDM LAN/MAN--Dey Koonen
And (2000) [1238]
wwwctit.cs.utwente.nl/.about.salvador/LEOS2000.pdf [1239]
Specification and Validation of a Real-Time Parallel . . . --de
Farias, Pires . . . (1997) [1240]
www.ub.utwente.nl/webdocs/ctit/1/00000066.pdf [1241] Mobile Ip:
Security Application--Tuquerres, Salvador, Sprenkels [1242]
ntrg.cs.tcd.ie/htewari/papers/MobileIP-Sec.pdf [1243] M3POC: a
multimedia multicast transport protocol for cooperative . . .
--Owezarski [1244] www.laas.fr/.about.owe/PUBLIS/99525.ps.gz [1245]
User Interfaces for All--Kobsa, (eds.) (1999) [1246]
www.gmd.de/publications/report/0074/Text.pdf [1247] Supporting
PIM-SM in All-Optical Lambda-Switched Networks--Marcos Rogrio
Salvador (2001) wwwctit.cs.utwente.nl/.about.salvador/SBRC2001.pdf
[1248] Managing Distributed Personal Firewalls with Smart . . .
--Haffner, Roth, Heuer, . . . [1249]
www.informatik.uni-trier.de/.about.meinel/papers/Managing01.ps
[1250] FINAL REPORT: LAURIN http://laurin.uibk.ac.at/--Version
November Author [1251]
germanistik.uibk.ac.at/laurin/reports/finalrep01.pdf [1252] Some
Implications of MSC, SDL and TTCN Time Extensions . . . --Hogrefe,
Koch . . . (2001) [1253]
www.itm.mu-luebeck.de/publications/DH_BK_HN2001SDLForum/sdlforum2001.pdf
[1254] Supporting IP Dense Mode Multicast Routing Protocols in . .
. --Marcos Rogerio Salvador (2000)
wwwctit.cs.utwente.nl/.about.salvador/OPTICOMM2000.pdf [1255]
Report on the course for Technology Teachers WWW Course of . . .
--Jyrki Pulkkinen And [1256]
telematics.ex.acuk/T3/0/downloads/d13-1.pdf [1257] A Multi-DSP
Laboratory Course--Rinner, Schneider, Steger, Weiss [1258]
www.iti.tu-graz.ac.at/de/people/schneider/papers/rinner98.pdf
[1259] Modularity--A Concept For New Neural Network
Architectures--Schmidt, Bandar (1998)
www.comp.lancs.ac.uk/.about.albrecht/pubs/pdf/schmidt_csa_irbid.sub.--199-
8.pdf [1260] Supporting IP Dense Mode Multicast Routing in
All-Optical . . . --Marcos Rogrio Salvador (2001)
wwwctit.cs.utwente.nl/.about.salvador/ONM2001.pdf [1261] Dagstuhl
Seminar on Ubiquitous Computing--September The International (2001)
[1262]
www.inf.ethz.ch/vs/events/dag2001/intro/DagstuhlIntroductions.pdf
[1263] A Framework For Video Modelling--Centre For Telematics
[1264] www.cs.utwente.nl/.about.milan/docs/innsb.ps [1265]
Conceptual Stage in Designing Multimedia for Tele Learning--Kommers
(2001) [1266] www.ub.utwente.nl/webdocs/ctit/1/00000060.pdf [1267]
Signed Preservation Of Online References--Heuer, Losemann, Meinel
[1268]
www.informatik.uni-trier.de/.about.meinel/papers/webnet00b.ps
[1269] Chapter 7 Implementation of Backpropagation Neural . . .
--Jim Torresen Department [1270]
www.ifi.uio.no/.about.jimtoer/chp3.ps [1271] TIMe at a
glance--Br.ae butted.k, Gorman, Haugen, Melby . . . [1272]
www.sintef.no/time/report.pdf [1273] Executive Summary--The Vision
Of [1274] www.it.bton.ac.uk/research/seake/knowledge.pdf [1275]
Supporting the Travelling Tradition: A report on the work . . .
--Ken Marks Department (2000)
ui4all.ics.forth.gr/i3SD2000/Marks.PDF
[1276] Circuits and Systems--Benini, De Micheli, Macii, Maloberti
[1277] www.nd.edu/.about.stjoseph/newscas/CASMagvol1no1.pdf [1278]
Enterprise Modelling For An Educational Information . . . --Ing
Widya Cees (2001) [1279]
wwwhome.cs.utwente.nl/.about.widya/webpapers/iceis2001.sub.--205.p-
df [1280] Telematics For Group-Based Learning: Simplicity Versus .
. . --van der Veen, Collis . . . [1281]
www.ub.utwente.nl/webdocs/ctit/1/00000057.pdf [1282] Research
Report 1997-1999--Department Of Computer (1997) [1283]
www.cs.ucy.ac.cy/Research/archives/rr97-99.ps [1284] Translation
Resources, Merging Strategies and Relevance . . . --Djoerd Hiemstra
Wessel [1285] janus.cs.utwente.nl/.about.hiemstra/papers/clef1.pdf
[1286] An Information System for Long-distance Cooperation in
Medicine . . . --Kosch, al. (2000) [1287]
www.ii.uib.no/para2000/program/jacek.ps [1288] Next Generation
Internet in Europe--Published By The [1289]
www.infowin.org/ACTS/ANALYSYS/PRODUCTS/THEMATIC/NGI/ngi_in_europe.pdf
[1290] R. Mu.about.noz, M. Saiz-Noeda, A. Su arez and M.
Palomar--Grupo De Investigaci (2000) [1291]
gplsi.dlsi.ua.es/gplsi/articulos/a2000/mt2000.ps [1292] Lazy Users
and Automatic Video Retrieval Tools in (the) Lowlands--The Lowlands
Team carol.wins.uva.nl/.about.cgmsnoek/pub/trec10video.pdf [1293]
Remote MIB item look-up service--Pras, Boros, Helthuis (2002)
[1294]
www.simpleweb.org/nm/research/results/publications/pras/2002-04-noms.pdf
[1295] Use Of Real And Contaminated Speech For Training Of A . . .
--Matassoni Omologo And (2001)
poseidon.itc.it:7117/.about.ssi/SHINE/ps/eurospeech01.ps.gz [1296]
Extending the Data Storage Capabilities of a Java-based . . .
--Clemens Cap Nico [1297]
wwwiuk.informatik.uni-rostock.de/.about.maibaum/docs/maibtune.ps
[1298] Towards Precision Tools For ATM Network Design, Dimensioning
. . . --Molnar, al. [1299]
hsnlab.ttt.bme.hu/.about.molnar/files/peripol.ps.gz [1300] Fair
Bandwidth Allocation of a Wireless Base Station--Gyorgy Mikl'os
Traffic [1301] hsnlab.ttt.bme.hu/.about.molnar/files/iqwim99.ps.gz
[1302] Forecasting the Success of Telecommunication Services in . .
. --Detlef Schoder . . . (2000) [1303]
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/Sc2000-
.pdf [1304] A General Fractal Model of Internet Traffic--Molnar
[1305] hsnlab.ttt.bme.hu/.about.molnar/files/multifractalLCN.pdf
[1306] Correlations in ATM Cell Streams Exposed to Cell Delay
Variation--Molnar, Blaabjerg [1307]
hsnlab.ttt.bme.hu/.about.molnar/files/hung1.ps.gz [1308] A General
Traffic Control Framework in ATM Networks--Fodor, Marosits, Molnar
(1996) hsnlab.ttt.bme.hu/.about.molnar/files/gtf.ps.gz [1309]
NAVIGATION IN CYBERSPACE Using Multi-Dimensional Scaling . . .
--Schoder Institut Fur (1999)
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/Sc1999-
a.pdf [1310] Performance Measurement Tool for Packet Forwarding
Devices--Tam As Kovacshazy [1311]
www.mit.bme.hu/.about.khazy/publications/imtc2001.sub.--3472.pdf
[1312] Benefits of a Universal Security Framework--Report By Arnd
(2000) [1313]
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/We2000-
f.pdf [1314] Methods for Computing B-ISDN Link Blocking
Probabilities--Molnar, Blaabjerg [1315]
hsnlab.ttt.bme.hu/.about.molnar/files/link.ps.gz [1316]
Inter-organizational Networking of Small and . . . --Framework And
. . . (1999) [1317]
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/EgEn19-
99.pdf [1318] Using Objects and Patterns to Implement Domain
Ontologies--Guizzardi, Falbo, Filho (2001)
wwwhome.cs.utwente.nl/.about.guizzard/jbcs.pdf [1319] Highly Secure
Low-cost Computers--Arnd Weber Today's (2000) [1320]
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/We2000-
e.pdf [1321] On Modeling and Shaping Self-Similar ATM
Traffic--Andor Moln'ar And [1322]
hsnlab.ttt.bme.hu/.about.molnar/files/itc97.ps.gz [1323] Pitfalls
in Long Range Dependence Testing and Estimation--Molnar, Dang
[1324] hsnlab.ttt.bme.hu/.about.molnar/files/pitfalls.pdf.gz [1325]
Distributed Fair Bandwidth Allocation of a Wireless Base . . .
--Gyorgy Miklos Traffic (2000)
hsnlab.ttt.bme.hu/.about.molnar/files/netw00.ps.gz [1326] Highly
Secure Low-cost PDA-phones--Weber (2000) [1327]
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/We2000-
d.pdf [1328] Sharing Telematics Courses--The CANDLE project--Aiko
Pras Centre (2001) [1329]
www.simpleweb.org/nm/research/results/publications/pras/2001-09-04-eunice-
.pdf [1330] A Prototype for an Agent-based Secure Electronic . . .
--Padovan, Sackmann . . . (2001) [1331]
www.iig.uni-freiburg.de/telematik/forschung/projekte/e_sicherheit/comet/p-
ublikationen/PaSaEyPi2001.pdf [1332] On Measurements of Multimedia
Traffic in ATM Networks--Cselenyi . . . [1333]
hsnlab.ttt.bme.hu/.about.molnar/files/icomt.ps.gz [1334] Advanced
Generation Tool of Application's Network Traffic--Petroczi, Molnar
[1335] hsnlab.ttt.bme.hu/.about.molnar/files/agentant.ps.gz [1336]
On Burst And Correlation Structure of Teletraffic Models--Molnar,
Miklos [1337] hsnlab.ttt.bme.hu/.about.molnar/files/ilkley97.ps.gz
[1338] Scaling Analysis of IP Traffic Components--Molnar, Dang
(2000) [1339] hsnlab.ttt.bme.hu/.about.molnar/files/itcssip00.ps.gz
[1340] A System for Supporting Cross-Lingual Information
Retrieval--Capstick, al. (1999) [1341]
speech.ftw.at/.about..gor/pub/ipm/mulinex-ipm99.pdf [1342]
Spatiotemporal Segmentation and Tracking of Objects for . . .
--Kompatsiaris, Strintzis (2000)
egnatia.ee.auth.gr/.about.ikom/CSVT2000.pdf [1343] Region-Based
Color Image Indexing And Retrieval--Ioannis Kompatsiaris Evagelia
(2001) egnatia.ee.auth.gr/.about.ikom/icip2001.pdf [1344]
Kompatsiaris--And Michael Strintzis [1345]
egnatia.ee.auth.gr/.about..ikom/ICIP00.pdf [1346] th IFLA Council
and General Conference Aug. 16-25, 2001--Code Number Division
[1347] www.ifla.org/IV/ifla67/papers/161-165e.pdf [1348]
Agent-Mediators In Media-On-Demand Eletronic Commerce--Joo Paulo
Andrade [1349]
wwwhome.cs.utwente.nl/.about..guizzard/mod-amec-cuba.pdf [1350]
AWeb-based Distributed Environment to Support Teleteaching: . . .
--Ch Bouras Computer [1351] ru6.cti.gr/Publications/261.pdf [1352]
Web-Enabled Distance Education Environment--Bouras, Lampsas,
Bazaios . . . (1998) [1353] ru6.cti.gr/Publications/296.pdf [1354]
ID-No. of presentation: t3a01391--Authors Christos Bouras [1355]
ru6.cti.gr/Publications/279.pdf [1356] Usability meets
Security--The Identity-Manager as your . . . --Jendricke, Markotten
(2000) [1357] www.acsac.org/2000/papers/90.pdf [1358] Deployment
Scenarios of DVEs in Education--Bouras Computer Technology [1359]
ru6.cti.gr/Publications/324.pdf [1360] Trends: Training Educators
Through Networks And . . . --Christos Bouras Computer (1996) [1361]
ru6.cti.gr/Publications/439.pdf [1362] On-Demand
Hypermedia/Multimedia Service over . . . --Bouras, Kapoulas. (1996)
[1363] ru6.cti.gr/Publications/358.pdf [1364] Tele-working services
from the Greek PTT--Christos Bouras Vaggelis (1999) [1365]
ru6.cti.gr/Publications/322.pdf [1366] HIPPOCRATES: A Tool for
Distance Education--Bouras Fotakis Kapoulas [1367]
ru6.cti.gr/Publications/305.pdf [1368] A Platform for the
Implementation of the Services . . . --Bouras, Gkamas . . . (1998)
[1369] ru6.cti.gr/Publications/259.pdf [1370] Training Centres: An
Architecture for the Realisation . . . --Christos Bouras Computer
[1371] ru6.cti.gr/Publications/292.pdf [1372] In-Service Training
through ODL Environments: From User . . . --Bouras Lampsas Spirakis
ru6.cti.gr/Publications/275.pdf [1373] Distributed Learning
Environment using Advanced Services . . . --Ch Bouras Computer
(1999) ru6.cti.gr/Publications/453.pdf [1374] Routing Management
Application Based On Mobile Agents On . . . --Anglica Reyes Ernesto
wwwtgs.cs.utwente.nl/eunice/summerschool/papers/paper9-2.pdf [1375]
Quality Of Service Monitoring In Ip Networks By Using . . . --Tams
Varga Andrs [1376]
wwwtgs.cs.utwente.nl/eunice/summerschool/papers/paper4-3.pdf [1377]
Issues on QoS based Routing in the Integrated Services . . . --Gbor
Rtvri Department [1378]
wwwtgs.cs.utwente.nl/eunice/summerschool/papers/paper4-1.pdf [1379]
Usability Research in a Housing Fair: Problems and . . .
--Sajaniemi, Tossavainen (1995) [1380]
cs.joensuu.fi/pub/Reports/A-1995-7.ps.gz [1381]
Tele-Education/-Co-Operation Pilot--Pilot Study Plan [1382]
www.cg.its.tudelft.nl/.about.charles/publications/MESH_Report_D213.pdf
[1383] CAVE--Speaker verification in bank and telecom
services--Lindberg, Blomberg, Melin [1384]
ftp.ling.umu.se/pub/phonum/phonum4/65.ps [1385] The Catallaxy as a
new Paradigm for the Design of . . . --Eymann, Padovan, Schoder
(2000) [1386]
www.iig.uni-freiburg.de/telematik/forschung/publikationen/pubfiles/EyPaSc-
2000.pdf [1387] Internet Accounting--Pras, van Beijnum, Sprenkels .
. . (2001) [1388]
www.simpleweb.org/nm/research/results/publications/pras/internet-accounti-
ng.pdf [1389] EWI Search and User Interface Functions--Ardo, Cao,
Lundberg, Roslund . . . [1390]
www.lub.lu.se/combine/docs/D34_search_ui.ps [1391] Algebras and
Automata for Timed and Stochastic Systems--D'Argenio [1392]
wwwhome.cs.utwente.nl/.about.dargenio/dissertation/dissertation.ps.gz
[1393] Characterizing Video Coding Computing in Conference
Systems--By Tuquerres Tuquerre
www.ub.utwente.nl/webdocs/ctit/1/0000004d.pdf [1394] A Model to
Evaluate Certificate Revocation--Form Castro Department (2000)
[1395] www-mat.upc.es/.about.jforne/jf_SCI2000.sub.--1.pdf [1396]
Dublin Bus Tracking Service--Design and implementation of a . . .
--Fallon (2000) [1397]
ftp.cs.tcd.ie/pub/tech-reports/reports.00/TCD-CS-2000-47.pdf [1398]
Integrating Different Strategies for Cross-Language . . .
--Buitelaar, Netter, Xu [1399] www.dfki.de/lt/mietta/mietta-twlt.ps
[1400] Integrating Trading and Load Balancing for Efficient . . .
--Thi.beta.en, Neukirchen (2000) [1401]
www.itm.mu-luebeck.de/publications/DT_HN.sub.--2000_ITaLBfEMoSiDS/USM2000-
.pdf [1402] Junction Point Aspect: A Solution to Simplify
Implementation of . . . --Berger (2000) [1403]
micado.project.free.fr/Publi/ecoop2000.ps.gz. [1404] Csaba
Antal--Jzsef Molnr Sndor [1405]
www.cs.kau.se/.about.soren/dkdoc/documentstore/cc_fp.ps [1406]
GRAVE Cave General Video Client--Wasskog (1995) [1407]
www.idi.ntnu.no/grupper/db/report_diplomas/il_myggo/diplom.ps.Z
[1408] Z39.50 Application programmer's Interface SYSTEM . . .
--Document No Document [1409] ftp.ddb.de/pub/dbvosi/ses_v3.ps.gz
[1410] Hardware Implementation of a Secure Bridge in Ethernet . . .
--Form Soriano Mels [1411]
www-mat.upc.es/.about.jforne/jf_GLOBECOM93.pdf [1412] Performance
Evaluation of Strategies for Integration . . . --Queija, van den
Berg, . . . (1999) [1413]
www.cwi.nl/ftp/CWIreports/PNA/PNA-R9903.ps.Z [1414] Inverse
Multiplexing for ATM. Operation . . . --Aguilar-Igartua . . .
(1999) [1415] marley.upc.es/pub/articles/icatm99.pdf [1416] An
integrated solution for secure communications over B-ISDN--Forn
Mels Department [1417] www-mat.upc.es/.about.jforne/jf_CMS96.pdf
[1418] Web Representation with Dynamic Thumbnails--Schmid [1419]
www.compiancs.ac.uk/computing/users/sschmid/Yuforic/YuforicExtAbstr.ps
[1420] Distributed educational multimedia databases: design,
production . . . --Hiddink (1998) [1421]
wwwhome.ctit.utwente.nl/.about.hiddinkg/professional/papers/romy/romy.ps
[1422] Sojourn Times in Non-Homogeneous QBD Processes with
Processor . . . --Queija (1999) [1423]
www.cwi.nl/ftp/CWIreports/PNA/PNA-R9901.ps.Z [1424] A guided tour
through LGM--How to generate spoken . . . --Krahmer, Landsbergen .
. . [1425] www.ipo.tue.nl/homepages/ekrahmer/Pubs/lgm.ps [1426]
Verifying a Smart Design of TCAP--Arts, van Langevelde (1999)
[1427] www.cwi.nl/ftp/CWIreports/SEN/SEN-R9910.ps.Z [1428] Securing
Multimedia Applications over B-ISDN--Jordi Forn Mels [1429]
www-mat.upc.es/.about.jforne/jf_PROMS96.pdf [1430] Teaching and
learning with the WWW in the undergraduate . . . --Oliver, Omari,
Cowan [1431] elrond.scam.ecu.edu.au/oliver/docs/96/AUSWEB2d.pdf
[1432] Toward a Standard for Guideline Representation: an . . .
--Domenico Pisanelli Aldo [1433]
saussure.irmkant.rm.cnr.it/onto/publ/amia99/amia99.pdf [1434] Time
Domain MLE of the Parameters of FBM Traffic--Vidacs, Virtamo (1999)
[1435] keskus.tct.hut.fi/tutkimus/com2/publ/fbm2.pdf [1436]
Artificial Coordination--Simulating Organizational . . . --Eymann,
Padovan, Schoder (1998) [1437]
www.iig.uni-freiburg.de/.about.padovan/publications/cefes98.pdf
[1438] REMOT-A Project to Remotely Monitor and Control
Scientific--Experiments Pucillo Oat
www.aps.anl.gov/icalepcs97/paper97/p235.pdf [1439] Performability
Analysis of Markov Reward Models with Rate and . . . --Andor Acz
And (1999) webspn.hit.bme.hu/.about.telek/cikkek/racz99a.ps.gz
[1440] Analysis of the Completion Time of Markov Reward Models . .
