U.S. patent application number 13/843204 was filed with the patent office on 2017-02-23 for locating a mobile station and applications therefor.
The applicant listed for this patent is TracBeam LLC. Invention is credited to Dennis J. Dupray, Charles L. Karr, Frederick W. LeBlanc.
Application Number | 20170055130 13/843204 |
Document ID | / |
Family ID | 27487446 |
Filed Date | 2017-02-23 |
United States Patent
Application |
20170055130 |
Kind Code |
A1 |
LeBlanc; Frederick W. ; et
al. |
February 23, 2017 |
LOCATING A MOBILE STATION AND APPLICATIONS THEREFOR
Abstract
A location system is disclosed for wireless telecommunication
infrastructures. The system is an end-to-end solution having one or
more location systems for outputting requested locations of hand
sets or mobile stations (MS) based on, e.g., AMPS, NAMPS, CDMA or
TDMA communication standards, for processing both local mobile
station location requests and more global mobile station location
requests via, e.g., Internet communication between a distributed
network of location systems. The system uses a plurality of mobile
station locating technologies including those based on: (1) two-way
TOA and TDOA; (2) home base stations and (3) distributed antenna
provisioning. Further, the system can be modularly configured for
use in location signaling environments ranging from urban, dense
urban, suburban, rural, mountain to low traffic or isolated
roadways. The system is useful for 911 emergency calls, tracking,
routing, people and animal location including applications for
confinement to and exclusion from certain areas.
Inventors: |
LeBlanc; Frederick W.;
(Jessup, MD) ; Dupray; Dennis J.; (Golden, CO)
; Karr; Charles L.; (Tuscaloosa, AL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TracBeam LLC |
Golden |
CO |
US |
|
|
Family ID: |
27487446 |
Appl. No.: |
13/843204 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12861817 |
Aug 23, 2010 |
8994591 |
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13843204 |
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11069441 |
Mar 1, 2005 |
7812766 |
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12861817 |
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09820584 |
Mar 28, 2001 |
6952181 |
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11069441 |
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09230109 |
Jul 8, 1999 |
6236365 |
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PCT/US97/15933 |
Sep 8, 1997 |
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09820584 |
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09230109 |
Jul 8, 1999 |
6236365 |
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PCT/US97/15933 |
Sep 8, 1997 |
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11069441 |
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60056603 |
Aug 20, 1997 |
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60044821 |
Apr 25, 1997 |
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60025855 |
Sep 9, 1996 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 4/027 20130101;
G01S 5/021 20130101; G01S 1/026 20130101; G01S 5/0205 20130101;
G01S 5/0252 20130101; H04W 28/04 20130101; G01S 5/02 20130101; H04W
76/50 20180201; G01S 5/0018 20130101; H04W 4/90 20180201; G01S 5/06
20130101; H04W 88/06 20130101; G01S 5/0009 20130101; G01S 2205/006
20130101; G01S 1/045 20130101; G01S 5/0054 20130101; H04W 64/00
20130101; G01S 5/0257 20130101; G01S 2205/008 20130101; G01C 21/206
20130101; G01S 1/028 20130101 |
International
Class: |
H04W 4/02 20060101
H04W004/02; H04W 4/22 20060101 H04W004/22 |
Claims
1. (canceled)
2. The method of claim 3, further including performing the
following by computational equipment: obtaining information
indicative of one of: an acceleration, and a speed of the
particular mobile station.
3. A method, for each mobile device (M) of a plurality of wireless
mobile telecommunication devices, of providing for a condition
related to an event or circumstance of the mobile device M or a
user thereof, a notification related to the condition, wherein the
mobile device M wirelessly communicates with one or more of a
plurality of wireless networks when the mobile device M is in a
corresponding area having wireless coverage provided by each of the
one or more networks, each of the plurality of networks having a
corresponding plurality of spaced apart stationary network access
units, the access units for receiving from and transmitting to the
mobile device M wireless signal communication, comprising
performing the following by computational equipment: transmitting a
wireless communication between the mobile device M and a first of
the plurality of networks, wherein information indicative of the
mobile device M is stored in a persistent machine storage, the
information used for registering the mobile device M for a wireless
service with a first of the plurality of networks; receiving first
geolocation related data for the mobile device M, the first
geolocation related data obtained using characteristics of wireless
signals received at the mobile device M; wherein the first
geolocation related data is used to determine whether a first
location estimate of the mobile device M is at least one of: (a)
ambiguous, (b) cannot be obtained, (c) is not within a desired
range of accuracy, and (d) has an extent greater than or equal to a
predetermined size; obtaining a second location estimate of the
mobile device M wherein the second location estimate is obtained
using additional location information obtained at least in part
from second data obtained using wireless signals communicated
between the mobile device M and a second of the plurality of
networks, wherein the mobile device M is not registered for
communicating with the second network, and wherein the second
network registers mobile devices for communication therewith;
outputting resulting location data for the mobile device M, wherein
said resulting location data is dependent upon at least one of the
first and second estimates of the particular mobile station.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/861,817, filed Aug. 23, 2010, which is a
continuation-in-part of U.S. patent application Ser. No. 11/069,441
filed Mar. 1, 2005, which is a continuation of U.S. application
Ser. No. 09/820,584 filed Mar. 28, 2001, now U.S. Pat. No.
6,952,181, which is a continuation of U.S. application Ser. No.
09/230,109 filed Jul. 8, 1999, now U.S. Pat. No. 6,236,365, which
is the National Stage of International Application No.
PCT/US97/15933 filed Sep. 8, 1997 which, in turn, claims the
benefit of the following three applications: U.S. Provisional
Application No. 60/056,603 filed Aug. 20, 1997, U.S. Provisional
Application No. 60/044,821 filed Apr. 25, 1997; and U.S.
Provisional Application No. 60/025,855 filed Sep. 9, 1996.
[0002] All the above cited references are fully incorporated by
reference herein.
RELATED FIELD OF THE INVENTION
[0003] The present invention is directed generally to a system and
method for locating people or objects, and in particular to a
system and method for locating a wireless mobile radio station in a
macro base station, distributed antenna, or home base station
environment.
BACKGROUND OF THE INVENTION
[0004] Wireless communications systems are becoming increasingly
important worldwide. Wireless cellular telecommunications systems
are rapidly replacing conventional wire-based telecommunications
systems in many applications. Commercial mobile radio service
provider networks, and specialized mobile radio and mobile data
radio networks are examples. The general principles of wireless
cellular telephony have been described variously, for example in
U.S. Pat. No. 5,295,180 to Vendetti, et al filed Apr. 8, 1992,
which is incorporated herein by reference. There is great interest
in using existing infrastructures for wireless communication
systems for locating people and/or objects in a cost-effective
manner. Such a capability would be invaluable in a variety of
situations, especially in emergency or crime situations. Due to the
substantial benefits of such a location system, several attempts
have been made to design and implement such a system. Systems have
been proposed that rely upon signal strength and trilateralization
techniques to permit location include those disclosed in U.S. Pat.
No. 4,818,998 filed Mar. 31, 1986 and U.S. Pat. No. 4,908,629 filed
Dec. 5, 1988 both to Apsell et al. ("the Apsell patents"), and U.S.
Pat. No. 4,891,650 to Sheffer ("the Sheffer patent") filed May 16,
1988. The Apsell patents disclose a system employing a "homing-in"
scheme using radio signal strength, wherein the scheme detects
radio signal strength transmitted from an unknown location. This
signal strength is detected by nearby tracking vehicles, such as
police cruisers using receivers with directional antennas.
Alternatively, the Sheffer patent discloses a system using the FM
analog cellular network. This system includes a mobile transmitter
located on a vehicle to be located. The transmitter transmits an
alarm signal upon activation to detectors located at base stations
of the cellular network. These detectors receive the transmitted
signal and transmit, to a central station, data indicating the
signal strength of the received signal and the identity of the base
stations receiving the signal. This data is processed to determine
the distance between the vehicle and each of the base stations and,
through trilateralization, the vehicle's position. However, these
systems have drawbacks that include high expense in that special
purpose electronics are required. Furthermore, the systems are
generally only effective in line-of-sight conditions, such as rural
settings. Radio wave surface reflections, refractions and ground
clutter cause significant distortion, in determining the location
of a signal source in most geographical areas that are more than
sparsely populated. Moreover, these drawbacks are particularly
exacerbated in dense urban canyon (city) areas, where errors and/or
conflicts in location measurements can result in substantial
inaccuracies.
[0005] Another example of a location system using time of arrival
and triangulation for location are satellite-based systems, such as
the military and commercial versions of the Global Positioning
Satellite system (GPS). GPS can provide accurate position
determination (i.e., about 100 meters error for the commercial
version of GPS) from a time-based signal received simultaneously
from at least three satellites. A ground-based GPS receiver at or
near the object to be located determines the difference between the
time at which each satellite transmits a time signal and the time
at which the signal is received and, based on the time
differentials, determines the object's location. However, the GPS
is impractical in many applications. The signal power levels from
the satellites are low and the GPS receiver requires a clear,
line-of-sight path to at least three satellites above a horizon of
about 60 degrees for effective operation. Accordingly, inclement
weather conditions, such as clouds, terrain features, such as hills
and trees, and buildings restrict the ability of the GPS receiver
to determine its position. Furthermore, the initial GPS signal
detection process for a GPS receiver is relatively long (i.e.,
several minutes) for determining the receiver's position. Such
delays are unacceptable in many applications such as, for example,
emergency response and vehicle tracking.
[0006] Differential GPS, or DGPS systems offer correction schemes
to account for time synchronization drift. Such correction schemes
include the transmission of correction signals over a two-way radio
link or broadcast via FM radio station subcarriers. These systems
have been found to be awkward and have met with limited
success.
[0007] Additionally, GPS-based location systems have been attempted
in which the received GPS signals are transmitted to a central data
center for performing location calculations. Such systems have also
met with limited success due, for example, to the limited reception
of the satellite signals and the added expense and complexity of
the electronics required for an inexpensive location mobile station
or handset for detecting and receiving the GPS signals from the
satellites.
[0008] The behavior of a mobile radio signal in the general
environment is unique and complicated. Efforts to perform
correlation between radio signals and distance between a base
station and a mobile station are similarly complex. Repeated
attempts to solve this problem in the past have been met with only
marginal success. Factors include terrain undulations, fixed and
variable clutter, atmospheric conditions, internal radio
characteristics of cellular and PCS systems, such as frequencies,
antenna configurations, modulation schemes, diversity methods, and
the physical geometry of direct, refracted and reflected waves
between the base stations and the mobile. Noise, such as man-made
externally sources (e.g., auto ignitions) and radio system
co-channel and adjacent channel interference also affect radio
reception and related performance measurements, such as the analog
carrier-to-interference ratio (C/I), or digital
energy-per-bit/Noise density ratio (E.sub.b/No) and are particular
to various points in time and space domains.
[0009] Before discussing real world correlation between signals and
distance, it is useful to review the theoretical premise, that of
radio energy path loss across a pure isotropic vacuum propagation
channel, and its dependencies within and among various
communications channel types.
[0010] Over the last forty years various mathematical expressions
have been developed to assist the radio mobile cell designer in
establishing the proper balance between base station capital
investment and the quality of the radio link, typically using radio
energy field-strength, usually measured in microvolts/meter, or
decibels.
[0011] One consequence from a location perspective is that the
effective range of values for higher exponents is an increased at
higher frequencies, thus providing improved granularity of ranging
correlation.
[0012] Actual data collected in real-world environments uncovered
huge variations with respect to the free space path loss equation,
giving rise to the creation of many empirical formulas for radio
signal coverage prediction. Clutter, either fixed or stationary in
geometric relation to the propagation of the radio signals, causes
a shadow effect of blocking that perturbs the free space loss
effect. Perhaps the best known model set that characterizes the
average path loss is Hata's, "Empirical Formula for Propagation
Loss in Land Mobile Radio", M. Hata, IEEE Transactions VT-29, pp.
317-325, August 1980, three pathloss models, based on Okumura's
measurements in and around Tokyo, "Field Strength and its
Variability in VHF and UHF Land Mobile Service", Y. Okumura, et al,
Review of the Electrical Communications laboratory, Vol 16, pp
825-873, September-October 1968.
[0013] Although the Hata model was found to be useful for
generalized RF wave prediction in frequencies under 1 GHz in
certain suburban and rural settings, as either the frequency and/or
clutter increased, predictability decreased. In current practice,
however, field technicians often have to make a guess for dense
urban an suburban areas (applying whatever model seems best), then
installing a base stations and begin taking manual
measurements.
[0014] In 1991, U.S. Pat. No. 5,055,851 to Sheffer filed Nov. 29,
1989 taught that if three or more relationships have been
established in a triangular space of three or more base stations
(BSs) with a location database constructed having data related to
possible mobile station (MS) locations, then arculation
calculations may be performed, which use three distinct P.sub.or
measurements to determine an X,Y, two dimensional location, which
can then be projected onto an area map. The triangulation
calculation is based on the fact that the approximate distance of
the mobile station (MS) from any base station (BS) cell can be
calculated based on the received signal strength. Sheffer
acknowledges that terrain variations affect accuracy, although as
noted above, Sheffer's disclosure does not account for a sufficient
number of variables, such as fixed and variable location shadow
fading, which are typical in dense urban areas with moving
traffic.
[0015] Most field research before about 1988 has focused on
characterizing (with the objective of RF coverage prediction) the
RF propagation channel (i.e., electromagnetic radio waves) using a
single-ray model, although standard fit errors in regressions
proved dismal (e.g., 40-80 dB). Later, multi-ray models were
proposed, and much later, certain behaviors were studied with radio
and digital channels. In 1981, Vogler proposed that radio waves at
higher frequencies could be modeled using optics principles. In
1988 Walfisch and Bertoni applied optical methods to develop a
two-ray model, which when compared to certain highly specific,
controlled field data, provided extremely good regression fit
standard errors of within 1.2 dB.
[0016] In the Bertoni two ray model it was assumed that most cities
would consist of a core of high-rise buildings surrounded by a much
larger area having buildings of uniform height spread over regions
comprising many square blocks, with street grids organizing
buildings into rows that are nearly parallel. Rays penetrating
buildings then emanating outside a building were neglected.
[0017] After a lengthy analysis it was concluded that path loss was
a function of three factors: 1.) the path loss between antennas in
free space; 2.) the reduction of rooftop wave fields due to
settling; and 3.) the effect of diffraction of the rooftop fields
down to ground level.
[0018] However, a substantial difficulty with the two-ray model in
practice is that it requires a substantial amount of data regarding
building dimensions, geometry, street widths, antenna gain
characteristics for every possible ray path, etc. Additionally, it
requires an inordinate amount of computational resources and such a
model is not easily updated or maintained.
[0019] Unfortunately, in practice clutter geometry and building
heights are random. Moreover, data of sufficient detail is
extremely difficult to acquire, and regression standard fit errors
are poor; i.e., in the general case, these errors were found to be
40-60 dB. Thus the two-ray model approach, although sometimes
providing an improvement over single ray techniques, still did not
predict RF signal characteristics in the general case to level of
accuracy desired (<10 dB).
[0020] Work by Greenstein has since developed from the perspective
of measurement-based regression models, as opposed to the previous
approach of predicting-first, then performing measurement
comparisons. Apparently yielding to the fact that low-power, low
antenna (e.g., 12-25 feet above ground) height PCS microcell
coverage was insufficient in urban buildings, Greenstein, et al,
authored "Performance Evaluations for Urban Line-of-sight
Microcells Using a Multi-ray Propagation Model", in IEEE Globecom
Proceedings, 12/91. This paper proposed the idea of formulating
regressions based on field measurements using small PCS microcells
in a lineal microcell geometry (i.e., geometries in which there is
always a line-of-sight path between a subscriber's mobile and its
current microsite). Additionally, Greenstein studied the
communication channels variable Bit-Error-Rate (BER) in a spatial
domain, which was a departure from previous research that limited
field measurements to the RF propagation channel signal strength
alone. However, Greenstein based his finding on two suspicious
assumptions: 1) he assumed that distance correlation estimates were
identical for uplink and downlink transmission paths; and 2)
modulation techniques would be transparent in terms of improved
distance correlation conclusions. Although some data held very
correlation, other data and environments produced poor results.
Accordingly, his results appear unreliable for use in general
location context.
[0021] In 1993 Greenstein, et al, authored "A Measurement-Based
Model for Predicting Coverage Areas of Urban Microcells", in the
IEEE Journal On Selected Areas in Communications, Vol. 11, No. 7,
9/93. Greenstein reported a generic measurement-based model of RF
attenuation in terms of constant-value contours surrounding a given
low-power, low antenna microcell environment in a dense,
rectilinear neighborhood, such as New York City. However, these
contours were for the cellular frequency band. In this case, LOS
and non-LOS clutter were considered for a given microcell site. A
result of this analysis was that RF propagation losses (or
attenuation), when cell antenna heights were relatively low,
provided attenuation contours resembling a spline plane curve
depicted as an asteroid, aligned with major street grid patterns.
Further, Greenstein found that convex diamond-shaped RF propagation
loss contours were a common occurrence in field measurements in a
rectilinear urban area. The special plane curve asteroid is
represented by the formula:
[0022] x.sup.2/3+y.sup.2/3=r.sup.2/3. However, these results alone
have not been sufficiently robust and general to accurately locate
an mobile station, due to the variable nature of urban clutter
spatial arrangements.
[0023] At Telesis Technology in 1994 Howard Xia, et al, authored
"Microcellular Propagation Characteristics for Personal
Communications in Urban and Suburban Environments", in IEEE
Transactions of Vehicular Technology, Vol. 43, No. 3, 8/94, which
performed measurements specifically in the PCS 1.8 to 1.9 GHz
frequency band. Xia found corresponding but more variable outcome
results in San Francisco, Oakland (urban) and the Sunset and
Mission Districts (suburban).
[0024] The physical radio propagation channel perturbs signal
strength, frequency (causing rate changes, phase delay, signal to
noise ratios (e.g., C/I for the analog case, or E.sub.b/No, RF
energy per bit, over average noise density ratio for the digital
case) and Doppler-shift. Signal strength is usually characterized
by: [0025] Free Space Path Loss (L.sub.p) [0026] Slow fading loss
or margin (Lslow) [0027] Fast fading loss or margin
(L.sub.fast)
[0028] The cell designer increases the transmitted power P.sub.TX
by the shadow fading margin L.sub.slow which is usually chosen to
be within the 1-2 percentile of the slow fading probability density
function (PDF) to minimize the probability of unsatisfactorily low
received power level P.sub.RX at the receiver. The P.sub.RX level
must have enough signal to noise energy level (e.g., 10 dB) to
overcome the receiver's internal noise level (e.g., -118 dBm in the
case of cellular 0.9 GHz), for a minimum voice quality standard.
Thus in this example P.sub.RX must never be below -108 dBm, in
order to maintain the quality standard.
[0029] Additionally the short term fast signal fading due to
multipath propagation is taken into account by deploying fast
fading margin L.sub.fast, which is typically also chosen to be a
few percentiles of the fast fading distribution. The 1 to 2
percentiles compliment other network blockage guidelines. For
example the cell base station traffic loading capacity and network
transport facilities are usually designed for a 1-2 percentile
blockage factor as well. However, in the worst-case scenario both
fading margins are simultaneously exceeded, thus causing a fading
margin overload.
[0030] In Roy Steele's, text, Mobile Radio Communications, IEEE
Press, 1992, estimates for a GSM system operating in the 1.8 GHz
band with a transmitter antenna height of 6.4 m and a mobile
station receiver antenna height of 2 m, and assumptions regarding
total path loss, transmitter power would be calculated as
follows:
TABLE-US-00001 TABLE 1 GSM Power Budget Example Parameter dBm value
Will require L.sub.slow 14 L.sub.fast 7 LI.sub.path 110 Min. RX pwr
required -104 TXpwr = 27 dBm
[0031] Steele's sample size in a specific urban London area of
80,000 LOS measurements and data reduction found a slow fading
variance of
.sigma.=7 dB
[0032] assuming log-normal slow fading PDF and allowing for a 1.4%
slow fading margin overload, thus
L.sub.slow=2.sigma.=14 dB
[0033] The fast fading margin was determined to be:
L.sub.fast=7 dB
[0034] In contrast, Xia's measurements in urban and suburban
California at 1.8 GHz uncovered flat-land shadow fades on the order
of 25-30 dB when the mobile station (MS) receiver was traveling
from LOS to non-LOS geometries. In hilly terrain fades of +5 to -50
dB were experienced. Thus it is evident that attempts to correlate
signal strength with mobile station ranging distance suggest that
error ranges could not be expected to improve below 14 dB, with a
high side of 25 to 50 dB. Based on 20 to 40 dB per decade,
Corresponding error ranges for the distance variable would then be
on the order of 900 feet to several thousand feet, depending upon
the particular environmental topology and the transmitter and
receiver geometries.
[0035] Although the acceptance of fuzzy logic has been generally
more rapid in non-American countries, the principles of fuzzy logic
can be applied in wireless location. Lotfi A. Zadeh's article,
"Fuzzy Sets" published in 1965 in Information and Control, vol. 8,
Pg 338-353, herein incorporated by reference, established the basic
principles of fuzzy logic, among which a key theorem, the FAT
theorem, suggests that a fuzzy system with a finite set of rules
can uniformly approximate any continuous (or Borel-measureable)
system. The system has a graph or curve in the space of all
combinations of system inputs and outputs. Each fuzzy rule defines
a patch in this space. The more uncertain the rule, the wider the
patch. A finite number of small patches can always cover the curve.
The fuzzy system averages patches that overlap. The Fat theorem was
proven by Bart Kosko, in a paper entitled, "Fuzzy Systems as
Universal Approximators", in Proceedings of the First IEEE
Conference on Fuzzy Systems, Pages 1153-1162, in San Diego, on
March, 1992, herein incorporated by reference.
[0036] Fuzzy relations map elements of one universe, say "X", to
those of another universe, say "Y", through the Cartesian product
of the two universes. However, the "strength" of the relation
between ordered pairs of the two universes is not measured with the
characteristic function (in which an element is either definitely
related to another element as indicated by a strength value of "1",
or is definitely not related to another element as indicated by a
strength value of "0", but rather with a membership function
expressing various "degrees" of strength of the relation on the
unit interval [0,1]. Hence, a fuzzy relation R is a mapping from
the Cartesian space X.times.Y to the interval [0,1], where the
strength of the mapping is expressed by the membership function of
the relation for ordered pairs from the two universes or kx,y).
[0037] Just as for crisp relations, the properties of
commutativity, associativity, distributivity, involution and
idempotency all hold for fuzzy relations. Moreover, DeMorgan's laws
hold for fuzzy relations just as they do for crisp (classical)
relations, and the null relations O, and the complete relation, E,
are analogous to the null set and the whole set in set-theoretic
from, respectively. The properties that do not hold for fuzzy
relations, as is the case for fuzzy sets in general, are the
excluded middle laws. Since a fuzzy relation R is also a fuzzy set,
there is overlap between a relation and its complement, hence.
R.orgate.R'.noteq.E
R.andgate.R'.noteq.O
[0038] As seen in the foregoing expression, the excluded middle
laws for relation do not result in the null relation, O, or the
complete relation, E. Because fuzzy relations in general are fuzzy
sets, the Cartesian product can be defined as a relations between
two or more fuzzy sets. Let A be a fuzzy set on universe X and B be
a fuzzy set on universe Y; then the Cartesian product between fuzzy
sets A and B will result in a fuzzy relation R, which is contained
within the full Cartesian product space, or
A.times.B=R.OR right.X.times.Y
where the fuzzy relation R has membership function:
.mu..sub.R(x,y)=.mu..sub.A.times.B(x,y)=min(.mu..sub.A(x),.mu..sub.B(y))
[0039] Fuzzy composition can be defined just as it is for crisp
(binary) relations. If R is a fuzzy relation on the Cartesian space
X.times.Y, and S is a fuzzy relation on the Cartesian space
Y.times.Z, and T is a fuzzy relation on the Cartesian space
X.times.Z; then fuzzy max-min composition is defined in terms of
the set-theoretic notation and membership function-theoretic
notation in the following manner:
.mu..sub.T(x,y)=(.mu..sub.R(x,y).mu..sub.s(x,y))=max{min[.mu..sub.R(x,y)-
,.mu..sub.s(y,z)]}
[0040] The fuzzy extension principle allows for transforms or
mappings of fuzzy concepts in the form y=f(x). This principle,
combined with a compositional rule of inference, allows for a crisp
input to be mapped through a fuzzy transform using membership
functions into a crisp output. Additionally, in mapping a variable
x into a variable y, both x and y can be vector quantities.
SUMMARY OF THE INVENTION
Objects of the Invention
[0041] It is an objective of the present invention to provide a
system and method for determining wireless location using one or
more commercial mobile radio telecommunication systems for
accurately locating people and/or objects in a cost effective
manner. Related objectives for the present invention include
providing a system and method that:
[0042] (1) can be readily incorporated into existing commercial
wireless telephony systems with few, if any, modifications of a
typical telephony wireless infrastructure;
[0043] (2) can use the native electronics of typical commercially
available telephony wireless mobile stations (e.g., handsets) as
location devices;
[0044] (3) can be used for locating people and/or objects residing
indoors.
[0045] Yet another objective is to provide a low cost location
system and method, adaptable to wireless telephony systems, for
using simultaneously a plurality of base stations owned and/or
operated by competing commercial mobile radio service providers
within a common radio coverage area, in order to achieve FCC phase
2 or other accuracy requirements, and for synergistically
increasing mobile station location accuracy and consistency.
[0046] Yet another objective is to provide a low cost location
system and method, adaptable to wireless telephony systems, for
using a plurality of location techniques In particular, at least
some of the following mobile station location techniques can be
utilized by various embodiments of the present invention:
[0047] (4.1) time-of-arrival wireless signal processing
techniques;
[0048] (4.2) time-difference-of-arrival wireless signal processing
techniques;
[0049] (4.3) adaptive wireless signal processing techniques having,
for example, learning capabilities and including, for instance,
neural net and genetic algorithm processing;
[0050] (4.4) signal processing techniques for matching MS location
signals with wireless signal characteristics of known areas;
[0051] (4.5) conflict resolution techniques for resolving conflicts
in hypotheses for MS location estimates;
[0052] (4.6) enhancement of MS location estimates through the use
of both heuristics and historical data associating MS wireless
signal characteristics with known locations and/or environmental
conditions.
[0053] Yet another objective is to provide a system and method for
flexible delivery of location information to Public Safety
Answering Points, end users, centralized dispatchers, as well as to
agents (either human or mechanized) associated with trigger-based
inventory and tracking systems. Flexible delivery used here
indicates providing location via various two dimensional
closed-form shapes, such as polygons, ellipses, etc., which bound
the location probabilities. In cases where height location
information is known, the bounding shape may be
three-dimensional.
[0054] Yet another objective is to provide a system and method for
a variety of new location-based services for public and private
group safety, including family support functions.
[0055] Yet another objective is to provide a system and method for
National Scale Wireless Location capability. Although the primary
focus of this patent is to provide wireless location with accuracy
to meet the FCC phase two requirements, a system and method is
provided that also utilizes roaming signaling to determine in which
city is a particular wireless mobile station located.
[0056] Yet another objective is to provide and system and method
for Parametric-driven, intelligent agent-based location services.
Parameters may include time, location, and user-specific and/or
group specific criteria.
[0057] Yet another objective is to provide a system and method for
determining and/or enhancing wireless location using one or more of
the following: (a.) CDMA-based Distributed Antenna technology; (b.)
Home Base Stations and AIN technology.
[0058] Yet another objective is to provide notification messages
and/or voice-synthesized call or text paging function to a
plurality of other mobile station users when a mobile station user
travels into, or away from, one or more zones or are within short
distances of shopping malls, stores, merchandising dealers etc.
[0059] Yet another objective is to provide notification messages
and/or voice-synthesized call or text paging functions to a
plurality of other mobile station users when a mobile station dials
a redefined telephone number, such as 911, or a type of "mild
emergency cry for help" number.
[0060] Yet another objective is to provide notification messages
and/or voice-synthesized call or text paging function to a
plurality of other mobile station users when a mobile station user
dials a predefined telephone number, such as 311, or a type of mild
emergency cry for help number, wherein the plurality of other
mobile station users are within a particular distance, or a minimum
distance to the mobile station user who dialed the predefined
number.
[0061] Yet another objective is to provide notification messages
and/or voice-synthesized call or text paging function to a
plurality of other mobile station users when a mobile station user
dials a predefined telephone number, such as 311, or a type of mild
emergency cry for help number, wherein the plurality of other
mobile station users are within a particular distance, or a minimum
distance to the mobile station user who dialed the predefined
number, and wherein the other mobile station users are provided
individualized directional or navigation information from their
current locations, to reach to the mobile station user who dialed
the predefined number.
[0062] Yet another objective is to provide automatic home office,
vehicle and boat security functions, which are activated and
deactivated based on a mobile station user's location to or away
from a location associated with the security functions.
[0063] Yet another objective is to provide notifications (e.g., via
fax, page, e-mail, text paging or voice synthesized call message),
or to setup a group conference call capability to a plurality of
predefined individuals, based on a mobile station user's call to
911, or based on a mobile station user's traveling into or away
from a location zone or area, or based upon a sensor input signal
to the user's mobile station, such as a sudden change in G forces,
such as falling down, having the car hit another object suddenly,
air bag deployment, etc.
[0064] Yet another objective is to provide location information to
a `searcher` mobile station user who then further refines or
narrows the scope of the location/search for a `target` mobile
station, or the mobile station to be located, using a small
microwave dish, in communication with, or to supplement/replace the
searcher mobile station antenna, whose physical orientation is used
to further determine the target mobile station location, relative
to the searcher's mobile station position/orientation.
[0065] Yet another objective is to provide a means to allow more
flexible storage, inventory and enhanced user accessibility of
rental vehicles, by combining location technology of rental car
driver carrying his/her own mobile station, along with a mobile
station which remains always active and fixed to a rental car. By
maintaining accurate location records of rental car locations and
automatic, remote-control of rental cars (or smart cars) which use
the mobile station to telemeter control data to and from the car,
whose doors, door locks, and general accessibility are controlled
by a centralized computer system, rental cars can be dropped off at
convenient shopping center malls, airport parking lots, hotels and
at other convenient locations.
[0066] Yet another objective is to provide location estimates to
users carrying mobile stations, via voice synthesis, data circuit
messaging or text paging.
[0067] Yet another objective is to provide a mechanism whereby
mobile station users may access and control their subscriber
profile for location purposes. The location subscriber profile is a
persistent data store which contains logic regarding under what
criteria will that mobile station user allow his/her location to be
made known, and to whom. The mobile station user may access the
location profile via several methods, including Internet means, and
mobile station handset keypad entry and voice recognition
circuits.
[0068] Yet another objective is to utilize signaling detection
characteristics of other CDMA base stations and systems in a given
area, owned and operated by an another commercial mobile radio
service provider (CMRS provider). By including other CMRS
providers' infrastructure in the location estimation analysis
process, improvements in location accuracy can be realized.
DEFINITIONS
[0069] The following definitions are provided for convenience. In
general, the definitions here are also defined elsewhere in this
document as well.
(1) The term wireless herein is, in general, an abbreviation for
digital wireless, and in particular, wireless refers to digital
radio signaling using one of standard digital protocols such as
CDMA, TDMA and GSM, as one skilled in the art will understand. (2)
As used herein, the term mobile station (equivalently, MS) refers
to a wireless device that is at least a transmitting device, and in
most cases is also a wireless receiving device, such as a portable
radio telephony handset. Note that in some contexts herein instead
or in addition to mobile station, the following terms are also
used: personal station (PS), and location unit (LU). In general,
these terms may be considered synonymous. However, the later two
terms may be used when referring to reduced functionality
communication devices in comparison to a typical digital wireless
mobile telephone. (3) The term, infrastructure, denotes the network
of telephony communication services, and more particularly, that
portion of such a network that receives and processes wireless
communications with wireless mobile stations. In particular, this
infrastructure includes telephony wireless base stations (BS) such
as those for radio mobile communication systems based on CDMA,
TDMA, and GSM wherein the base stations provide a network of
cooperative communication channels with an air interface with the
mobile station, and a conventional telecommunications interface
with a Mobile Switch Center (MSC). Thus, an MS user within an area
serviced by the base stations may be provided with wireless
communication throughout the area by user transparent communication
transfers (i.e., hand-offs) between the user's mobile station and
these base stations in order to maintain effective telephony
service. The mobile switch center provides communications and
control connectivity among base stations and the public telephone
network. (4) An example of a Parametric-driven intelligent
agent-based location service follows: An intelligent agent software
process monitors sets of Parametric conditions and location
scenarios. When appropriate conditions and location criteria are
satisfied, then a set of notifications or other actions are
triggered to occur. A specific example follows: given that a
certain child carrying a mobile station should be in a certain
school between 8:00 A.M. and 3:00 P.M. on regular school days, then
a wireless location request is invoked periodically, within the
school day time frame. If a location request determines that the
child's mobile station is located substantially outside of the
general school area, then a parent/guardian is notified of that
fact, and of the child's location via any of several methods, such
as: (a.) a voice-synthesized telephone message, (b.) various
extranet/internet means, such as electronic mail, netcasting, such
as the product Castanet, by Marimba Software, Inc., (c.) fax to a
pre-determined telephone number, or (d.) alpha-numeric text paging.
(5) Commercial mobile radio service (CMRS) service provider is the
referenced name of the company that owns and/or operates a publicly
accessible wireless system in the cellular or PCS spectrum radio
bands. (6) The term "geolocation" as used herein refers to "a
representation of at least one of: a geographical location or a
geographical extent". Thus, the term "GeoLocation Message" refers
to a message that contains a content representative of at least one
of: a geographical location or a geographical extent. Moreover, the
term "geolocation result" refers to a result that represents at
least one of: a geographical location or a geographical extent, and
the term "geolocation related processing" is intended to mean
"processing that is related to a result that represents at least
one of: a geographical location or a geographical extent".
SUMMARY DISCUSSION
[0070] The location system of the present invention accomplishes
the above and other objectives by the following steps:
[0071] (1.) receiving signal data measurements corresponding to
wireless communications between a mobile station to be located
(herein also denoted the target mobile station) and a wireless
telephony infrastructure, wherein the mobile station, MS and/or
mobile switch center may be enhanced in certain novel and cost
effective ways so as to provide an extended number of values
characterizing the wireless signal communications between the
target mobile station and the base station infrastructure, such
infrastructure including multiple, distinct CMRS where base
stations share a common coverage area;
[0072] (2.) organizing and processing the signal data measurements
received from a given target mobile station and surrounding base
stations so that composite wireless signal characteristic values
may be obtained from which target mobile station location estimates
may be derived. In particular, the signal data measurements are
ensembles of samples from the wireless signals received from the
target mobile station by the base station infrastructure, and from
associated base stations wherein these samples are subsequently
filtered using analog and digital spectral filtering.
[0073] (3.) providing the resultant location estimation
characteristic values to a mobile station location estimate model,
wherein each such model (also denoted a "first order model" or FOM)
subsequently determines the estimate of the location of the target
mobile station based on, for example, the signal processing
techniques (1.) through (2.) above.
[0074] Accordingly, steps (1.) and (2.) above are performed by a
subsystem of the invention denoted the Signal Processing and
Filtering Subsystem (or simply the Signal Processing Subsystem). In
particular, this subsystem receives samples of wireless signal
characteristic measurements such as a plurality of relative signal
strengths and corresponding signal time delay value pairs, wherein
such samples are used by this subsystem to produce the component
with the least amount of multipath, as evidenced in the sample by
the short time delay value, wherein each such value pair is
associated with wireless signal transmissions between the target
mobile station and a particular base station of a predetermined
wireless base station infrastructure. Extremely transient signal
anomalies such as signal reflection from tree leaves or the passing
of a truck are likely to be filtered out by the Signal Processing
Subsystem. For example, such an ensemble of data value pairs can be
subjected to input cropping and various median filters employing
filtering techniques such as convolution, median digital, Fast
Fourier transform, Radon transform, Gabar transform, nearest
neighbor, histogram equalization, input and output cropping, Sobel,
Wiener, and the like.
[0075] It is a further aspect of the present invention that the
wireless personal communication system (PCS) infrastructures
currently being developed by telecommunication providers offer an
appropriate localized infrastructure base upon which to build
various personal location systems employing the present invention
and/or utilizing the techniques disclosed herein. In particular,
the present invention is especially suitable for the location of
people and/or objects using code division multiple access (CDMA)
wireless infrastructures, although other wireless infrastructures,
such as, time division multiple access (TDMA) infrastructures and
GSM are also contemplated. Note that CDMA personal communications
systems are described in the Telephone Industries Association
standard IS-95, for frequencies below 1 GHz, and in the Wideband
Spread--Spectrum Digital Cellular System Dual-Mode Mobile
Station-Base Station Compatibility Standard, for frequencies in the
1.8-1.9 GHz frequency bands, both of which are incorporated herein
by reference. Furthermore, CDMA general principles have also been
described, for example, in U.S. Pat. No. 5,109,390, to Gilhousen,
et al filed Nov. 7, 1989, and CDMA Network Engineering Handbook by
Qualcomm, Inc., each of which is also incorporated herein by
reference.
[0076] In another aspect of the present invention, in environments
where a home base station capability exists, then wireless location
can be provided under certain circumstances, wherein when a mobile
station user is within a predetermined range of, for example, 1000
feet of his/her premises, the user's mobile station is detected
through mobile station receiving electronics provided in, for
example, cordless telephone units as being at home. Thus, the local
public telephone switching network may be provided with such
information for registering that user is at home, and therefore the
mobile station may be allowed to function as a cordless home
telephone utilizing the local public telephone switching network
instead of the base station infrastructure. According to this
aspect of the present invention, the location center of the present
invention receives notification from the local public switched
telephone network that the mobile station is at or near home and
utilizes this notification in outputting a location estimate for
the mobile station.
[0077] For example, in one embodiment, the present invention
includes low cost, low power base stations, denoted location base
stations (LBS) above, providing, for example, CDMA pilot channels
to a very limited area about each such LBS. The location base
stations may provide limited voice traffic capabilities, but each
is capable of gathering sufficient wireless signal characteristics
from an MS within the location base station's range to facilitate
locating the MS. Thus, by positioning the location base stations at
known locations in a geographic region such as, for instance, on
street lamp poles and road signs, additional MS location accuracy
can be obtained. That is, due to the low power signal output by
such location base stations, for there to be communication between
a location base station and a target MS, the MS must be relatively
near the location base station. Additionally, for each location
base station not in communication with the target MS, it is likely
that the MS is not near to this location base station. Thus, by
utilizing information received from both location base stations in
communication with the target MS and those that are not in
communication with the target MS, the present invention can
substantially narrow the possible geographic areas within which the
target MS is likely to be. Further, by providing each location base
station (LBS) with a co-located stationary wireless transceiver
(denoted a built-in MS above) having similar functionality to an
MS, the following advantages are provided:
[0078] (4.1) assuming that the co-located base station capabilities
and the stationary transceiver of an LBS are such that the base
station capabilities and the stationary transceiver communicate
with one another, the stationary transceiver can be signaled by
another component(s) of the present invention to activate or
deactivate its associated base station capability, thereby
conserving power for the LBS that operate on a restricted power
such as solar electrical power;
[0079] (4.2) the stationary transceiver of an LBS can be used for
transferring target MS location information obtained by the LBS to
a conventional telephony base station;
[0080] (4.3) since the location of each LBS is known and can be
used in location processing, the present invention is able to
(re)train and/or (re)calibrate itself in geographical areas having
such LBSs. That is, by activating each LBS stationary transceiver
so that there is signal communication between the stationary
transceiver and surrounding base stations within range, wireless
signal characteristic values for the location of the stationary
transceiver are obtained for each such base station.
[0081] In yet another aspect, the present invention includes a
capability for locating a target mobile station within areas of
poor reception for infrastructure base stations by utilizing
distributed antennas. A distributed antenna system as used herein
is a collection of antennas attached in series to a reduced
function base station, wherein the antennas are distributed
throughout an area for improving telephony coverage. Such
distributed antenna systems are typically used in indoor
environments (e.g., high rise buildings) or other areas wherein the
signal to noise ratio is too high for adequate communication with
standard infrastructure base stations. Also a distributed antenna
system may be located such that its coverage pattern overlaps the
area of coverage of another distributed antenna system. In such
cases each of the overlapping distributed antenna systems includes
purposeful delay elements to provide different signal delays for
each of the overlapping antenna systems and thereby provide
multipath signals with sufficient delay spread for signal
discrimination, as one skilled in the art will understand.
Accordingly, the present invention receives and utilizes location
information communicated from distributed antenna systems for
locating a target mobile station. That is, the present invention
may receive information from the base station infrastructure
indicating that a target mobile station is communicating with such
a distributed antenna system and provide distributed antenna signal
characteristic values related to the distributed antenna system.
Accordingly, to process such target mobile station location signal
data, the present invention includes a distributed antenna system
for generating target mobile station location estimate derived from
the location signal data obtained from the distributed antenna
system.
[0082] The location system of the present invention offers many
advantages over existing location systems. The system of the
present invention, for example, is readily adaptable to existing
wireless communication systems and can accurately locate people
and/or objects in a cost-effective manner. In particular, the
present invention requires few, if any, modifications to commercial
wireless communication systems for implementation. Thus, existing
personal communication system infrastructure base stations and
other components of, for example, commercial CDMA infrastructures
are readily adapted to the present invention. The present invention
can be used to locate people and/or objects that are not in the
line-of-sight of a wireless receiver or transmitter, can reduce the
detrimental effects of multipath on the accuracy of the location
estimate, can locate people and/or objects located indoors as well
as outdoors, and uses a number of wireless stationary transceivers
for location. The present invention employs a number of distinctly
different location computational models (FOMs) for location which
provides a greater degree of accuracy, robustness and versatility
than is possible with existing systems. For instance, the location
models provided include not only the radius-radius/TOA and TDOA
techniques but also adaptive neural net techniques. Further, the
present invention is able to adapt to the topography of an area in
which location service is desired. The present invention is also
able to adapt to environmental changes substantially as frequently
as desired. Thus, the present invention is able to take into
account changes in the location topography over time without
extensive manual data manipulation.
[0083] Moreover, there are numerous additional advantages of the
system of the present invention when applied in CDMA communication
systems. The location system of the present invention readily
benefits from the distinct advantages of the CDMA spread spectrum
scheme, namely the exploitation of radio frequency spectral
efficiency and isolation by (a) monitoring voice activity, (b)
management of two-way power control, (c) provision of advanced
variable-rate modems and error correcting signal encoding, (d)
inherent resistance to fading, (e) enhanced privacy, and (f)
multiple "rake" digital data receivers and searcher receivers for
correlation of signal multipaths.
[0084] Additionally, note that this architecture need not have all
modules co-located. In particular, it is an additional aspect of
the present invention that various modules can be remotely located
from one another and communicate with one another via
telecommunication transmissions such as telephony technologies
and/or the Internet. Accordingly, the present invention is
particularly adaptable to such distributed computing environments.
For example, some number of the location center modules may reside
in remote locations and communicate their generated hypotheses of
mobile station location estimates (each such hypothesis also
denoted a "location hypothesis" herein) via the Internet.
[0085] In an alternative embodiment of the present invention, the
processing following the generation of location estimates by the
modules may be such that this processing can be provided on
Internet user nodes and the modules may reside at Internet server
sites. In this configuration, an Internet user may request
hypotheses from such remote modules and perform the remaining
processing at his/her node.
[0086] Additionally, note that it is within the scope of the
present invention to provide one or more central location
development sites that may be networked to, for example, dispersed
location centers or systems providing location services according
to the present invention, wherein the modules may be accessed,
substituted, enhanced or removed dynamically via network
connections with a central location development site. Thus, a small
but rapidly growing municipality in substantially flat low density
area might initially be provided with access to, for example, two
or three modules for generating location hypotheses in the
municipality's relatively uncluttered radio signaling environment.
However, as the population density increases and the radio
signaling environment becomes cluttered by, for example, thermal
noise and multipath, additional or alternative modules may be
transferred via the network to the location center for the
municipality.
[0087] Of course, other software architectures may also to used in
implementing the processing of the location center without
departing from scope of the present invention. In particular,
object-oriented architectures are also within the scope of the
present invention. For example, the modules may be object methods
on an mobile station location estimator object, wherein the
estimator object receives substantially all target mobile station
location signal data output by the signal filtering subsystem 20.
Alternatively, software bus architectures are contemplated by the
present invention, as one skilled in the art will understand,
wherein the software architecture may be modular and facilitate
parallel processing.
[0088] One embodiment of the present invention includes providing
the location of a mobile station (MS) using the digital air
interface voice channel and an automatic call distributor device.
This embodiment provides location information to either the
initiating caller who wishes to learn of his location, using the
voice channel, and/or location information could be provided to
another individual who has either a wireline or wireless telephone
station.
[0089] Another embodiment of the present invention includes
providing the location of a mobile station using the digital air
interface voice channel and a hunt group provided from a central
office or similar device. This embodiment provides location
information to either the initiating caller who wishes to learn of
his location, using the voice channel, and/or location information
could be provided to another individual who has either a wireline
or wireless telephone station.
[0090] Another embodiment of the present invention includes
providing the location of a mobile station using the digital air
interface text paging, or short message service channel and a hunt
group provided from a central office or similar device. This
embodiment provides location information to either the initiating
caller who wishes to learn of his location, using the voice
channel, and/or location information could be provided to another
individual who has either a wireline or wireless telephone
station.