. --Mikl'os Telek Andri'as [1441]
webspn.hit.bme.hu/.about.telek/cikkek/tele98b.ps.gz [1442] A New
Method for Spectral Shaping Coding--Peter Amos Aszl'o [1443]
webspn.hit.bme.hu/.about.telek/cikkek/vamo98a.ps.gz [1444]
MRMSoIve: A Tool for Transient Analysis of Large Markov . . .
--Racz, Toth, Telek [1445]
webspn.hit.bme.hu/.about.telek/cikkek/racz00f.ps.gz [1446] Managing
Services in Distributed Systems by Integrating . . . --Thi.beta.en,
Neukirchen (2000) [1447]
www.itm.mu-luebeck.de/publications/ISCC2000/ISCC2000.pdf.gz [1448]
Conformance Testing with TTCN--Schieferdecker, Grabowski (2000)
[1449]
www.itm.mu-luebeck.de/publications/I_J.sub.--2000_CTwT/Telektronnikk4.sub-
.--2000_CTandTTCN.pdf [1450] Analysis and Modelling of
Collaborative Learning Interactions--Workshop Notes (2000)
collide.informatik.uni-duisburg.de/.about.martin/publication/Muehlenbrock-
-ECAI-2000.pdf [1451] Aligning IT and Organization in the MediaSite
project--Iacucci, Axelsson (2000) [1452]
iris23.htu.se/proceedings/PDF/20final.PDF [1453] Enriching Textual
Documents with Time-codes from Video . . . --van der Sluis, de Jong
(2000)
133.23.229.11/.about.ysuzuki/Proceedingsall/RIAO2000/Wednesday/37C-
P1.ps [1454] Modular Automated Transport--Frequently Asked
Questions (FAQ)--Schweizer (2000) [1455]
circwww.epfl.ch/staff/joerg/mat/doc/faq/faq.ps [1456] The CIMI
Profile Release 1.0H--Profile For Cultural [1457]
www.cimi.org/public_docs/HarmonizedProfile/CIMIProfile10H.pdf
[1458] Real-Time Traffic Simulation of the German Autobahn
Network--Rickert, Wagner, Gawron (1996)
www.zpr.uni-koeln.de/.about.mr/documents/PASA.sub.--96.ps.gz [1459]
Analysis of a Distributed Wireless Fair Scheduling Scheme--Miklos
[1460] hsnlab.ttt.bme.hu/.about.molnar/files/itcssmob00.ps.gz
[1461] CAC Algorithm Based on Advanced Round Robin Method for QoS .
. . --Marosits, Molnar [1462]
hsnlab.ttt.bme.hu/.about.molnar/files/iscc01.pdf.gz [1463] Link
Capacity Sharing Between Guaranteed- and Best Effort . . . --Racz,
Telek [1464] webspn.hit.bme.hu/.about.telek/cikkek/racz01a.ps.gz
[1465] Quality of Service on the Internet: Evaluation of the . . .
--Elisabete Reis Elreis (2001) [1466]
dragao.co.it.pt/conftele2001/proc/pap101.pdf [1467] A
MixDemonstrator for teaching Security in the Virtual . . .
--Jendricke, Rannenberg [1468]
www.scis.cowan.edu.au/research/wise/WISE1Proceedings/pdf/jendricke.pdf
[1469] Fair Allocation Of Elastic Traffic For A Wireless Base
Station--Gyorgy Miklos Traffic (1999)
hsnlab.ttt.bme.hu/.about.molnar/files/globe99.ps.gz [1470] Cell
Delay Variation in an ATM Multiplexer--Molnar, Blaabjerg [1471]
hsnlab.ttt.bme.hu/.about.molnar/files/cdvsnew.ps.gz [1472]
Supporting All Service Classes in ATM: A Novel . . . --Marosits . .
. (1999) [1473] hsnlab.ttt.bme.hu/.about.molnar/files/info99.ps.gz
[1474] The Impact Of Long Range Dependence On Cell Loss In An . . .
--Vidacs, Molnar, Gordos (1998)
hsnlab.ttt.bme.hu/.about.molnar/files/globe98.ps.gz [1475]
Investigation of Fractal Properties in Data Traffic--Dinh, Molnar .
. . [1476] hsnlab.ttt.bme.hu/.about.molnar/files/jc98.ps.gz [1477]
Performance Evaluation of a General Traffic Control . . .
--Marosits . . . [1478]
hsnlab.ttt.bme.hu/.about.molnar/files/ipccc99.ps.gz [1479] The
Demand for Stored Value Payment Instruments--Ingo Pippow Detlef
(2001) [1480]
www.iig.uni-freiburg.de/telematik/forschung/projekte/e_sicherheit/-
comet/publikationen/PiScho2001.pdf [1481] On The Effects Of
Non-Stationarity In Long-Range Dependence Tests--Trang Dinh And
[1482] hsnlab.ttt.bme.hu/.about.molnar/files/trendeff.ps.gz [1483]
Bottlenecks on the Way Towards Fractal Characterization of . . .
--Andor Moln'ar Attila [1484]
hsnlab.ttt.bme.hu/.about.molnar/files/prnnccn97.ps.gz [1485]
Multimedia Databases in Education--Gerrit Hiddink Centre [1486]
wwwhome.ctit.utwente.nl/.about.hiddinkg/professional/papers/dolls97.ps
[1487] Content-based video retrieval--Petkovic (2000) [1488]
www.edbt2000.uni-konstanz.de/phd-workshop/papers/Petkovic.pdf
[1489] Adaptive Optimisation of Importance Sampling for . . .
--Heegaard (1996) [1490]
www.idi.ntnu.no/.about.poulh/publications/nts13a.ps [1491] Factors
of reuse of Units of Learning Material--Gerrit Hiddink Centre
[1492]
wwwhome.ctit.utwente.nl/.about.hiddinkg/professional/papers/reuse.ps
[1493] Multilateral Security A concept and examples for balanced
security--Rannenberg (2000) [1494]
csrc.nist.gov/nissc/2000/proceedings/papers/202ra.pdf [1495]
Educational Multimedia Databases: Past and Present--Gerrit Hiddink
Centre [1496]
wwwhome.ctit.utwente.nl/.about.hiddirikg/professional/papers/systems.ps
[1497] Resource-limited information retrieval in Web-based . . .
--Daan Velthausz And (1997) [1498]
www.trc.nl/publicaties/1997/reslim/resource-limited.pdf [1499] CRL
supported a smart redesign of a real-life protocol--Thomas Arts
Email [1500]
extranet.telin.nl/dscgi/ds.py/Get/File-8309/fmics99.ps.Z [1501]
Convergence In The Digital Age--Table Of Content [1502]
ftp.cordis.lu/pub/libraries/docs/proceedings.pdf [1503] Using
Automated Assistance Systems--Putting The Driver Into
Focus--Reichardt (1998) [1504]
www.daimler-benz.com/research/events/pdf/IV980240.PDF [1505] The
Cave-Wp4 Generic Speaker Verification System--Jaboulet, KOOLWAAIJ .
. . (1998) [1506]
www.ubilab.org/publications/print_versions/pdf/jab98.pdf [1507]
Field Test Of A Calling Card Service Based On . . . --den Os, Boves
. . . [1508]
www.ubilab.org/publications/print_versions/pdf/den97.pdf [1509]
Distributed Electronic Commerce Systems--Sonja Zwil Er [1510]
ftp.cs.umass.edu/pub/net/pub/hgschulz/i96/zwissler.ps.gz [1511]
Needed Services For Network Performance Evaluation--Dung Dinh Luong
[1512] gollum.ttt.bme.hu/.about.luong/tools/atmip.ps [1513] Link
Proposals with Case-Based Reasoning Techniques--Haffner, Roth,
Heuer . . . [1514] www.ti.fhg.de/conferences/200011171414080.ps
[1515] Remote Access to Medical Records via the Internet:
Feasibility, . . . --Pj Lees Ce (1999) [1516]
www.ics.forth.gr/ICS/acti/cmi_hta/publications/papers/1999/cic99/l-
ees_cic99.pdf [1517] Partial Methods Versus End-to-End
Measurements--Dung Dinh Luong [1518]
gollum.ttt.bme.hu/.about.luong/tools/ifip.ps [1519] The Role of
Packet-dropping Mechanisms in QoS Differentiation--Goncalo Quadros
Antonio (2000) www.dei.uc.pt/.about.boavida/papers/2000icon.pdf
[1520] Component-Based Groupware Tailorability using Monitoring . .
. --de Farias, Diakov (2000) [1521]
amidst.ctit.utwente.nl/publications/cscw_cbg2000.pdf [1522]
Modeling of Time and Document Aging for Request . . . --Haffner,
Roth, Engel, . . . (2000) [1523]
www.ti.fhg.de/conferences/200009211730520.ps [1524] Mpeg-4
Authoring Tool For The Composition Of 3D . . . --Daras . . . (2001)
[1525] egnatia.ee.auth.gr/.about.ikom/ISCAS2001.pdf [1526]
Disambiguation Strategies for Cross-language Information . . .
--Djoerd Hiemstra And (1999)
www.cs.utwente.nl/.about.hiemstra/papers/ecd199.ps [1527] the IFLA
Council and General Conference Aug. 16-25, 2001--Code Number
Division [1528] www.ifla.org/IV/ifla67/papers/161-165e.pdf [1529]
CANDLE: an European E-Education project to . . . --Batlogg, al.
(2000) [1530] www.ssgrr.it/en/ssgrr2000/papers/164.pdf [1531]
State-dependent M/G/1 Type Queueing Analysis for . . . --Altman . .
. (2000) [1532] www.cwi.nl/ftp/CWIreports/PNA/PNA-R0005.ps.Z [1533]
Continuous Queries within an Architecture for Querying . . .
--Brinkhoff, Weitkamper (2001)
www.fh-wilhelmshaven.de/oow/institute/iapg/personen/brinkhoff/paper/SSTD2-
001.pdf [1534] The Distribution And Partitioning Scheme Of The . .
. --Jimenez. [1535]
ches.ing.ula.ve/INVESTIGACION/ARTICULOS/TANIA/SIM-71.ps.gz [1536]
An Architecture For Video On Demand Agent-Mediated . . . --Almeida,
Guizzardi . . . [1537]
wwwhome.cs.utwente.nl/.about.guizzard/vod-amec-workcomp99.pdf
[1538] Reusing Multi-Media Components: A Catalogue
Implementation--Steinmann, Shearer [1539]
www.fernuni-hagen.de/DVT/Publikationen/Papers/emmsec.pdf [1540]
Multiagent Systems--Instructor Prof Dh [1541]
136.159.122.221/seminar/enmf619.sub.--02/enmf02.pdf [1542]
Twenty-One at CLEF-2000: Translation resources, merging . . .
--Djoerd Hiemstra Wessel [1543]
www.iei.pi.cnr.it/DELOS/CLEF/twentyon.pdf [1544] Papabiles--Torday,
Bierlaire (2001) [1545] rosowww.epfl.ch/mbi/strc-papabiles.pdf
[1546] Using Objects and Patterns to Implement Domain
Ontologies--Guizzardi, Filho (2001) [1547]
wwwhome.cs.utwente.nl/.about.guizzard/SBES2001vf.pdf [1548]
Decision Support Systems from a Health Informatics
Perspective--Nykanen (2000) [1549]
acta.uta.fi/pdf/951-44-4897-9.pdf [1550] NetTrouble: A TTS for
Network Management--Lus Santos Pedro [1551]
www.dei.uc.pt/.about.psimoes/papers/its98.pdf [1552] Results and
experience from the application of a common . . . --Antonis Bouras
. . . (1998) [1553] ru6.cti.gr/Publications/318.pdf [1554] The
Information and Communication Technologies In Education--Christos
Bouras Computer ru6.cti.gr/Publications/289.pdf [1555] Internet
Protocols for Synchronous Distance Learning--Ch Bouras Computer
(2000) [1556] ru6.cti.gr/Publications/431.pdf [1557] The Euro in
the Electronic Purse--Allard, Alyankian, Ankri, Collin . . . (2000)
[1558] www.eurosmart.com/download/WhitePaper.pdf [1559] Monitoring
Extensions for Component-Based Distributed . . . --Diakov, van
Sinderen . . . (2000)
amidst.ctit.utwente.nl/publications/proms2000.pdf [1560] The Q-bit
Scheme--Congestion Avoidance Using (1992) [1561]
gatekeeper.dec.com/pub/doc/sigcomm/ccr/archive/1992/apr92/qbit.ps.Z
[1562] Performance of a Parallel Transport Subsystem
Implementation--Torsten Braun Institute [1563]
www.iam.unibe.ch/.about.braun/lit/hpcs93.ps.gz [1564] Towards
Dynamic Composition of Hybrid Communication Services--Floch, Br.ae
butted.k (2000) www.item.ntnu.no/.about.jacf/paper/smarnett2000.pdf
[1565] Optimising the Operation of the World Wide Web in . . .
--Hadjiefthymiades . . . [1566]
www.cs.auc.dk/.about.tryfona/papers/cacherel.ps [1567] Generating
Test Cases for Infinite System Specifications--Stefan Heymer And
[1568]
www.itm.mu-luebeck.de/publications/GTCflSS/HeymerGrabowski.ps.gz
[1569] Computational Perspectives on Discourse and Dialogue--Bonnie
Lynn Webber [1570]
www.dai.ed.ac.uk/daidb/people/homes/bonnie/handbook.ps.gz [1571]
Virtual Universities--Ebner, Hogrefe (1999) [1572]
www.itm.mu-luebeck.de/publications/VFH/ebner_hogrefe_waki99.ps.gz
[1573] Compensation methods to support generic graph editing: A
case . . . --Even, Spelt [1574]
wwwhome.cs.utwente.nl/.about.seven/EC00PWS.pdf [1575] Towards the
Generation of Distributed Test Cases Using Petri . . . --Heymer,
Grabowski [1576]
www.itm.mu-luebeck.de/publications/FBT99/fbt99.ps.gz [1577] Test
Case Specification with Real-Time TTCN--Walter, Grabowski [1578]
www.itm.mu-luebeck.de/publications/TCSwRMCN/WalterGrabowski:ps.gz
[1579] Scientific Approaches and Techniques for Negotiation . . .
--Gerding, van Bragt, . . . [1580]
www.cwi.nl/projects/TA/reports/negotiation.ps [1581] Towards an
Integrated Test Methodology for Advanced . . . --Grabowski, Walter
[1582] www.itm.mu-luebeck.de/publications/tcs99.ps.gz [1583]
TTCN-3--A new Test Specification Language for Black-Box Testing . .
. --Grabowski (2000)
www.itm.mu-luebeck.de/publications/ttcn3/Grabowski.pdf.gz [1584]
Test Architectures for Distributed Systems--State of the Art and .
. . --Walter (1998) [1585]
www.itm.mu-luebeck.de/publications/IWTCS98TA/IWTCS98Testarchitectures.ps.-
gz [1586] Asbru: A Task-Specific, Intention-Based, and . . .
--Miksch, Shahar, Johnson [1587]
ftp.ifs.tuwien.ac.at/pub/publications/mik_keml97.pdf [1588]
Protocol Specifications--Written By Jacob [1589]
cmc.dsv.su.se/select/SEL-prot-spec-v11-jp-991009.pdf [1590] Towards
The Third Edition Of TTCN--Grabowski, Hogrefe (1999) [1591]
www.itm.mu-luebeck.de/publications/iwtcs99.ps.gz [1592] A Framework
for the Specification of Test Cases for . . . --Walter, Grabowski
(1999) [1593]
www.itm.mu-luebeck.de/publications/Walter-Grabowski-JIST99/jist.ps-
.gz [1594] Verification of Compensation Requirements for the SEPIA
. . . --Even, Spelt (1998) [1595]
wwwhome.cs.utwente.nl/.about.seven/CTIT-TR-98-25.pdf [1596] Cote de
Resyste--Conformance Testing Reactive [1597]
wwwtios.cs.utwente.nl/Docs/projects/cote-de-resyste/stw.ps [1598]
Long Cycles and Long Paths in the Kronecker Product of a . . .
--Jha, Agnihotri, al. (1995) [1599]
www.cs.jhu.edu/.about.rajesh/ps/cta.ps [1600] Tutorial on Message
Sequence Charts (MSC'96)--Rudolph, Grabowski, Graubmann (1996)
www.itm.mu-luebeck.de/publications/MSC96/dis-tutorial.ps.gz [1601]
The Standardization of Core INAP CS-2 by ETSI--Grabowski, Hogrefe
(1999) [1602]
www.itm.mu-luebeck.de/publications/CS2-Standardization.ps.gz [1603]
On The Design Of The New Testing Language TTCN-3--Grabowski, Wiles,
Willcock . . . (2000)
www.itm.mu-luebeck.de/publications/New_TTCN3/GrabowskiEtAll.pdf.gz
[1604] omVR--A Safety Training System for a Virtual
Refinery--Haller, Kurka, Volkert . . . [1605]
www.gup.uni-linz.ac.at:8001/staff/kurka/docs/ismcr99.pdf [1606]
Senior Online--Telematics De Report [1607]
cmc.dsv.su.se/sol/sol-transfer-spec.pdf [1608] Formal Methods and
Conformance Testing--or--What are we . . . --Heymer, Grabowski
[1609] www.itm.mu-luebeck.de/publications/FBT98/FBT98.ps.gz [1610]
A Theorem Prover-Based Analysis Tool for Object-Oriented
Databases--Spelt, Even (1999)
wwwhome.cs.utwente.nl/.about.seven/CTIT-TR-98-22.pdf [1611]
Chemistry in Action: Discovering the Behaviour of a Network . . .