[0091] Another embodiment of the present invention includes
providing the location of a plurality of mobile stations using the
public Internet or an intranet, with either having the ability to
further use "push", or "netcasting" technology. This embodiment
provides location information to either the initiating Internet or
Intranet user who wishes to learn of one or more mobile station
locations, using either the Internet or an intranet. Either the
mobile station user to be located can initiate a request for the
user to be located, or an Internet/intranet user may initiate the
location request. Optionally the location information could be
provided autonomously, or periodically, or in accordance with other
logic criteria, to the recipient of the location information via
the Internet or a intranet. As a further option, location
information can be superimposed onto various maps (e.g.,
bit/raster, vector, digital photograph, etc.) for convenient
display to the user.
[0092] Yet another embodiment of the present invention includes
providing a multicast notification to a group of mobile station
users, based on distress call from a particular mobile station,
wherein the group of mobile station users are relatively nearby the
distress caller. The multicast notification provides individual
directions for each group mobile station user, to direct each user
to the fastest route to reach the distressed caller.
[0093] Other aspects of the present invention can be described as
follows: [0094] Aspect 1. An apparatus for locating a first mobile
station for at least transmitting and receiving radio signals,
wherein said radio signals are received on a forward radio
bandwidth and said radio signals are transmitted on a different
reverse radio bandwidth, comprising: [0095] a first wireless
network infrastructure for communicating with said first mobile
station, said first wireless network infrastructure having: [0096]
(A1) a plurality of spaced apart base stations for communicating
via said radio signals with said first mobile station, and [0097]
(A2) a mobile switching center for communicating with said first
mobile station, via said radio signals with the base stations,
wherein said mobile switching center also communicates with said
plurality of base stations for receiving measurements of said radio
signals, said measurements including: (i) first measurements of
said radio signals received by said first mobile station in said
forward radio bandwidth, and (ii) second measurements of said radio
signals transmitted by said first mobile station in said reverse
radio bandwidth; [0098] a location determining means for locating
said first mobile station, wherein said location determining means
receives said first and second measurements from the mobile
switching center for estimating a location of said first mobile
station, wherein said estimate is a function of both said first
measurements and said second measurements. [0099] Aspect 2. An
apparatus for locating a mobile station as in Aspect 1, further
including an interface means between said location determining
means and said mobile switching center, wherein said interface
means generates a location request for a primary one of said base
stations to which said first mobile signaling means is in
communication. [0100] Aspect 3. An apparatus for locating a mobile
station as in Aspect 1, further including a means for requesting
data related to additional radio signals between said first mobile
station and at least a second wireless network infrastructure
different from said first wireless network infrastructure. [0101]
Aspect 4. An apparatus for locating a mobile station as in Aspect
1, wherein said first wireless network infrastructure is capable of
communicating at least one of voice and visual information with
said first mobile station. [0102] Aspect 5. An apparatus for
locating a mobile station, comprising: [0103] a wireless network
infrastructure for communicating with a plurality of mobile
stations, each said mobile station for transmitting and receiving
wireless signals, wherein said wireless signals are received in a
forward bandwidth and said wireless signals are transmitted in a
different reverse bandwidth, and, said wireless network
infrastructure having a plurality of spaced apart base stations for
communicating via said wireless signals with said plurality of
mobile stations; [0104] a location determining means for
communicating with said plurality of mobile stations, via said
radio signals with the base stations, wherein said location
determining means communicates with said plurality of base stations
for receiving measurements related to said radio signals for
estimating a location of at least a first of said plurality of
mobile stations, said measurements including: (i) first
measurements of said wireless signals received by said first mobile
station in said forward radio bandwidth, and (ii) second
measurements of said wireless signals transmitted by said first
mobile station in said reverse radio bandwidth; wherein said
location determining means estimates a location of said first
mobile station using both said first measurements and said second
measurements. [0105] Aspect 6. An apparatus for locating a mobile
station as in Aspect 5, wherein said second measurements are
determined from said wireless signals being received by said base
stations. [0106] Aspect 7. An apparatus for locating a mobile
station as in Aspect 5, wherein said measurements include at least
one of: a delay spread, a signal strength, a ratio of energy per
bit versus signal to noise, a word error rate, a frame error rate,
a mobile signaling means, a power control value, a pilot index, a
finger identification, an arrival time, an identification of said
first mobile station for communicating with the wireless network
infrastructure, a make of said first mobile station, a revision of
said first mobile station, a sector identification of one of the
base stations receiving said radio signals transmitted from said
first mobile station. [0107] Aspect 8. An apparatus for locating a
mobile station as in Aspect 5, wherein said radio signals are
communicated using one of: CDMA, W-CDMA, TDMA and advanced mobile
phone service. [0108] Aspect 9. An apparatus for locating a mobile
station as in Aspect 5, wherein said location determining means
includes a location estimator using time difference of arrival data
from said measurements. [0109] Aspect 10. An apparatus for locating
a mobile station as in Aspect 9, wherein said location estimator
receives said measurements from a distributed antenna system.
[0110] Aspect 11. An apparatus for locating a mobile station as in
Aspect 9, wherein said location estimator receives active,
candidate and remaining set information from said first mobile
signaling means. [0111] Aspect 12. An apparatus for locating a
mobile station as in Aspect 1, wherein said location determining
means includes: a receiving means for receiving first data related
to at least one of said first measurements and said second
measurements between said first mobile station and said wireless
network infrastructure; activating a first location estimator for
outputting a first estimate of a location of said first mobile
station when supplied with location information from said receiving
means, said location information related to the first data;
outputting said first estimate of the location of said first mobile
station when said first estimate has an extent less than or equal
to a predetermined size; activating a second location estimator for
outputting a second estimate of a location of said first mobile
station when said first location estimator does not provide said
first estimate having an extent less than or equal to a
predetermined size; outputting an estimate of the location of said
first mobile station when said second location estimator provides
said second estimate. [0112] Aspect 13. A method for locating a
wireless mobile station, comprising: transmitting, by a first short
range transceiver station, a status change related to whether the
mobile station and said first short range transceiver station are
able to wirelessly communicate through a telephony network to a
predetermined storage; storing, in said predetermined storage, said
status of a mobile station, wherein said status has a first value
when the mobile station communicates with said short range
transceiver station as a cordless telephone, and said status has a
second value when the mobile station communicates with a network of
base stations, wherein said base stations are cooperatively linked
for providing wireless communication; detecting, by said first
short range transceiver station, a change accessing said
predetermined storage for determining a location of the mobile
station. [0113] Aspect 14. A method for locating a wireless mobile
station, as in Aspect 13, wherein said short range transceiver is a
home base station. [0114] Aspect 15. A method for locating a
wireless mobile station, as in Aspect 13, wherein said
predetermined storage is accessible via one of: an autonomous
notification message and a request-response message. [0115] Aspect
16. A method for locating a wireless mobile station, as in Aspect
13, wherein said predetermined storage is a home location register.
[0116] Aspect 17. A method for locating a wireless mobile station,
as in Aspect 13, wherein said predetermined storage includes one or
more of the following data items related to said mobile station:
mobile station identification number, short range transceiver
identification and mobile switch center identification. [0117]
Aspect 18. A method for locating a wireless mobile station, as in
Aspect 13, wherein said step of accessing includes responding to a
query of said predetermined storage location using an
identification of the mobile station. [0118] Aspect 19. A method
for locating a wireless mobile station, as in Aspect 13, further
including providing said status from said predetermined storage
together with an identification of the mobile station to a mobile
station location estimator for estimating a location of the mobile
station. [0119] Aspect 20. A method for location a wireless mobile
station, as in Aspect 17, wherein said step of transmitting further
includes associating said change with a predetermined fixed
location and said short range transceiver identification. [0120]
Aspect 21. A method for location a wireless mobile station, as in
Aspect 13, wherein said step of accessing includes translating the
mobile identification number and said short range transceiver
identification into a predetermined location when the status has
said first predetermined value. [0121] Aspect 22. A method for
location a wireless mobile station, as in Aspect 13, further
including a prior step of provisioning a translating database from
a customer care system containing the location of the short range
transceiver. [0122] Aspect 23. A method for locating a wireless
mobile station, comprising: receiving data of wireless signals
communicated between a mobile station and a wireless network;
detecting, using said first data, that the mobile station is in
wireless communication with a distributed antenna system having a
plurality of antennas connected in series and distributed along a
signal conducting line so that there is a predetermined signal time
delay between said antennas and at predetermined locations;
determining a plurality of signal time delay measurements for
signals transmitted between the mobile station and a collection of
some of said antennas, wherein said signals are also communicated
through said line; estimating a location of the mobile station
using said plurality of signal time delay measurements. [0123]
Aspect 24. A method for locating a wireless mobile station as in
Aspect 23, wherein said step of estimating includes correlating
each measurement of said plurality of signal time delay
measurements with a unique corresponding one of said antennas.
[0124] Aspect 25. A method for locating a wireless mobile station
as in Aspect 24, wherein said step of estimating includes:
identifying a plurality of antennas in said collection using
correlation obtained in said step of correlating; determining a
corresponding signal time delay between the mobile station and each
antenna in said collection; determining a location of each antenna
in said collection; estimating a location of the mobile station
using said corresponding signal time delays and said locations of
each antenna in said collection. [0125] Aspect 26. A method for
locating a wireless mobile station as in Aspect 23, wherein said
step of estimating includes determining, for said signal time delay
measurements, a common signal time delay corresponding to
transmitting signals from said distributed antenna system to a
receiver of the first wireless network. [0126] Aspect 27. A method
for locating a wireless mobile station as in Aspect 23, wherein
said step of estimating includes using an absolute delay time with
respect to a pilot channel for a base station on the wireless
network. [0127] Aspect 28. A method for locating a wireless mobile
station as in Aspect 23, wherein said step of estimating includes
performing a triangulation using values related to one of: a signal
time of arrival, and a signal time difference of arrival for time
difference of arrival corresponding to each antenna in said
collection. [0128] Aspect 29. A method for locating a wireless
mobile station, as in Aspect 23 wherein said step of estimating
includes a step of computing a most likely location of said mobile
station using a fuzzy logic computation. [0129] Aspect 30. A method
for locating a wireless mobile station as in Aspect 23, wherein
said step of activating includes activating one of: [0130] (a) a
location estimator for determining whether the mobile station is
detected by a base station of the network, wherein said base
station communicates with the mobile station as a cordless
telephone; [0131] (b) a location estimator for estimating a
location of the mobile station using location information obtained
from said distributed antenna system; [0132] (c) a location
estimator for estimating a location of the mobile station by one
of: triangulation and trilateration. [0133] Aspect 31. A method for
locating a wireless mobile station, comprising: first receiving
first signal characteristic measurements of wireless signals
communicated between a mobile station and a first network of base
stations, wherein said base stations in the first network are
cooperatively linked by a first wireless service provider for
providing wireless communication; instructing the mobile station to
search for a wireless signal from a second network of base stations
that are cooperatively linked by a second wireless service provider
for providing wireless communication, wherein said first and second
wireless service providers are different; second receiving second
signal characteristic measurements of wireless signals communicated
between the mobile station and said second network of base
stations; estimating a location of the mobile station using said
first and second signal characteristic measurements. [0134] Aspect
32. A method for locating a wireless mobile station as in Aspect
31, wherein the mobile station is registered for a wireless
communication service with the first wireless service provider, and
the mobile station is not registered for the wireless communication
service with the second wireless service provider. [0135] Aspect
33. A method for locating a wireless mobile station as in Aspect
31, wherein said step of instructing includes transmitting a
command to the mobile station for instructing the mobile station to
search for a signal from a base station of said second wireless
service provider in a frequency bandwidth different from a
frequency bandwidth for communicating with the base stations of
said first wireless service provider. [0136] Aspect 34. A method
for locating a wireless mobile station as in Aspect 31, wherein
said step of instructing includes transmitting a command to the
mobile station for instructing the mobile station to hand-off from
said first service provider to a base station associated with said
second service provider, for purposes of performing additional
signal measurements. [0137] Aspect 35. A method for locating a
wireless mobile station as in Aspect 31, wherein said first signal
characteristic measurements include measurements for time delay,
signal strength pairs of signal communicated from at least one
of:
[0138] (a) the base stations of said first network to the mobile
station, and [0139] (b) the mobile station to the base stations of
said first network, and wherein said second signal characteristic
measurements include measurements for time delay, signal strength
pairs of signals communicated from the base stations of said second
network to the mobile station. [0140] Aspect 36. A method for
locating a wireless mobile station, comprising: receiving first
data related to wireless signals communicated between a mobile
station and at least a first network of a plurality of commercial
mobile service provider networks of base stations, wherein for each
said network, there is a plurality of base stations for at least
one of transmitting and receiving wireless signals with a plurality
of mobile stations; instructing the mobile station to communicate
with a second network of the plurality of networks for supplying
second data; activating a mobile station location estimator, when
said first and second data are obtained for providing an estimate
of a location of the mobile station. [0141] Aspect 37. A method for
locating a wireless mobile station, as in Aspect 36, wherein said
second network includes a second plurality of base stations,
wherein a majority of base stations in said second plurality of
base stations has a location different from the locations of base
stations in said first network. [0142] Aspect 38. A method for
locating a wireless mobile station, as in Aspect 36, wherein at
least one of said first and second data includes signal
characteristic measurements of communication with the mobile
station for a time interval of less than 10 seconds. [0143] Aspect
39. A method for locating a wireless mobile station, comprising:
first receiving first signal characteristic measurements of
wireless signals communicated between a mobile station and a first
network of base stations, wherein said base stations in the first
network are cooperatively linked by a first wireless service
provider for providing wireless communication; instructing a second
network of base stations that are cooperatively linked by a second
wireless service provider for providing wireless communication so
that the second network searches for wireless signals from the
mobile station, wherein said first and second wireless service
providers are different; second receiving second signal
characteristic measurements of wireless signals communicated
between the mobile station and said second network of base
stations; estimating a location of the mobile station using said
first and second signal characteristic measurements. [0144] Aspect
40. A method for locating a wireless mobile station, as in Aspect
39, further including a step of requesting the mobile station to
raise it's transmitter power level to a predetermined level, prior
to said step of instructing. [0145] Aspect 41. A method for
locating a wireless mobile station, comprising: receiving, by a
receiving means, first data related to wireless signals
communicated between a mobile station and at least a first network
of a plurality of commercial mobile service provider networks,
wherein for each said network, there are a plurality of
communication stations for at least one of transmitting and
receiving wireless signals with a plurality of mobile stations;
first activating a location estimator for providing a first
estimate of a location of the mobile station when supplied with
first location information from said receiving means, said first
location information related to the first data; when one of: (a)
said first estimate does not exist, and (b) said first estimate has
an extent greater than or equal to a predetermined size, the steps
(A1) and (A2) are performed: [0146] (A1) instructing the mobile
station to communicate with a second network of the plurality of
networks for supplying second data to said receiving means, wherein
said second data is related to wireless signals communicated
between the mobile station and the second network; [0147] (A2)
second activating said location estimator a second time for
providing a second estimate of a location of the mobile station
when supplied with additional location information from said
receiving means, said additional location information related to
the second data; outputting at least one of the estimates of the
location of the mobile station provided by said location estimator
when said location estimator provides at least one estimate of the
location of the mobile station. [0148] Aspect 42. A method for
locating a wireless mobile station as in Aspect 41, wherein said
additional location information and said first location information
are utilized together by said location estimator. [0149] Aspect 43.
A method of locating a wireless mobile station as in Aspect 41,
wherein said communication stations include wireless base stations
for one of CDMA, TDMA, and GSM. [0150] Aspect 44. A method of
locating a wireless mobile station as in Aspect 43, wherein said
communication stations include home base stations. [0151] Aspect
45. A method of locating a wireless mobile station as in Aspect 41,
wherein the mobile station includes one of: a CDMA transmitter, a
TDMA transmitter, and a GSM transmitter, and a AMPS transmitter.
[0152] Aspect 46. A method for locating a wireless mobile station
as in Aspect 41, wherein one or more of said activating steps
includes: [0153] (a) said location estimator for determining
whether the mobile station is detected by a communication station
which communicates with the mobile station as a cordless telephone;
[0154] (b) said location estimator for estimating a location of the
mobile station using location information related to data from a
distributed antenna system; [0155] (c) said location estimator for
estimating a location of the mobile station by one of:
triangulation and trilateration. [0156] Aspect 47. A method for
locating a wireless mobile station as in Aspect 41, wherein said
predetermined extent is less than one thousand feet. [0157] Aspect
48. A method for locating a wireless mobile station, comprising:
receiving, by a receiving means, first data related to wireless
signals communicated between a mobile station and at least a first
network of one or more commercial mobile service provider networks,
wherein for each said network, there is a different plurality of
base stations for at least one of transmitting and receiving
wireless signals with a plurality of mobile stations; activating a
first location estimator for outputting a first estimate of a
location of the mobile station when supplied with location
information from said receiving means, said location information
related to the first data; outputting said first estimate of the
location of the mobile station when said first estimate has an
extent less than or equal to a predetermined size; activating a
second location estimator for outputting a second estimate of a
location of the mobile station when said first location estimator
does not provide said first estimate having an extent less than or
equal to a predetermined size; outputting an estimate of the
location of the mobile station when said second location estimator
provides said second estimate. [0158] Aspect 49. A method for
locating a wireless mobile station as in Aspect 48 further
including a step of instructing the mobile station to communicate
with a second network of the plurality of networks for supplying
second data to said receiving means, wherein said second data is
related to wireless signals communicated between the mobile station
and the second network. [0159] Aspect 50. A method for locating a
wireless mobile station as in Aspect 49, wherein said step of
instructing includes a step of instructing the mobile station to
hand-off to said second network for synchronizing timing signals
and performing measurements between the mobile station an said
second network. [0160] Aspect 51. A method for locating a wireless
mobile station as in Aspect 48, wherein one or more of said
activating steps includes activating one of: [0161] (a) a location
estimator for determining whether the mobile station is detected by
one of the base stations which communicates with the mobile station
as a cordless telephone; [0162] (b) a location estimator for
estimating a location of the mobile station using location
information related to data from a distributed antenna system;
[0163] (c) a location estimator for estimating a location of the
mobile station by one of: triangulation and trilateration. [0164]
Aspect 52. A method for locating a mobile station, comprising:
receiving, by said mobile station, a request control message from
one of a plurality of base stations, wherein said message is
received by a receiving antenna of said mobile station; the control
message providing information related to said message to at least
one of a control processor and a searcher receiver in said mobile
station; determining, using at least one of said control processor
and said searcher receiver, a plurality of pairs of radio signal
strength related values and corresponding signal time delays for a
wireless communication between said mobile station and at least a
first of the base stations, wherein for at least some of said
pairs, said signal time delays are different, and for each pair,
said signal strength related value for said pair is obtained using
a signal strength of said communication at said corresponding
signal time delay of said pair; transmitting signals for said pairs
to one or more of the base stations via a transmitting antenna of
said mobile station; routing data for at least one of said pairs
from said one or more base stations to a mobile station location
estimator for estimating a location of said mobile station. [0165]
Aspect 53. A method for locating a mobile station, as in Aspect 52,
wherein said step of receiving uses one of a CDMA, an AMPS, a NAMPS
and a TDMA wireless standard. [0166] Aspect 54. A method for
locating a mobile station, as in Aspect 52, wherein said step of
determining is performed for a wireless communication between said
mobile station and each of a plurality of the base stations. [0167]
Aspect 55. A method for locating a mobile station, as in Aspect 52,
wherein each of said signal time delays is included within a
predetermined corresponding time delay spread. [0168] Aspect 56. A
method for locating a mobile station, as in Aspect 52, wherein said
step of determining includes a step of instructing, by said control
processor, said searcher receiver to output a plurality of said
radio signal strength related values for a plurality of fingers
resulting from said communication from said first base station to
said mobile station. [0169] Aspect 57. A method for locating a
mobile station, as in Aspect 52, wherein said step of determining
includes inputting data for said pairs to a modulator for
modulating said data prior to said step of transmitting. [0170]
Aspect 58. A method for locating a mobile station, as in Aspect 57,
further including a step of establishing a software controllable
data connection between said control processor and a mobile station
component including at least one of: a user digital baseband
component and said modulator, wherein said connection inputs said
data to said component. [0171] Aspect 59. A method for locating a
mobile station, as in Aspect 52 further including a step of
providing said data for said pairs to a mobile station location
estimating system having a first mobile station location estimating
component using time difference of arrival measurements for
locating said mobile station via one of trilateration and
triangulation. [0172] Aspect 60. A method for locating a mobile
station, as in Aspect 59, wherein said step of providing includes
selecting one of: said first mobile station estimating component, a
second mobile station estimating component using data obtained from
a distributed antenna system, and a third mobile station estimating
component for using data obtained from activation of a home base
station. [0173] Aspect 61. A method for locating a mobile station,
as in Aspect 60, further including a step of computing a most
likely location of said mobile station using a fuzzy logic
computation. [0174] Aspect 62. A method for locating a mobile
station, as in Aspect 61, wherein said step of computing is
performed by said second mobile station estimating component for
determining a most likely floor that said mobile station resides in
a multi-story building having a distributed antenna system. [0175]
Aspect 63. A method for locating a mobile station, as in Aspect 59,
further including a step of requesting data for additional pairs of
radio signal strength related values and corresponding signal time
delays for a wireless communication between said mobile station and
at least a second base station of a commercial mobile radio service
provider different from a commercial mobile service provider for
said first base station. [0176] Aspect 64. A method for obtaining
data related to wireless signal characteristics, comprising:
providing a user with a mobile station for use when the user
traverses a route having one or more predetermined route locations,
wherein one or more of the route locations have a corresponding
telephone number and a corresponding description stored in the
mobile station; performing the following substeps when the user
visits each of the route locations: activating a call to said
corresponding telephone number; transmitting a code identifying the
route location when the user is substantially at the route
location; storing an association of: [0177] (a) signal
characteristic measurements for wireless communication between the
mobile station and one or more base stations, and [0178] (b) a
unique identifier for the route location obtained using said code
transmitted by said call; [0179] Wherein said stored signal
characteristic measurements are accessible using said unique
identifier. [0180] Aspect 65. A method as in Aspect 64, wherein
said unique identifier corresponds to one of: (a) an address for
the route location, and (b) a latitude and longitude of the route
location. [0181] Aspect 66. A method as in Aspect 64, wherein said
route is periodically traversed by a user having a mobile station
for accomplishing said step of performing. [0182] Aspect 67. A
method as in Aspect 64, wherein said step of storing includes
retaining said signal characteristic measurements in a data storage
for analyzing signal characteristic measurements of wireless
communications between mobile stations and a wireless
infrastructure of base stations. [0183] Aspect 68. A method as in
Aspect 64, further including, prior to said step of activating, a
step of determining, by the user, that a display on the mobile
station uniquely identifies that said corresponding description of
the route location is available for calling said corresponding
telephone number and transmitting said identifying code.
[0184] Aspect 69. A method as in Aspect 64, wherein said step of
storing includes: obtaining a phone number identifying the mobile
station; providing said phone number identifying the mobile station
to a commercial mobile radio service provider in a request for said
signal characteristic measurements. [0185] Aspect 70. A method as
in Aspect 64, wherein said step of storing includes using a phone
number identifying the mobile station in combination with said
transmitted identifying code for determining said unique
identifier. [0186] Aspect 71. A method as in Aspect 64, wherein
said corresponding description includes at least one of: a textual
description of its corresponding route location, and an address of
its corresponding route location. [0187] Aspect 72. A method as in
Aspect 64, further including steps of: associating said identifying
code for the route location and said unique identifier in a data
storage prior to performing said step of performing; accessing said
data storage using said identifying code for obtaining said unique
identifier in said step of storing. [0188] Aspect 73. A method as
in Aspect 64, further including a step of accessing said stored
signal characteristic measurements for enhancing a performance of a
process for locating mobile stations. [0189] Aspect 74. A method as
in Aspect 64, wherein at least two of said one or more base
stations are in networks of different commercial mobile radio
service providers. [0190] Aspect 75. A method as in Aspect 64,
further including a step of filtering said signal characteristic
measurements so that when said signal characteristic measurements
are suspected of being transmitted from a location substantially
different from the route location, said step of storing is one of:
(a) not performed, and (b) performed so as to indicate that said
signal characteristic measurements are suspect. [0191] Aspect 76. A
method as in Aspect 75, wherein said step of filtering includes at
least one of: (a) determining an amount by which an estimated
location of the mobile station using said signal characteristic
measurements differs from a location of the mobile station obtained
from said unique identifier; (b) determining whether a
predetermined amount of time has elapsed between successive
performances of said step of activating. [0192] Aspect 77. A method
for locating a wireless mobile station, comprising: first receiving
first signal characteristic measurements of wireless signals
communicated between a mobile station and a first network of base
stations, wherein said first signal characteristic measurements
includes: [0193] (a) one or more pairs of wireless signal strength
related values and corresponding signal time delays for a wireless
communication between the mobile station and at least a first of
the base stations; [0194] (b) data identifying operational
characteristics of the mobile station including information related
to a signal transmission power for the mobile station and
information for determining a maximum transmission power level of
the mobile station; adjusting, for at least one of said pairs, its
corresponding wireless signal strength, using said data, thereby
obtaining corresponding adjusted pairs, wherein each adjusted pair
has the corresponding adjusted signal strength, and wherein said
adjusted signal strength is an expected signal strength of a
predetermined standardized mobile station transmitter power level
having a predetermined maximum transmission power and operating at
a predetermined transmission power level; outputting second signal
characteristic information, obtained using said adjusted signal
strength, to a mobile station location estimator for determining a
location estimate of said first mobile station. [0195] Aspect 78. A
method for locating a mobile station as in Aspect 77, further
including applying sequence of one or more signal processing
filters to one of: said pairs and said adjusted pairs. [0196]
Aspect 79. A method for locating a mobile station as in Aspect 78,
wherein said sequence of filters is dependent upon a corresponding
mobile station location estimator. [0197] Aspect 80. A method for
locating a mobile station as in Aspect 79, wherein said sequence of
filters is pipelined so that for first and second filters of said
sequence, an output of said first filter is an input to said second
filter. [0198] Aspect 81. A method for locating a mobile station as
in Aspect 79, wherein said filters include Sobel, Weiner, median
and neighbor. [0199] Aspect 82. A method for locating a wireless
mobile station, comprising: first receiving first signal
characteristic measurements of wireless signals communicated
between a mobile station and a first network of base stations,
wherein said first signal characteristic measurements includes one
or more pairs of wireless signal strength related values and
corresponding signal time delays for a wireless communication
between the mobile station and at least a first of the base
stations; categorizing said pairs into categories according to
ranges of signal strength related values and ranges of
corresponding signal time delays for obtaining a representation of
a frequency of occurrence of said one or more pairs in said
categories; applying one or more filters to said representation for
one of: (a) reducing characteristics of said representation that
are expected to be insufficiently repeatable for use in identifying
a location of the mobile station, and (b) enhancing a signal to
noise ratio; supplying an output obtained from said step of
applying to a mobile station location estimator; estimating a
location of the mobile station using said mobile station location
estimator. [0200] Aspect 83. A method for locating a wireless
mobile station as in Aspect 82, further including a step of
requesting data for additional pairs of wireless signal strength
related values and corresponding signal time delays for a wireless
transmission between the mobile station and at least a second base
station of a second network of base stations different from the
base stations of the first network, wherein said first and second
networks communicate with the mobile station in different signal
bandwidths. [0201] Aspect 84. A method for locating a wireless
mobile station as in Aspect 83, wherein the first network is
operated by a first commercial mobile radio service provider and
the second network is operated by a second commercial mobile radio
service provider. [0202] Aspect 85. A method for locating a
wireless mobile station as in Aspect 82, wherein said
representation corresponds to a histogram. [0203] Aspect 86. A
method for locating a wireless mobile station as in Aspect 82,
further including a step of normalizing one of: (a) said pairs, and
(b) values corresponding to said output. [0204] Aspect 87. A method
for locating a wireless mobile station as in Aspect 23, wherein
said step of activating further includes the step of applying a
fuzzy logic module which further discretizes the location estimate
provided from one of: [0205] (a) a location estimator for
estimating a location of the mobile station using location
information obtained from said distributed antenna system; [0206]
(b) a location estimator for estimating a location of the mobile
station by one of: triangulation and trilateration. [0207] Aspect
88. A method for contacting a telephony station, comprising:
associating, by a user, a particular telephony number with a
collection of one or more telephony station numbers of telephony
stations with which the user desires to communicate when said
particular telephony number is called from a predetermined
telephony station; receiving said particular telephony number from
the predetermined telephony station; determining a location of said
predetermined telephony station and at least some of said telephony
stations having telephony station numbers in said collection;
selecting a first of said telephony stations having telephony
station numbers in said collection, wherein said first telephony
station is selected according to a location of said predetermined
telephony station and a location of first telephony station;
transmitting a user desired message to said first telephony
station. [0208] Aspect 89. A method for locating a mobile station,
comprising: establishing, by a user of a particular mobile station,
a collection of identities of one or more persons having permission
to receive a location of said particular mobile station; receiving
a request by a first of said persons for locating said particular
mobile station; determining a location of said particular mobile
station in response to said request, said location determined using
measurements of wireless transmissions between said particular
mobile station and a first wireless network of base stations,
wherein said base stations are cooperatively linked for wireless
communication; outputting said location to the first person. [0209]
Aspect 90. A method as in Aspect 89, wherein said step of
determining includes using measurements of wireless transmissions
between said particular mobile station and a second wireless
network of base stations provided by a different commercial
wireless service provider from a commercial wireless service
provider for the first wireless network. [0210] Aspect 91. An
apparatus for locating a mobile station as in Aspect 3, further
including a means for providing a location estimate using the
Internet. [0211] Aspect 92. An apparatus for locating a mobile
station as in Aspect 3, further including a means for providing a
location estimate using digital certificate keys and the Internet.
[0212] Aspect 93. An apparatus for locating a mobile station as in
Aspect 91, further including a means for providing a location
estimate using push technology on the Internet.
[0213] Further description of the advantages, benefits and
patentable aspects of the present invention will become evident
from the accompanying drawings and description hereinbelow. All
novel aspects of the invention, whether mentioned explicitly in
this Summary section or not, are considered subject matter for
patent protection either singly or in combination with other
aspects of the invention. Accordingly, such novel aspects of the
present invention disclosed hereinbelow and/or in the drawings that
may be omitted from, or less than fully described in, this Summary
section are fully incorporated herein by reference into this
Summary. In particular, all claims of the Claims section
hereinbelow are fully incorporated herein by reference into this
Summary section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0214] FIG. 1 illustrates an overall view of a wireless location
system and method for using multiple commercial mobile radio
service providers;
[0215] FIG. 2 shows is a high level wireless location architecture
using the intelligent network, which illustrates aspects of the
home base station and Internet connectivity for receiving location
requests and for providing location estimates;
[0216] FIG. 3 illustrates how the signals from the base stations
associated with various multiple commercial radio service providers
can be shared with the wireless location system to provide an
improved geometry and thus improved wireless location accuracy.
[0217] FIG. 4 shows how the mobile station database in the location
system is updated via interfaces in communication with multiple
commercial mobile radio service providers using customer care
systems.
[0218] FIG. 5 shows a method of direct access to multiple CMRS base
stations, from the location system perspective, thus avoiding the
need to significantly modify network infrastructure systems.
[0219] FIG. 6 illustrates physical components and the effects of
predetermined signal delay, and total system delay in a distributed
antenna environment for purposes of wireless location;
[0220] FIG. 7 shows the timing relationships among the signals
within a distributed antenna system.
[0221] FIG. 8 shows a flowchart of the methods and procedures
required to implement a DA database;
[0222] FIG. 9 illustrates an exemplary DA configuration with a
direct antenna connection to the base stations;
[0223] FIG. 10 illustrates an alternative DA configuration using
multipoint microwave;
[0224] FIG. 11 illustrates how multiple base stations could be used
via a microwave circuit to provide PCS and location service to a
multilevel building via virtual pilot channels;
[0225] FIG. 12 shows the DA delay spread ranges possible for a 500
microsecond guard zone;
[0226] FIG. 13 shows DA-cell layout a geometry and how location
geometries can be constructed;
[0227] FIG. 14 illustrates the realization of actual measurements
and classification utilized within DA cell ranges to determine a
percent range within each cell.
[0228] FIG. 15 shows the standard components of a CDMA MS.
[0229] FIG. 16 shows one embodiment for MS modification that
facilities enhanced RF measurement telemetry.
[0230] FIG. 17 shows how the LC is used in a Home Base Station
architecture.
[0231] FIG. 18 illustrates a typical case where signals from three
base stations can be detected.
[0232] FIG. 19 illustrates a typical case where signals from four
base stations (including remaining set information) can be
detected.
[0233] FIG. 20 shows a MS detection scheme with a two base station
geometry.
[0234] FIG. 21 illustrates a typical amorphous location area with
only the signal detection of a single base station sector, by a
MS.
[0235] FIGS. 22A-C shows a series of typical reverse path CDMA RF
measurements in a dense urban area.
[0236] FIGS. 23A-C shows a series of typical reverse path CDMA RF
measurements in a rural setting.
[0237] FIG. 24 shows a typical Location Center connection to a CTIA
Model.
[0238] FIG. 25 shows a typical national Location Center and
relevant network connections.
[0239] FIG. 26 illustrates a typical three dimensional delay spread
profile.
[0240] FIG. 27 shows the magnifying effects of convoluting
similar-property forward and reverse path three-dimensional
images.
[0241] FIG. 28 illustrates an image and relief representation of a
CDMA Delay Spread Profile.
[0242] FIG. 29 illustrates the main components of the Signal
Processing Subsystem 20.
[0243] FIG. 30 illustrates an image based on an RF signal
measurement sample set, before image histogram equalization
filtering is applied.
[0244] FIG. 31 illustrates an image based on an RF signal
measurement sample set, after image histogram equalization input
cropping filtering is applied.
[0245] FIG. 32 illustrates an image sample grid before image
filtering.
[0246] FIG. 33 shows a CDMA profile image after input cropping is
used at a level of 50 percent.
[0247] FIG. 34 illustrates the results of combining input cropping
at 40 percent, then performing four by four median filtering on the
resultant.
[0248] FIG. 35 shows the results of combining input cropping at 50
percent with four by four median filtering.
[0249] FIG. 36 illustrates how location estimates can be provided
using voice channel connections via an ACD and Internet
technology.
[0250] FIG. 37 shows wireless Location of a MS using the Voice
Channel from a Hunt Group.
[0251] FIG. 38 illustrates how location information can be provided
via Text paging or short message service messaging.
[0252] FIG. 39 shows how location information of an MS can be
provided via Internet via "Push" technology.
[0253] FIG. 40 illustrates how location directions can be provided
to nearest members, regarding directions for each individual member
to reach a distressed MS caller.
[0254] FIG. 41 illustrates how traveling instructions from two
different points can be provided to an initiator.
[0255] FIG. 42 illustrates how wireless location services can be
used to facilitate automotive rental car tracking and control.
[0256] FIG. 43 indicates the addition of a fuzzy logic module which
discretizes the wireless location estimate output from the TOA/TDOA
location estimator module.
DETAILED DESCRIPTION
[0257] Various digital wireless communication standards have been
introduced such as code division multiple access (CDMA) and Time
Division Multiple Access (TDMA) (e.g., Global Systems Mobile (GSM).
These standards provide numerous enhancements for advancing the
quality and communication capacity for wireless applications.
Referring to CDMA, this standard is described in the Telephone
Industries Association standard IS-95, for frequencies below 1 GHz,
and in J-STD-008, the Wideband Spread-Spectrum Digital Cellular
System Dual-Mode Mobile Station-Base station Compatibility
Standard, for frequencies in the 1.8-1.9 GHz frequency bands.
[0258] Additionally, CDMA general principles have been described,
for example, in U.S. Pat. No. 5,109,390, Diversity Receiver in a
CDMA Cellular Telephone System, by Gilhousen, et al, filed Nov. 7,
1989. There are numerous advantages of such digital wireless
technologies such as CDMA radio technology. For example, the CDMA
spread spectrum scheme exploits radio frequency spectral efficiency
and isolation by monitoring voice activity, managing two-way power
control, provision of advanced variable-rate modems and error
correcting signal design, and includes inherent resistance to
fading, enhanced privacy, and provides for multiple "rake" digital
data receivers and searcher receivers for correlation of multiple
physical propagation paths, resembling maximum likelihood
detection, as well as support for multiple base station
communication with a mobile station, i.e., soft or softer hand-off
capability. When coupled with a location center as described
herein, substantial improvements in radio location can be achieved.
For example, the CDMA spread spectrum scheme exploits radio
frequency spectral efficiency and isolation by monitoring voice
activity, managing two-way power control, provision of advanced
variable-rate modems and error correcting signal design, and
includes inherent resistance to fading, enhanced privacy, and
provides for multiple "rake" digital data receivers and searcher
receivers for correlation of multiple physical propagation paths,
resembling maximum likelihood detection, as well as support for
multiple base station communication with a mobile station, i.e.,
soft hand-off capability. Moreover, this same advanced radio
communication infrastructure can also be used for enhanced radio
location. As a further example, the capabilities of IS-41 and AIN
already provide a broad-granularity of wireless location, as is
necessary to, for example, properly direct a terminating call to a
mobile station. Such information, originally intended for call
processing usage, can be re-used in conjunction with the location
center described herein to provide wireless location in the large
(i.e., to determine which country, state and city a particular
mobile station is located) and wireless location in the small
(i.e., which location, plus or minus a few hundred feet within one
or more base stations a given mobile station is located).
[0259] FIG. 1 illustrates a wireless location network using two
commercial mobile radio service provider networks for the present
invention. Accordingly, this figure illustrates the
interconnections between the components of a typical wireless
network configuration and various components that are specific to
the present invention. In particular, as one skilled in the art
will understand, a typical wireless network includes: (a) a mobile
switching center (MSC) 112a; (b) generally a service control point
4a, and base stations (not shown) which are in communication with a
mobile switch center 112a. Within a typical metropolitan area it is
also common for a second commercial mobile radio service (CMRS)
provider to offer wireless service within essentially similar
coverage areas, such systems typically including an mobile switch
center 112b, service control point 4b, and associated base stations
(not shown). Added to this wireless network, the present invention
provides the following additional components:
[0260] (1) a location system or center 142 which is required for
determining a location of a target mobile station using signal
characteristic values as measured by the target mobile station (not
shown) and nearby base stations (not shown), further including of
the following modules or subsystem components:
[0261] (1.1) an application programming interface 14 (having a
controller also denoted by the label "14"), for physically
interfacing with and controlling the messaging to and from each
CMRS mobile switch center 112a, 112b, service control points 4a and
4b, receiving location requests from either the mobile switch
center 112a, or 112b, or the Internet 468, and providing connection
to the signal processing subsystem 20;
[0262] (1.2) a signal processing subsystem 20, which is in
communication with the application programming interface (L-API)
14. The signal processor 20 receives, queues, filters and processes
signal measurement messages into various formats suitable for the
location estimate modules DA 10 and TOA/TDOA 8;
[0263] (1.3) a TOA/TDOA location estimate module 8, in
communication with the signal processing subsystem 20. The TOA/TDOA
module 8 provides a location estimate result, using a time of
arrival or a time difference of arrival technique based on
conditioned signals from the signal processing subsystem 20; in
addition the TOA/TDOA module may also process signals from the
distributed antenna module 10, in order to provide a location
estimate within environments containing distributed antenna
systems;
[0264] (1.4) a distributed antenna (DA) module 10, which receives
signals related to distributed antennas, from the signal processor
20 in communication a location estimating capability for utilizing
one or more distributed antenna systems 168 as shown in FIG. 2,
wherein each such system 168 provides wireless location information
for an MS 140 within the area in communication with one or more
distributed antenna system 168.
[0265] (1.5) a home base station module (HBS) 6 in FIG. 1, which
receives signals from the (application programming interface)
controller 14 and determines wireless location (i.e., providing a
location estimate result) based on registration principles of the
wireless user's mobile station when in communication with the
user's home base station (not shown) in communications with a given
service control point 4a or 4b, containing a home base station
application (not shown).
[0266] Since home base stations and distributed antenna systems can
be located on potentially each floor of a multi-story building, in
such cases where infrastructure is installed, the wireless location
technology described herein can be used to perform location in
terms of height as well as by Latitude and Longitude.
[0267] Referring to FIG. 2, additional detail is provided of
typical base station coverage areas, sectorization, and high level
components used in the present invention's scope, including the
mobile switch center 112, a mobile station 140 in communication
with a home base station 160, and communication between the
location system 142 and the public Internet 468, via an Internet
service provider interface 472. A novel aspect of this invention
includes providing wireless location estimate information to
various designated users via the public Internet. Although base
stations may be placed in any configuration, a typical deployment
configuration is approximately in a cellular honeycomb pattern,
although many practical tradeoffs exist, such as site availability,
versus the requirement for maximal terrain coverage area. To
illustrate, such exemplary base stations (BSs) 122a through 122g
are shown, each of which radiate referencing signals within their
area of coverage to facilitate mobile station (MS) 140 radio
frequency connectivity, and various timing and synchronization
functions. A given base station may contain no sectors (not shown),
thus radiating and receiving signals in a 360 degree
omnidirectional coverage area pattern, or the base station may
contain "smart antennas" (not shown) which have specialized
coverage area patterns.
[0268] Alternatively and generally most frequent are base stations
having three sector coverage area patterns. Shown in FIG. 2, each
sector for base station 122a through 122g contains three sectors,
labeled a, b, and c, which represent antennas that radiate and
receive signals in an approximate 120 degree arc, from an overhead
view. As one skilled in the art will understand, actual base
station coverage areas generally are designed to overlap to some
extent, thus ensuring seamless coverage in a geographical area.
Control electronics within each base station are used to
communicate with a given mobile station 140. Further, during
communication with the mobile station the exact base station
identification and sector identification information are known and
are provided to the location center 142.
[0269] The base stations located at their cell sites may be coupled
by various transport facilities 176 such as leased lines, frame
relay, T-Carrier links, optical fiber links or by microwave
communication links.
[0270] When the mobile station is powered on and in the idle state,
it constantly monitors the pilot signal transmissions from each of
the base stations located at nearby cell sites. As illustrated in
FIG. 3, base station/sector coverage areas may often overlap both
in the context of a single CMRS base station network, and also in
the context of multiple CMRS base station networks, thus enabling
mobile stations to detect, and, in the case of certain
technologies, communicate simultaneously along both the forward and
reverse paths, with multiple base stations/sectors, either with a
single CMRS network or, in the case of hand-offs and roaming,
multiple CMRS network equipment. In FIG. 3 the constantly radiating
pilot signals from base station sectors 122a, 122b and 122c are
detectable by mobile station 140 at its location. The mobile
station 140 scans each pilot channel, which corresponds to a given
base station/sector ID, and determines which cell it is in by
comparing signals strengths of pilot signals transmitted from these
particular cell-sites.
[0271] The mobile station 140 then initiates a registration request
with the mobile switch center 112a, via the base station controller
(not shown). The mobile switch center 112a determines whether or
not the mobile station 140 is allowed to proceed with the
registration process (except in the case of a 911 call, wherein no
registration process is required). At this point, calls may be
originated from the mobile station 140 or calls or short message
service messages can be received from the mobile switch center
112a.
[0272] As shown in FIG. 2, the mobile switch center 112
communicates as appropriate, with a class 4/5 wireline telephony
circuit switch or other central offices, with telephone trunks in
communication with the public switch telephone network (PSTN) 124.
Such central offices connect to wireline stations, such as
telephones, or any communication device compatible with the line,
such as a personal or home base station. The PSTN may also provide
connections to long distance networks and other networks.
[0273] The mobile switch center 112 may also utilize IS/41 data
circuits or trunks 522, which in turn connects to a service control
point 104, using, for example, signaling system #7 (SS7) signaling
link protocols for intelligent call processing, as one skilled in
the art will understand. In the case of wireless advanced
intelligent network (AIN) services such trunks and protocols are
used for call routing instructions of calls interacting with the
mobile switch center 112 or any switch capable of providing service
switching point functions, and the public switched telephone
network (PSTN) 124, with possible termination back to the wireless
network. In the case of an mobile station 140 in communication with
a corresponding home or office base station (HBS) 160, the HBS 160
controls, processes and interfaces the mobile station 140 to the
PSTN 124, in a manner similar to a cordless telephone system,
except that added AIN logic within, for example, the service
control point (SCP) 104 is used to determine if the mobile station
140 is being controlled by the HBS 160 or a wireless base station
122. Regarding non-HBS calls, the mobile switch center 112 may
direct calls between mobile stations 140 via the appropriate cell
site base stations 122 a through 122h since such mobile stations
140 do not typically communicate directly with one another in such
wireless standards as CDMA, TDMA NAMPS, AMPS and GSM.
[0274] Referring again to FIG. 2, the Location system 142
interfaces with the mobile switch center 112 either via dedicated
transport facilities 178, using for example, any number of LAN/WAN
technologies, such as Ethernet, fast Ethernet, frame relay, virtual
private networks, etc., or via the PSTN 124 (not shown). The
location system 142 receives autonomous (e.g., unsolicited) or
command/response messages regarding, for example: (a) the wireless
network states, including for example, the fact that a base station
has been taken in or out of service, (b) mobile station 140 and BS
122 radio frequency (RF) signal measurements, (c) notifications
from a SCP 104 indicating that an HBS 160 has detected and
registered with the SCP 104 the mobile station 140 corresponding to
the HBS 160, and (d) any distributed antenna systems 168.
Conversely, the location system 142 provides data and control
information to each of the above components in (a)-(d).