--Heymer, Grabowski (1998)
www.itm.mu-luebeck.de/publications/A-98-18/Report-A-98-18.ps.gz
[1612] ERP in the e-commerce era--Luttighuis, Biemans [1613]
extranet.telin.nl/dscgi/ds.py/Get/File-2092/baanUSP.pdf [1614]
Business-Driven Design of Transaction Services--Biemans, Janssen,
Luttighuis, . . . (1999) [1615]
extranet.telin.nl/dscgi/ds.py/Get/File-664/ICE.pdf [1616] Modelling
organisations--Wetering (1999) [1617]
extranet.telin.nl/dscgi/ds.py/Get/File-2902/modellingV2.pdf [1618]
On Wrapping Query Languages and Ecient XML Integration--Vassilis
Christophides Sophie (2000)
www.oasis-open.org/cover/vassilisQueryWrap.pdf [1619] MESH Release
2 implementation at CTIT--Diakov, van Sinderen, Koprinkov [1620]
amidst.ctit.utwente.nl/publications/ctit_tr99-08.pdf [1621]
EUROgatherer: a Personalised Gathering and Delivery . . . --Amato,
Straccia, Thanos (2000)
faure.iei.pi.cnr.it/%7Estraccia/download/papers/SCI2000/SCI2000.pd-
f [1622] Frameworks for protocol implementation--Barbosa, Pires,
van Sinderen (1998) [1623]
wwwhome.cs.utwente.nl/.about.sinderen/publications/sbrc98.pdf
NEURAL NETWORKS REFERENES APPENDIX
[1623] [1624] www.inference.phy.cam.ac.uk/mackay/Bayes_FAQ.html
[1625] www-2.cs.cmu.edu/Groups/Al/html/faqs/ai/neural/faq.html
[1626] www.cs.stir.ac.uk/.about.Iss/NNIntro/InvSlides.html [1627]
dir.yahoo.com/Science/Engineering/Electrical_Engineering/Neural_Networks/
[1628] www.aist.go.jp/NIBH/.about.b0616/Links.html [1629]
www.creative.net.au/.about.adrian/mirrors/neural/www.fi.uib.no/Fysisk/Teo-
ri/NEURO/neurons.html [1630]
aass.oru.se/.about.tdt/ann/faq/FAQ.html [1631]
www.cis.hut.fi/.about.jari/research.html [1632]
www.eg3.com/WebID/elect/neur-net/blank/overview/a-z.htm [1633]
directory.google.com/Top/Computers/Artificial_Intelligence/Neural_Network-
s/ [1634]
directory.google.com/Top/Computers/Artificial_Intelligence/Neura-
l_Networks/FAQs,_Help,_and_Tutorials/ [1635]
dmoz.org/Computers/Artificial_Intelligence/Neural_Networks/ [1636]
dmoz.org/Computers/Artificial_Intelligence/Neural_Networks/FAQs,_Help,_an-
d_Tutorials/ [1637]
www.cs.qub.ac.uk/.about.J.Campbell/myweb/book/nn.html [1638]
www.cere.pa.cnr.it/IDAschool/lectures/neural.html [1639]
cognet.mit.edu/MITECS/Entry/jordan2 [1640]
www.faqs.org/faqs/ai-faq/neural-nets/part1/preamble.html [1641]
zhanshou.hypermart.net/thesis.htm [1642]
www.links999.net/hardware/neural.html [1643]
www-ra.informatik.uni-tuebingen.de/links/neuronal/welcome_e.html
[1644] www.cogneuro.ox.ac.uk/links/ann.html [1645]
faculty.cs.tamu.edu/choe/resources/www.galm.com/galaxy/Engineering-and-Te-
chnology/Electrical-Engineering/Neural-Networks/ [1646]
mu.dmt.ibaraki.ac.jp/yanai/neu/faq/ [1647]
bubl.ac.uk/link/n/neuralnetworks.htm [1648]
www.webopedia.com/TERM/n/neural_network.html [1649]
www.ie.ncsu.edu/fangroup/neural.dir/indexneural.html [1650]
www.geneticprogramming.com/AI/nn.html [1651]
www.cs.utk.edu/.about.yarkhan/neural_networks.html [1652]
www.physiol.ox.acuk/.about.ket/nn.html [1653]
www.aaai.org/AITopics/html/neural.html [1654]
www.inference.phy.cam.ac.uk/mackay/itprnn/book.html [1655]
www.hh.se/staff/nicholas/NN_Links.html [1656]
xpidea.com/products/neurovcl/neuroabout.htm [1657]
www.msm.ele.tue.nl/research/neural/homepages.goldsmiths.ac.uk/nikolaev/Nn-
ets.htm [1658] www.triumf.ca/project_ETA/neural_network.html [1659]
personal.bgsu.edu/.about.suny/nn.html [1660]
www.icmc.sc.usp.br/.about.andre/ann_links.html [1661]
www.stud.ntnu.no/.about.hirpa/links/AI_links.htm [1662]
it.umary.edu/Library/research/www_subjects/neural_networks.html
[1663] cindy.cis.nctu.edu.tw/NN/NN5/www.html [1664]
www.public.iastate.edu/.about.acl/links/links.html [1665]
www.cs.cf.ac.uk/User/O.F.Rana/neural.html [1666]
www.cs.unr.edu/.about.bebis/CS791S/ [1667]
www.geocities.com/fastiland/NNwww.html [1668]
cns-web.bu.edu/pub/snorrason/bookmarks/neural.html [1669]
www.open.brain.riken.go.jp/.about.cao/index_work.html [1670]
svr-www.eng.cam.ac.uk/research/neural/other_neural_net_sites.html
[1671] R. O. Duda and P. E. Hart. Pattern Classication and Scene
Analysis. Wiley, New York, 1973. [1672] S. Ripley, "Pattern
Recognition and Neural Networks", Statistics, 33, 1065-1076.
Ripley, B. D., 1996: Pattern Recognition and Neural Networks.
Cambridge: University Press, 1996,
citeseer.ist.psu.edu/ripley96complements.html, and cited
references: [1673] Aha, D. W., Kibler, D. & Albert, M. K.
(1991) Instance-based learning algorithms. Machine Learning 6(1),
37-66. [1674] Ali, K. M. & Pazzani, M. J. (1995) On the link
between error correlation and error reduction in decision tree
ensembles. Technical Report 95-38, Department of Information and
Computer Science, University of California at Irvine. [1675]
Almond, R. G. (1995) Graphical Belief Modeling. London: Chapman
& Hall. ISBN 0-412-06661-0. [Despite the date, this book was
actually published in May 1996]. [1676] Angluin, D. & Valiant,
L. G. (1979) Fast probabilistic algorithms for Hamiltonian circuits
and matchings. Journal of Computer and System Sciences 18, 155-193.
[1677] Anthony, M. & Shawe-Taylor, J. (1993) A result of Vapnik
with applications. Discrete Applied Mathematics 47, 207-217.
[Erratum (1994) 52, 211 (the proof of theorem 2.1 is corrected)].
[1678] Arbib, M. A. (ed.) (1995) The Handbook of Brain Theory and
Neural Networks. Cambridge, Mass.: MIT Press. ISBN 0-262-01148-4.
[1679] Atkeson, C. G. (1991) Using locally weighted regression for
robot learning. In Proceedings of the IEEE Conference on Robotics
and Automation (Sacremento, Calif., 1991), pp. 958-963. IEEE Press.
[1680] Auer, P., Nolte, R. C. & Maass, W. (1995) Theory and
application of agnostic PAC-learning with small decision trees. In
Proceedings of the Twelfth International Conference on Machine
Learning, pp. 21-29. San Francisco: Morgan Kaufmann. Also NeuroCOLT
Technical Report NC-TR-96-034 (February 1996). [1681] Bartlett, P.
L & Williamson, R. C. (1996) The VC dimension and
pseudodimension of two-layer neural networks with discrete inputs.
Neural Computation 8(3), 625-628. [1682] Benveniste, A., M'etivier,
M. & Priouret, P. (1990) Adaptive Algorithms and Stochastic
Approximations. Berlin: Springer. [1683] Bratko, I. &
Muggleton, S. (1995) Applications of inductive logic programming.
Communications of the Association for Computing Machinery 38(11),
65-70. [1684] Breiman, L. (1994) Bagging predictors. Technical
Report 421, Department of Statistics, University of California at
Berkeley. [1685] Breiman, L (1996a) Bagging predictors. Machine
Learning. [1686] Breiman, L. (1996b) The heuristics of instability
in model selection. Annals of Statistics. [1687] Breiman, L.
(1996c) Bias, variance and arcing classifiers. Technical report,
Department of Statistics, UC Berkeley. [1688] Brodley, C. E. &
Utgoff, P. E. (1995) Multivariate decision trees. Machine Learning
19, 45-77. [1689] Buntine, W. & Niblett, T. (1992) A further
comparison of splitting rules for decision-tree induction. Machine
Learning 8, 75-86. [1690] Burnell, L. & Horvitz, E. (1995)
Structure and chance: Melding logic and probability for software
debugging. Comm. ACM 38(3), 31-41, 57. [1691] Catlett, J. (1991) On
changing continuous attributes into ordered discrete attributes. In
Proceedings of the EuropeanWorking Session on Learning--EWSL-91,
ed. Y. Kodratoff, pp. 164-178. Berlin: Springer. [1692]
Cesa-Bianchi, M., Freund, Y., Helmbold, D. P., Haussler, D.,
Schapire, R. E. & Warmuth, M. K. (1993) How to use expert
advice. In Proceedings of the Twenth-Fifth ACM Symposium on the
Theory of Computing (San Diego, Calif., 1993), pp. 382-391. NY: ACM
Press. [1693] Cesa-Bianchi, M., Freund, Y., Helmbold, D. P.,
Haussler, D., Schapire, R. E. & Warmuth, M. K. (1996) How to
use expert advice. Journal of the ACM. [1694] Cortes, C. &
Vapnik, V. (1995) Support-vector networks. Machine Learning 20,
273-297. [1695] Cost, S. & Salzberg, S. (1993) A weighted
nearest neighbor algorithm for learning with symbolic features.
Machine Learning 10, 57-78. [1696] Cover, T. M. (1968) Capacity
problems for linear machines. In Pattern Recognition, ed. L. Kanal,
pp. 283-289. Thompson. [1697] Craven, M. W. & Shavlik, J. W.
(1996) Extracting tree-structured representations of trained
networks. In Touretzky et al. (1996), pp. 24-30. ISBN
0-262-20107-0. [1698] Dasarathy, B. V. (ed.) (1991) Nearest
Neighbor (NN) Norms: NN Pattern Classification Techniques. Los
Alamitos, Calif.: IEEE Computer Society Press. [1699] Dougherty,
J., Kohavi, R. & Sahami, M. (1995) Supervised and unsupervised
discretization of continuous features. In Proceedings of the
Twelfth International Conference on [1700] Machine Learning, eds A.
Prieditis & S. Russell, pp. 194-202. San Francisco: Morgan
Kaufmann. [1701] Drucker, H. (1996) Fast decision tree ensembles
for optical character recognition. In Proceedings of the Fifth
Annual Symposium on Document Analysis and Information Retrival.
[1702] Drucker, H. & Cortes, C. (1996) Boosting decision trees.
In Touretzky et al. (1996), pp. 479-485. ISBN 0-262-20107-0. [1703]
Drucker, H., Schapire, R. & Simard, P. (1993) Boosting
performance in neural networks. International Journal of Pattern
Recognition and Artificial Intelligence 7(4), 705-719. [1704]
Drucker, H., Cortes, C., Jaeckel, L. D., LeCun, Y. & Vapnik, V.
(1994) Boosting and other ensemble methods. Neural Computation
6(6), 1289-1301. [1705] Edwards, D. (1995) Introduction to
Graphical Modelling. Springer. [1706] Elomaa, T. & Rousu, J.
(1996) Finding optimal multi-splits for numerical attributes in
decision tree learning. NeuroCOLT Technical Report Series
NC-TR-96-041, Department of Computer Science, University of
Helsinki. [1707] Fayyad, U. M. & Irani, K. B. (1993)
Multi-interval discretization of continuous-valued attributes in
decision tree generation. In Proceedings of the Thirteenth
International Joint Conference on Artificial Intelligence
(Chambery, France, 1993), pp. 1022-1027. San Francisco Morgan
Kaufmann. [1708] Freund, Y. (1990) Boosting a weak learning
algorithm by majority. In Proceedings of the Third Workshop on
Computational Learning Theory, pp. 202-216. Morgan Kaufmann. [1709]
Freund, Y. (1995) Boosting a weak learning algorithm by majority.
Information and Computation 121(2), 256-285. [1710] Freund, Y.
& Schapire, R. E. (1995) A decision-theoretic generalization of
on-line learning and an application to boosting. In Proceedings of
the Second European Conference on Computational Learning Theory,
pp. 23-37. Springer. [1711] Freund, Y. & Schapire, R. E.
(1996a) Game theory, on-line prediction and boosting. In
Proceedings of the Ninth Annual Conference on Computational
Learning Theory. [1712] Freund, Y. & Schapire, R. E. (1996b)
Experiments with a new boosting algorithm. In Proceedings of the
Thirteenth International Conference on Machine Learning. [1713]
Friedman, J. H. (1994) Flexible metric nearest neighbor
classification. Technical report, Department of Statistics,
Stanford U. [1714] Fukunaga, K. & Flick, T. E. (1984) An
optimal global nearest neighbor metric. IEEE Transactions on
Pattern Analysis and Machine Intelligence 6, 314-318. [Reprinted in
Dasarathy (1991)]. [1715] Fulton, T., Kasif, S. & Salzberg, S.
(1995) Efficient algorithms for finding multi-way splits for
decision trees. In Proceedings of the Twelfth International
Conference on Machine Learning, eds A. Prieditis & S. Russell,
pp. 244-251. San Francisco: Morgan Kaufmann. [1716] Fung, R. &
Del Favarro, B. (1995) Applying Bayesian networks to information
retrival. Comm. ACM 38(3), 42-48, 57. [1717] Hampson, S. E. &
Volper, D. J. (1986) Linear function neurons: structure and
training. Biological Cybernetics. [1718] Hastie, T. &
Tibshirani, R. (1996a) Discriminant adaptive nearest neighbor
classification and regression. In Touretzky et al. (1996), pp.
409-415. ISBN 0-262-20107-0. [1719] Hastie, T. & Tibshirani, R.
(1996b) Discriminant adaptive nearest neighbor classification. IEEE
Transactions on Pattern Analysis and Machine Intelligence 18,
607-618. [1720] Heath, D., Kasif, S. & Salzberg, S. (1993)
Learning oblique decision trees. In Proceedings of the Thirteenth
International Joint Conference on Artificial Intelligence
(Chambery, France, 1993), pp. 1002-1007. San Francisco: Morgan
Kaufmann. [1721] Heckerman, D. & Wellman, M. P. (1995) Bayesian
networks. Communications of the ACM 38(3), 26-30. [1722] Heckerman,
D., Breese, J. S. & Rommelse, K. (1995) Decision-theoretic
troubleshooting. Comm. ACM 38(3), 49-57. [1723] Helmbold, D. P.
& Schapire, R. E. (1995) Predicting nearly as well as the best
pruning of a decision tree. In Proceedings of the Eight Annual
Conference on Computational Learning Theory, pp. 61-68. New York:
ACM Press. [1724] Helmbold, D. P. & Schapire, R. E. (1996)
Predicting nearly as well as the best pruning of a decision tree.
Machine Learning. [1725] Ho, T. K. (1995) Random decision forests.
In Proceedings of the Third International Conference on Document
Analysis and Recognition, pp. 278-282. IEEE Computer Society Press.
[1726] Hochreiter, S. & Schmidhuber, J. (1995) Simplifying
neural nets by discovering flat minima. In Tesauro et al. (1995),
pp. 529-536. ISBN 0-262-20104-6. [1727] Hochreiter, S. &
Schmidhuber, J. (1996) Flat minima. Neural Computation. [1728]
Holte, R. C. (1993) Very simple classification rules perform well
on most commonly used datasets. Machine Learning 11, 63-91. [1729]
Hoffgen, K.-U., Simon, H.-U. & Van Horn, K. S. (1995) Robust
trainability of single neurons. Journal of Computer and System
Sciences 50(1), 114-125. [1730] Karpinski, M. & Macintyre, A.
(1995a) Bounding VC-dimension of neural networks: Progress and
prospects. In Proceedings of the Second European Conference on
Computational Learning Theory (Barcelona, Spain), ed. P. Vitanyi,
number 904 in Lecture Notes in Artificial Intelligence, pp.
337-341. Berlin: Springer. [1731] Karpinski, M. & Macintyre, A.
(1995b) Polynomial bounds for VC dimension of sigmoidal neural
networks. In Proceedings of the Twenty-Seventh Annual ACM Symposium
on Theory of Computing (Las Vegas), pp. 200-208. ACM Press. [1732]
Koiran, P. & Sontag, E. D. (1996) Neural networks with
quadratic VC dimension. In Touretzky et al. (1996), pp. 197-203.
ISBN 0-262-20107-0. [1733] Kooperberg, C., Bose, S. & Stone, C.
J. (1996) Polychotomous regression. Journal of the American
Statistical Association. [1734] Krogh, A. & Vedelsby, J. (1995)
Neural network ensembles, cross validation, and active learning. In
Tesauro et al. (1995), pp. 231-238. ISBN 0-262-20104-6. [1735]
Langley, P. (1996) Elements of Machine Learning. San Francisco:
Morgan Kaufmann. [1736] Langley, P. & Simon, H. A. (1995)
Applications of machine learning and rule induction. Comm. ACM
38(11), 54-64. [1737] Lauritzen, S. L (1996) Graphical Models.
Oxford: Clarendon Press. ISBN 0-19-852219-3. [1738] Ljung, L.,
Pflug, H. & Walk, H. (1992) Stochastic Approximation and
Optimization of Random Systems. Berlin: Birkhauser. [1739] Lowe, D.
G. (1995) Similarity metric learning for a variable-kernel
classifier. Neural Computation 7(1), 72-85. [1740] Maass, W. &
Turan, G. (1994) How fast can a threshold gate learn? In
Computational Learning Theory and Natural Learning Systems:
Constraints and Prospects, eds S. J. [1741] Hanson, G. A. Drastal
& R. L. Rivest, volume I, pp. 381-414. MIT Press. [1742]
Marchand, M., Golea, M. & Rujan, P. (1990) A convergence theorm
for sequential learning in two-layer perceptrons. Europhysics
Letters 11, 487-492. [1743] Muroga, S. (1965) Lower bounds of the
number of threshold functions and a maximum weight. IEEE
Transactions on Electronic Computers 14, 136-148. [1744] Muroga,
S., Toda, I. & Takasu, S. (1961) Theory of majority decision
elements. Journal of the Franklin Institute 271, 376-418. [1745]
Murthy, S. K., Kasif, S., Salzberg, S. & Beigel, R. (1993) OC1:
randomized induction of oblique decision tress. In Proceedings of
the Eleventh National Conference on Artificial Intelligence
(Washington, D.C., 1993), pp. 322-327. AAAI Press. ISBN
0-262-51071-5. [1746] Murthy, S. K., Kasif, S. & Salzberg, S.
(1994) A system for the induction of oblique decision trees. J.
Art. Intelligence Res. 2, 1-33.
[1747] Oliver, J. J. & Hand, D. J. (1995) On pruning and
averaging decision trees. In Machine Learning: Proceedings of the
Twelfth International Conference, pp. 430-437. Morgan Kaufmann.
[1748] Parberry, I. (1994) Circuit Complexity and Neural Networks.
Cambridge, Mass.: MIT Press. ISBN 0-262-16148-6. [1749] Parrondo,
J. M. R. & Van der Broeck, C. (1993) Vapnik-Chervonenkis bounds
for generalization. J. Phys. A 26, 2211-2223. [1750] Przytula, K.
W. & Prasanna, V. K. (1993) Parallel Digital Implementation of
Neural Networks. Englewood Cliffs, N.J.: Prentice Hall. [1751]
Quinlan, J. R. (1996a) Bagging, boosting, and C4.5. In Proceedings
of the Fourteenth National Conference on Artificial Intelligence.
Menlo Park, Calif.: AAAI Press. [1752] Quinlan, J. R. (1996b)
Improved use of continuous attributes in C4.5. Journal of
Artificial Intelligence Research 4, 77-90. [1753] Rachlin, J.,
Kasif, S., Salzberg, S. & Aha, D. (1994) Towards a better
understanding of memory-based and Bayesian classifiers. In
Proceedings of the Eleventh International Conference on Machine
Learning (New Brunswick, N.J.), pp. 242-250. [1754] Sakurai, A.
(1993) Tighter bounds of the VC-dimension of three-layer networks.
In Proceedings of the 1993World Congress on Neural Networks, volume
3, pp. 540-543. Hillsdale, N.J.: Erlbaum. [1755] Schapire, R. E.
(1990) The strength of weak learnability. Machine Learning 5(2),
197-227. [1756] Shafer, G. (1996) Probabilistic Expert Systems.
Number 67 in CBMS-NSF Regional Conference Series in Applied
Mathematics. Philadelphia, Pa.: SIAM. ISBN 0-89871-373-0. [1757]
Shlien, S. (1990) Multiple binary decision tree classifiers.
Pattern Recognition 23(7), 757-763. [1758] Short, R. D. &
Fukunaga, K. (1980) A new nearest neighbor distance measure. In
Proceedings of the Fifth IEEE International Conference on Pattern
Recognition (Miami Beach, 1980), pp. 81-86. Los Alamitos, Calif.:
IEEE Computer Society Press. [1759] Short, R. D. & Fukunaga, K.
(1981) The optimal distance measure for nearest neighbor
classification. IEEE Transactions on Information Theory 27,
622-627. [Reprinted in Dasarathy (1991)]. [1760] Stone, C. J.,
Hansen, M., Kooperberg, C. & Truong, Y. K. (1997) Polynomial
splines and their tensor products in extended linear modeling.
Annals of Statistics. [1761] Tesauro, G., Touretzky, D. S. &
Leen, T. K. (eds) (1995) Advances in Neural Information Processing
Systems 7. Proceedings of the 1994 Conference. Cambridge, Mass.:
MIT Press. ISBN 0-262-20104-6. [1762] Touretzky, D. S., Moser, M.
C. & Hasselmo, M. E. (eds) (1996) Advances in Neural
Information Processing Systems 8. Proceedings of the 1995
Conference. Cambridge, Mass.: MIT Press. ISBN 0-262-20107-0. [1763]
Utgoff, P. E. (1989) Perceptron trees: a case study in hybrid
concept representations. Connection Science 1(4), 377-391. [1764]
Valentin, D., Abdi, H., O'Toole, A. J. & Cottrell, G. (1994)
Connectionist models of face processing: A survey. Pattern
Recognition 27, 1208-1230. [1765] Vapnik, V. N. (1995) The Nature
of Statistical Learning Theory. New York: Springer. [1766] Vapnik,
V. N. (1996) Statistical Learning Theory. New York: Wiley. [1767]
Wahba, G., Wang, Y., Gu, C., Klein, R. & Klein, B. (1996)
Smoothing spline anova for exponential families, with application
to the wisconsin epidemiological study of diabetic retinopathy.