Additionally, the Location system 142 may provide location
information to a mobile station 140, via a BS 122, using, for
example the short message service protocol, or any data
communication protocol supported by the air interface between the
base station and the mobile station. Interface 106 connecting the
location system 142 with the service control point 104 may also be
required in the event the home location register and/or the home
base station AIN function is located in the SCP 104.
[0275] Assuming the wireless technology CDMA is used, each BS 122a,
122b, 122c, through 122g uses a time offset of the pilot PN
sequence to identify a forward CDMA pilot channel. Furthermore,
time offsets, in CDMA chip sizes, may be re-used within a PCS
system, thus providing efficient use of pilot time offset chips,
thus achieving spectrum efficiency.
[0276] The use of distributed antennas is another technique for
improving or extending the RF coverage of a radio coverage area 120
of a wireless system. Such distributed antennas are typically used
in buildings or other areas of dense clutter, such as numerous
walls, partitions and/or similar structures causing substantial
signal attenuation. As shown in FIGS. 6,9, 10, 11, and 13,
distributed antennas 168 are typically connected together in a
serial fashion for communicating with one or more infrastructure
base stations 122. Distributed antennas may be connected to the
mobile switch center 112 via various air interfaces, as shown in
FIGS. 10 and 11, or alternatively distributed antennas may be
connected to the MSC via a directed connection to a base station
122 as shown in FIG. 9, or via a private branch exchange (PBX) as
shown in FIG. 13.
[0277] Referring to FIG. 11, distributed antennas 168 are useful
particularly in wireless system configurations involving
microcells, and potentially indoor environments, such as wireless
systems in communication with private branch exchange systems
(reference FIG. 13) in business offices, and in wireless local loop
applications (not shown) as one skilled in the art will understand.
Additionally, a distributed antenna embodiment can provide
significant improvements in decreasing location error, as compared
with an indoor mobile station 140 (reference FIG. 11) user with a
wireless connection to an outdoor, infrastructure base station 122,
as illustrated in FIGS. 11, 12, 13 and 14.
Mobile Station Description
[0278] As an example of a mobile station 140, such a mobile station
will be described using CDMA technology. FIG. 15 illustrates a
typical block diagram of the functional components of a CDMA mobile
station (MS) 140, based on the patent, "Diversity Receiver in a
CDMA Cellular Telephone System", U.S. Pat. No. 5,109,390. The MS
140 contains an antenna 510 coupled through diplexer 512 to analog
receiver 514 and transmit power amplifier 516. Antenna 510 and
diplexer 512 permit simultaneous transmission and reception of
signals through an antenna 510. Antenna 510 collects transmitted
signals and provides them through diplexer 512 to analog receiver
514. Receiver 514 receives the RF frequency signals, typically
either in the 800-900 MHZ or 1.8-1.9 GHz band, from diplexer 512,
for amplification and frequency down conversion to an intermediate
frequency (IF). Translation is accomplished through the use of a
frequency synthesizer of standard design which permits the receiver
514 to be tuned to any of the frequencies within the designated
receive frequency band. The IF signal is passed through a surface
acoustic wave bandpass filter, typically of 1.25 MHZ bandwidth, to
match the waveform of the signal transmitted by a base station 122.
Receiver 514 also provides an analog to digital converter (not
shown) for converting the IF signal to a digital signal. The
digital signal is provided to each of four or more data receivers
(520, 522, 524, and 526), one of which is a searcher receiver (526)
with the remainder being data receivers, as one skilled in the art
will understand.
[0279] Analog receiver 514 also performs a open-loop type of power
control function for adjusting the transmit power of the mobile
station 140 on the reverse link channel. Receiver 514 measures the
forward link signal strength of the signals from base stations 122,
then generates an analog power control signal to circuitry in the
transmit power amplifier 516, which can effect a range up to about
80 dB. The power control for the transmit power amplifier 516 is
also supplemented by a closed-loop power control or mobile
attenuation code (MAC) control parameter sent to the mobile station
140 via the air (i.e., wireless) interface from a BS 122, with
either the CMAC or VMAC command (as one knowledgeable in CDMA
standards will understand). The MAC can take on one of eight values
0 through 7, which effect a closed loop to raise or lower the power
correction. The transmit amplifier 516 may utilize one of three
transmit power classes when transmitting within a transmitted power
control group in the 800-900 MHZ cellular band: class I (1 to 8
dBW), class II (-3 to 4 dBW), or class III (-7 to 0 dBW), for a
closed-loop range of about ''32 dB. In the PCS 1.8-1.9 GHz band
five classes are defined: class I (-2 to 3 dBW), class II (-7 to 0
dBW), class III (-12 to -3 dBW), class IV (-17 to -6 dBW), class V
(-22 to -9 dBW), for a closed-loop range of about ''40 dB. The
mobile station 140 power class and transmit power level for a
communicating mobile station 140 is known to the wireless
infrastructure network, and may be utilized for location
estimation, as is described hereinbelow.
[0280] The digitized IF signal may contain the signals from several
telephone calls together with the pilot channels and multipath
delayed signals from each of several pilot channels. Searcher
receiver 526, under control of control processor 534, continuously
scans the time domain around the nominal time delay offsets of
pilot channels contained within the active, candidate, neighboring
and remaining sets of pilot channels. The initial sets of pilot
channels and a defined search window size for each set are provided
by a control message from a BS 122 via the air interface to the
mobile station 140. The searcher receiver 526 measures the strength
of any reception of a desired waveform at times other than the
nominal time and measures each pilot channel's arrival time
relative to each pilot's PN sequence offset value. Receiver 526
also compares signal strength in the received signals. Receiver 526
provides a signal strength signal to control processor 534
indicative of the strongest signals and relative time
relationships.
[0281] Control processor 534 provides signals to control digital
data receivers 520, 522 and 524 such that each of these receivers
processes a different one of the strongest signals. Note, as one
skilled in the art will understand, the strongest signal, or
finger, may not be the signal of shortest arrival time, but rather
may be a reflected, and therefore delayed, signal (such reflected
denoted collectively as "multipath"). Data receivers 520, 522 and
524 may track and process multipath signals from the same forward
channel pilot channel offset or from a different forward channel
pilot offset. In the case where a different pilot channel offset
signal is of greater strength than the current cell site (or more
specifically the current base station 122) pilot channel offset,
then control processor 534 generates a control message for
transmission on a reverse channel from the mobile station 140 to
the current BS 122, requesting a transfer of the call, or a soft
hand-off, to the now strongest cell site Base station 122. Note
that each of the four receivers 520, 522, 524 and 526 can be
directed independently from each other. The three data receivers
520, 522, and 524 are capable of tracking and demodulating
multipath signals from of the forward CDMA pilot channel. Thus data
receivers 520, 522 and 524 may provide reception of information via
separate multipath signals from one BS 122 (e.g., in particular, an
antenna face of a sectored antenna at the BS 122, or reception of
signals from a number of sectors at the same BS 122, or reception
of signals from multiple BSs 122 or their antenna faces of sectored
antennas. Upon receiving a CDMA pilot measurement request order
command, or whenever: (a) the mobile station 140 detects a pilot
signal of sufficient strength, not associated with any of the
assigned forward traffic channels currently assigned, or (b) the
mobile station 140 is in preparation for a soft or hard hand-off,
then the searcher receiver 526 responds by measuring and reporting
the strengths of received pilots and the receiver's definition of
the pilot arrival time of the earliest useable multipath component
of the pilot, in units of PN chips (one chip=0.813802
microseconds). The receiver 526 computes the strength of a pilot by
adding the ratios of received pilot energy per chip E.sub.c, to
total received spectral density, I.sub.0, of at most k useable
multipath components, where k is the number of data receivers
supported in the mobile station 140.
[0282] The outputs of data receivers 520, 522, and 526 are provided
to diversity combiner and decoder circuitry 538 (i.e., simply
diversity combiner). The diversity combiner 538 performs the
function of adjusting the timing of a plurality of streams of
received signals into alignment and adds them together. In
performing this function, the diversity combiner 538 may utilize a
maximal ratio diversity combiner technique. The resulting combined
signal stream is then decoded using a forward stream error
detection contained within the diversity combiner. The decoded
result is then passed on to the user digital baseband circuitry
542.
[0283] The user digital baseband circuitry 542 typically includes a
digital vocoder which decodes the signals from diversity combiner
538, and then outputs the results to a digital to analog (D/A)
converter (not shown). The output of the D/A serves as an interface
with telephony circuitry for providing mobile station 140 user
analog output information signals to the user corresponding to the
information provided from diversity combiner 538.
[0284] User analog voice signals typically provided through an
mobile station 140 are provided as an input to baseband circuitry
542. Baseband 542 serves as an interface with a handset or any
other type of peripheral device, to the user for audio
communication. Baseband circuitry 542 includes an analog to digital
(A/D) converter which converts user information signals from analog
form into a digital form. This digital form is then input to a
vocoder (not shown) for encoding, which includes a forward error
correction function. The resulting encoded signals are then output
to transmit modulator 546.
[0285] Transmit modulator 546 modulates the encoded signal on a PN
carrier signal whose PN sequence is based on the assigned address
function for a wireless call. The PN sequence is determined by the
control processor 534 from call setup information that was
previously transmitted by a cell site BS 122 and decoded by the
receivers 520, 522, 524 as one skilled in the art will understand.
The output of transmit modulator 546 is provided to transmit power
control circuitry 550. Note that signal transmission power is
controlled partially by an open-loop analog power control signal
provided from receiver 514. In addition, control bits are also
transmitted by the controlling BS 122 in the form of a supplemental
closed-loop power adjustment command and are processed by data
receivers 520, 522. In response to this command, control processor
534 generates a digital power control signal that is provided to
the transmit power amplifier 516. Transmit power control 550 also
provides the digitized and encoded user information signals in an
IF format to output to the transmit power amplifier 516. The
transmit power amplifier 516 converts the IF format signals into an
RF frequency by mixing this signal with a frequency synthesizer
(not shown) output signal for providing a corresponding signal at
the proper output transmission frequency signal. Subsequently,
transmit power amplifier 516 amplifies the signal to the final
power output level. The transmission signal is then output from the
transmit power amplifier 516 to the diplexer 512. The diplexer 512
then couples the transmission signal to antenna 510 for air
interface transmission to the infrastructure base stations 122.
[0286] Additionally, note that control processor 534 is also
responsive to various control and information request messages from
the controlling BS 122, including for example, sync channel
messages, the system parameters messages, in-traffic system
parameters messages, paging/alert messages, registration messages,
status requests, power control parameters messages and hand-off
direction messages, as one skilled in the art will understand.
[0287] Referring still to a CDMA mobile station 140, in one
embodiment of the present invention, the above-described standard
CDMA mobile station architecture in an mobile station 140 is
sufficient. However, in a second embodiment, this architecture may
be modified in minor, cost effective ways so that additional
information may be transmitted from an mobile station 140 to the BS
122. The modifications for this second embodiment will now be
described. The following modifications, either together or in any
combination, provide improvements in location accuracy from the
perspective of capturing RF measurement data: (1) increasing
measurement quantity, (2) improving measurement transmission, (3)
extending the pilot set and search, (4) extending the pilot signal
reporting capabilities, (5) decreasing the Quantization size of the
units used to report the pilot PN phase arrival time, (6) improving
the accuracy of the mobile and base station time reference, and (7)
increasing the number of data receivers and related circuitry, for
correlation tracking of a larger plurality of pilot channels and
each of their multipath signals.
[0288] Using the standard system parameters overhead message in the
paging channel as one method of reporting to the base station the
signal strengths and delays of detectable pilot channels, a mobile
station has various timers indicating the upper bounds of time
needed to respond to a request, and to bid for access to the
forward channel (if not already using it's assigned traffic
channel). These timers restrict the frequency of measurement
reporting and thus limit the aggregate amount of measurement data
which can be sent in a given time period.
[0289] For example, CDMA standard timer T.sub.33m establishes the
maximum time of a mobile station to enter the update overhead
information substate of the system access state to respond to
messages received while in the mobile station idle state, typically
0.3 seconds. Timer T.sub.58m, the maximum time for the mobile
station to respond to one service option request, is typically 0.2
seconds. Thus during a period of about five seconds, this
measurement reporting method would provide for a maximum of about
fifteen measurements.
[0290] However the same CDMA receiver design infrastructure, with
slight circuitry modification can be used to support improved
measurement transmission.
[0291] In order to collect a data ensemble of RF measurements that
represents a statistically significant representation of data
values in a geographical area of interest, it is the intention that
the second (CDMA) mobile station 140 embodiment be capable of
sending to the network base station infrastructure approximately
128 samples of each multipath peak signal strength and its relative
delay, for each detectable pilot channel, in less than a preferred
period of about five seconds. In order to transmit this amount of
data, other means are needed to efficiently send the needed data to
the network (i.e., from the mobile station to the base station, and
then to forward data to the wireless switch, and then to forward
data to the Location Center).
[0292] The CDMA air interface standard provides several means for
transmitting data at higher rates. The Data Burst message can be
used, or various blank-and-burst, dim-and-burst multiplex options
can be used, and well as selecting various service options 2
through 9, through the setup of a normal voice or data telephone
call. In one embodiment, the user dials a speed number representing
a data-type call to the Location Center 142, which initiates a
command to the mobile station 140, responsive by the mobile station
140, which then provides the location center 142, via the base
station 122, mobile switch center 112 with the needed measurement
data.
[0293] Referring to FIG. 16, in one embodiment a software
controllable data connection or path 49 is established between the
control processor 46, and the user digital baseband 30 functional
components in the mobile station, a much larger quantity of RF
measurements, on the order of 128 data samples, can be transmitted
as a data burst, multiplexed, or sent by other means such as a data
circuit call, back to the network, and to the Location Center. Note
that the existing connection between the control processor 534 and
the transmit modulator 546 may also be used, as well via any other
virtual path, such as software register-to-register move
instructions, as long as sufficient signal measurement content and
data samples can be sent to the wireless network and the location
center 142 via the associated interfaces. Those skilled in the art
will understand the wireless network consists of the base station,
mobile switch center, and related infrastructure equipment,
interfaces and facilities circuits to telemeter the measurement
content and data samples to the location center 142. Additional
design issues include, for example, the fact that existing memory
in the mobile station must be allocated to the temporary storage of
RF sample measurements, and new control means, such as selecting a
future use control bit pattern in the CDMA air standard, are
required to telemeter, preferably upon command, RF measurement
sample data to the Location Center 142 in FIG. 1. In the case where
a location request is received by the location engine 139 in the
location center 142, the location engine 139 initiates a message to
the mobile station 140 via a signal processing subsystem and the
location center mobile switch center physical interface, the
location applications programming interface 136 (e.g., FIG. 36,
L-API-MSC) for the mobile switch center 112 and the wireless
network infrastructure.
[0294] The addition of a controllable data connection or path 49
can be easily performed by CDMA application-specific integrated
circuit (ASIC) manufacturers. In the case of one ASIC manufacturer
known to the authors, the Qualcomm ASIC chip mobile station modem,
model number MSM 2300, provides both the control processor function
534 and the user digital baseband 542 functions or the same chip,
thus the external pinout physical configuration would not have to
change to accommodate the wireless location software controllable
data connection or path 49 modification.
[0295] If the mobile station 140 searcher receiver detects 4 pilots
with 4 multipaths each, with each measurement consisting of a pilot
index, finger identification, multipath signal strength, and
multipath arrival time, then about 480 bytes are needed per
measurement. Assuming the searcher receiver performs one
measurement every 10 microSeconds, about 1 second is needed to
compile and buffer each sample of 128 measurements per sample, or
about 48 kilobytes. Using a typical 9600 kbps CDMA data channel
between the mobile station 140 and a BS 122, and assuming a 50
percent overhead, the mobile station can complete the collection
and transmission of a location measurement sample in less than ten
seconds, which is within a reasonable period for satisfying a
location request.
Network Data Services
[0296] The implementation of the data services required to
telemeter the necessary signal measurements may be performed in any
of several embodiments. In one embodiment the location signal
measurements request-response application message set utilizes the
air interface services provided by the spare bits and digital
control words not currently in the air interface standards IS-95
and ANSI-J-STD-008. Such bits and control words can be reserved for
the purpose of requesting and providing the required location
signal measurements discussed herein. Using this embodiment the
base station and mobile switch center must be modified to support
the interworking function required between the location center and
the mobile station. In a second embodiment the location signal
measurements request-response application message set is
implemented using service options 4 and 12, which provides
asynchronous data transmission capability, as defined in TR45 Data
Standard, Async and Fax Section, document number TIA/EIA/IS-DATA.4.
Using this second embodiment, the mobile station control processor
provides, or would interface with a function emulating mobile
termination 0 or 2 services at the R.sub.m network reference point.
The L-API 14 then provides, or would interface with a function
emulating the physical interface connecting a data
circuit-terminating equipment (DCE) to the PSTN at the W network
reference point, in communication with the PSTN, which is also in
communication with reference point Ai, which is in communication
with reference point U.sub.m, which is in turn in communication
with reference point R.sub.m. An advantage of this embodiment is
that no ASIC or circuit board modifications are needed in the
mobile station.
[0297] The ANSI standards J-008 and IS-95 provide several means for
the base station 122 to establish and to extend the search window
size that the mobile station 140 should use in its scanning
process, and to identify further pilots. For location purposes,
either existing standard parameters can be extended, or a location
message request from the Base station can inform the searcher
receiver of the mobile station to extend its search range, as
necessary, to capture all relevant base station pilots and their
multipath fingers, in order to complete the location measurement
sample.
[0298] The search performance criteria defined in ANSI IS-98,
Recommended Minimum Performance Standards for Dual Mode, can be
increased as appropriate to accommodate a larger set of potentially
detectable base stations, including Location Base stations and
Mobile Base stations. Additionally the search window table size for
various search window values must be increased to accommodate new
pilot channel pn-offsets associated with Location Base Stations and
Mobile Base stations.
[0299] Existing standard parameters include, for example using the
In-traffic System Parameters Message, the values SRCH_WIN_A (for
active and candidate set), SRCH_WIN_N (for neighboring set), and
SRCH_SIN_R (for remaining set) can be used to cause the searcher
receiver to increase its search area to detect and thus measure as
many pilots as can be detected in the area. Extending the range of
T_ADD and T_DROP parameters can also be used to facilitate the
mobile to retain data on additional pilots in the area. The
extended neighbor list message is used to inform the mobile station
of the necessary characteristics of neighboring pilot signals. For
example if location base stations are used on a different frequency
assignment, and/or utilize unique, non-public pilot PN sequence
offset indices, for example, in using increments other than 64 PN
chips, then the extended neighbor list message can be used to
instruct the mobile station to scan for those types of base
stations, accordingly.
[0300] There can be several combinations of delay spread signal
strength measurements made available to the location center, from
the mobile station 140. In some cases the mobile station 140 may
detect up to three to four pilot channels (representing 3-4 base
stations), or as few as one signal from one pilot channel.
[0301] For each pilot channel detection case, multiple, up to three
to four fingers, or multipath signals may be detected per pilot
channel.
[0302] Note that multiple multipath signals, or multiple "fingers"
could exist from a less-strong BS pilot signal, or in any of
several combinations, which can depend widely upon the mobile
station's location within the base station environment.
[0303] By modifying the CDMA Base station, mobile station and
controller capabilities to provide the location center 142 with
data that exceeds the 1:1 fingers to data receiver correspondence,
additional information can be collected and processed in order to
further improve the accuracy of the location estimate. A control
message from the location center 142 and carried through the
network, is sent to the control processor in the mobile station,
requiring the searcher receiver in the mobile station to transmit
to the location center 142 via the network, all detectable delay
spread fingers related to each detectable pilot channel.
[0304] In one embodiment the control message is implemented in the
CDMA receiver via a multiplexing technique, including appropriate
manipulation of the hand-off parameters T_ADDs, T_DROPs, search
window and the active, neighbor and remaining pilot sets held
within the mobile station' memory.
[0305] Although the CDMA ANSI J-STD 008 requires reporting of the
pilot channel arrival time in a time period of units of one chip
size, or 813.802 nanoseconds, typical CDMA receivers contain an
internal Quantization interval of one eighth chip size.
[0306] Within the mobile station, by modifying the time of arrival
message response message to output the delay value in unit
increments of one-eighth chip size, the precision of location
accuracy can be increased from about 800 feet in radius to about
110 feet. At the base station the arrival time measurement is
forwarded in one-eighth units to the Location Center. A multiplier
function applied to the received measurement at the base station
rescales the measurement for routine CDMA control and monitoring
purposes, in order to be consistent with the CDMA standard. In
order to distinguish among several mobile station models which
report arrival time in either one-eighth chip units or one chip
unit sizes, an encoding can be used in the mobile station's
hardware or software identifications, telemetered to the base
station and Location Center, in order to determine the arrival time
measurement units. In one embodiment the analog receiver in the
mobile station utilizes a clock signal which runs eight times
faster than the clock originally disclosed in the Gilhousen patent,
U.S. Pat. No. 5,109,390. In this manner the digital signal provided
to the data receivers and the searcher receiver will include an
improved resolution in ability to detect delay spread signals,
which are directly used to improve wireless location.
[0307] Although the CDMA air interface standard only requires a
1,000 nanosecond tolerance accuracy within respect to the base
station, location accuracy can be improved if manufacturing
calibration precision's are held to within tighter tolerances, such
as less than 250 nanoseconds. However in any given location
request, as long as the base station to base station tolerances are
tuned properly to an amount less than 500 nanoseconds, then very
good location estimates can be performed due to the self canceling
time effect geometries typically present in multi pilot channel
detection found in urban and suburban areas.
[0308] Increasing the typical number of data receivers in either
the mobile station or base station provide added capabilities to
lock and track more delay spread fingers and respective base
station pilot channels. The resulting additional information, if
available in a given radio coverage area 120 in FIG. 1, can be used
for enhanced location estimate accuracy due to confluence or voting
methods which can be deployed at the Location system 142.
Fuzzy Logic for Vertical Location
[0309] In certain cases wireless location signals are received
representing distributed antennas (or other base stations) across
building floor boundaries being received from a specific floor on a
multi-storied building. As a specific example, consider signals are
being received from both the 40th and the 41st floor; the objective
is to resolve the ambiguity of the situation. Fuzzy logic is used
to resolve this ambiguity. The determination as to which floor the
user of the mobile station is on is based on the strength of the
signal, S, and the past reliability of the information associated
with the two antennae, R. The spaces of S and R are discretized
using fuzzy sets. The strength is defined as being: (1) VERY STRONG
(VS), (2) STRONG (S), (3) WEAK (W), and (4) VERY WEAK (VW) as
defined by membership functions. The reliability of information is
defined as being: (1) VERY RELIABLE (VR), (2) RELIABLE (R), and (3)
NOT RELIABLE (NR), again as defined by membership functions. A
fuzzy relation or mapping is described which descretizes how
confident it is that the signal is coming for a given floor, e.g.,
the 40th floor, using the following notation:
TABLE-US-00002 VS S W VW VR 1.0 0.85 0.45 0.2 R 0.85 0.6 0.4 0.1 NR
0.6 0.4 0.3 0.0
[0310] The above relation matrix is read, for example, that when
the signal information is RELIABLE and the strength is WEAK, then
the confidence that the signal is coming from the 40th floor is
0.4. A similar fuzzy relation matrix is established for the
distributed antenna on the 41st floor, and thus the result would be
a confidence factor associated with the mobile station being
located on either floor. A single solution, that is, whether the
mobile station is on the 40th or 41st floor is determined using a
compositional rule of inference. The compositional rule of
inference is a function that prescribes a mechanism for
consolidating membership function values into a single crisp
function. This function can take a variety of forms including
max-min composition, max-product composition. etc. The
compositional rule of inference can be implemented, for example, by
a summing junction which collects the results of each firing rule.