Annals of Statistics 23(6), 1865-1895. [1768] Waltz, D. (1990)
Memory-based reasoning. In Natural and Artificial Parallel
Computation, eds M. Arbib & J. Robinson, pp. 251-276.
Cambridge, Mass.: MIT Press. [1769] Wang, L. & Oja, E. (1993)
Image compression by MLP and PCA neural networks. In Proceedings of
the Eight Scandinavian Conference on Image Analysis (Tromso,
Norway), pp. 1317-1324. [1770] Werbos, P. (1987) Learning how the
world works. In Proceedings of the IEEE Conference on Systems, Man
and Cybernetics, pp. 320-310. New York: IEEE Press. [1771] Werbos,
P. J. (1995) Backpropagation: Basics and new developments. pp.
134-139 of Arbib (1995). [1772] Willems, F. M. J., Shtarkov, Y. M.
& Tjalkens, T. J. (1993) Context tree weighting: A sequential
universal source coding procedure for FSMX sources. In Proceedings
of the 1993 IEEE International Symposium on Information Theory, p.
59. IEEE Press. [1773] Willems, F. M. J., Shtarkov, Y. M. &
Tjalkens, T. J. (1995) The context-tree weighting method: Basic
properties. IEEE Transactions on Information Theory pp.
653-664.
WAVELETS REFERENCES APPENDIX
Introductions to Wavelets
[1773] [1774] G. Kaiser, "A Friendly Guide to Wavelets" [1775] C.
S. Burrus and R. A. Gopinath, "A Tutorial Overview of Wavelets,
Filter Banks and Interrelationships" [1776] R. A. DeVore and B. J.
Lucier, "Wavelets" [1777] T. Edwards, "Discrete Wavelet Transforms:
Theory and Application." [1778] E. Gootman and M. Wickerhauser,
"Elementary Wavelets." [1779] A. Graps, "An Introduction To
Wavelets." [1780] C. Heil and D. Walnut, "Continuous and Discrete
Wavelet Transforms." [1781] B. Jawerth and W. Sweldens, "An
Overview of Wavelet Based Multiresolution Analysis". An abstract is
also available. [1782] J. Lewalle, "Tutorial on Wavelet Analysis of
Experimental Data" [1783] P. Schroder and W. Sweldens, "Building
Your Own Wavelets at Home." An abstract is also available. [1784]
G. Strang, "Wavelets." [1785] G. Strang "Wavelets and dilation
equations: a brief introduction." [1786] C. Torrence and G. P.
Compo, "A Practical Guide to Wavelet Analysis, with Significance
and Confidence Testing." [1787] B. Vidakovic, "Wavelets for Kids,"
also part 2. [1788] E. Tolkova, "Orthogonal Wavelets Construction."
[1789] Y. Meyer, Wavelets: Algorithms and Applications, Society for
Industrial and Applied Mathematics, 1993, pp. 13-31, 101-105.
[1790] G. Kaiser, A Friendly Guide to Wavelets, Birkhauser, Boston,
1994, pp. 44-45.
[1791] General Theory [1792] L. Andersson, N. Hall, B. Jawerth and
G. Peters, "Wavelets on Closed Subsets of the Real Line" [1793] P.
Auscher, G. Weiss and M. V. Wickerhauser, "Local Sine and Cosine
Bases of Coifman and Meyer and the Construction of Smooth Wavelets"
[1794] C. Basdevant and V. Perrier, "Besov Norms in Terms of
Continuous Wavelet Transforms and Application to Structure
Functions." [1795] B. E. Bassil, G. J. Dickson and D. M. Monro,
"Orthonormal Wavelets With Balanced Uncertainty". [1796] G. Beylkin
and N. Saito, "Multiresolution Representations using the
Autocorrelation Functions of Compactly Supported Wavelets." [1797]
G. Beylkin and N. Saito, "Wavelets, their Autocorrelation Functions
and Multiresolution Analysis of Signals." [1798] G. Beylkin and B.
Torresani, "Implementation of Operators via Filter Banks,
Autocorrelation Shell and Hardy Wavelets." [1799] A. G. Bruce, H.
Gao and D. Ragozin, "Non-smooth Wavelets: Graphing Functions
Unbounded on Every Interval." [1800] C. Cabrelli, C. Heil, and U.
Molter, "Accuracy of Lattice Translates of Several Multidimensional
Refinable Functions." [1801] R. C. Calderbank, I. Daubechies, W.
Sweldens and B. Yeo "Wavelet Transforms that Map Integers to
Integers." There is also an uncompressed version. [1802] D. Chen,
"Extended Families of Cardinal Spline Wavelets." [1803] D. Chen,
"Spline Wavelets of Small Support." [1804] D. Chen,
"Characterization of Biorthogonal Cardinal Spline Wavelet Bases."
[1805] D. Chen, "Cardinal Spline Wavelets", dissertation. Also part
2, part 3, part 4, part 5 and part 6. [1806] S. Chen and D. Donoho,
"Atomic Decomposition by Basis Pursuit." [1807] A. Cohen, W. Dahmen
and R. DeVore, "Multiscale Decompositions on Bounded Domains."
[1808] J. Cohen, "The Foot Problem in Wavelet Packet Splitting." A
Mathematica notebook converted to Postscript. [1809] J. Cohen,
"Schauder Basis for [0,1]." A Mathematica notebook converted to
Postscript. [1810] J. Cohen, "The Littlewood-Paley-Stein Wavelet."
A Mathematica notebook converted to Postscript. [1811] J. Cohen,
"Battle-Lemarie Wavelets." A Mathematica notebook converted to
Postscript. [1812] J. Cohen, "The Daubechies Minimum Phase
Wavelets." A Mathematica notebook converted to Postscript. [1813]
J. Cohen, "Meyer Wavelets." A Mathematica notebook converted to
Postscript. [1814] R. Coifman and M. V. Wickerhauser,
"Entropy-Based Algorithms for Best Basis Selection" [1815] R.
Coifman and M. Wickerhauser, "Best-adapted Wave Packet Bases."
[1816] R. Coifman, "Numerical Harmonic Analysis." [1817] R.
Coifman, Y. Meyer and M. Wickerhauser, "Size Properties of Wavelets
Packets." [1818] R. Coifman and Y. Meyer, "Orthonormal Wave Packet
Bases." [1819] R. Coffman and M. V. Wickerhauser, "Wavelets and
Adapted Waveform Analysis" [1820] R. Coifman, Y. Meyer and M.
Wickerhauser, "Adapted Wave Form Analysis, Wavelet Packets and
Applications." [1821] D. Colella and C. Heil, "Matrix Refinement
Equations: Existence and Accuracy." [1822] S. Dahlke, W. Dahmen, E.
Schmitt and I. Weinreich, "Multiresolution Analysis and Wavelets on
S 2 and S 3." [1823] W. Dahmen, "Stability of Multiscale
Transformations." [1824] W. Dahmen and C. A. Mitchel "Biorthogonal
Wavelet Expansions." [1825] G. Davis, S. Mallat and Z. Zhang,
"Adaptive Nonlinear Approximations." [1826] G. Davis, "Adaptive
Nonlinear Approximations." [1827] G. Davis, S. Mallat and Z. Zhang,
"Adaptive Time-Frequency Approximations with Matching Pursuits."
[1828] I. Daubechies and W. Sweldens, An abstract is also
available. [1829] C. deBoor, R. DeVore and R. Amos, "On the
Construction of Multivariate (Pre)Wavelets." [1830] R. L.
deQueiroz, "On Lapped Transforms." [1831] M. Girardi and W.
Sweldens, "A New Class of Unbalanced Haar Wavelets That Form an
Unconditional Basis for Lp on General Measure Spaces." An abstract
is also available. [1832] S. Haykin and S. Mann, "The Chirplet
Transform: A New Signal Analysis Technique Based on Affine
Relationships in the Time-Frequency Plane." This about 3.5 MB.
[1833] C. Heil, G. Strang and V. Strela, "Approximation By
Translates of Refinable Functions." [1834] C. Heil and G. Strang,
"Continuity of the Joint Spectral Radius: Application to Wavelets."
[1835] B. Jawerth and W. Sweldens, "Biorthogonal Smooth Local
Trigonometric Bases." An abstract is also available. [1836] B.
Jawerth and W. Sweldens, "Weighted Multiwavelets on General
Domains." [1837] M. K. Kwong and P. T. Peter Tang, "W-Matrices,
Nonorthogonal Multiresolution Analysis and Finite Signals of
Arbitrary Length." [1838] G. Leaf, J. M. Restrepo and G.
Schlossnagle, "Periodized Daubechies Wavelets." [1839] J. Lippus,
"Wavelet Coefficients of Functions of Generalized Lipschitz
Classes." [1840] S. Mallat and Z. Zhang, "Matching Pursuit with
Time-Frequency Dictionaries." [1841] E. J. McCoy, D. B. Percival
and A. T. Walden, "On the Phase of Least-Asymmetric Scaling and
Wavelet Filters." [1842] R. Piessens and W. Sweldens, "Wavelet
Sampling Techniques." An abstract is also available. [1843] J. Shen
and G. Strang, "The zeros of the Daubechies polynomials." [1844] J.
Shen and G. Strang, "Asymptotics of Daubechies Filters, Scaling
Functions and Wavelets." [1845] M. J. Shensa, "An Inverse DWT for
Nonorthogonal Wavelets" [1846] W. Sweldens, "Compactly Supported
Wavelets which are Biorthogonal to a Weighted Inner Product."
[1847] W. Sweldens, "The Lifting Scheme: A Custom-Design
Construction of Biorthogonal Wavelets." An abstract is also
available. [1848] W. Sweldens, "The Lifting Scheme: A Construction
of Second Generation Wavelets." An abstract is also available.
[1849] B. Suter and X. Xia, "Vector Valued Wavelets and Vector
Filter Banks." [1850] C. Taswell, "Wavelet Transform Algorithms for
Finite Duration Discrete-Time Signals." [1851] C. Taswell,
"Near-Best Basis Selection Algorithms with Non-Additive Information
Cost Functions." [1852] K. Urban, "On Divergence-Free Wavelets."
[1853] R. O. Wells Jr., "Recent Advances in Wavelet Technology"
[1854] M. V. Wickerhauser, "Entropy of a Vector Relative to a
Decomposition." [1855] M. V. Wickerhauser, "Lectures on Wavelet
Packet Algorithms" [1856] M. V. Wickerhauser, "Smooth Localized
Orthonormal Bases" [1857] C. Zarowski, "Notes on Orthogonal
Wavelets and Wavelet Packets" [1858] V. Zavadsky, "Multiresolution
Approximations of Banach Spaces." [1859] V. Zavadsky, "Wavelet
Approximation of Sampled Functions." [1860] B. G. Sherlock and D.
M. Monro, "On the Space of Orthonormal Wavelets." [1861] M.
Vetterli and C. Herley, "Wavelets and Filter Banks: Theory and
Design," IEEE Trans. Sig. Proc., Vol. 40, 1992, pp. 2207-2232.
[1862] Frame Decompositions [1863] J. Benedetto, C. Heil, and D.
Walnut, "Differentiation and the Balian-Low Theorem." [1864] O.
Christensen and C. Heil, "Perturbations of Banach Frames and Atomic
Decompositions." [1865] D. M. Healy, Jr. and S. Li, "On Pseudo
Frame Decompositions and Discrete Gabor Expansions." [1866] S. Li,
"General Frame Decompsotions, Pseudo-Duals and Applications for
Weyl-Heisenberg Frames." [1867] S. Li, "On Dimension Invariance of
Discrete Gabor Expansions."
[1868] M-Band Wavelets and Filter Banks [1869] C. S. Burrus and R.
A. Gopinath, "On the Correlation Structure of Multiplicity M
Scaling Functions" [1870] C. S. Burrus and R. A. Gopinath,
"Wavelets and Filter Banks" [1871] C. S. Burrus and R. A. Gopinath,
"Unitary FIR Filter Banks and Symmetry" [1872] C. S. Burrus and R.
A. Gopinath, "Theory of Modulated Filter Banks and Modulated
Wavelet Tight Frames" [1873] C. S. Burrus and R. A. Gopinath,
"Factorization Approach to Time-Varying Unitary Filter Bank Trees
and Wavelets" [1874] C. Herley, "Boundary Filters for Finite-Length
Signals and Time-Varying Filter Banks." [1875] P. Steffen, P.
Heller, R. A. Gopinath and C. S. Burrus, "The Theory of Regular
M-Band Wavelets"
[1876] Wavelets and General Signal Processing [1877] M. Vetterli
and J. Kovacevic, "Wavelets and Subband Coding", Prentice Hall,
1995. [1878] D. E. Ashpis and J. Lewalle, "Transport in bypass
transition: mapping the active time scales using wavelet
techniques" [1879] D. E. Ashpis and J. Lewalle, "Demonstration of
wavelet techniques in the spectral analysis of bypass transition
data" [1880] C. Basdevant, V. Perrier and T. Philipovitch, "Wavelet
Spectra Compared to Fourier Spectra." [1881] J. P. Bonnet, J.
Lewalle and M. N. Glauser, "Coherent Structures: Past, Present and
Future." [1882] G. Buresti, J. Lewalle and P. Petagna, "Wavelet
statistics and the near-field structure of coaxial jets" [1883] C.
S. Burrus and R. A. Gopinath, "Wavelet-Based Lowpass/Bandpass
Interpolation" [1884] C. S. Burrus, R. A. Gopinath and J. E.
Odegard, "Design of Linear Phase Cosine Modulated Filter Banks for
Subband Image Compression" [1885] S. Cabrera, V. Krienovich and O.
Sirisaengtaksin, "Wavelets Compress Better Than All Other Methods:
A 1-D Theorem." [1886] S. Cabrera, V. Krienovich and O.
Sirisaengtaksin, "Wavelet Nerual Networks are Optimal Approximators
for Functions of One Variable." [1887] R. Carmona, W. L. Hwang and
B. Torresani, "Characterization of Signals by the Ridges of Their
Wavelet Transforms." [1888] R. Carmona, W. L. Hwang and B.
Torresani, "Multi-Ridge Detection and Time-Frequency
Reconstruction." [1889] R. Coifman, "Adapted Multiresolution
Analysis, Computation, Signal Processing and Operator Theory"
[1890] R. Coifman, Y. Meyer, S. Quake and M. Wickerhauser, "Signal
Processing and Compression with Wave Packets." [1891] R. Coifman,
Y. Meyer and M. V. Wickerhauser, "Wavelet Analysis and Signal
Processing" [1892] P. Crane, H. Higuchi and J. Lewalle, "On the
structure of two-dimensional wakes behind a pair of flat plates"
[1893] M. Goldburg, "Applications of Wavelets to Quantization and
Random Process Representations." About 1.1 MB. [1894] D. M. Healy,
Jr., J. Lu and J. B. Weaver, "Signal Recovery and Wavelet
Reproducing Kernels." [1895] D. M. Healy, Jr., J. Lu, J. B. Weaver
and Y. Xu, "Noise Reduction With Multiscale Edge Representation and
Perceptual Criteria." [1896] D. M. Healy, Jr. and J. Lu, "Contrast
Enhancement via Multiscale Gradient Transformations." [1897] W.
Hwang and S. Mallat, "Singularity Detection and Processing with
Wavelets." [1898] B Jawerth, Y. Liu and W. Sweldens, "Signal
Compression with Smooth Local Trigonometric Bases." An abstract is
also available. [1899] M. M. Lankhorst and M. D. van der Laan,
"Wavelet-Based Signal Approximation with Genetic Algorithms."
[1900] J. Lewalle, K. Read and M. T. Schobeiri, "Effect of unsteady
wake-passing frequency on boundary layer transition--experimental
investigation and wavelet analysis" [1901] J. Lewalle, S. J. Murphy
and F. W. Peek, "Wavelet analysis of olfactory nerve response to
stimulus" [1902] J. Lewalle, "Wavelet analysis of experimental
data: some methods and the underlying physics" [1903] G. Strang,
"Eigenvalues of (12)H and convergence of the cascade algorithm."
[1904] G. Strang, "Creating and comparing wavelets." [1905] A. R.
Tate, "Pattern Recognition Analysis of in vivo Magnetic Resonance
Spectra" [1906] D. Donoho, "Nonlinear Wavelet Methods for Recovery
of Signals, Densities, and Spectra from Indirect and Noisy Data,"
Different Perspectives on Wavelets, Proceeding of Symposia in
Applied Mathematics, Vol 47, I. Daubechies ed. Amer. Math. Soc.,
Providence, R.I., 1993, pp. 173-205.
[1907] Wavelets and Image Processing [1908] E. Adelson and E.
Simoncelli, "Subband Image Coding with Three-tap Pyramids." [1909]
E. H. Adelson, W. T. Freeman, D.1. Heeger and E. P. Simoncelli,
"Shiftable Multi-Scale Transforms." [1910] E. H. Adelson and E. P.
Simoncelli, "Subband Transforms." [1911] V. R. Algazi, R. R. Estes
and J. Lu, "Comparison of wavelet image coders using the Picture
Quality Scale (PQS)." [1912] M. Bhatia, W. C. Karl, and A. S.
Willsky, "A Wavelet-Based Method for Multiscale Tomographic
Reconstruction." [1913] M. Bhatia, W. C. Karl, and A. S. Willsky,
"Using Natural Wavelet Bases and Multiscale Stochastic Models for
Tomographic Reconstruction." [1914] M. Louys, J. L. Starck, S. Mei,
F. Bonnarel, and F. Murtagh, "Astronomical Image Compression."
[1915] M. Louys, J. L. Starck and F. Murtagh, "Lossless Compression
of Astronomical Images." [1916] F. Murtagh and J. L. Starck,
"Wavelets and Multiscale Transforms in Massive Data Sets." [1917]
F. Murtagh and J. L. Starck, "Image Processing through Multiscale
Analysis and Measurement Noise Modeling." [1918] J. L. Starck and
F. Murtagh, "Multiscale Entropy Filtering." [1919] J. L. Starck and
F. Murtagh, "Image Filtering by Combining Multiple Vision Models".
[1920] F. Murtagh, "Wedding the Wavelet Transform and Multivariate
Data Analysis." [1921] F. Murtagh and J. L. Starck, "Pattern
Clustering based on Noise Modeling in Wavelet Space." [1922] G.
Zheng, J. L. Starck, J. G. Campbell and F. Murtagh, "Multiscale
Transforms for Filtering Financial Data Streams." [1923] M.
Morehart, F. Murtagh and J. L. Starck, "Multiresolution Spatial
Analysis." [1924] F. Murtagh, J. L. Starck and M. W. Berry,
"Overcoming the Curse of Dimensionality in Clustering by means of
the Wavelet Transform." [1925] R. A. Carmona, R. D. Frostig and W.
L. Hwang, "Wavelet Analysis for Brain Function Imaging." [1926] A.
Chambolle, R. A. DeVore, N. Lee, and B. J. Lucier, "Nonlinear
Wavelet Image Processing: Variational Problems, Compression, and
Noise Removal through Wavelet Shrinkage." [1927] H. Chao and P.
Fisher, "An Approach of Fast Integer Reversible Wavelet Transforms
for Image Compression." [1928] R. A. DeVore and B. J. Lucier, "Fast
Wavelet Techniques for Near-Optimal Image Processing" [1929] B.
Deng, B. D. Jawerth, G. Peters and W. Sweldens, "Wavelet Probing
for Compression Based Segmentation". J. Fan and A. Laine, "An
Adaptive Approach for Texture Segmentation by Multi-Channel Wavelet
Frames.". [1930] W. T. Freeman and E. P. Simoncelli, "The Steerable
Pyramid: A Flexible Architecture for Multi-Scale Derivative
Computation."/C Source Code (75k) [1931] A. Grzeszczak, M. K.
Mandal, S. Panchanathan and T. Yeap, "VLSI Implementation of
Discrete Wavelet Transform." [1932] O. Guleryuz, M. T. Orchard and
Z. Xiong, "A DCT-based Embedded Image Coder." [1933] D. M. Healy,
Jr., J. Lu and J. B. Weaver, "Contrast Enhancement of Medical
Images Using Multiscale Edge Representation." [1934] C. Heil, P. N.
Heller, G. Strang, V. Strela, and P. Topiwala, "Accuracy of Lattice
Translates of Several Multidimensional Refinable Functions." [1935]
C. Herley, M. T. Orchard, K. Ramchandran and Z. Xiong, "Flexible
Tree-structured Signal Expansions for Compression Using
Time-Varying Filter Banks." [1936] M. L. Hilton, B. D. Jawerth and
A. Sengupta, "Compressing Still and Moving Images with Wavelets"
with figure. [1937] P. Kovesi, "Image Features from Phase
Congruency" [1938] B. Lin, "Wavelet Phase Filter for Denoising
Tomographic Image Reconstruction" [1939] M. K. Mandal, T. Aboulnasr
and S. Panchanathan, "Image Indexing Using Moments and Wavelets."
[1940] M. K. Mandal, E. Chan, X. Wang and S. Panchanathan,
"Multiresolution Motion Estimation Techniques for Video
Compression." [1941] M. K. Mandal, S. Panchanathan and T.
Aboulnasr, "Choice of Wavelets for Image Compression." [1942] D. M.
Monro and B. G. Sherlock, "Psychovisually Tuned Wavelet Fingerprint
Compression". [1943] D. M. Monro and B. G. Sherlock, "Optimised
Wavelets for Fingerprint Compression". [1944] P. Moulin, "A
Multiscale Relaxation Algorithm for SNR Maximization in 2-D
Nonorthogonal Subband Coding." [1945] M. T. Orchard, Z. Xiong and
Y. Zhang, "A Simple Deblocking Algorithm for JPEG Compressed Images
Using Overcomplete Wavelet Representations." [1946] M. T. Orchard,
K. Ramchandran and Z. Xiong, "Wavelet Packets Image Coding Using
Space-Frequency Quantization." [1947] M. T. Orchard, K. Ramchandran
and Z. Xiong, "Space-frequency Quantization for Wavelet Image
Coding." [1948] H. Pan, "Uniform Full-Information Image Matching
Using Complex Conjugate Wavelet Pyramids", with figures. [1949] H.
Pan, "General Stereo Image Matching Using Symmetric Complex
Wavelets," presented at SPIE Conference: Wavelet Applications in
Signal and Image Processing, VI. Denver, August 1996, Published in
SPIE Proceedings, vol. 2825. [1950] P. Schroder and W. Sweldens,
"Spherical wavelets: Efficiently representing functions on the
sphere." P. Schroder and W. Sweldens, "Spherical Wavelets: Texture
Processing." An abstract is also available. [1951] J. A. Solomon,
J. Villasenor, A. B. Watson and G. Y. Yang, "Visual Thresholds For
Wavelet Quantization Error." [1952] V. Strela, P. Heller, G.
Strang, P. Topiwala and C. Heil, "The application of multiwavelet
filter banks to signal and image processing." [1953] Y. Wang,
"Image representations using multiscale differential operators."
[1954] Y. Wang and S. L. Lee, "Scale-space derived from B-splines."
[1955] G. Weiss, "Time-Frequency and Time-Scaling Methods in Signal
and Image Processing" [1956] M. Wickerhauser, "Picture Compression
by Best-Basis Subband Coding." [1957] M. V. Wickerhauser,
"High-Resolution Still Picture Compression" [1958] Z. Xiong,
"Representation and Coding of Images Using Wavelets." [1959] D. M.
Monro and B. G. Sherlock, "Space-Frequency Balance in Biorthogonal
Wavelets." [1960] Xuejun Li, "Low Bit Rate Wavelet Image and Video
Coding Algorithm and Software."
[1961] The FBI Wavelet Fingerprint Compression Standard [1962] J.
N. Bradley and C. M. Brislawn, "Proposed First-Generation WSQ Bit
Allocation Procedure" [1963] J. N. Bradley and C. M. Brislawn, "The
Wavelet/Scalar Quantization Compression Standard for Digital
Fingerprint Images." [1964] J. Bradley, C. Brislawn and T. Hopper,
"WSQ Gray-Scale Fingerprint Image Compression Specification."
[1965] J. Bradley, C. Brislawn and T. Hopper, "The FBI
Wavelet/Scalar Quantization Standard for Gray-Scale Fingerprint
Image Compression" with figures. [1966] C. M. Brislawn,
Classification of Nonexpansive Symmetric Extension Transforms for
Multirate Filter Banks" [1967] C. M. Brislawn, "Fingerprints Go
Digital" [1968] C. M. Brislawn, "Preservation of Subband Symmetry
in Multirate Signal Coding." [1969] "The FBI Wavelet/Scalar
Quantization Fingerprint Image Compression Standard."
[1970] Wavelets and Speech Processing [1971] E. Wesfreid and M. V.
Wickerhauser, "Adapted Local Trigonometric Transforms and Speech
Processing" [1972] M. Wickerhauser, "Acoustic Signal Compression
with Wavelets Packets."
[1973] Wavelets and Ordinary Differential Equations [1974] G.
Beylkin, "On Wavelet-based Algorithms for Solving Differential
Equations." [1975] B Jawerth and W. Sweldens, "Wavelet
Multiresolution Analyses Adapted for the Fast Solution of Boundary
Value Ordinary Differential Equations." An abstract is also
available. [1976] P. Monasse and V. Perrier, "Ondelettes sur
l'Intervalle pour la Prise en Compte de Conditions aux Limites."
[1977] A. Rieder, "Semi-Algebraic Multi-level Methods Based on
Wavelet Decompositions I: Application to Two-Point Boundary
Problems" [1978] W. C. Shann and J. C. Xu, "Galerkin-wavelet
Methods for Two Point Boundary Value Problems."
[1979] Wavelets and Partial Differential Equations [1980] G.
Kaiser, "Complex-Distance Potential Theory and Hyperbolic
Equations" [1981] A. Averbuch, G. Beylkin R. R. Coifman and M.
Israeli, "Multiscale Inversion of Elliptic Operators." [1982] E.
Bacry, S. Mallat and G. Papanicolaou, "A Wavelet Based Space-Time
Adaptive Numerical Method for Partial Differential Equations"
[1983] G. Beylkin and N. Coult, "A Multiresolution Strategy for
Reduction of Elliptic PDE's and Eigenvalue Problems." [1984] G.
Beylkin and J. H. Keiser, "On the Adaptive Numerical Solution of
Nonlinear Partial Differential Equations in Wavelet Bases." [1985]
D. M. Bond and S. A. Vavasis, "Fast Wavelet Transforms for Matrices
Arising From Boundary Element Methods." [1986] T. Chan, W. Tang and
W. Wan, [1987] P. Charton and V. Perrier, "Factorisation sur Bases
d'Ondelettes du Noyeau de la Chaleur et Algorithmes Matriciels
Rapides Associes." [1988] P. Charton and V. Perrier, "Towards a
Wavelet Based Numerical Scheme for the Two-Dimensional
Navier-Stokes Equations." [1989] P. Charton and V. Perrier, "A
Pseudo-Wavelet Scheme for the Two-Dimensional Navier-Stokes
Equations." [1990] S. Dahlke and A. Kunoth, "Biorthogonal Wavelets
and Multigrid." [1991] S. Dahlke and I. Weinreich,
"Wavelet-Galerkin Methods: An Adapted Biorthogonal Wavelet Basis."
[1992] S. Dahlke and I. Weinreich, "Wavelet Bases Adapted to
Pseudo-Differential Operators." [1993] W. Dahmen and A. Kunoth,
"Multilevel Preconditioning." [1994] W. Dahmen, A. Kunoth and K.
Urban "A Wavelet-Galerkin Method for the Stokes-Equations," also
full version with pictures. [1995] R. Glowinski, T. Pan, R. O.
Wells, Jr. and X. Zhou, "Wavelet and Finite Element Solutions for
the Neumann Problem Using Fictitious Domains" [1996] R. Glowinski,
A. Rieder, R. O. Wells, Jr. and X. Zhou, "A Wavelet Multigrid
Preconditioner for Dirichlet Boundary Value Problems in General
Domains." [1997] R. Glowinski, A. Rieder, R. O. Wells, Jr. and X.
Zhou, "A Preconditioned CG-Method for Wavelet-Galerkin
Discretizations of Elliptic Problems" [1998] F. Heurtaux, F.
Planchon and M. V. Wickerhauser, "Scale Decomposition in Burgers'
Equation" [1999] A. Jiang, [2000] J. H. Keiser, "On I. Wavelet
Based Approach to Numerical Solution on Nonlinear Partial
Differential Equations and II. Nonlinear Waves in Fully Discrete
Dynamical Systems." [2001] A. Kunoth, "Multilevel
Preconditioning--Appending Boundary Conditions by Lagrange
Multipliers." [2002] G. Leaf and J. M. Restrepo, "Wavelet-Galerkin
Discretization of Hyperbolic Equations." [2003] J. Lewalle,
"Wavelet Transforms of some Equations of Fluid Mechanics" [2004] J.
Lewalle, "Energy Dissipation in the Wavelet-Transformed
Navier-Stokes Equations" [2005] J. Lewalle, "On the effect of
boundary conditions on the multifractal statistics of
incompressible turbulence" [2006] J. Lewalle, "Diffusion is
Hamiltonian". [2007] D. Lu, T. Ohyoshi and L. Zhu, "Treatment of
Boundary Conditions in the Application of Wavelet-Galerkin Method
to a SH Wave Problem" [2008] P. Monasse and V. Perrier,
"Orthonormal Wavelet Bases Adapted for Partial Differential
Equations with Boundary Conditions." [2009] A. Rieder and X. Zhou,
"On the Robustness of the Damped V-Cycle of the Wavelet Frequency
Decompositions Multigrid Method" [2010] A. Rieder, R. O. Wells, Jr.
and X. Zhou, "A Wavelet Approach to Robust Multilevel Solvers for
Anisotropic Elliptic Problems." [2011] A. Rieder, R. O. Wells, Jr.
and X. Zhou, "On the Wavelet Frequency Decomposition Method" [2012]
K. Urban, "A Wavelet-Galerkin Algorithm for the
Driven-Cavity-Stokes-Problem in Two Space Dimensions." [2013] O. V.
Vasilyev and S. Paolucci, "A Dynamically Adaptive Multilevel
Wavelet Collocation Method for Solving Partial Differential
Equations in a Finite Domain." [2014] O. V. Vasilyev and S.
Paolucci, "Thermoacoustic Wave Propagation Modeling Using a
Dynamically Adaptive Wavelet Collocation Method." [2015] O. V.
Vasilyev and S. Paolucci, "A Fast Adaptive Wavelet Collocation
Algorithm for Multi-Dimensional PDEs." with figures. [2016] O. V.
Vasilyev, S. Paolucci and M. Sen, "A Multilevel Wavelet Collocation
Method for Solving Partial Differential Equations in a Finite
Domain." [2017] O. V. Vasilyev, Y. Y. Podladchikov and D. A. Yuen,
"Modeling of Compaction Driven Flow in Poro-Viscoelastic Medium
Using Adaptive Wavelet Collocation Method." with figures. [2018] O.
V. Vasilyev, D. A. Yuen and S. Paolucci, "The Solution of PDEs
Using Wavelets." with figures. [2019] O. V. Vasilyev, D. A. Yuen
and Y. Y. Podladchikov, "Applicability of Wavelet Algorithm for
Geophysical Viscoelastic Flow." with figures. [2020] R. O. Wells,
Jr. and X. Zhou, "Wavelet Solutions for the Dirichlet Problem"
[2021] R. O. Wells, Jr. and X. Zhou, "Wavelet Interpolation and
Approximate Solution of Elliptic Partial Differential Equations"
[2022] R. O. Wells, Jr. and X. Zhou, "Representing the Geometry of
Domains by Wavelets with Applications to Partial Differential
Equations" [2023] R. O. Wells, Jr., "Multiscale Applications of
Wavelets to Solutions of Partial Differential Equations"
[2024] Wavelets and Numerical Analysis [2025] G. Beylkin, R.
Coifman and V. Rokhlin, "Fast Wavelet Transforms and Numerical
Algorithms I." [2026] G. Beylkin, "On the Representation of
Operators in Bases of Compactly Supported Wavelets." [2027] G.
Beylkin, "On the Fast Algorithm for Multiplication of Functions in
the Wavelet Bases." [2028] G. Beylkin, "Wavelets and Fast Numerical
Algorithms." Lecture notes for an AMS short course, 1993. [2029] G.
Beylkin, "Wavelets, Multiresolution Analysis and Fast Numerical
Algorithms." Draft of INRIA lectures, May 1991. [2030] G. Beylkin
and M. E. Brewster, "A Multiresolution Strategy for Numerical
Homogenization." [2031] P. Charton and V. Perrier, "Produits
Rapides Matrices-Vecteur en Bases d'Ondelettes: Application a la
Resolution Numerique d'Equation aux Derivees Partielles." [2032] P.
Charton, "Produits de Matrices Rapides en Bases d'Ondelettes:
Application a la Resolution Numerique d'Equation aux Derivees
Partielles." [2033] N. H. Getz, "A Fast Discrete Periodic Wavelet
Transform." An associated toolbox of Matlab routines is also
available. [2034] L. Jameson, "On the Spline-Based Wavelet
Differentiation Matrix." [2035] L. Jameson, "On the Differention
Matrix for Daubechies-Based Wavelets on an Interval." [2036] L.
Jameson, "On the Daubechies-Based Wavelet Differentiation Matrix."
[2037] L. Jameson, "On the Wavelet Optimized Finite Difference
Method." [2038] E. Kolaczyk, "Wavelet Methods for the Inversion of
Certain Homogeneous Linear Operators in the Presence of Noisy
Data," with FIG. 5.1, FIG. 5.2, FIG. 5.4, FIG. 5.5, FIG. 5.6, FIG.
5.8, FIG. 5.10, FIG. 5.11, FIG. 5.13, and FIG. 5.14. [2039] R.
Piessens and W. Sweldens, "Quadrature Formulae and Asymptotic Error
Expansion of Wavelet Approximations of Smooth Functions." [2040] R.
Piessens and W. Sweldens, "Asymptotic Error Expansion of Wavelet
Approximations of Smooth Functions II." [2041] W. C. Shann,
"Quadratures Involving Polynomials and Daubechies' Wavelets."
[2042] W. Sweldens, "Construction and Application of Wavelets in
Numerical Analysis." [2043] M. Wickerhauser, "Nonstandard Matrix
Multiplication." [2044] M. V. Wickerhauser, "Computation with
Adapted Time-Frequency Atoms" [2045] M. V. Wickerhauser, "Wavelet
Approximations to Jacobians and the Inversion of Complicated
Maps"
[2046] Wavelets and Statistics [2047] F. Abramovich, T. Sapatinas
and B. W. Silverman, "Wavelet Thresholding via a Bayesian
Approach." [2048] F. Abramovich, T. Sapatinas and B. W. Silverman,
"Stochastic Atomic Decompositions in a Wavelet Dictionary." [2049]
F. Abramovich and B. W. Silverman, "The Vaguelette-Wavelet
Decomposition Approach to Statistical Inverse Problems." [2050] E.
H. Adelson and E. P. Simoncelli, "Noise Removal via Bayesian
Wavelet Coring." [2051] A. Antoniadis, G. Gregoire and G. P. Nason,
"Density and Hazard Rate Estimation for Right Censored Data using
Wavelet Methods." [2052] T. Bailey, T. Sapatinas, K. Powell and W.
J. Krzanowski, "Signal Detection in Underwater Sounds using
Wavelets." [2053] A. G. Bruce, D. L. Donoho, H. Gao and R. D.
Martin, "Denoising and Robust Non-linear Wavelet Analysis." [2054]
A. G. Bruce and H. Gao, "WaveShrink: Shrinkage Functions and
Thresholds." [2055] A. G. Bruce and H. Gao, "WaveShrink with
Semisoft Shrinkage." [2056] A. G. Bruce and H. Gao, "Understanding
WaveShrink: Variance and Bias Estimation." [2057] A. G. Bruce, H.
Gao and D. Ragozin, "S+WAVELETS: An Object-Oriented Toolkit for
Wavelet Analysis." [2058] A. G. Bruce and H. Gao, "S+WAVELETS:
Algorithms and Technical Details." [2059] J. Buckheit and D.
Donoho, "WaveLab and Reproducible Research." [2060] J. F. Burn, A.
M. Wilson and G. P. Nason, "Impact During Equine Locomotion:
Techniques for Measurement and Analysis." [2061] R. Coifman and N.
Saito, "Local Discriminant Bases." [2062] R. Coifman and F. Majid,
"Adapted Waveform Analysis and Denoising." [2063] R. Coifman and D.
Donoho, "Translation-Invariant De-Noising." [2064] R. Dahlhaus, M.
H. Neumann and R. von Sachs, "Non-linear Wavelet Estimation of
Time--Varying Autoregressive Processes." [2065] A. Davis, A.
Marshak and W. Wiscombe, "Wavelet-Based Multifractal Analysis of
Non-Stationary and/or Intermittent Geophysical Signals." with
figures. [2066] B. Deylon and A. Juditsky, "Wavelet Estimators.
Global Error Mesures Revisited." [2067] D. Donoho, "Nonlinear
Solution of Linear Inverse Problems by Wavelet-Vaguelette
Decomposition" [2068] D. Donoho, "Smooth Wavelet Decompositions
with Blocky Coefficient Kernels" [2069] D. Donoho, "De-noising by
Soft Thresholding" [2070] D. Donoho, "Interpolating Wavelet
Transforms" [2071] D. Donoho, "Unconditional Bases are Optimal
Bases for Data Compression and for Statistical Estimation" [2072]
D. Donoho and I. Johnstone, "Adapting to Unknown Smoothness by
Wavelet Shrinkage" [2073] D. Donoho and I. Johnstone, "Ideal
Spatial Adaptation via Wavelet Shrinkage" [2074] D. Donoho and I.
Johnstone, "Minimax Estimation via Wavelet Shrinkage" [2075] D.
Donoho and I. Johnstone, "Minimax Risk over I_p Balls" [2076] D.
Donoho, I. Johnstone, G. Kerkyacharian and D. Picard, "Density
Estimation via Wavelet Shrinkage" [2077] D. Donoho, I. Johnstone,
G. Kerkyacharian and D. Picard, "Wavelet Shrinkage: Asymptopia?"
[2078] D. Donoho and I. Johnstone, "Ideal Denoising in an
Orthonormal Basis Chosen From a Library of Bases." [2079] D.
Donoho, S. Mallat and R. von Sachs, "Estimating Covariances of
Locally Stationary Processes: Rates of Convergence of Best Basis
Methods." [2080] T. Downie and B. W. Silverman, "The Discrete
Multiple Wavelet Transform and Thresholding Methods." [2081] H. Y.
Gao, "Choice of Thresholds for Wavelet Shrinkage Estimate of the
Spectrum." [2082] P. Goel and B. Vidakovic, "Wavelet
Transformations as Diversity Enhancers" [2083] P. Hall and G. P.
Nason, "On Choosing a Non-integer Resolution Level when Using
Wavelet Methods." [2084] I. Johnstone, "Minimax Bayes, Asymptotic
Minimax and Sparse Wavelet Priors" [2085] I. M. Johnstone and B. W.
Silverman, "Wavelet Threshold Estimators for Data with Correlated
Noise." [2086] A. Juditsky, "Wavelet Estimators. Adapting To Unkown
Smoothness." [2087] A. Juditsky and F. Leblanc, "Computing Wavelet
Density Estimators for Stochastic Processes." [2088] G. Katul and
B. Vidakovic, "Partitioning eddy motion using Lorentz wavelet
filtering." [2089] R. Morgan and G. P. Nason, "Wavelet Shrinkage of
Itch Response Sata." [2090] P. Moulin, "Wavelet Thresholding
Techniques for Power Spectrum Estimation." [2091] G. P. Nason and
B. W. Silverman, "The Discrete Wavelet Transform in S." [2092] G.
P. Nason and B. W. Silverman, "The Stationary Wavelet Transform and
some Statistical Applications." [2093] G. P. Nason and B. W.