The summing junction's output is then provided to a centroidal
defuzzier which provides the discretized output.
[0311] FIG. 43 indicates the addition of a fuzzy logic module 41
which optionally discretizes the wireless location estimate output
from the TOA/TDOA location estimator module 8. In the above case
fuzzy logic rules related to the distributed antenna relation
matrix would be fired or activated as a result of examining the
message header data structure that indicates that the location
estimate was the result of a distributed antenna case around the
40th and 41st floor of a particular building within which such
fuzzy relations exist or in any other localized case wherein such
fuzzy relations have been predetermined. Otherwise, in cases where
no such fuzzy rules apply, the location estimate is passed to the
recipient without further discretization.
[0312] Note that the confidence associated with the location of the
mobile station can be considered a function of several variables,
not just the two (S and R) described above. For instance, it would
not be unreasonable to segregate the reliability information by
time signal delay as determined within this invention. The fuzzy
relation is capable of handling a variety of such situations. Thus
which floor the mobile station is on can be considered to be a
function of numerous variables; the ultimate decision can be made
based on a great deal of information.
Location Center--Network Elements API Description
[0313] A location application programming interface 14 (FIG. 1), or
L-API, is required between the location system's 142 signal
processor 20 and the mobile switch center 12 network element type,
in order to send and receive various control, signals and data
messages for wireless location purposes. The L-API 14 is
implemented using a preferably high-capacity physical layer
communications interface, such as IEEE standard 802.3 (10 baseT
Ethernet), although other physical layer interfaces could be used,
such as fiber optic ATM, frame relay, etc. Two forms of API
implementation are possible. In the first case the control signals
and data messages are realized using the mobile switch center 112
vendor's native operations messages inherent in the product
offering, without any special modifications. In the second case the
L-API 14 includes a full suite of commands and messaging content
specifically optimized for wireless location purposes, which may
require some, although minor development on the part of the mobile
switch center vendor. A minimum set of L-API message types
includes:
[0314] A first message type, an autonomous notification message
from the mobile switch center 112 to the location system 142, is
required in the event a wireless enhanced 9-1-1 call has been sent
to the mobile switch center from a mobile station 140, including
the mobile identification number (MIN), along with various CMRS
identification and mobile station detected active, candidate,
neighbor and remaining pilot set information, pilot strength
measurements message.
[0315] A second message type, forward path request-response
message, from location system 142 to mobile switch center 112, is
required to request a mobile station (MS) for signal measurements
and hand-off information, with a response message back from the
mobile switch center 112 to the location system 142, along with
various CMRS identification.
[0316] A third message type, Reverse path request-response message,
from location system 142 to mobile switch center 112, to a BS for
signal measurements received at the BS and hand-off information,
for a given mobile station MIN, along with various CMRS
identification. It is preferable for the received signal strength
measurements performed at the mobile station along the forward
path, and at the base station along the reverse path, to be
reported in a variable-length data structure as follows: for each
pilot channel offset, include the phase of the earliest arriving
usable multipath component pilot PN sequence relative to the zero
offset pilot PN sequence of this pilot, termed pilot PN phase or
pilot arrival, in units of one-eighth PN chip, instead of units of
one PN chip as stated in the standards. Furthermore, in accordance
with the standards, the pilot strength shall be included, measured
based on at most k usable components, where k is the number of
demodulating elements supported by the receiver system. In addition
the total number of each detectable multipath components shall be
reported. In addition each multipath component, for a given pilot,
shall be identified by both its delay component and signal
strength, for inclusion in the signal measurements to the location
system 142. Regarding each individual multipath component, signal
strength is expressed as is commonly known, by adding the ratios of
received pilot-multipath component energy per chip, E.sub.c, to
total received spectral density (noise and signals), i.sub.0 of at
most that one multipath component (i.e., k is equal to one).
[0317] A fourth message type, an autonomous notification message
from the mobile switch center 112 to the location system 142 is
required, in the event of a mobile station hand-off state change,
along with various CMRS identification.
[0318] In order to implement additional location functions such as
wide area location, wherein location is determined across roaming
boundaries, out-of-coverage area conditions or mobile station 140
turned off, and home base station applications, the L-API 14 must
include access to and receive data from a data store contained in
the home location register (HLR) network element type associated
with the mobile switch center 112.
[0319] A fifth message type is required which provides the location
system 142 with the mobile station MIN, hand-off, along with
various CMRS identification information (e.g., old and new state
changes, old and new BS identifications, and hand-offs to another
CMRS), roaming location and status changes. A typical
communications protocol such as Signaling System number 7, running
on a V.35 communications channel could be used for implementation,
but numerous other protocols (e.g., TCIP/IP, ROSE, CMISE, etc.)
could be used to implement this capability. If the home location
register is local to the mobile switch center 112 then the
LC--mobile switch center communications link could be used,
otherwise a separate communications link is used between the
location system 142 and the home location register.
[0320] A sixth message type, an autonomous notification message
type issued from the location system 142 to the home location
register, is required for those location applications that rely on
an alert from the home location register when ever a particular
mobile station state change occurs, along with various CMRS
identification. Consider the case wherein an mobile station 140
whose location is to be tracked constantly. In such cases a history
of locations is maintained in the location system 142. Should the
mobile station 140 user turn off the power, or exit from the
coverage area, then by using previous location values a vector and
approximate velocity can be determined. This sixth message type
provides a notification message from the home location register to
the location system 142 whenever a previously identified mobile
station MIN has a state change. Examples of state changes include
cases where the base station 122 discovers the mobile station 140
has traveled to another base station, or that the current primary
base station 122 can no longer communicate with the mobile station
140 (i.e., no power), or that a new registration has occurred. In
general this message type should support the notification from the
home location register to the location system 142 of all messaging
and data associated with the nine types of registration, in the
case of CDMA. Specifically these include power-up, power-down,
timer-based, distance-based, zone-based, parameter-change, ordered,
implicit and traffic channel registration. The location system 142
should also be informed of the registration enablement status of
each type of registration, which can be provided to the location
system 142 via a redirection of the systems parameters message. It
should also be possible (in a seventh message type) for the
location system 142 to initiate an ordered registration through an
order message, from the location system 142 to the mobile switch
center 112. The mobile switch center 112 then shall route the
message to the appropriate base station, and then to the mobile
station. The location system 142 should also be able to receive the
results of the message.
[0321] In order to implement additional location functions such as
providing users with location information and routing instructions
to certain locations via the wireless short message text paging
service, an L-API 14 is required between the location system 142
and the network element type used to implement the short message
service. Such network elements may be termed an intelligent
peripheral or a service node. A number of existing paging
interfaces have been proposed in standards bodies, and one or more
modifications can be made to accommodate L-API 14 content. In any
case, the following L-API addition is required: an eighth message
type which allows the location system 142 to send a text message
containing location information or instructions to a particular
mobile station MIN, and a related message to verify response.
Optionally in another, ninth message type, an autonomous message
may be provided to alert the location system 142 under conditions
wherein a state change occurs on a previously pending text message.
This last message type provides improved quality feedback to the
initiating party regarding the acceptance situation of the
attempted-to-send page.
Utilizing Multiple CMRS Infrastructure in a Shared Coverage
Area
[0322] As a consequence in practical deployment situations that
base stations are not placed in a uniform manner in a geographical
area, and the fact that variable and fixed clutter introduce a
variety of signal measurements which can result in the provision of
an ambiguous location estimation, a novel aspect of this patent
includes the utilization of the inherent ability of the wireless
protocol and receiver design to request and receive signal
measurements along the forward and reverse air interface
communications path with a given mobile station and other
commercial mobile radio service providers, in cases where multiple
service providers share a common coverage area. Thus in a coverage
area shared by two service providers A and B, utilization of
received signal measurements from both service provider A and
service provider B can be used by the location center as unique,
orthogonal information to both resolve ambiguous location estimates
and to further improve the location estimate accuracy.
[0323] The CDMA air interface, for example, provides a soft
hand-off capability for the mobile station to hand-off a voice
communication channel to another base station, and even to another
CMRS provider, termed a hard hand-off.
[0324] Referring to FIG. 3, assume three sectored base stations
122a, 122b, and 122c, in communication with mobile switch center-A
112a, are owned and operated by CMRS provider A. Further, assume
three sectored base stations 122d and 122e, in communication with
mobile switch center-B 112b, are owned and operated by CMRS
provider B, and that the coverage area with CMRS-A and CMRS-B
substantially overlap. In order to locate a mobile station 140
whose subscriber normally does business with CMRS provider A,
assume that the receiver of mobile station 140 can detect signals
from base stations 122a, 122b, and 122c, as well as from base
stations 122d and 122e, although normal mode use would preclude
such measurements from being initiated. Assume further that the
resulting location estimate 131 (FIG. 5), generated from the
location center 142 contains either an ambiguous location estimate
value pair, or otherwise cannot render a location estimate with the
desired range of accuracy.
[0325] From an inspection of the overall base station geometry of
base stations owned by CMRS A and CMRS B it is evident that a
strong possibility exists that either 1.) the receivers in mobile
station 140 have the possibility to detect the pilot channels
associated with base stations 122d and 122e; 2.) the receivers in
base stations 122d and 122e have the possibility to detect the
transmitter signal from mobile station 140. The location system 142
contains a data store of both CMRS provider's base station
geometries and is in communication with each mobile switch
center--A 112a and mobile switch center--B 112b. An application in
the location system 142 sends a control message to the mobile
station 140, instructing the mobile station to tune its searcher
receiver to listen for and report back signal measurement data
regarding the pilot channel information associated with base
stations 122d and 122e, in addition to a request to report of pilot
signals relative to base stations 122a, 122b, and 122c. Similarly
the application in the location system 142 sends messages to each
of base stations 122d and 122e, with instructions to take signal
measurements and report back the resulting information regarding
the mobile stations transmitter 140. Since the signaling
information from base stations 122d and 122e are based on a
substantially different location geometry, the resultant
information is orthogonal and thus can be used by the location
center to provide enhanced location estimates.
[0326] If appropriate, a variation of the above process includes a
location center initiated forced hard hand-off of the mobile
station from a primary base station, e.g., 122b associated with
CMRS-A, to a new primary base station associated with CMRS-B, e.g.,
122d. A forced hand-off will further provide improvements in
reducing systemic timing errors which may be inherent among base
stations owned by different CMRS. After the appropriate signal
measurements have been reported the location system 142 can revert
the hand-off back to the original CMRS. Other location system
components shown in FIG. 3 include the L-API 14 which includes the
location applications programming interface 136 (L-API-MSC) as a
communications interface with multiple CMRS mobile switching
centers, via physical interfaces 176a and 176b.
[0327] In order to provide the most economically efficient and
accurate wireless location service capabilities among multiple CMRS
providers in a shared coverage area, a common location applications
programming interface (L-API 14) is highly desirable. A common
interface also supports the natural competitive behaviors among
wireless consumers and CMRS by providing flexible relationships
among consumers who may want to switch service providers, yet
retain consistent wireless location services for public safety.
This approach minimizes the L-API design and deployment costs among
infrastructure vendors and location service providers in a shared
coverage area. Based on a L-API between a wireless location center
and the mobile switch centers of multiple CMRS, a novel aspect of
this invention further includes a method and process that provides
account management clearing house and revenue settlement capability
with appropriate security management controls. This capability is
implemented as wireless location control, accounting and security
mediation agent functions to compensate CMRS providers for
providing various location-specific network services as described
herein.
[0328] As wireless location requests are sent to the location
center for a given CMRS, operated by a wireless location service
provider (WLSP), the location center: 1.) assesses the
appropriateness of soliciting additional signal and control
measurements from another CMRS' base station in the same coverage
area, in order to improve the quality of the location estimate, 2.)
accesses, requests and receives signal and control information with
another CMRS base station infrastructure, 3.) provides as
appropriate a record of compensation entitlement between or among
multiple CRMS and WLSPs, and 4.) provides security management
controls that protect the privacy needs of wireless customers and
the unauthorized sharing of information between or among CMRS.
Security controls also include audit trails and controls regarding
customer access of their location subscriber profile and the
administration of network security processes and related base
station parameters and inventory.
[0329] Referring to FIG. 5, Location Center-base station access,
multiple CMRS, an alternative embodiment is provided to extract the
wireless location signal measurement data from each base station
associated with each of multiple CMRS. Given base station 122i and
122j are operated by CMRS-A and base station 122k and 122m are
operated by CMRS-B, a communication circuit provides connectivity
with the location application programming interface--base station
(L-API-BS) (not shown). The L-API-BS is in communication with the
L-API 14 in the location center 142. The communications circuit can
be any of several conventional transport facilities, such as a
private line circuit, a DS-1 or T-1 carrier circuit, frame relay
circuit, microwave circuit, or other data communications
circuit.
[0330] The advantage of this embodiment is that no modifications
are required by the infrastructure vendor in terms of the embedded
operations circuit, and related functions and systems which
otherwise would be needed to telemeter wireless location signal
measurement data from the base station to the location center 142.
The termination equipment (not shown) in communication with the
transport facilities, within each base station typically includes a
small computer with an in-circuit connection, such as an ASIC
clip-on device, with connections to the control processor circuitry
with the base station in the receiver section. The small computer
provides a conversion of the signals provided on the in-circuit
connection to the ASIC chip, for serialization and transmission to
the location center via the transport facilities.
Home Base Station Description
[0331] The Home Base station (HBS) concept in the PCS wireless
network environment allows a user's mobile station to be also used
as a low cost cordless phone, whenever the mobile station is
physically near (generally within 700-1,000 feet) of a Home Base
station Device (HBSD). This enables the user to avoid the typically
higher cost air time charges associated with traditional wireless
service.
[0332] The HBSD is similar to ordinary cordless phone transceiver
devices in current use today, but is modified to function with a
PCS wireless mobile station. Although the HBSD has been typically
used at a residential consumer's home, the HBSD could also be used
in business settings and other environments.
[0333] When a mobile station (MS) is near the HBSD as shown in FIG.
17, and the HBSD detects the presence of a mobile station over the
cordless phone air interface, the HBSD signals the Home Location
Register (HLR) software in the Service Control Point in the AIN
network associated with the mobile station and mobile station's
home mobile switch center. The home location register redirects
mobile station terminating calls from the network away form the
mobile station's mobile identification number in the mobile switch
center, and to the AIN/SSP wireline class V switch which connects
the wireline number associated with the HBSD. Similarly, the HBSD,
upon detecting a mobile station call origination attempt, redirects
the mobile station signal from a PCS network fixed base station, to
the control of the HBSD. The HBSD redirects the mobile station
originating call through the wireline network, similar to any other
wireline network call.
[0334] A reverse scenario occurs whenever the mobile station and
HBSD lose communication: the mobile station registers in a wireless
PCS network fixed base station, causing redirection of calls to the
wireless network. The cordless phone air interface may be of a
vendor proprietary design, or it may be a similar design as the
CDMA air interface.
[0335] In order to perform a location estimate in the HBS concept,
a connection is used between the Location Center (LC) and the home
location register/HBS application in the SCP. In addition, a new
process, termed a Location Notification Process (LNP) within the
home location register/SCP is used to send a message to the LC,
autonomously whenever a state change occurs in the mobile station'
(either via a specific list of mobile identification numbers or all
mobile identification numbers) registration: registering either to
a fixed Base station in the Wireless PCS network or to a HBSD.
[0336] Alternatively the process may respond to an on-demand
message from the LC to the LNP within the home location
register/HBS application. In either case a response message from
the LNP to the LC provides the information regarding whether or not
a mobile station is within range of its, or a designated HBSD. In
either case the response message contains a message header
information which provides the signal processing subsystem 20
(equivalently this may be known by signal filtering subsystem) with
the ability to determine and distribute the information to the HBS
First Order Location Estimate Model.
Location Using Distributed Antennas Description
[0337] CDMA distributed antennas are useful particularly in system
configurations involving microcells, and potentially indoor
environments, such as CDMA PBX (private branch exchange) systems in
business offices, and in wireless local loop applications. From a
mobile station location perspective, the distributed antenna
configuration can provide significant improvements in location
error, as compared with an indoor mobile station user with a
wireless connection to an outdoor, macrocell Base station. Wireless
location can be achieved provided certain methods and procedures
(M&Ps) are followed during the installation process. Data
related to these M&Ps is then used by various location
processes discussed elsewhere in this invention.
[0338] First, a general description of CDMA distributed antennas is
presented, followed by the M&Ps necessary to support wireless
location.
[0339] In the CDMA distributed antenna concept, a set of simple
antennas, placed apart in a given area, similarly to any other cell
placement arrangement for coverage objectives, are fed by a common
radio signal. Antennas are usually placed such that their coverage
patterns are substantially or completely overlapped in area of
coverage. From a wireless location perspective, completely
overlapping coverage is preferred (this approach also improves
perceived signal quality by the end users).
[0340] The importance of understanding and characterizing the
aggregate system delay elements is shown in FIG. 6: Distributed
Antenna Delay Characterization. For any given Pilot Channel offset
"I", additional delay is introduced by the microwave propagation
channel (Point A) and any internal repeater/amplifier equipment
(Point B). Each of four delay elements t.sub.1 through t.sub.4
introduce further delay. A mobile station detecting all four DA
antennas' delayed signals would determine various sets of
cumulative system propagation delays. Since each delay is
essentially fixed in a location, such information can be used to
determine the mobile station location within the building. FIG. 7
illustrates the effective system timing among the delay elements
324, relative to the GPA system time 336, along each point in the
diagram shown in FIG. 6.
[0341] FIG. 9: One Exemplary DA Configuration, illustrates a
typical configuration where the CDMA base station antenna is also
directed connected to three delay elements and antenna
radiators.
[0342] The CDMA Base station transmitter common output signal is
fed through a distribution coaxial cable system, optical fibers or
other means, to a string of two or more antennas. Each antenna is
connected to the distribution cable via a transmission line tap or
delay element, which may or may not provide further broadband gain.
The transmission system normally consists of two media channels,
one for transmit and one for receive signals. FIG. 10 illustrates
an Alternative DA Configuration, using multi-point microwave
antennas connected to individual delay elements and their
respective radiating antennas.
[0343] FIG. 11: Serving Dense Multi-level buildings via Virtual
Pilots, illustrates a typical application where a multi-level
building is served by two base stations with pilot offsets "I" and
"j". Pilot offset "I" serves floor X and pilot offset "j" serves
floor Y. As shown, a microwave link, either active or passive,
relays the base station signals between the distributed antennas
within the building to the base stations.
[0344] The main concept is to introduce purposeful delay and
multipath signals with sufficient delay spread for signal
discrimination. Each antenna radiates a signal which is
substantially delayed with respect to any other antenna in the
area. If two or more paths are available for the mobile station
receivers with greater than one eighth microsecond differential
path delay (or whatever resolution is available in the CDMA mobile
station receivers), then two or more PN receivers in the same
mobile station can be employed to separately receive and combine
these signals and thus achieve processing gains through path
diversity. Antennas may be omni-directional or directional.
[0345] Delay elements may be simple delay lines such as lengths of
coaxial cabling, or other active or passive delay elements, such
that the combination of components provides the needed delay. The
transmission line between the CDMA Base station/PBX and the
distributed antennas may be via a pair of dedicated, beam-focused
high gain antennas, and/or a repeater system. Provided sufficient
delay exists between the multipath signals from separate
distributed antennas exists, each Data Receiver within the mobile
station tracks the timing of the received signal it is receiving.
This is accomplished by the technique of correlating the received
signal by a slightly earlier reference PN and correlating the
received signal with a slightly late local reference PN. Further
distributed antenna details can be seen from Gilhousen, et al, U.S.
Pat. No. 5,280,472, assigned to Qualcomm, Inc.
[0346] The total measured delay of both forward and reverse link
signals between the BS and the mobile station are thus determined
naturally by the CDMA radio receiver designs as a part of the
multipath tracking process, and can be made available to a location
entity for performing location estimates of the mobile station.
[0347] However, the measurements of delay between a particular
distributed antenna and the mobile station will include the
aggregate delay components of several mechanisms, beyond the BS
pilot PN offset delay. In the case of distributed antenna
configurations, the simple TOA or TDOA model which is based solely
of the speed of light, must now be adjusted to account for the
purposefully introduced delay.
[0348] The mobile station measures the arrival time T.sub.i, for
each pilot I reported to the BS. The pilot arrival time is the time
of occurrence, as measured at the mobile station antenna
connection, of the earliest arriving usable multipath of the pilot.
The arrival time is measured relative to the mobile station' time
reference in units of PN chips. The mobile station computes the
reported pilot PN phase f.sub.i as:
f.sub.i=(T.sub.i+64.times.PILOT_PN)mod 2.sup.15,
[0349] where PILOT_PN is the PN sequence offset of the pilot.
[0350] Reference FIG. 6, which illustrates a typical distributed
antenna configuration consisting of a repeater/amplifier and four
distributed antennas. The total system delay, T.sub.i is:
T.sub.i=T.sub.offset+T.sub.0+T.sub.R+T.sub.1+T.sub.2+T.sub.3+T.sub.4
[0351] During the installation phase of the high gain antenna (if
required), repeater (if required) and the distributed antennas, if
the system delay is measured at each distributed antenna and the
values stored in a location database, including each antenna
identification, and exact physical location (in three dimensions),
then during a location request, all fixed delays will be known,
thus the TP value can be determined by subtracting the fixed, known
delay values from Ti, the measured time of arrival. The TP value
can now be used to determine a TOA and or a TDOA value in a manner
similar to the non-distributed antenna case, thus location can be
determined based on these TOA/TDOA ranging values.
[0352] The required installation methods and procedures required to
support wireless location are illustrated in FIG. 8: Methods and
Procedures for DA Installation. By following these methods, the
Location Center (LC) will contain a database populated with the
necessary data values to perform accurate location estimates within
the building containing the distributed antennas. Table B
illustrates typically data element types and values required in the
DA location estimate model database. Table DA-11 below illustrates
how a simple TOA location estimate model can be used to determine
wireless location in a DA environment. Based on the known geometry
and coverage areas of each DA cell, and the percentage of maximum
radius, determined by the above classification, it is possible to
construct radius-radius circles of the DA cells. The intersection
of the three circles (in this case) provides the location
estimate.