Silverman, "Wavelets for Regression and other Statistical
Problems." [2094] G. P. Nason, T. Sapatinas and A. Sawczenko,
"Statistical Modelling of Time Series using Non-decimated Wavelet
Representations." [2095] G. P. Nason, "Wavelet Regression by
Cross-Validation" [2096] G. P. Nason, "Functional Projection
Pursuit." [2097] M. H. Neumann and R. von Sachs, "Wavelet
Thresholding in Anisotropic Function Classes and Application to
Adaptive Estimation of Evolutionary Spectra." [2098] A. B. Owen,
"Monte Carlo Variance of Scrambled Equidistribution Quadrature."
[2099] D. B. Percival, "On the Estimation of the Wavelet Variance."
[2100] A. Pinheiro and B. Vidakovic, "Estimating the Square Root of
a Density Via Compactly Supported Wavelets." [2101] J. Raz, L.
Dickerson and B. Turetsky, "A Wavelet Packet Model of Evoked
Potentials." [2102] N. Saito, "Local Feature Extraction and Its
Appplications Using a Library of Bases." [2103] N. Saito,
"Simultaneous Noise Supression and Signal Compression using a
Library of Orthonormal Bases and the Minimum Description Length
Criterion." [2104] B. Vidakovic, "A Note on Random Densities via
Wavelets" [2105] B. Vidakovic, "Nonlinear Wavelet Shrinkage with
Bayes Rules and Bayes Factors." [2106] R. von Sachs, G. P. Nason
and G. Kroisandt, "Adaptive Estimation of the Evolutionary Wavelet
Spectrum." [2107] R. von Sachs and K. Schneider, "Smoothing of
Evolutionary Spectra by Non-linear Thresholding." Also available
are the figures. [2108] R. von Sachs and M. H. Neumann, "A
Wavelet-based Test for Stationarity." [2109] R. von Sachs and B.
MacGibbon, "Non-parametric Curve Estimation by Wavelet Thresholding
with Locally Stationary Errors." [2110] A. T. Walden, D. B.
Percival and E. J. McCoy, "Spectrum Estimation by Wavelet
Thresholding of Multitaper Estimators." [2111] Yazhen Wang, "Jump
and sharp cusp detection by wavelets." [2112] Yazhen Wang,
"Function estimation via wavelet shrinkage for long-memory data."
[2113] Yazhen Wang, "Small ball problems via wavelets for Gaussian
processes." [2114] Yazhen Wang, "Fractal function estimation via
wavelet shrinkage." [2115] Yazhen Wang, "Minimax estimation via
wavelets for indirect long-memory data." [2116] Yazhen Wang,
"Change curve estimation via wavelets" (with an application to
image processing); FIG. 4(a), FIG. 4(b). [2117] Yazhen Wang,
"Change-point analysis via wavelets for indirect data." [2118]
Yazhen Wang, "Self-similarity index estimation via wavelets for
locally self-similar processes" (with Cavanaugh and Song). [2119]
M. V. Wickerhauser, "Fast Approximate Factor Analysis."
[2120] Wavelets and Econometrics [2121] S. A. Greenblatt, "Wavelets
in Economics: An Application to Outlier Testing." [2122] M. J.
Jensen, "Wavelet Analysis of Fractionally Integrated Processes."
[2123] M. J. Jensen, "OLS Estimate of the Fractional Differencing
Parameter Using Wavelets Derived From Smoothing Kernels."
[2124] Wavelets and Fractals [2125] A. Davis, A. Marshak and W.
Wiscombe, "Wavelet-Based Multifractal Analysis of Non-Stationary
and/or Intermittent Geophysical Signals." with figures. [2126] C.
Jones, 2-D Wavelet Packet Analysis of Structural Self-Organization
and Morphogenic Regulation in Filamentous Fungal Colonies. [2127]
J. Lewalle, "Wavelet Transforms of the Navier-Stokes Equations and
the Generalized Dimensions of Turbulence" [2128] W. Hwang and S.
Mallat, "Characterization of Self-Similar Multifractals with
Wavelet Maxima."
[2129] Wavelets and Communication Theory [2130] J. Dill and A. R.
Lindsey, "Wavelet Packet Modulation: A Generalized Method for
Orthogonally Multiplexed Communication." [2131] R. Learned, H.
Krim, B. Claus, A. S. Willsky, and W. C. Karl,
"Wavelet-Packet-Based Multiple Access Communication." [2132] A. R.
Lindsey, "Multidimensional Signaling via Wavelet Packets." [2133]
A. R. Lindsey, Generalized Orthogonally Multiplexed Communication
via Wavelet Packet Bases, chapter 1, chapter 2, chapter 3, chapter
4, chapter 5, chapter 6. Also with appendix and references.
[2134] Wavelets and Computer Graphics [2135] M. Cohen, S. Gortler,
P. Hanrahan and P. Schroder, "Wavelet Radiosity." With FIG. 12 and
FIG. 14. [2136] M. Cohen, S. Gortler, P. Hanrahan and P. Schroder,
"Wavelet Projections for Radiosity." [2137] A. Dreger, M. H. Gross
R. Koch and L. Lippert, "A New Method to Approximate the Volume
Rendering Equation using Wavelet Bases and Piecewise Polynomials,"
with FIGS. 5-6, FIGS. 7-10, and FIGS. 11-13. Also abstract
available. Technical Report No. 220, Computer Science Department,
ETH Zurich, 1994. [2138] A. Fournier, "Wavelets and their
Applications in Computer Graphics." This is 2.5 MB compressed.
[2139] M. H. Gross and L. Lippert, "Fast Wavelet Based Volume
Rendering by Accumulation of Tranparent Texture Maps." With FIG. 6,
FIG. 7, FIG. 8, FIG. 9, FIG. 10 and FIG. 11. Also abstract
available. Technical Report No. 228, Computer Science Department,
ETH Zurich, 1995. [2140] M. H. Gross and R. Koch, "Visualization of
Multidimensional Shape and Texture Features in Laser Range Data
using Complex-Valued Gabor Wavelets." [2141] M. H. Gross and L.
Lippert, "Ray-tracing of Multiresolution B-Spline Volumes." Also
abstract available. Technical Report No. 239, Computer Science
Department, ETH Zurich, 1996. [2142] P. Hanrahan and P. Schrader,
"Wavelet Methods for Radiance Computations." With FIG. 8, FIG. 9
left, FIG. 9 right, FIG. 10, FIG. 10 top left and FIG. 10 top
right. [2143] C. Herley, "Exact Interpolation and Iterative
Subdivision Schemes." [2144] P. Schroder, W. Sweldens and D. Zorin,
"Interpolating Subdivision for Meshes with Arbitrary Topology".
[2145] Wavelets and Physics [2146] J. C. van den Berg, ed.,
"Wavelets in Physics", Cambridge University Press, 1999 (a survey
of many applications). [2147] G. Kaiser, "A Detailed Introduction
to Mathematical and Physical Wavelets" [2148] C. Best and A.
Schafer, "Variational Description of Statistical Field Theories
using Daubechies' Wavelets." [2149] G. Beylkin, J. Dunn and D.
Gines, "Order N Static and Quasi-Static Computations in
Electrodynamics using Wavelets." [2150] J. C. Cohen and T. Chen,
"Fundamentals of the Discrete Wavelet Transform for Seismic Data
Processing." [2151] A. Fournier, "Wavelet Analysis of Observed
Geopotential and Wind: Blocking and Local Energy Coupling Across
Scales." [2152] A. Fournier, "Wavelet Multiresolution Analysis of
Numerically Simulated 3d Radiative Convection." [2153] A. Fournier,
"Wavelet Representation of Lower-Atmospheric Long Nonlinear Wave
Dynamics, Governed by the Benjamin-Davis-Ono-Burgers Equation."
[2154] F. Herrmann, "A scaling medium representation, a discussion
on well-logs, fractals and waves." An abstract is also available.
[2155] I. Pierce and L. Watkins, "Modelling optical pulse
propagation in nonlinear media using wavelets." [2156] W. C. Shann,
"Finite Element Methods for Maxwell's Equations with Stationary
Magnetic Fields and Galerkin-wavelet Methods for Two Point Boundary
Value Problems," with separate abstract and table of contents.
[2157] L. R. Watkins and Y. R. Zhou, "Modelling Propagation in
Optical Fibres using Wavelets." [2158] R. O. Wells, "Adaptive Wave
Propogailon Modelling." [2159] L. Zubair, "Studies in Turbulence
using Wavelet Transforms for Data Compression and
Scale-Separation." [2160] A. Fournier, "An introduction to
orthonormal wavelet analysis with shift invariance: Application to
observed atmospheric-blocking spatial structure", to appear in J.
Atmos. Sci., 2000 Dec. 1. [2161] A. Fournier, "Atmospheric
energetics in the wavelet domain I: Governing equations and
interpretation for idealized flows", submitted to J. Atmos. Sci.,
2000 (revised). [2162] A. Fournier, "Atmospheric energetics in the
wavelet domain II: Time-averaged observed atmospheric blocking",
submitted to J. Atmos. Sci., 1999. [2163] A. Fournier, "Atmospheric
energetics in the wavelet domain III: Instantaneous transfers
between block and local eddies", submitted to J. Atmos. Sci.,
1999.
[2164] Hardware and Software Implementation of Wavelet Transforms
[2165] J. Fridman and E. S. Manolakos, "On Linear Space-Time
Mapping for the 1-D Discrete Wavelet Transform." [2166] J. Fridman
and E. S. Manolakos, "Distributed Memory and Control VLSI
Architectures for the 1-D Discrete Wavelet Transform." [2167] J.
Lu, "Computation of 2-D Wavelet Transform on the Massively Parallel
Computer for Image Processing." [2168] MathSoft Engineering &
Education, Inc, "Wavelets Extension Pack", 1999. [2169] O. Nielsen
and M. Hegland, "A Scalable Parallel 2D Wavelet Transform
Algorithm."
GAME THEORY REFERENCES APPENDIX
[2169] [2170] GEB: Games and Economic Behavior EMA: Econometrica
JET: Journal of Economic Theory [2171] UGT: International Journal
of Game Theory AER: American Economic Review QJE: Quarterly Journal
of Economics [2172] JPE: Journal of Political Economy REStud:
Review of Economic Studies
[2173] Description of Games [2174] Roger Myerson, Nash Equilibrium
and the History of Economic Theory. JEL 1999
[2175] Rationality, Dominance, Weak Dominance etc [2176] Douglas
Bernheim, Rationalizable strategic behavior. EMA 1984 [2177] David
Pearce, Rationalizable strategic behavior and the problem of
perfection. EMA 1984 [2178] Douglas Bernheim, Axiomatic
characterization of rational choice in strategic enviroments.
Scand. J. of E. 1986 [2179] Shimoji and Watson, Conditional
Dominance, rationalizability and game forms. JET 1998 [2180] David
Roth, Rationalizable predatory pricing. JET 1996 [2181] Basu and
Weibul, strategy subsets closed under rational behavior. E. Letters
1991 [2182] Larry Samuelson, Dominated strategies and common
knowledge. GEB 1992 [2183] Marx and Swinkels, Order independence
for iterated weak dominance. GEB 1997
[2184] Equilibrium: Nash, Refinements, Correlated [2185] Selten,
Reexamination of the Perfectness concept for equilibrium points in
extensive form games. IJGT 1975. [2186] Myerson, Refinements of the
Nash equilibrium concept. IJGT 1975. [2187] Kalai and Samet,
Persistent equilibria in strategic games. IJGT 1984. [2188]
Kohlberg and Mertens, On the strategic stability of Equilibria.
Econometrica, 1986. [2189] Aumann, Correlated equilibria as an
expression of baysian rationality. Econometrica, 1987. [2190]
Aumann and Brandenberger, Espitemic conditions for equilibrium. EMA
1995 [2191] Hal Varian, A model of Sales. AER 1980
[2192] The Extensive Form Games with Perfect Information [2193]
Rubinstein, On the interpretation of game theory. Econometrica 1991
[2194] Reny, Common beleifs and the theory of games with perfect
information. JET 1993. [2195] Aumann Backward induction and common
knowledge of rationality. GEB 1995 [2196] Binmore, A note on
backward induction: Aumann, Reply to Binmore. GEB 1996 [2197]
Selten, A Reexamination of the perfectness . . .
[2198] Hyperbolic Discounting [2199] O'Donoghue and Rabin, Doing it
now or doing it later. AER 1999 [2200] David Laibson, Golden Eggs
and Hyperbolic Discounting. QJE 1997
[2201] The Economics of Altruism [2202] Gary Becker, A theory of
social interactions. JPE 1974 [2203] Ted Bergstrom, A fresh look at
the rotten kid theorem and other household mysteries. JPE 1989
[2204] Bernheim and Stark, Altruism within the family reconsidered:
do nice guys finish last. AER 1988 [2205] Lindbeck and Weibull,
Altruism and time consistency: the economics of fait accompli. JPE
1988 [2206] Bruce and Waldman, Transfers in kind: why they can be
efficient and non-paternalistic. AER 1991 [2207] Jack Robles,
Paternal altruism or smart parent altruism? CU WP 98-10 [2208]
Mathew Rabin, Incorporating fairness into economics and game
theory. AER 1993. [2209] Ray and Ueda, Egalitarianism and
incentives. JET 1996 [2210] Bernheim, Shleifer adn Summers, The
strategic bequest motive. JPE 1985
[2211] Extensive Form Games without Perfect Information [2212]
Kreps and Wilson, Sequential Equilibrium. Econometrica, 1983.
[2213] Van Damme, Stable Equilibria and forward induction. JET
1989.
[2214] Strategic Information Transmision [2215] Crawford and Sobel,
Strategic information transmission. Econometrica 1982. [2216] Cho
and Kreps, Signalling games and stable equilibria. QJE 1987 [2217]
Mailath, Okuno-Fujiwara and Postlewaite, Beleif based refinements
in signalling games. JET 1993 [2218] Milgrom, Roberts, Limit
pricing and entry under incomplete information: an equilibrium
analysis. EMA 1982 (pages 443-459) [2219] Cho and Sobel, Strategic
Stability and uniqueness in signalling games. JET 1990. [2220]
Farrell, Meaning and credibility in cheap talk games. GEB [2221]
Milgrom and Roberts, Limit pricing and entry under incomplete
information, an equilibrium analysis, EMA 1982 [2222] Milgrom, Good
news and bad news, representation and applications, Rand.
[2223] Folk Theorems for Repeated Games [2224] Dilip Abreu. On the
theory of infinitely repeated games with Discounting. Econometrica
1988 [2225] Benoit and Krishna. Finitely Repeated games.
Econometrica, 1985. [2226] James Friedman. A noncooperative
equilibrium for supergames. REStud 1971. [2227] James Friedman.
Cooperative equilibria in finite horizon supergames. JET 1985.
[2228] Fudenberg, Maskins. The Folk Theorem in repeated games with
discounting or with incomplete information. Economet. 1986. [2229]
Roy Radner. Collusive Behavior in non-cooperative epsilon
equilibria in oligopolies with long but finite lives. JET 1980.
[2230] Ariel Rubinstein. Equilibrium in supergames with the
overtaking criterion. JET 1977.
[2231] Renegotiation [2232] Benoit and Krisna, Renegotiation in
finitely repeated games. EMA 1993 [2233] Bergin and MacCleod,
Efficiency adn renegotiation in repeated games. JET 1993 [2234]
Andreas Blume, Interplay communication in repeated games. GEB 1994
[2235] Geir Asheim, Extending renegotiation proofness to infinite
horizon games. GEB 1991 [2236] Bernheim and Ray, Collective dynamic
consistency in repeated games. GEB 1989 [2237] Farrel and Maskin,
Renegotiation in Repeated Games. GEB 1989
[2238] Cooperative Game Theory [2239] Freidman, Game theory with
applications to economics chapter 6 and 7 [2240] Nash, The
Bargaining problem. EMA 1950 [2241] Kalai and Smordinski, Other
Solutions to Nash's problem. EMA 1975
[2242] Noncooperative Bargaining [2243] Rubinstein, Perfect
equiibrium in a bargaining model. EMA 1982 [2244] Joel Watson,
Alternating offer bargaining with two sided incomplete information.
REStud 1999
[2245] Reputation [2246] Kreps, Milgrom, Roberts and Wilson,
Reputation and imperfect information: predation, reputation and
entry deterence: rational cooperation in the finitely repeated
prisoner's dilemna. JET 1981 [2247] Aumann and Sorin, Cooperation
and Bounded recal. GEB 1989 [2248] Schmidt, Reputation and
equilibrium characterization in repeated games with conflicting
interests, Economet. 1993, 325-352 [2249] Cripps and Thomas,
Reputation and Commitment in Two person games without discounting,
EMA, 1995, 1401-1420 [2250] Joel Watson, A reputation refinement
withough equilibrium, EMA 1993, 199-206 [2251] Celentani, Fudenberg
and Levine, Maintaining a reputation against a long lived opponent
EMA 1996, 691-704
[2252] Evolutionary Game Theory [2253] Vince Crawford, An
Evolutionary interpretation of VHBB's experimental results on
coordination. GEB 1991 [2254] Gilboa and Matsui, Social Stability
and Equilibrium, EMA 1991 [2255] Kandori, Mailath and Rob,
Learning, Mutation, and Long Run Equilibria in games, EMA 1993.
[2256] Peyton Young, An Evolutionary Model of Bargaining, JET 1993
[2257] Peyton Young, The Evolution of Conventions, EMA 1993 [2258]
Larry Samuelson, Stochastic Stability with alternative best
replies. JET [2259] Noldeke and Samuelson, The Evolution of
Backwards and Forwards Induction, GEB 1993 [2260] Jack Robles, An
Evolutionary Folk Theorem For Finitely Repeated Games CU WP 99
[2261] Kim and Sobel, An Evolutionary Approach to Preplay
Communication EMA 1995
[2262] General Game Theory [2263] Bierman H. S. & Fernandez L.,
Game Theory with Economic Applications, Addison-Wesley, 1993.
[2264] Dixit & Nalebuff, Thinking Strategically: the
Competitive Edge in Business, Politics, and Everyday Life, New
York: Norton, 1991. [2265] McMillan J., Games, Strategies, and
Managers, Oxford: OUP, 1992. [2266] Baird D. G., Gertner R. H., and
Picker R. C., Game Theory and the Law, Harvard U. P., 1994. [2267]
Rasmusen E., Games and Information: An Introduction to Game Theory,
Oxford: B. Blackwell, 2nd edition, 1994. [2268] Ghemawat P., Games
Businesses Play: Cases and Models, New York: Wiley, 1995. [2269]
Gardner R., Games for Business and Economics, New York: Wiley,
1995.
[2270] Strategic Decision Making [2271] Dixit & Nalebuff,
Intro; Ch2 Anticipating your rival's response; [2272] Ch3 Seeing
through your rival's response. [2273] Barnett, F. W. Making game
theory work in practice, Wall Street Journal, 1995. [2274] Bierman
& Fernandez, Ch5 Nash equilibrium I, Chi 1 Nash equilibrium II
[2275] O'Neill B., International escalation and the dollar auction,
Journal of Conflict Resolution, 1986. [2276] Schelling T. C., Ch7
Hockey helmets, daylight saving, and other binary choices, in his
Micromotives and Macrobehavior, NY: Norton, 1978. [2277] Marks R.
E., Competition and common property, 1998. [2278] McMillan J., Ch3
Understanding cooperation and conflict. [2279] McAfee R. P. &
J. McMillan, Competition and game theory, Journal of Marketing
Research, 1996. [2280] Baird, Gertner, & Picker, Chi
Simultaneous decision-making and the normal form game. [2281]
Gardner, Ch1 Introduction, Ch2 Two-person games, Ch16 Voting games.
[2282] Rasmusen, Chi The rules of the game. [2283] Schelling, What
is game theory? in his Choice and Consequence: Perspectives of an
Errant Economist, Camb.: Harvard UP, 1980.