TABLE-US-00003 TABLE DA-11 DA Cell Classification and Radius
Percentage ##STR00001##
[0353] In order for the TOA and TDOA location calculations to be
determined, it is a necessary condition that during distributed
antenna installation, the minimum values of the Delay Elements be
set to each exceed the maximum practical (i.e., within the coverage
area) TP values be at least 1/2 of a PN chip duration (about 500
nanoseconds), to easily allow for the CDMA Data Receivers to be
able to correlate between the delay element values and the TP delay
values. FIG. 12: DA Delay Spread Ranges, illustrates typical
maximum ranging variable delay values (e.g., up to 1,960 feet) if
500 nanosecond guard zones (t) are used. If larger ranging values
are required, then guard zone delays must be increased
proportionally.
[0354] FIG. 13: DA Cell Layout and Geometry, illustrates, for DA
omnicell sizes with a radius of about 2,000 feet and guard zones of
500 nanoseconds, that the minimum required cumulative delay values
for the delay elements are: t.sub.2=2.46 microseconds (uS),
t.sub.3=4.92 uS, and t.sub.4=7.38 uS, respectively.
[0355] It should also be noted that a maximum upper bound exists
for the maximum amount of cumulative system propagation delay which
can be tolerated by the CDMA mobile station. The total delay cannot
exceed an amount that would interfere with the next pilot PN
offset, or substantially delay the scanning time of the search
receiver in the mobile station. In any case, 30 to 40 microseconds
of total delay is acceptable, and would allow for a relatively
large number of distributed antenna components to be included, thus
no unusual impacts are required of the system to accommodate
location methods.
[0356] By purposefully introducing a relatively large amount of
delay in the distributed antenna delay elements, relative to the
maximum permissible TP delay values, it is possible to utilize the
large Delay Element values to uniquely identify the distributed
antenna ID, and thus via the distributed antenna database, to
determine the antennas' exact location. Knowing the antenna's
location and TP value (last stage of propagation delay), TOA and
TDOA ranging can be achieved, and thus mobile station location
within a distributed antenna configuration, can be determined.
[0357] FIG. 14: Actual Measurements and Classification, illustrates
how CDMA delay spread measurements are used in a DA configuration
to form a relationship with the mobile station location with
respect to the DA locations. Although the CDMA air interface
standard only requires the signal strength and time of arrival of
the first useable delay spread signal to be reported from the
mobile station to the BS, assume here that the mobile station has
the capability to provide the BS, and consequently the LC, with a
list of all peak values of CDMA fingers.
[0358] Assume that the mobile station detects and telemeters three
CDMA finger RF measurements, as shown in the table A below, New
Message Type Data Structure Content.
TABLE-US-00004 TABLE A New Message Type Data Structure Content.
Signal Strength Delay Time of Arrival -77 dBm 1.68 microseconds -66
3.98 -95 9.16
[0359] Note that the measurements may be averaged over a sample
space of 128 individual measurements. Referring now back to FIG.
14, it can be seen that the first finger is associated with the DA
cell-1, range 0 to 1.96 microseconds, and DA cell-2, range 2.46
microseconds to 4.42 microseconds (uS), and DA cell-4, range 7.38
to 9.34 microseconds. Since the DA cell antennas are fixed, with
known locations, correlation's can be derived and established to
relate actual measurements with locations. Any one of several
location estimating models may be used, using the radius-radius
method, or multiple invocations of different modules may
alternatively be used to form a location estimate of the mobile
station within the DA environment.
[0360] It is now possible to classify the above actual measurements
as propagation delayed signals for the DA cells 1, 2, and 4, since
each DA cell delay range is known, and sufficient guard zones exist
between delay spread ranges to unambiguously classify the
measurements, and thus to determine mobile station location. The
following table illustrates a typical database containing the
classification columns for each DA cell and their corresponding
location in an x,y plane.
TABLE-US-00005 TABLE B New Message Type Data Structure Content for
Exemplary DA Location Database Records High Range DA Cell Location
(X, Y) in DA Cell Low Range (In ID feet) Radius (microseconds)
microseconds) 1 (0, 0) 1.96 0 1.96 2 (-20, 3000) 1.96 2.46 4.42 3
(4000, 2800) 1.96 4.92 6.88 4 (1600, 2800) 1.96 7.38 9.34
[0361] Translating the actual delay measurements into a percentage
of the maximum radius of each cell (i.e., cell 1 radius actual is
88%, cell 2 radius actual is 78%, and cell radius 4 actual is 91%)
provides wireless location using familiar radius-radius
calculations.
[0362] Depending upon the combinations of embodiments, the Location
Center and Gateway may contain from one to three interfaces into
the digital PCS network, shown as interfaces X, Y, and Z, in FIG.
24, Location and CTIA/TR45 Network Reference Model. Network
interface reference points Um, A, Ai, B, C, D and H are part of the
Cellular Telecommunications Industry of America (CTIA)/Technical
Reference 45 standards, and are not discussed further.
[0363] Network interface reference point X provides a direct
connection to the mobile switch center, used for transferring RF
measurement signals from the mobile station and BS to the LC and
for transferring location control between the LS and mobile
station, and between the LC and BS. This interface can be
implemented via any number of data communications circuit
configurations and protocols in current use, such as a T-carrier
data circuit, with DSU/CSUs at each end, using an intranet/internet
protocol suite, such as TCP/IP, RPC messaging, or other middleware
solutions, such as Pipes, IBM MQ series, world wide web protocols,
such as JAVA/VRML scripts, hypertext markup language (HTML) links,
and may also include various firewall schemes and data encryption
mechanisms, etc., in order to communicate asynchronous messaging
among the endpoints, and in particular, in reference to the final
distribution of the location information to the desired end
user.
[0364] Network interface reference point Y is used in the
embodiment wherein a public switched telephone network interface is
required or desired. This interface is a straightforward method to
support location applications wherein, for example, a mobile
station user dials a telephone number in order to initiate a
location request, and could also be used to telemeter RF
measurement and location control messages between the LC and the
mobile station/BS. Alternatively a timer-initiated process internal
to the LC may be used to start a location request, or via any
number of events external to the network. Point Y also has the
advantage of not requiring a direct connection to a commercial
radio mobile service providers' network elements, thus affording a
convenient interface for use by third party location service
providers unrelated to the commercial radio mobile service
provider.
National Scale Wireless Location
[0365] By utilizing specific data items used in the Home Location
Register in the Advanced Intelligent Network, it is possible to
determine the mobile station location on a national scale, i.e.,
location within the context of a state, and in which city.
[0366] Referring now to FIGS. 24 and 25, network interface
reference point Z is used in the embodiment wherein a gross
location must be determined. A gross location is defined as an area
associated with a particular mobile switch center coverage area.
Mobile switch center coverage areas are typically bounded by a
large metropolitan area, such as a city. The Home Location Register
(HLR) contains gross location information. The Z interface allows
the LC 142 to query the home location register to determine if the
user is in their "home area, or whether the user is roaming to
another mobile switch center coverage area, such as another city.
IS-41 Cellular Radio Telecommunications intersystem operations
communications protocols provide mechanisms that allow a user to
roam into authorized areas outside of their "home" area.
[0367] If the user is roaming in another area, then the LC 142 can
use that information to initiate location control messages toward
the CDMA network currently hosting the mobile station user. FIG. 25
illustrates how a user based in Los Angeles, Calif., for example,
may roam to a CDMA system in New York City, and be "located" within
that metropolitan area, through a data communications network and a
national Location Center Clearinghouse system.
Signal Processor Subsystem
[0368] The signal processing subsystem receives control messages
and signal measurements and transmits appropriate control messages
to the wireless network via the location applications programming
interface referenced earlier, for wireless location purposes. The
signal processing subsystem additionally provides various signal
identification, conditioning and pre-processing functions,
including buffering, signal type classification, signal filtering,
message control and routing functions to the location estimate
modules.
[0369] There can be several combinations of Delay Spread/Signal
Strength sets of measurements made available to the signal
processing subsystem 20 within the Location Center/System 142,
shown in FIG. 3. In some cases the mobile station 140 may be able
to detect up to three or four Pilot Channels representing three to
four Base Stations, or as few as one Pilot Channel, depending upon
the environment. Similarly, possibly more than one BS 122 can
detect a mobile station 140 transmitter signal, as evidenced by the
provision of cell diversity or soft hand-off in the CDMA standards,
and the fact that multiple CMRS' base station equipment commonly
will overlap coverage areas. For each mobile station 140 or BS 122
transmitted signal detected by a receiver group at a station,
multiple delayed signals, or "fingers" may be detected and tracked
resulting from multipath radio propagation conditions, from a given
transmitter.
[0370] In typical spread spectrum diversity CDMA receiver design,
the "first" finger represents the most direct, or least delayed
multipath signal. Second or possibly third or fourth fingers may
also be detected and tracked, assuming the mobile station contains
a sufficient number of data receivers. Although traditional TOA and
TDOA methods would discard subsequent fingers related to the same
transmitted finger, collection and use of these additional values
can prove useful to reduce location ambiguity, and are thus
collected by the Signal Processing subsystem in the Location Center
142.
[0371] For each pilot channel detection case, multiple fingers (up
to three or four) may be detected and thus reported to the Location
system 142, as shown in FIGS. 22A-C and 23A-C, for dense urban and
rural settings, respectively. From the mobile receiver's
perspective, a number of combinations of measurements could be made
available to the Location Center. Table SP-1 illustrates the
available combinations for three and four receiver cases,
respectively.
TABLE-US-00006 TABLE SP-1 Nominal CDMA Location Measurement
Combinations No. of No. of No. of No. of No. of No. of Fingers, BS
Fingers, BS Fingers, BS Fingers, No. of BSs Fingers 1-S (first 2-S
(second 3-S (third 4-S (fourth Receivers detected Detected
strongest) strongest) strongest) Strongest 3 1 1 1 0 0 0 3 1 2 2 0
0 0 3 1 3 3 0 0 0 3 2 2 1 1 0 0 3 2 3 2 1 0 0 3 2 3 1 2 0 0 3 3 3 1
1 1 0 4 4 4 1 1 1 1 4 3 4 1 2 1 0 4 3 4 1 2 1 0 4 3 4 2 1 1 0 4 2 4
3 1 0 0 4 2 4 2 2 0 0 4 2 4 1 3 0 0 4 1 4 4 0 0 0
[0372] The above Table SP-1 scenario assumes that the mobile
station design and data collection structure only permits a 1:1
correspondence to exist between the number of base stations
detected and the number of data receivers reporting multipath CDMA
fingers.
[0373] Table SP-1 illustrates the potential combinations of
detected CDMA signals representing multipath fingers and total
number of detectable base station pilot signals in a given location
within the radio coverage area 120. Due to the disperse and
near-random nature of CDMA radio signals and propagation
characteristics, traditional TOA/TDOA location methods have failed
in the past, because the number of signals received in different
locations area different. In a particularly small urban area, say
less than 500 square feet, the number of RF signals and there
multipath components may vary by over 100 percent.
[0374] FIGS. 18 and 19 illustrate a certain case from a location
measurement perspective, of signals received for a three-data
receiver and a four-data receiver configuration, in a nominal three
sector honeycomb base station configuration. In FIG. 18, a mobile
station at location "A" detects base stations 1b, 5c, and 4a.
However although a triad of signals are received, if varying
multipath signals are received from one or more base stations, then
ambiguity can still result. FIG. 19 illustrates a mobile station
located at position "A", detecting base stations 1b, 5c, 4a, and
2c. Although additional information is made available in this
second case, traditional hyperbolic combinations taken three at a
time, yield multiple location estimates. In certain cases the limit
of the back-side of a "far-away" sectored antenna can be used to
determine the limit of RF coverage in another base station sector
area. FIG. 20 shows that normally a delay spread in sector 1b would
imply a range of a 120 degree solid angle. However by using the
known fact that base station sector 2a contains a coverage limit,
such negative logic can be used to further restrict the apparent
coverage area in sector 1b, from 120 degrees to approximately 90
degrees as shown in the illustration, in order to locate the mobile
station B. Such information regarding sector 2a can be determined
by collecting the remaining set information from mobile station
B.
[0375] Now consider more practical, less ideal cases. Due to the
large capital outlay costs associated with providing three or more
overlapping base station coverage signals in every possible
location, most practical digital PCS deployments result in fewer
than three base station pilot channels being reportable in the
majority of location areas, thus resulting in a larger, more
amorphous location estimate. FIGS. 20 and 21 illustrate a typical
relative error space wherein a mobile station detects only two base
station pilot channels, and only one pilot channel, respectively.
This consequence requires a family of location estimate location
modules or models, each firing whenever suitable data has been
presented to a model, thus providing a location estimate to a
backend subsystem which resolves ambiguities.
[0376] In one embodiment of this invention using backend hypothesis
resolution, by utilizing existing knowledge concerning base station
coverage area boundaries (such as via the compilation a RF coverage
database--either via RF coverage area simulations or field tests),
the location error space is decreased. Negative logic Venn diagrams
can be generated which deductively rule out certain location
estimate hypotheses.
[0377] Base Station Cell site planning tools which utilize antenna
gain radiation patterns, environmental clutter, such as buildings,
dense forests, terrain heights, etc., can provide reasonable
training data to bootstrap the initial operation of the LC.
[0378] An example of the types of data typically collected during
field tests/runs is shown in the following database table SP-2
below:
TABLE-US-00007 TABLE SP-2 Typical CDMA Field Test Measurements
Column Position Mobile Data Test Set: Data Type Logged 1 CDMA Time
(absolute, from GPS) 2 Vehicle Speed (in mph) 3 Vehicle Latitude
(in deg. North) 4 Vehicle Longitude (in deg. East) 5 GPS Source
(binary, e.g., GPS or Dead Reckoning) 6 GPS Data available
indicator (binary states) 7 First BS-Mobile Received Power (in dBm,
1 second averages) 8 Mobile transmit Gain Adjust (in dBm, 1 second
average) 9 First BS Mobile Rx Pilot E.sub.c/I.sub.o (dB, 1 second
average) 10 First BS Mobile received Frame Counts (integers per
measurement period) 11 Mobile Finger's Average Time Separation (in
nano/microseconds) 12 Mobile Fingers' Maximum Time Separation (in
nano/microseconds) 13 Mobile Fingers' Number of Pilots locked (per
1 second average) 14 Mobile finger Lock Counts 15 First BS Received
Frame Counts 16 First BS Eb/No set Point (in dB, 1 second average)
17 First BS cell Rx Eb/No per antenna (in dB, 1 second average) 18
Hand-off State (relative to the First, or connected-to BS) 19 First
BS Traffic Channel Gain 20 First BS Power Control Subchannel Gain
21 First BS Reverse Link full Frame Error Rate, over 500 frames 22
Forward Link full Frame Error Rate, over 500 frames 23 First BS
Pilot Channel Delay Spread (in nanoseconds) 24 Second BS-Ranked
Pilot Delay Spread (in nanoseconds) 25 Second BS-Ranked Pilot
Relative Signal Strength (in dB) 26 Third BS-Ranked Pilot Delay
Spread 27 Third BS-Ranked Pilot Relative Signal Strength (in dB) 28
Mobile Antenna Identification (in the case of a multi-sectored
antenna) 29 Vehicle compass orientation (bearing or heading) 30
Mobile Station Power Class (an integer, 0-7, indicating max. power
capabilities of the mobile station transmitter)
[0379] Although the forward link mobile station's received relative
signal strength (RRSS.sub.BS) of detected nearby base station
transmitter signals can be used directly by the location estimate
modules, the base station's reverse link received relative signal
strength (RRSS.sub.MS) of the detected mobile station transmitter
signal must be modified prior to location estimate model use, since
the mobile station transmitter power level changes nearly
continuously, and would thus render relative signal strength
useless for location purposes.
[0380] One adjustment variable and one factor value are required by
the signal processing subsystem: 1.) instantaneous relative power
level in dBm (IRPL) of the mobile station transmitter, and 2.) the
mobile station Power Class. By adding the IRPL to the RRSS.sub.MS,
a synthetic relative signal strength (SRSS.sub.MS) of the mobile
station 140 signal detected at the BS 122 is derived, which can be
used by location estimate model analysis, as shown below:
SRSS.sub.MS=RRSS.sub.MS+IRPL (in dBm)
[0381] SRSS.sub.MS, a corrected indication of the effective path
loss in the reverse direction (mobile station to BS), is now
comparable with RRSS.sub.BS and can be used to provide a
correlation with either distance or shadow fading because it now
accounts for the change of the mobile station transmitter's power
level. The two signals RRSS.sub.BS and SRSS.sub.MS can now be
processed in a variety of ways to achieve a more robust correlation
with distance or shadow fading.
[0382] Although Rayleigh fading appears as a generally random noise
generator, essentially destroying the correlation value of either
RRSS.sub.BS or SRSS.sub.MS measurements with distance individually,
several mathematical operations or signal processing functions can
be performed on each measurement to derive a more robust relative
signal strength value, overcoming the adverse Rayleigh fading
effects. Examples include averaging, taking the strongest value and
weighting the strongest value with a greater coefficient than the
weaker value, then averaging the results. This signal processing
technique takes advantage of the fact that although a Rayleigh fade
may often exist in either the forward or reverse path, it is much
less probable that a Rayleigh fade also exists in the reverse or
forward path, respectively. A shadow fade however, similarly
affects the signal strength in both paths.
[0383] At this point a CDMA radio signal direction-independent "net
relative signal strength measurement" is derived which is used to
establish a correlation with either distance or shadow fading, or
both. Although the ambiguity of either shadow fading or distance
cannot be determined, other means can be used in conjunction, such
as the fingers of the CDMA delay spread measurement, and any other
TOA/TDOA calculations from other geographical points. In the case
of a mobile station with a certain amount of shadow fading between
its BS 122 (FIG. 2), the first finger of a CDMA delay spread signal
is most likely to be a relatively shorter duration than the case
where the mobile station 140 and BS 122 are separated by a greater
distance, since shadow fading does not materially affect the
arrival time delay of the radio signal.
[0384] By performing a small modification in the control
electronics of the CDMA base station and mobile station receiver
circuitry, it is possible to provide the signal processing
subsystem 20 (reference FIG. 1) within the Location system 142
(FIG. 1) with data that exceed the one-to-one CDMA delay-spread
fingers to data receiver correspondence. Such additional
information, in the form of additional CDMA fingers (additional
multipath) and all associated detectable pilot channels, provides
new information which is used to enhance to accuracy of the
Location Center's location estimate location estimate modules.
[0385] This enhanced capability is provided via a control message,
sent from the Location system 142 to the mobile switch center 12,
and then to the base station(s) 122 (FIG. 2) in communication with,
or in close proximity with, mobile stations 140 to be located. Two
types of location measurement request control messages are needed:
one to instruct a target mobile station 140 (i.e., the mobile
station to be located) to telemeter its BS pilot channel
measurements back to the primary BS 122 and from there to the
mobile switch center 112 and then to the location system 142. The
second control message is sent from the location system 142 to the
mobile switch center 112, then to first the primary BS 122,
instructing the primary BS' searcher receiver to output (i.e.,
return to the initiating request message source) the detected
target mobile station 140 transmitter CDMA pilot channel offset
signal and their corresponding delay spread finger (peak) values
and related relative signal strengths.
[0386] The control messages are implemented in standard mobile
station 140 and BS 122 CDMA receivers such that all data results
from the search receiver and multiplexed results from the
associated data receivers are available for transmission back to
the Location Center 142. Appropriate value ranges are required
regarding mobile station 140 parameters T_ADD.sub.s, T_DROP.sub.s,
and the ranges and values for the Active, Neighboring and Remaining
Pilot sets registers, held within the mobile station 140 memory.
Further mobile station 140 receiver details have been discussed
above.
[0387] In the normal case without any specific multiplexing means
to provide location measurements, exactly how many CDMA pilot
channels and delay spread fingers can or should be measured vary
according to the number of data receivers contained in each mobile
station 140.
[0388] As a guide, it is preferred that whenever RF characteristics
permit, at least three pilot channels and the strongest first three
fingers, are collected and processed.
[0389] From the BS 122 perspective, it is preferred that the
strongest first four CDMA delay spread fingers and the mobile
station power level be collected and sent to the location system
142, for each of preferably three BSs 122 which can detect the
mobile station 140.
[0390] Table SP-3 illustrates the resulting extended combinations
of BS signals (pilot channels) and finger measurements potentially
available, based on the above preferred conditions. The philosophy
is to collect as much reasonable data as is practical, given the
constraints of CDMA receivers, search times, receiver memory
storage and available CPU and data transmission bandwidth, in order
that sufficient orthogonal information can be processed to minimize
location estimate error.
TABLE-US-00008 TABLE SP-3 Extended CDMA Location Measurement
Combinations No. of No. of No. of No. of No. of No. of Fingers, BS
Fingers, BS Fingers, BS Fingers, No. of BSs Fingers 1-S (first 2-S
(second 3-S (third 4-S (fourth Receivers detected Detected
strongest) strongest) strongest) Strongest 3 1 1 1 0 0 0 3 1 2 2 0
0 0 3 1 3 3 0 0 0 3 2 2 1 1 0 0 3 2 3 2 1 0 0 3 2 3 1 2 0 0 3 2 4 2
2 0 0 3 2 5 2 3 0 0 3 2 5 3 2 0 0 3 2 4 3 1 0 0 3 2 4 1 3 0 0 4 2 5
4 1 0 0 4 2 5 1 4 0 0 3 3 3 1 1 1 0 3 2 6 3 3 0 0 3 3 3 1 1 1 0 3 3
4 2 1 1 0 3 3 4 1 2 1 0 3 3 4 1 1 2 0 3 3 5 2 2 1 0 3 3 5 2 1 2 0 3
3 5 1 2 2 0 3 3 6 2 2 2 0 3 3 6 3 2 1 0 3 3 6 2 3 1 0 3 3 6 1 2 3 0
3 3 6 1 3 2 0 4 4 4 1 1 1 1 4 4 5 2 1 1 1 4 4 5 1 2 1 1 4 4 5 1 1 2
1 4 4 5 1 1 1 2 4 4 6 2 2 1 1 4 4 6 2 1 2 1 4 4 6 1 1 2 2 4 4 6 1 2
2 1 4 4 6 1 2 1 2 4 4 6 2 1 1 2 4 4 7 3 2 1 1 4 4 7 3 1 2 1 4 4 7 2
3 1 1 4 4 7 2 1 3 1 4 4 7 2 1 1 3 4 4 7 1 3 2 1 4 4 7 1 2 3 1 4 4 7
1 1 2 3 4 4 7 1 1 3 2 4 4 7 3 1 1 2 4 4 <13 . . . . . . . . . .
. .
[0391] As can be seen from the table, a much larger combination of
measurements is potentially feasible using the extended data
collection capability of the CDMA receivers. In the case of the
last row shown, additional combinations are also possible using a
similar scheme of allocating the number of CDMA fingers detected at
the first or strongest BS, followed by the second strongest base
station, then the third strongest base station, etc.