[2284] Decision Analysis--Games Against Nature [2285] Apocalpse
maybe, and An insurer's worst nightmare, The Economist, 1995/96
[2286] Bierman & Fernandez, Chs 1-3. [2287] Ulvila J. W. &
R. Brown, Decision analysis comes of age, Harvard Buisness Review
1982. [2288] Howard R. A., Decision analysis: practice and promise,
Management Science, 1988. [2289] Clemen R. T., Making Hard
Decisions: An Introduction to Decision Analysis, Belmont, Calif.:
Duxbury, 1996. [2290] Samson D., Chs 2-6, 11, Managerial Decision
Analysis, Chicago: R. D. Irwin, 1988.
[2291] Strategic Moves [2292] Dixit & Nalebuff, Ch5 Strategic
moves. [2293] Brams S. J. & J. M. Togman, Cooperation through
threats: the Northern Ireland case, PS: Political Science &
Politics, March 1998. [2294] Gardner, Ch4 n-person games, Ch5
Non-cooperative games. [2295] Colman A. M., Ch8 Multi-person games:
social dilemmas, in his Game Theory and Exper. Games, Oxford:
Pergamon, 1982. [2296] Kay J., Ch3 Co-operation and Co-ordination,
in his Foundations of Corporate Success: How Business Strategies
Add Value, Oxford: OUP, 1993. [2297] Brams S. J., Chi International
relations games, in Game Theory and Politics, NY: Macmillan,
1975.
[2298] Credible Commitment [2299] Dixit & Nalebuff, Ch6
Credible commitments. [2300] Bierman & Fernandez, Ch23
Subgame-perfect equilibrium [2301] Rasmusen, Ch4.1 Subgame
perfection. [2302] Gardner, Ch6 Credibility and subgame perfection.
[2303] Ghemawat, Ch3 Preemptive capacity expansion in the titanium
dioxide industry.
[2304] Repetition and Reputation [2305] Dixit & Nalebuff, Ch4
Resolving the Prisoner's Dilemma; Ch9 Cooperation and coordination.
[2306] Nowak, M., R. May, & K. Sigmund, The arithmetic of
mutual help, Scientific American, 1995 [2307] Hofstadter D., Ch29
The Prisoner's Dilemma computer tournaments and the evolution of
cooperation, in his Metamagical Themas, Penguin, 1985. [2308] Marks
R. E., Midgley FD. F., & Cooper L. G., Adaptive behaviour in an
oligopoly, in Evolutionary Algorithms in Management Applications,
ed. by J. Biethahn & V. Nissen, (Berlin: Springer-Verlag),
1995. [2309] Baird Gertner & Picker, Ch2 Dynamic interaction
and the extensive-form game, Ch5 Reputation and repeated games.
[2310] Gardner, Ch7 Repeated games, Ch8 Evolutionary stability and
bounded rationality. [2311] Rasmusen, Ch4 Dynamic games and
symmetric information, Ch5 Reputation and repeated games with
symmetric information.
[2312] Unpredictability [2313] Dixit & Nalebuff, Ch7
Unpredictability; Ch8 Brinkmanship. [2314] Bierman & Fernandez,
Ch11.9 [2315] Gardner, Ch3 Mixed strategies. [2316] Rasmusen, Ch3
Mixed and continuous strategies.
[2317] Bargaining [2318] Dixit & Nalebuff, Ch10 The voting
strategy; Ch11 Bargaining. [2319] McMillan, Ch5 Gaining bargaining
power; Ch6 Using information strategically. [2320] Elster J., Ch14
Bargaining, in Nuts and Bolts for the Social Sciences, Camb.: CUP,
1989 [2321] Murnighan J. K., Game's End, Chapter 15 in his:
Bargaining Games: A New Approach to Strategic Thinking in
Negotiations, NY: William Morrow, 1992. [2322] Bierman &
Fernandez, Ch6 Bargaining. [2323] Schelling T. C., Ch2 Essay on
bargaining, in The Strategy of Conflict, Camb.: Harvard UP, 1980.
[2324] Baird Gertner & Picker, Ch7 Noncooperative bargaining
[2325] Gardner, Ch12 Two-person bargains. Ch14 n-person bargaining
and the core. [2326] Rasmusen, Ch11 Bargaining. [2327] Brams S. J.,
Negotiation Games: Applying Game Theory to Bargaining and
Arbitration, NY: Routledge, 1990.
[2328] Using Information Strategically [2329] McMillan, Ch6 Using
information strategically [2330] Bierman & Fernandez, Ch17
Bayesian equilibrium, Ch19 Adverse selection and credit rationing
[2331] Rasmusen, Ch2 Information P-13 [2332] Baird Gertner &
Picker, Ch4 Signalling, screening, and nonverifiable information
[2333] Gardner, Ch9 Signaling games.
[2334] Bidding in Competition [2335] Revenge of the nerds, It's
only a game, and Learning to play the game, The Economist, 1994
[2336] Landsburg S. E., Cursed winners and glum losers, Ch18 of his
The Armchair Economist: Economics and Everyday life, New York: The
Free Press, 1993. [2337] Norton, R., Winning the game of business,
Fortune, 1995, [2338] Koselka, R., Playing poker with Craig McCaw,
Forbes, 1995, [2339] Dixit & Nalebuff, Ch12 Incentives. [2340]
McMillan, Ch11 Bidding in competition [2341] McAfee R. P. & J.
McMillan, Analyzing the airwaves auction, Journal of Economic
Perspectives, 1996 [2342] R. Marks, Closed tender vs. open bidding
auctions, 22 December, 1994. [2343] The Economist, Secrets and the
prize, 12 Oct. 1996, p. 98. [2344] Scientific American, Making
honesty pay, January 1997, p. 13. [2345] Gardner, Ch11 Auctions.
[2346] Brams S. J. & A. D. Taylor, Fair division by auctions,
Ch9 of their Fair Division: From Cake-Cutting to Dispute
Resolution, Cambridge: CUP, 1996. [2347] Rasmusen, Ch12
Auctions.
[2348] Contracting, or the Rules of the Game [2349] Kay, Ch4
Relationships and contracts. [2350] Dixit & Nalebuff, Ch12
Incentives. [2351] McMillan, Ch8 Creating incentives; Ch9 Designing
contracts; Ch10 Setting executives' salaries. [2352] Williamson O.
E., Strategizing, economizing, and economic organization, Strategic
Management Journal, 1991. [2353] Bierman & Fernandez, Ch7
Involuntary unemployment. [2354] Gardner, Ch10 Games between a
principal and an agent. [2355] Milgrom P. & Roberts J., Ch5
Bounded rationality and private information; Ch6 Moral hazard and
performance incentives. Economics, Organization and Management,
Englewood Cliffs: Prentice-Hall, 1992.
[2356] Choosing the Right Game: Co-Opetition [2357] Brandenburger
A. M. & B. J. Nalebuff, The right game: using Game Theory to
shape strategy, Harvard Business Review, 1995 [2358]
mayet.som.yale.edu/coopetition/index2.html [2359] Koselka R.,
Businessman's dilemma, and Evolutionary economics: nice guys don't
finish last, Forbes, Oct. 11, 1993. [2360] Brandenburger A. M.
& B. J. Nalebuff, Co-opetition: 1. A revolutionary mindset that
combines competition and cooperation; 2. The Game Theory Strategy
that's changing the game of business. New York: Currency Doubleday,
1996. [2361] Brandenburger A. M. & Harborne W. S. Jr.,
Value-based business strategy, J. Economics and Management
Strategy, 5(1), 1996. [2362] Baird Gertner & Picker, Ch6
Collective action, embedded games, and the limits of simple models.
[2363] Morrow J. D., Game Theory for Political Scientists,
Princeton: P.U.P., 1994. [2364] Casson M., The Economics of
Business Culture: Game Theory, Transaction Costs and Economic
Performance, Oxford: OUP, 1991. [2365] Schelling T. C., Altruism,
meanness, and other potentially strategic behaviors, Am. Economic
Rev 68(2): 229-231, May 1978. [2366] Crawford, Schelling and the
analysis of strategic behavior, in Strategy and Choice, ed. by R.
J. Zeckhauser, MIT Press, 1991. [2367] For a history of game theory
since Old Testament times, point your browser at the following URL:
www.canterbury.ac.nz/econ/hist.htm [2368] For further surfing on
the Net about game theory, start at the following URLs: [2369]
www.pitt.edu/.about.alroth/alroth.html [2370] Eddie Dekel, Drew
Fudenberg and David K. Levine, Learning to Play Bayesian Games
(Jun. 20, 2001). [2371] www.gametheory.net/html/lectures.html
[2372] Drew Fudenberg and David K. Levine, The Nash Threats Folk
Theorem With Communication and Approximate Common Knowledge in Two
Player Games (Jun. 10, 2002).
GAME THEORY AND AD HOC NETOWRKS REFERENCES APPENDIX
[2372] [2373] E. Altman, R. El Azouzi, and T. Jimenez. Slotted
aloha as a stochastic game with partial information. In Proc.
WiOpt'03, 2003. [2374] A Archer and E Tardos. Truthful mechanisms
for one-parameter agents. In Proc. 42nd IEEE Symp. On Foundations
of Computer Science, 2001. [2375] N. Ben Salem, L. Buttyan, J. P.
Hubaux, and Jakobsson M. A charging and rewarding scheme for packet
forwarding. In Proceeding of Mobihoc, June 2003. [2376] L.
Blazevic, L. Buttyan, S. Capkun, S. Giordiano, J.-P. Hubaux, and
J.-Y. Le Boudec. Self-organization in mobile ad-hoc networks: the
approach of terminodes. IEEE Communications Magazine,
39(6):166-174, June 2001. [2377] G. E. Bolton and A. Ockenfels.
ERC: A theory of equity, reciprocity and competition. The American
Economic Review, 90:166-193, March 2000. [2378] A. Bovopoulos and
A. Lazar. Asynchronous iterative algorithms for optimal load
balancing. In Proceedings of the 22nd Annual Conference on
Information Sciences and Systems, pages 1051-1057, 1988. [2379]
Felix Brandt and Gerhard Wei.beta., Antisocial Agents and Vickrey
Auctions. In Pre-proceedings of the Eighth International Workshop
on Agent Theories, Architectures, and Languages (ATAL-2001), pages
120-132, 2001. [2380] Felix Brandt. A Verifiable, Bidder-Resolved
Auction Protocol. In Proceedings of the 5th International Workshop
on Deception, Fraud and Trust in Agent Societies, pages 18-25,
2002. [2381] S. Buchegger and J. Le Boudec. Performance analysis of
the CONFIDANT protocol. In Proceedings of IEEE/ACMWorkshop on
Mobile Ad Hoc Networking and Computing (MobiHOC), June 2002. [2382]
R. Buyya, H. Stockinger, J. Giddy, and D. Abramson. Economic Models
for Management of Resources in Peer-to-Peer and Grid Computing. In
Proceedings of the SPIE International Symposium on The Convergence
of Information Technologies and Communications (ITCOM), August
2001. [2383] M. Castro, P. Druschel, A. Ganesh, A. Rowstron, and D.
S. Wallach. Security for structured peer-to-peer overlay networks.
In Proc. 5th Symposium on Operating Systems Design and
Implementation, Boston, Mass., December 2002. [2384] Clarke, E. H.
(1971). Multipart pricing of public goods, Public Choice 11, 17-33.
[2385] T. Clausen and P. Jacquet. Optimized link state routing
protocol. October 2003. http://hipercom.inria.fr/olsr/ [2386] S.
Corson and J. Macker. Mobile ad hoc networking (MANET): Routing
protocol performance issues and evaluation considerations. Request
for comments 2501, Internet Engineering Task Force, 1999.
http://www.rfc-editor.org/ [2387] J. Crowcroft, R. Gibbens, F.
Kelly, and S. Ostring. Modelling incentives for collaboration in
mobile ad hoc networks. In Proceedings of WiOpt'03, 2003. [2388]
Dasgupta, P., P. Hammond, and E. Maskin (1979). The implementation
of social choice rules, Review of Economic Studies 46, 185-216.
[2389] Deering, S., D. Estrin, D. Farinacci, V. Jacobson, C. Liu,
and L. Wei (1996). The PIM architecture for wide-area multicast
routing, ACM/IEEE Transactions on Networking 54, 153-162. [2390] A.
Demers, S. Keshav, and S. Shenker. Analysis and simulation of a
fair queueing algorithm. In SIGCOMM '89, Proceedings of the ACM
Symposium on Communications Architectures & Protocols, pages
1-12, 1989. [2391] C. Douligeris and R. Mazumdar. User optimal flow
control in an integrated environment. In Proceedings of the Indo-US
Workshop on Signals and Systems, 1988. [2392] Joan Feigenbaum,
Christos H Papadimitriou, and Scott Shenker. Sharing the cost of
multicast transmissions. Journal of Computer and System Sciences,
63:21-41, 2001. [2393] Feigenbaum, Joan, Christos Papadimitriou,
Rahul Sami, and Scott Shenker (2002). "A BGP-based Mechanism for
Lowest-Cost Routing." In Proc. 21st Symposium on Principles of
Distributed Computing, ACM Press, 173-182. [2394] J. Feigenbaum and
S. Shenker. Distributed algorithmic mechanism design: Recent
results and future directions. In Proc. 6th Int'l Workshop on
Discrete Algorithms and Methods for Mobile Computing and
Communications, pages 1-13, Atlanta, Ga., September 2002. [2395] T.
Fent, G. Feichtinger, and G. Tragler. A dynamic game of offending
and law enforcement. International Game Theory Review, 4(1):71-89,
2002. [2396] Ferguson, D., C. Nikolaou, and Y. Yemini (1989). An
economy for flow control in computer networks, in "Proceedings of
the 8th Infocom," pp. 100-118, IEEE Computer Society Press, Los
Alamitos. [2397] S. Floyd and K. Fall. Promoting the use of
end-to-end congestion control. IEEE/ACM Transactions on Networking,
7(4):458-472, August 1999. [2398] E. Friedman and D. Parkes,
"Pricing WiFi at Starbucks--Issues in Online Mechanism Design", In
Proc. Fourth ACM Conf. on Elec. Commerce (EC'03), 2003. Extended
version at www.eecs.harvard.edu/econcs/pubs/online.pdf. [2399]
citeseer.nj.nec.com/article/friedman03pricing.html [2400] Friedman,
E., and S. Shenker (1997). "Learning and Implementation in the
Internet," preprint. www.aciri.org/shenker/decent.ps [2401] A. C.
Fuqua, T-W Ngan, and D. S. Wallach, "Economic Behavior of
Peer-to-Peer Storage Networks", Workshop on Economics of
Peer-to-Peer Systems, Berkeley, Calif., 2003,
citeseer.nj.nec.com/fuqua03economic.html [2402] Goldberg, A. V., J.
D. Hartline, and A. Wright (1999). "Competitive Auctions and
Digital Goods," InterTrust Technical Report 99-01. Available at
http://www.intertrust.com/star/tr/tr-99-01.html [2403] A. Goldsmith
and S. Wicker. Design challenges for energy-constrained ad hoc
wireless networks. IEEE Wireless Communications, 9(4):8-27, 2002.
[2404] P. Golle, K. Leyton-Brown, I. Mironov, and M. Lillibridge.
Incentives for sharing in peer-to-peer networks. In Proc. 3rd ACM
Conf. on Electronic Commerce, Tampa, Fla., October 2001. [2405] Z.
Haas. A new routing protocol for reconfigurable wireless networks.
In IEEE 6th International Conference on Universal Communications
Record, volume 2, pages 562-566, October 1997. [2406] Garrett
Hardin. The Tragedy of the Commons. Science, 162:1243-1248,1968.
Alternate Location: http://dieoff.com/page95.htm. [2407] Michael
Harkavy, J. D. Tygar, and Hiroaki Kikuchi. Electronic Auctions with
Private Bids. In 3rd USENIX Workshop on Electronic Commerce, pages
61-74, September 1998. [2408] X. Hong, K. Xu, and M. Gerla.
Scalable routing protocols for mobile ad hoc networks. IEEE
Networks, 16(4):11-21, July 2002. [2409] M.-T. Hsiao and A. Lazar.
Optimal decentralized flow control of markovian queueing networks
with multiple controllers. Performance Evaluation, 13(3):181-204,
1991. [2410] Jackson, Matthew O., and Asher Wolinsky (1996). "A
Strategic Model of Social and Economic Networks." Journal of
Economic Theory 71, 44-74. [2411] M. Jakobsson, J. P. Hubaux, and
L. Huttyan. A micro-payment scheme encouraging collaboration in
multi-hop cellular networks. In Proceedings of Financial Crypto
2003, January 2003. [2412] Y. Jin and G. Kesidis. Equilibria of a
noncooperative game for heterogenous users of an ALOHA network.
IEEE Communications Letters, 6(7):282-284, July 2002. [2413] D.
Johnson, D. Maltz, and Y.-C. Hu. The dynamic source routing
protocol for mobile ad hoc networks, April 2003. [2414]
http://www.ietf.org/internet-drafts/draft-ietf-manet-dsr-09.txt
[2415] Johnson, D. S., M. Minko_, and S. Phillips (2000). The prize
collecting Steiner tree problem: theory and practice, in
"Proceedings of the 11th Symposium on Discrete Algorithms," pp.
760-769, ACM Press/SIAM, New York/Philadelphia. [2416] Y. Korilis
and A. Lazar. On the existence of equilibria in noncooperative
optimal flow control. J ACM, 42(3):584-613, 1995. [2417] Korilis,
Y., A. A. Lazar, and A. Orda (1995). Architecting noncooperative
networks, J. Sel. Areas in Comm 13, 1241-1251. [2418] R. La and V.
Anantharam. Charge-sensitive tcp and rate control in the internet.
In Proceedings of INFOCOM 2000, 2000. [2419] R. La and V.
Anantharam. Optimal routing control: Repeated game approach. IEEE
Transactions on Automatic Control, 47(3):437-450, 2002. [2420] Ron
Lavi and Noam Nisan. Competitive analysis of incentive compatible
on-line auctions. In Proc. 2nd ACM Conf. on Electronic Commerce
(EC-00), 2000. [2421] S.-J. Lee, W. Su, J. Hsu, M. Gerla, and R.
Bagrodia. A performance comparison study of ad hoc wireless
multicast protocols. In Proceedings of IEEE INFOCOM 2000, pages
565-574, March 2000. [2422] A. Legout and E. W. Biersack.
Revisiting the fair queueing paradigm for end-to-end congestion
control. IEEE Network Magazine, 16(5):38-46, September 2002. [2423]
A. B. MacKenzie and S. B. Wicker. Selfish users in aloha: A
game-theoretic approach. In Vehicular Technology Conference, 2001.
VTC 2001 Fall. IEEE VTS 54th, volume 3, October 2001. [2424] J.
MacKie-Mason and H. Varian. Pricing congestible network resources.
IEEE Journal on Selected Areas in Communications, 13(7):1141-1149,
1995. [2425] P. Marbach. Priority service and max-min fairness. In
Proceedings of IEEE INFOCOM 2002, volume 1, pages 266-275, 2002.
[2426] S. Marti, T. J. Giuli, K. Lai, and M. Baker. Mitigating
routing misbehavior in mobile ad hoc networks. In Proceedings of
MOBICOM 2000, August 2000. [2427] K. Mase, Y. Wada, N. Mori, K.
Nakano, M. Sengoku, and S. Shinoda. Flooding schemes for a
universal ad hoc network. In Industrial Electronics Society, 2000.
IECON 2000., volume 2, pages 1129-1134, 2000. [2428] R. Mazumdar,
L. Mason, and C. Douligeris. Fairness in network optimal flow
control: Optimality of product forms. IEEE Transactions on
Communications, 39(5):775-782, 1991. [2429] P. Michiardi and R.
Molva. Core: A collaborative reputation mechanism to enforce node
cooperation in mobile ad hoc networks. In Communication and
Multimedia Security 2002 Conference, 2002. [2430] P. Michiardi and
R. Molva. Game theoretic analysis of security in mobile ad hoc
networks. Technical Report RR-02-070, Institut Eurecom, 2002.
[2431] P. Michiardi and R. Molva. A game theoretical approach to
evaluate cooperation enforcement mechanisms in mobile ad hoc
networks. In Proceedings of WiOpt'03, March 2003. [2432] Dov
Monderer and Moshe Tennenholtz. Distributed Games: From Mechanisms
to Protocols. In Proceedings of the 16th National Conference on
Artificial Intelligence (AAAI), pages 32-37, 1999. [2433] Moulin,
H. (1999). Incremental cost sharing; characterization by
strategyproofness, Social Choice and Welfare 16, 279-320. [2434]
Moulin, H. and S. Shenker (1997). Strategyproof Sharing of
Submodular Costs: Budget Balance Versus Efficiency, to appear in
Economic Theory. www.aciri.org/shenker/cost.ps [2435] Moulin,
Herve, and Scott Shenker (2001). "Strategyproof Sharing of
Submodular Costs: Budget Balance versus Efficiency." Economic
Theory 18, 511-533. [2436] J. B. Nagle. On packet switches with
infinite storage. IEEE Transactions on Communications,
35(4):435-438, April 1987. [2437] J. F. Nash. Non-cooperative
games. Annals of Mathematics, 54(2):286-295, September 1951. [2438]
T.-W. J. Ngan, D. S. Wallach, and P. Druschel. Enforcing fair
sharing of peer-to-peer resources. In Proc. 2nd Intl Workshop on
Peer-to-Peer Systems, Berkeley, Calif., February 2003. [2439] Noam
Nisan and Amir Ronen. Algorithmic mechanism design. Games and
Economic Behavior, 35:166-196, 2001. [2440] Nisan, N. (1999).
Algorithms for selfish agents, in "Proceedings of the 16th
Symposium on Theoretical Aspects of Computer Science," pp. 1-17,
Springer-Verlag, Berlin. Lecture Notes in Computer Science, Vol.
1563. [2441] Nisan, N. and A. Ronen (2000). Computationally
Feasible VCG Mechanisms, to be presented at "Games 2000."
http:/www.cs.huji.ac.il/.about.noam/vcgbased.ps [2442] Noam Nisan
and Amir Ronen. Algorithmic Mechanism Design. In Proceedings of the
31st ACM Symposium on Theory of Computing, pages 129-140, 1999.
[2443] Osborne, M.-J. and A. Rubinstein (1994). "A Course in Game
Theory," MIT Press, Cambridge Mass. [2444] R. Ogier, F. Templin,
and M. Lewis. Topology dissemination based on reversepath
forwarding, October 2003. [2445]
vesuvio.ipv6.cselt.it/internet-drafts/draft-ietf-manet-tbrpf-11.tx-
t [2446] E. Ogston and S. Vassiliadis. A Peer-to-Peer Agent
Auction. In Proceedings of the First International Joint Conference
on Autonomous Agents and Multi-Agent Systems (AAMAS), 2002. [2447]
A. Orda, R. Rom, and N. Shimkin. Competitive routing in multi-user
communication networks. IEEE/ACM Transactions on Networking,
1(5):510-521, October 1993. [2448] M. J. Osborne and A. Rubinstein.
A Course in Game Theory. MIT Press, Cambridge, 1994. [2449] C.
Papadimitriou. Algorithms, games, and the Internet. In Proc. 33rd
ACM Symposium on Theory of Computing, pages 1-5, Hersonissos,
Crete, Greece, July 2001. [2450] D. C. Parkes. Iterative
Combinatorial Auctions: Achieving Economic and Computational
Efficiency (Chapter 2). PhD thesis, Univesity of Pennsylvania, May
2001. http://www.eecs.harvard.edu/.sup..about.parkes/pubs/ch2.ps.
[2451] W. Peng, X.-C. Lu. On the reduction of broadcast redundancy
in mobile ad hoc networks. In Mobile and Ad Hoc Networking and
Computing, 2000. MobiHOC., pages 129-130, 2000. [2452] C. Perkins,
E. Belding-Royer, and S. Das. Ad hoc on-demand distance vector
(AODV) routing. Request for comments 3561, Internet Engineering
Task Force, 2003. [2453] C. E. Perkins, editor. Ad Hoc Networking.
Addison-Wesley, Boston, 2001. [2454] Adrian Perrig, Sean Smith,
Dawn Song, and J. Doug Tygar. SAM: A Flexible and Secure Auction
Architecture Using Trusted Hardware, 1991.
citeseer.nj.nec.com/perrig91sam.html [2455] V. Rodoplu and H.-Y.
Meng. Minimum energy mobile wireless networks. IEEE Journal on
Selected Areas in Communications, 17(8):1333-1344, August 1999.
[2456] A. Rowstron and P. Druschel. Pastry: Scalable, distributed
object address and routing for large-scale peer-to-peer systems. In
Proc. IFIP/ACM Intl Conf. on Distributed Systems Platforms, pages
329-350, Heidelberg, Germany, November 2001. [2457] A. Rowstron and
P. Druschel. Storage management and caching in PAST, a large-scale,
persistent peer-to-peer storage utility. In Proc. 18th ACM
Symposium on Operating Systems Principles, pages 188-201, Chateau
Lake Louise, Banff, Canada, October 2001. [2458] E. Royer and C.-K.
Toh. A review of current routing protocols for ad hoc mobile
wireless networks. IEEE Personal Communications, 6(2):46-55, April
1999. [2459] T. Sandholm. Distributed rational decision making. In
G. Weig, editor, Multiagent Systems: A Modern Approach to
Distributed Artificial Intelligence, chapter 5. The MIT Press,
1999. [2460] Tuomas Sandholm. Limitations of the Vickrey Auction in
Computational Multiagent Systems. In Proceedings of the 2nd
International Conference on Multi-Agent Systems (ICMAS). AAAI
Press, 1996. Menlo Park, Calif. [2461] S. Shenker. Making greed
work in networks: A game-theoretic analysis of switch service
disciplines. IEEE/ACM Transactions on Networking, 3(6):819-831,
December 1995. [2462] S. Singh, M. Woo, and C. S. Raghavendra.
Power-aware routing in mobile ad hoc networks. In Proceeding of
MOBICOM 1998, pages 181-190, 1998. [2463] Shapley, L. S. (1953). A
value for n-person games, in
"Contributions to the Theory of Games," pp. 31-40, Princeton Press.
[2464] Sharman Networks. Kazaa Guide: Supernode FAQ, 2003.
http://www.kazaa.com/us/help/faq/supernodes.htm. [2465] J.
Shneidman and D. Parkes, "Rationality and Self-Interest in Peer to
Peer Networks", In Proc. 2nd Int. Workshop on Peer-to-Peer Systems
(IPTPS'03), 2003, citeseer.nj.nec.com/shneidman03rationality.html
[2466] Jeffrey Shneidman and David C. Parkes. Using Redundancy to
Improve Robustness of Distributed Mechanism Implementations, 2003.
Working Paper. Poster version to appear at ACM Conference on
Electronic Commerce EC'03. [2467] V. Srinivasan, P. Nuggehalli, C.
Chiasserini, and R. Rao. Cooperation in wireless ad hoc networks.
In Proceedings of INFOCOM 2003, volume 2, pages 808-817, 2003.
[2468] A. Urpi, M. Bonuccelli, and S. Giordano. Modelling
cooperation in mobile ad hoc networks: a formal description of
selfishness. In Proceedings of WiOpt'03, March 2003. [2469] A. van
den Nouweland, P. Borm, W. van Golstein Brouwers, R. Groot
Bruinderink, and S. Tijs. A game theoretic approach to problems in
telecommunication. Management Science, 42(2):294-303, February
1996. [2470] H. R. Varian. Mechanism design for computerized
agents. In Proc. First Usenix Workshop on Electronic Commerce, NY
1995 [2471] Vickrey, W. (1961). Counterspeculation, auctions, and
competitive sealed tenders, Journal of Finance 16, 8-37. [2472]
Walsh, W. and M. Wellman (1998). A market protocol for
decentralized task allocation, in "Proceedings of the Third
International Conference on Multi-Agent Systems," pp. 325-332, IEEE
Computer Society Press, Los Alamitos. [2473] J. E. Wieselthier, G.
D. Nguyen, and A. Ephremides. Algorithms for energy-efficient
multicasting in static ad hoc wireless networks. Mobile Networks
and Applications, 6:251-263, 2001. [2474] C. Jason Woodard and
David C. Parkes, 1st Workshop on the Economics of P2P systems,
Strategyproof Mechanisms for Ad Hoc Network Formation, 2003,
citeseernj.nec.com/woodard03strategyproof.html,
www.sims.berkeley.edu/research/conferences/p2pecon/papers/s6-woodard.pdf
[2475] Z. Zhang and C. Douligeris. Convergence of synchronous and
asynchronous greedy algorithms in a multiclass telecommunications
environment. IEEE Transactions on Communications,
40(8):1277-1281,1992. [2476] Urs Anliker, Jan Beutel, Matthias
Dyer, Rolf Enzler, Paul Lukowicz, Lothar Thiele, Gerhard Troester
[AnlikerBDELTT:03] A Systematic Approach to the Design of
Distributed Wearable Systems IEEE Transactions on Computers [2477]
Samuel Bendahan, Giovanni Camponovo, Yves Pigneur [BendahanCP:03]
Multi-issue actor analysis: tools and models for assessing
technology environments Journal of Decision Systems [2478] Aslan
Tchamkerten [Tchamkerten:03] On the Discreteness of
Capacity-Achieving Distributions IEEE Trans on Information Theory
[2479] Stephan ten Brink, Aslan Tchamkerten [BrinkT:03] Capacity of
the Binary Input Rayleigh Channel with Perfect Side Information
IEEE Transactions on Communications [2480] L. Buttyan, J.-P. Hubaux
and S. Capkun [ButtyanHC:03] A Formal Model of Rational Exchange
and its Application to the Analysis of Syverson's Protocol Journal
of Computer Security [2481] Marc Heissenbuttel, Torsten Braun,
Thomas Bernoulli, and Markus Waelchli [HeissenbuettelB:04a] BLR:
Beacon-Less Routing Algorithm for Mobile Ad-Hoc Networks Elsevier's
Computer Communications Journal [2482] Olivier Dousse, Francois
Baccelli, Patrick Thiran [DousseBT:03a] Impact of Interferences on
Connectivity in Ad Hoc Networks IEEE/ACM Transactions on Networking
[2483] Mario Cagalj, Jean-Pierre Hubaux and Christian Enz
[CagaljHE:03] Energy-efficient Broadcasting in All-wireless
Networks ACM Mobile Networks and Applications (MONET) [2484] Irena
Maravic, Martin Vetterli [MaravicV:04a] Exact Sampling Results for
Some Classes of Parametric Non-Bandlimited 2-D Signals IEEE
Transactions on Signal Processing, Volume 52, Issue 1, January 2004
[2485] Christian Plessl, Rolf Enzler, Herbert Walder, Jan Beutel,
Marco Platzner, Lothar Thiele and Gerhard Troester
[PlessIEWBPTT:03] The Case for Reconfigurable Hardware in Wearable
Computing Personal and Ubiquitous Computing, Springer-Verlag, Vol.
7, No. 5, pages 299-308, October 2003 [2486] L. Buttyan, J P.
Hubaux [ButtyanH:03a] Stimulating Cooperation in Self-Organizing
Mobile Ad Hoc Networks ACM/Kluwer Mobile Networks and Applications,
Vol. 8, No. 5, October 2003 [2487] Karl Aberer, Philippe
Cudre-Mauroux, Anwitaman Dana, Zoran Despotovic, Manfred Hauswirth,
Magdalena Punceva, Roman Schmidt [AbererCDDHPS:03] P-Grid: A
Self-organizing Structured P2P System ACM SIGMOD Record, 32(3),
September 2003 [2488] Olivier Dousse, Patrick Thiran [DousseT:03]
Physical connectivity of self-organized ad hoc wireless networks
IEEE Intelligent systems, Vol. 18, Iss. 4, July-August 2003 [2489]
Frank Siegemund, Michael Rohs [SiegemundR:03] Rendezvous layer
Protocols for Bluetooth-Enabled Smart Devices (extended version)
Personal and Ubiquitous Computing Journal (PUC), vol. 7, nr. 2,
July 2003 [2490] Benoit Garbinato, Philippe Rupp [GarbinatoR:03b]
From Ad Hoc Networks to Ad Hoc Applications ERCIM News, no 54, July
2003 [2491] M. Gastpar, B. Rimoldi and M. Vetterli [GastparRV:03]
To code or not to code: Lossy source-channel communication
revisited IEEE Transactions on Information Theory, 49(5):1147-1158,
May 2003 [2492] Karl Aberer, Philippe Cudre-Mauroux, Anwitaman
Dana, Zoran Despotovic, Manfred Hauswirth, Magdalena Punceva, Roman
Schmidt, Jie Wu [AbererCDDHPSW:03] Advanced Peer-to-Peer
Networking: The P-Grid System and its Applications PIK Journal
February 2003: Special Issue on Peer-to-Peer Systems; April-June
2003 [2493] Samarjit Chakraborty, Simon Kunzli, Lothar Thiele,
Andreas Herkersdorf, Patricia Sagmeister [ChakrabortyKTHS:03]
Performance Evaluation of Network Processor Architectures:
Combining Simulation with Analytical Estimation Computer Networks,
special issue on Network Processors, Volume 41, Issue 5, pages
641-665, Elsevier Science, April 2003 [2494] Srdjan Capkun, Levente
Buttyan and Jean-Pierre Hubaux [CapkunBH:03] Self-Organized
Public-Key Management for Mobile Ad Hoc Networks IEEE Transactions
on Mobile Computing, Vol. 2, No. 1, January-March 2003 [2495] D.
Tuninetti and G. Caire [TuninettiG:03] The Long-term average
capacity region per unit cost with application to protocol for
sensor networks European Transactions on Telecommunications.
Special Issue on Selected Papers from the Conference European
Wireless 2002. ETT Vol 14, No. 1, January-February 2003 [2496] L.
Buttyan and J.-P. Hubaux (eds.), G. Avoine, S. Buchegger, S.
Capkun, J Y. Le Boudec, S. Vaudenay et al. [ButtyanH:03b] Report on
a Working Session on Security in Wireless Ad Hoc Networks ACM
Mobile Computing and Comm Rev. Vol. 7, No. 1, January 2003 [2497]
Karl Aberer, Anwitaman Dana, Zoran Despotovic, Andreas Wombacher
[AbererDDW:03] Separating Business Process from User Interaction in
Web-Based Information Commerce Electronic Commerce Research, 3
(1-2): 83-111, January-April, 2003, Kluwer [2498] G. Camponovo, Y.
Pigneur [CamponovoP:02a] Analyzing the m-business landscape Annals
of Telecommunications, Hermes, January-February 2003, vol. 58, no.
1-2 [2499] Jeremy Elson, Kay Romer [ElsonR:03] Wireless Sensor
Networks: A New Regime for Time Synchronization ACM SIGCOMM
Computer Communication Review (CCR), January 2003 [2500] Karl
Aberer, Philippe Cudre-Mauroux, Manfred Hauswirth [AbererCH:02a] A
Framework for Semantic Gossiping ACM SIGMOD Record, December 2002
[2501] G. Avoine and S. Vaudenay [AvoineV:03a] Cryptography with
Guardian Angels: Bringing civilization to pirates--Abstract In L.
Buttyan and J.-P. Hubaux (Eds.), Report on a Working Session on
Security in Wireless Ad Hoc Networks, ACM Mobile Computing and
Communications Review (MC2R), Vol. 7, No. 1, 2003, pp. 74-94 [2502]
Kay Romer, Oliver Kasten, Friedemann Mattern [RomerKM:02]
Middleware Challenges for Wireless Sensor Networks ACM SIGMOBILE
Mobile Computing and Communication Review (MC2R), Fall 2002 [2503]
P. L. Dragotti, S. Servetto and M. Vetterli [DragottiSV:02] Optimal
filter banks for multiple description coding: analysis and
synthesis IEEE Transactions on Information Theory, 48(7):2036-2052,
July 2002 [2504] R. Karrer and T. Gross [KarrerG:02] Location
Selection for Active Services Cluster Computing 5(3): 265-275; July
2002 [2505] M. Vetterli, P. Marziliano, T. Blu [VetterliMB:02]
Sampling Signals with Finite Rate of Innovation IEEE Transactions
on Signal Processing, 50(6), 1417-1428, June 2002 [2506] Q. Li, B.
Rimoldi, and M. K. Simon [LiRS:02] Bandwidth-Efficient
Constant-Energy Trellis-Coded Modulation Schemes with Prescribed
Decoding Delay IEEE Trans. on Information Theory, Vol. 48, Number
5, May 2002 [2507] L. Blazevic, S. Giordano, J.-Y. Le Boudec
[BlazevicGL:02a] Self Organized Terminode Routing Cluster Computing
J, 5(2) April 2002 [2508] Mark Heitmann, Peter Aschmoneit
[HeitmannA:02a] Customer Centred Community Application Design
International Journal on Media Management (4:1, Spring 2002) [2509]
S. Capkun, M. Hamdi, J. P. Hubaux [CapkunHH:02] GPS-free
Positioning in Mobile Ad-Hoc Networks In Cluster Computing Journal,
April 2002, Vol. 5, No. 2 [2510] Magaly Dubosson, Alexander
Osterwalder, Yves Pigneur [DubossonOP:02] eBusiness Model Design,
Classification and Measurements Thunderbird International Business
Review, January 2002, vol. 44, no. 1: 5-23 [2511] K. Aberer, M.
Punceva, M. Hauswirth, R. Schmid [AbererPHS:02] Improving Data
Access in P2P Systems IEEE Internet Computing, January/February
2002, pp. 58-67 [2512] L. Blazevic, L. Buttyan, S. Capkun, S.
Giordano, J. P. Hubaux, J. Y. Le Boudec [BlazevicBCGHL:01]
Self-Organization in Mobile Ad-Hoc Networks: the Approach of
Terminodes IEEE Communications Magazine, June 2001. [2513] S.
Servetto, K. Nahrstedt [ServettoN:01] Broadcast-Quality Video over
IP IEEE Trans on Multimedia, 3(1):162-173, March 2001 [2514] J. P.
Hubaux, Th. Gross, J. Y. Le Boudec, M. Vetterli [HubauxGLV:01]
Towards self-organized mobile ad hoc networks: the Terminodes
project IEEE Communications Magazine, January 2001. [2515]
Evaluation of the Zaurus SL5600 PDA as a platform for ad-hoc
networking L. Previtali
http://www.terminodes.org/MV2003-Present/Lu13/Zaurus_Previtali.pdf
[2516] Simulating large ad-hoc networks with ns-2 V. Naoumov,
http://www.terminodes.org/MV2003-Present/Lu13/Simulating-Naoumov.pdf
[2517] Security of emergent properties in ad-hoc networks Prof. V.
Gligor, Univ. of Maryland
www.terminodes.org/MV2003-Present/Ma14/Gligor-MonteVerita.pdf
[2518] On the self-organization of security in multi-hop networks
Prof. JP. Hubaux
www.terminodes.org/MV2003-Present/Ma14/Multi-Hop-JPH.pdf [2519]
Immune Networking Systems Prof. J.-Y. Le Boudec
www.terminodes.org/MV2003-Present/Ma14/ImmuneLeBoudec.pdf [2520]
Fair exchange with guardian angels G. Avoine
www.terminodes.org/MV2003-Present/Ma14/FairExchange-Avoine.pdf
[2521] Spatial analysis of mobile ad-hoc networks under the Signal
to Interference Ratio connectivity model Prof. F. Baccelli, Ecole
Normale Superieure and INRIA, Paris
www.terminodes.org/MV2003-Present/Me15/Spacial-Baccelli.pdf [2522]
Connectivity and interferences in wireless ad-hoc networks, a
percolation approach O. Dousse
www.terminodes.org/MV2003-Present/Me15/OlivierDousseMonteverita.pdf
[2523] Ad-hoc networks: the worst and the average case Prof. R.
Wattenhofer
www.terminodes.org/MV2003-Present/Me15/MV-Wattenhofer.pdf [2524]
www.terminodes.org [2525] www.google.com/search?&q=terminodes
[2526] www.ietf.org/html.charters/manet-charter.html. [2527]
citeseer.nj.nec.com/cs?cs=1&q=manet&submit=Documents [2528]
www.google.com/search?&q=%22ad+hoc%22+and+game [2529]
citeseer.nj.nec.com/cs?cs=1&q=game+and+%22ad+hoc%22 [2530]
carmen.cselt.it/idxwg/manet.html
* * * * *
References