[0392] FIG. 29 illustrates the components of the Signal Processing
Subsystem 20. The main components consist of the input queue(s) 7,
signal classifier/filter 9, digital signaling processor 17, imaging
filters 19, output queue(s) 21, router/distributor 23, a signal
processor database 26 and a signal processing controller 15.
[0393] Input queue(s) 7 are required in order to stage the rapid
acceptance of a significant amount of RF signal measurement data,
used for either location estimate purposes or to accept autonomous
location data. Each location request using fixed base stations may,
in one embodiment, contain from 1 to 128 radio frequency
measurements from the mobile station, which translates to
approximately 61.44 kilobytes of signal measurement data to be
collected within 10 seconds and 128 measurements from each of
possibly four base stations, or 245.76 kilobytes for all base
stations, for a total of approximately 640 signal measurements from
the five sources, or 307.2 kilobytes to arrive per mobile station
location request in 10 seconds. An input queue storage space is
assigned at the moment a location request begins, in order to
establish a formatted data structure in persistent store. Depending
upon the urgency of the time required to render a location
estimate, fewer or more signal measurement samples can be taken and
stored in the input queue(s) 7 accordingly.
[0394] The signal processing subsystem 20 supports a variety of
wireless network signaling measurement capabilities by detecting
the capabilities of the mobile and base station through messaging
structures provided by the location application programming
interface 14 in FIG. 1. Detection is accomplished in the signal
classifier 9 (FIG. 29) by referencing a mobile station database
table within the signal processor database 26, which provides,
given a mobile station identification number, mobile station
revision code, other mobile station characteristics. Similarly, a
mobile switch center table 31 provides MSC characteristics and
identifications to the signal classifier/filter 9. The signal
classifier/filter 9 adds additional message header information that
further classifies the measurement data which allows the digital
signal processor and image filter components to select the proper
internal processing subcomponents to perform operations on the
signal measurement data, for use by the location estimate
modules.
[0395] Regarding service control point messages autonomously
received from the input queue 7, the signal classifier/filter 9
determines via a signal processing database 26 query that the
message is to be associated with a home base station module. Thus
appropriate header information is added to the message, thus
enabling the message to pass through the digital signal processor
17 unaffected to the output queue 21, and then to the
router/distributor 23. The router/distributor 23 then routes the
message to the HBS module 6 shown in FIG. 1. Those skilled in the
art will understand that associating location requests from Home
Base Station configurations require substantially less data: the
mobile identification number and the associated wireline telephone
number transmission from the home location register are on the
order of less than 32 bytes. Consequentially the home base station
message type could be routed without any digital signal
processing.
[0396] Output queue(s) 21 are required for similar reasons as input
queues 7: relatively large amounts of data must be held in a
specific format for further location processing by the location
estimate modules.
[0397] The router and distributor component 23 is responsible to
directing specific signal measurement data types and structures to
their appropriate modules. For example, the HBS module has no use
for digital filtering structures, whereas the TDOA module would not
be able to process an HBS response message.
[0398] The controller 15 is responsible for staging the movement of
data among the signal processing subsystem 20 components input
queue 7, digital signal processor 17, router/distributor 23 and the
output queue 21, and to initiate signal measurements within the
wireless network, in response from an internet 468 location request
message in FIG. 1, via the location application programming
interface 14.
[0399] In addition the controller 15 receives autonomous messages
from the MSC, via the location applications programming interface
14 (FIG. 1) or L-API and the input queue 7, whenever a 9-1-1
wireless call is originated. The mobile switch center provides this
autonomous notification to the location system as follows: By
specifying the appropriate mobile switch center operations and
maintenance commands to surveil calls based on certain digits
dialed such as 9-1-1, the location applications programming
interface 14 (FIG. 1), in communication with the MSC 112a and/or
112b in FIG. 1, receives an autonomous notification whenever a
mobile station user dials 9-1-1. Specifically, a bi-directional
authorized communications port is configured, usually at the
operations and maintenance subsystem of the MSC 112a and/or 112b in
FIG. 1, or with their associated network element manager system(s),
with a data circuit, such as a DS-1, with the location applications
programming interface 14 in FIG. 1. Next, the "call trace"
capability of the mobile switch center is activated for the
respective communications port. The exact implementation of the
vendor-specific man-machine or Open Systems Interface (OSI)
commands(s) and their associated data structures generally vary
among MSC vendors, however the trace function is generally
available in various forms, and is required in order to comply with
Federal Bureau of Investigation authorities for wire tap purposes.
After the appropriate surveillance commands are established on the
MSC, such 9-1-1 call notifications messages containing the mobile
station identification number (MIN) and, in FCC phase 1 E9-1-1
implementations, a pseudo-automatic number identification (a.k.a.
pANI) which provides an association with the primary base station
in which the 9-1-1 caller is in communication, are communicated. In
cases where the pANI is known from the onset, the signal processing
subsystem 20 avoids querying the MSC in question to determine the
primary base station identification associated with the 9-1-1
mobile station caller.
[0400] After the signal processing controller 15 receives the first
message type, the autonomous notification message from the mobile
switch center 112 to the location system 142, containing the mobile
identification number and optionally the primary base station
identification, the controller 15 queries the base station table 13
in the signal processor database 26 to determine the status and
availability of any neighboring base stations, including those base
stations of other CMRS in the area. The definition of neighboring
base stations include not only those within a provisionable "hop"
based on the cell design reuse factor, but also includes, in the
case of CDMA, results from remaining set information autonomously
queried to mobile stations, with results stored in the base station
table. Remaining set information indicates that mobile stations can
detect other base station (sector) pilot channels which may exceed
the "hop" distance, yet are nevertheless candidate base stations
(or sectors) for wireless location purposes. Although cellular and
digital cell design may vary, "hop" distance is usually one or two
cell coverage areas away from the primary base station's cell
coverage area.
[0401] Having determined a likely set of base stations which may
both detect the mobile station's transmitter signal, as well as to
determine the set of likely pilot channels (i.e., base stations and
their associated physical antenna sectors) detectable by the mobile
station in the area surrounding the primary base station (sector),
the controller 15 initiates messages to both the mobile station and
appropriate base stations (sectors) to perform signal measurements
and to return the results of such measurements to the signal
processing system regarding the mobile station to be located. This
step may be accomplished via several interface means. In a first
case the controller 15 utilizes, for a given MSC, predetermined
storage information in the MSC table 31 to determine which type of
commands, such as man-machine or OSI commands are needed to request
such signal measurements for a given MSC 112a or 112b in FIG. 1.
The controller generates the mobile and base station signal
measurement commands appropriate for the MSC and passes the
commands via the input queue 7 and the locations application
programming interface 14 in FIG. 1, to the appropriate MSC 112a and
112b, using the authorized communications port mentioned earlier.
In a second case the controller 15 communicates directly with the
base stations as discussed above and shown in FIG. 5, Location
Center-base station access, multiple CMRS. In this second case, an
alternative embodiment is provided to directly extract the wireless
location signal measurement data from each base station associated
with each of the multiple CM RS networks having to interface
directly with the MSC for signal measurement extraction.
[0402] Upon receipt of the signal measurements, the signal
classifier 9 examines location application programming
interface-provided message header information from the source of
the location measurement (for example, from a fixed BS 122, a
mobile station 140, a distributed antenna system 168 or message
location data related to a home base station), provided by the
location applications programming interface (L-API 14) via the
input queue 7 and determines whether or not device filters 17 or
image filters 19 are needed, and assesses a relative priority in
processing, such as an emergency versus a background location task,
in terms of grouping like data associated with a given location
request. In the case where multiple signal measurement requests are
outstanding for various base stations, some of which may be
associated with a different CMRS network, an additional signal
classifier function includes sorting and associating the
appropriate incoming signal measurements together such that the
digital signal processor 17 processes related measurements in order
to build ensemble data sets. Such ensembles allow for a variety of
functions such as averaging, outlier removal over a time period,
and related filtering functions, and further prevent association
errors from occurring in location estimate processing.
[0403] Another function of the signal classifier/low pass filter
component 9 is to filter information that is not useable, or
information that could introduce noise or the effect of noise in
the location estimate modules. Consequently low pass matching
filters are used to match the in-common signal processing
components to the characteristics of the incoming signals. Low pass
filters match: Mobile Station, base station, CMRS and MSC
characteristics, as well as to classify Home Base Station
messages.
[0404] The signal processing subsystem 20 in FIG. 1 contains a base
station database table 13 (FIG. 29) which captures the maximum
number of CDMA delay spread fingers for a given base station,
containing information structures as shown in table SP-4 below:
TABLE-US-00009 TABLE SP-4 Base Station Characteristics Primary Base
Latitude, Pilot BS Maximum Station Longitude, Channel Identifier
No. of CDMA Identification elevation Offset code Fingers DEN-001 x,
y, z 5 CODENABC001 4 DEN-002 p, q, r 25 CODENABC002 4 DEN-003 s, t,
u 20 CODENABC003 3 DEN-004 a, b, c 15 CODENABC004 4 BLD-005 d, e, f
45 COBLDABC005 4
[0405] The base station identification code, or CLLI or common
language level identification code is useful in identifying or
relating a human-labeled name descriptor to the Base Station.
Latitude, Longitude and elevation values are used by other
subsystems in the location system for calibration and estimation
purposes. As base stations and/or receiver characteristics are
added, deleted, or changed with respect to the network used for
location purposes, this database table must be modified to reflect
the current network configuration.
[0406] Just as an upgraded base station may detect additional CDMA
delay spread signals, newer or modified mobile stations may detect
additional pilot channels or CDMA delay spread fingers.
Additionally different makes and models of mobile stations may
acquire improved receiver sensitivities, suggesting a greater
coverage capability. The table below establishes the relationships
among various mobile station equipment suppliers and certain
technical data relevant to this location invention.
[0407] Although not strictly necessary, the MIN can be populated in
this table from the PCS Service Provider's Customer Care system
during subscriber activation and fulfillment, and could be changed
at deactivation, or anytime the end-user changes mobile stations.
Alternatively, since the MIN, manufacturer, model number, and
software revision level information is available during a telephone
call, this information could extracted during the call, and the
remaining fields populated dynamically, based on manufacturer's
specifications information previously stored in the signal
processing subsystem 20. Default values are used in cases where the
MIN is not found, or where certain information must be
estimated.
TABLE-US-00010 TABLE SP-5 Mobile Station Characteristics Table
Allowed Maximum Maximum Transmit Rec. Mobile Station S/W No. of No.
of Power Thermal Identification Model Revision CDMA Pilots Class
Noise Floor (MIN) Manufacturer No. Levels Fingers Detectable (Max)
(dBm) 3034561234567 Sony 5 R1.0 3 3 2 -114 3034561234568 Qualcomm
25 R2.01 4 4 4 -115 3034561234569 Panasonic 20 R1.1 3 3 5 -113
3034561234570 Fujutshu 15 R2.5 4 4 0 -116 3034561234571 Sony 45
R1.1 3 3 7 -115 Default Default Default R1.0 3 3 3 -112
[0408] A low pass mobile station filter, contained within the
signal classifier/low pass filter 9 of the signal processing
subsystem 20, uses the above table data to perform the following
functions: 1) act as a low pass filter to adjust the nominal
assumptions related to the maximum number of CDMA fingers, pilots
detectable; and 2) to determine the transmit power class and the
receiver thermal noise floor. Given the detected reverse path
signal strength, the required value of SRSS.sub.MS, a corrected
indication of the effective path loss in the reverse direction
(mobile station to BS), can be calculated based on the SP-5 table
data contained within the mobile station table 11, in the signal
processing database 26.
[0409] The effects of the maximum Number of CDMA fingers allowed
and the maximum number of pilot channels allowed essentially form a
low pass filter effect, wherein the least common denominator of
characteristics are used to filter the incoming RF signal
measurements such that a one for one matching occurs. The effect of
the Transmit Power Class and Receiver Thermal Noise floor values is
to normalize the characteristics of the incoming RF signals with
respect to those RF signals used.
[0410] FIG. 4, Location Provisioning from Multiple CMRSs,
illustrates a system architecture to enable the customer care
systems belonging to different CMRSs, either on an autonomous or
periodic basis, to update a provisionable signal processing
database 26, containing the mobile station characteristics, in
communication with the signal classifier/filter 9, input queue 7,
and the location applications programming interface for customer
care systems (L-API-CCS) 138. The signal classifier/filter 9 is in
communication with both the input queue 7 and the signal processing
database 26. In the early stage of a location request the signal
processing subsystem 20 in FIG. 4, will receive the initiating
location request from either an autonomous 9-1-1 notification
message from a given MSC, or from a location application 146 (for
example, see FIG. 36), for which mobile station characteristics
about the target mobile station 140 (FIG. 2) is required. Referring
to FIG. 29, a query is made from the signal processing controller
15 to the signal processing database 26, specifically the mobile
station table 11, to determine if the mobile station
characteristics associated with the MIN to be located are available
in table 11. if the data exists then there is no need for the
controller 15 to query the wireless network in order to determine
the mobile station characteristics, thus avoiding additional
real-time processing which would otherwise be required across the
air interface, in order to determine the mobile station MIN
characteristics. The resulting mobile station information may be
provided either via the signal processing database 26 or
alternatively a query may be performed directly from the signal
processing subsystem 20 to the MSC in order to determine the mobile
station characteristics.
[0411] A location application programming interface, L-API-CCS 138
to the appropriate CMRS customer care system provides the mechanism
to populate and update the mobile station table 11 within the
database 26. The L-API-CCS 138 contains its own set of separate
input and output queues or similar implementations and security
controls to ensure that provisioning data is not sent to the
incorrect CMRS. The interface 1155a to the customer care system for
CMRS-A 1150a provides an autonomous or periodic notification and
response application layer protocol type, consisting of add,
delete, change and verify message functions in order to update the
mobile station table 11 within the signal processing database 26,
via the controller 15. A similar interface 1155b is used to enable
provisioning updates to be received from CMRS-B customer care
system 1150b.
[0412] Although the L-API-CCS application message set may be any
protocol type which supports the autonomous notification message
with positive acknowledgment type, the T1M1.5 group within the
American National Standards Institute has defined a good starting
point in which the L-API-CCS could be implemented, using the robust
OSI TMN X-interface at the service management layer. The object
model defined in Standards proposal number T1M1.5/96-22R9,
Operations Administration, Maintenance, and Provisioning
(OAM&P)--Model for Interface Across Jurisdictional Boundaries
to Support Electronic Access Service Ordering: Inquiry Function,
can be extended to support the L-API-CCS information elements as
required and further discussed below. Other choices in which the
L-API-CCS application message set may be implemented include ASCII,
binary, or any encrypted message set encoding using the Internet
protocols, such as TCP/IP, simple network management protocol,
http, https, and email protocols.
[0413] Referring to the digital signal processor (DSP) 17, in
communication with the signal classifier/LP filter 9, the DSP 17
provides a time series expansion method to convert non-HBS data
from a format of an signal measure data ensemble of time-series
based radio frequency data measurements, collected as discrete
time-slice samples, to a three dimensional matrix location data
value image representation. Other techniques further filter the
resultant image in order to furnish a less noisy training and
actual data sample to the location estimate modules.
[0414] Referring now to digital signal and image filter processing,
by way of example, a forward-path CDMA mobile station delay spread
RF measurement sample is illustrated in FIGS. 22A-C, for the mobile
station reception of one sample of transmission signal related to
BS-1, located at 16th and Stout Streets. In this sample three
fingers or groups of RF energy (relative signal strength is
indicated along the vertical axis) were detected. A first CDMA
finger was found at a delay of about 3.4 microseconds, and relative
signal strength of about -80 dBm. A second finger was found at a
delay of about 5 microseconds, and peak strength of about -55 dBm,
followed by a third finger at 6.5 microseconds and a strength of
about -92 dBm. Two other base stations were detected, BS-5 and
BS-2, along with their respective three CDMA delay spread
fingers.
[0415] Refer now to the left image shown in FIG. 26: Delay Spread
Profile Image. After 128 samples of data are collected of the delay
spread-relative signal strength RF data measurement sample: mobile
station RX for BS-1 and grouped into a Quantization matrix, where
rows constitute relative signal strength intervals and columns
define delay intervals. As each measurement row, column pair (which
could be represented as a complex number or Cartesian point pair)
is added to their respective values to generate a Z direction of
frequency of recurring measurement value pairs or a density
recurrence function. By next applying a grid function to each x, y,
and z value, a three-dimensional surface grid is generated, which
represents a location data value or unique print of that 128-sample
measurement. FIG. 28 illustrates the result of image generation
when a number of data samples, or an ensemble of signal strength,
delay pairs of values are added within a given bin area or matrix,
to thus create a type of three-dimensional image, representing a
particular RF signaling behavior at a given location.
[0416] Refer now to the right image shown in FIG. 26. In the
general case where a mobile station is located in an environment
with varied clutter patterns, such as terrain undulations, unique
man-made structure geometries (thus creating varied multipath
signal behaviors), such as a city or suburb, although the first
CDMA delay spread finger may be the same value for a fixed distance
between the mobile station and BS antennas, as the mobile station
moves across such an arc, different finger-data are measured. In
the right image for the defined BS antenna sector, location
classes, or squares numbered one through seven, are shown across a
particular range of line of position (LOP).
[0417] A traditional TOA/TDOA ranging method between a given BS and
mobile station only provides a range along the arc, thus
introducing ambiguity error. However a unique three dimensional
image can be used in this method to specifically identify, with
recurring probability, a particular unique location class along the
same Line Of Position, as long as the multipath is unique by
position but generally repeatable, thus establishing a method of
not only ranging, but also of complete latitude, longitude location
estimation in a Cartesian space. In other words, the unique shape
of the "mountain image" enables a correspondence to a given unique
location class along a line of position, thereby eliminating
traditional ambiguity error.
[0418] Although man-made external sources of interference, Rayleigh
fades, adjacent and co-channel interference, and variable clutter,
such as moving traffic introduce unpredictability (thus no
"mountain image" would ever be exactly alike), three basic types of
filtering methods can be used to reduce matching/comparison error
from a training case to a location request case: 1.) select only
the strongest signals from the forward path (BS to mobile station)
and reverse path (mobile station to BS), 2.) Convolute the forward
path 128 sample image with the reverse path 128 sample image, and
3.) process all image samples through various digital image filters
to discard noise components.
[0419] The strongest signal technique has been discussed previously
in the data filter section. FIG. 27: Convolution of Forward and
Reverse Images, illustrates one method that essentially nulls noise
completely, even if strong and recurring, as long as that same
noise characteristic does not occur in the opposite path.
[0420] The third technique of processing CDMA delay spread profile
images through various digital image filters, provides a resultant
"image enhancement" in the sense of providing a more stable pattern
recognition paradigm to the neural net location estimate model. For
example, image histogram equalization can be used, as illustrated
in FIGS. 30 (before equalization) and 31 (after equalization) to
rearrange the images' intensity values, or density recurrence
values, so that the image's cumulative histogram is approximately
linear.
[0421] Other methods which can be used to compensate for a
concentrated histogram include: 1) Input Cropping, 2) Output
Cropping and 3) Gamma Correction. Equalization and input cropping
can provide particularly striking benefits to a CDMA delay spread
profile image. FIGS. 32 and 33 illustrate the three dimensional
grid images of the before and after input cropping filter example.
As shown in FIG. 33, input cropping removes a large percentage of
random signal characteristics that are non-recurring.
[0422] Other filters and/or filter combinations can be used to help
distinguish between stationary and variable clutter affecting
multipath signals. For example, it is desirable to reject multipath
fingers associated with variable clutter, since over a period of a
few minutes such fingers would not likely recur. Further filtering
can be used to remove recurring (at least during the sample
period), and possibly strong but narrow "pencils" of RF energy. A
narrow pencil image component could be represented by a near
perfect reflective surface, such as a nearby metal panel truck
stopped at a traffic light.
[0423] On the other hand, stationary clutter objects, such as
concrete and glass building surfaces, adsorb some radiation before
continuing with a reflected ray at some delay. Such stationary
clutter-affected CDMA fingers are more likely to pass a 4.times.4
neighbor Median filter as well as a 40 to 50 percent Input Crop
filter, and are thus more suited to neural net pattern recognition.
FIG. 33 illustrate five "pencils" of CDMA finger energy that passed
a simple 50 percent Input Crop filter. However, as shown in FIG. 34
when subjected to a 4.times.4 neighbor Median filter and 40 percent
clipping, all five pencil-shaped fingers have been deleted. FIG. 35
illustrates the further simplified result of a 50 percent cropping
and 4.times.4 neighbor median filtering. Other filtering methods
include custom linear filtering, adaptive (Weiner) filtering, and
custom nonlinear filtering.
[0424] The DSP 17 may provide data ensemble results, such as
extracting the shortest time delay with a detectable relative
signal strength, to the router/distributor 23, or alternatively
results may be processed via one or more image filters 19, with
subsequent transmission to the router/distributor 23. The
router/distributor 23 examines the processed message data from the
DSP 17 and stores routing and distribution information in the
message header. The router/distributor 23 then forwards the data
messages to the output queue 21, for subsequent queuing then
transmission to the appropriate location estimators DA module 10,
TOA/TDOA module 8 or the HBS module 6, in FIG. 1.
Home Base Station Module
[0425] Upon receiving a message from the Data Capture Gateway or
the signal processing subsystem 20, the HBS location estimate model
examines a Home Base Station Table which defines relationships
among a wireless MIN, and wireline telephone number,
characteristics of the HBSD, and the possibility to use various
signal types in order to further define the location within the
address area of the fixed location HBSD. The following table,
populated by the commercial mobile radio service provider at HBSD
installation time, is used by the HBS model to determine location
whenever the mobile station 140 is located within communication
range of the HBSD:
TABLE-US-00011 TABLE HBS-1 HBSD Characteristics HBSD location CDMA
Wireline Wireless Latitude, Strength/Delay MIN MIN HBSD Model
Longitude Fixed HBSD Location Measurements? 3035561234 3035661299
Sony Qx-9000, Rev. 52.619488 N, 727 Magnolia Drive, No 1.1
112.4197601 W Boulder, CO 3035561236 3035661200 Panasonic PF-130,
52.645488 N, 1401 Digit Drive, Yes Rev. 5.0 112.4197601 W Boulder,
CO 3035561236 3035661240 Panasonic PF-130, 52.779488 N, 1698 Folsom
St., No Rev. 3.4 112.4197601 W Boulder, CO. 3035561284 3035661205
Panasonic PF-180, 51.619488 N, 990 Nutcracker Dr., NO Rev. 5.0
111.9197601 W Niwot, CO. 3035561224 3035661266 Panasonic PF-5000,
52.619558 N, 5606 Bismark Circle, Yes Rev. 1.0 112.4197601 W
Denver, CO . . . . . . . . . . . . . . .
[0426] In the event RF signals are available for telemetry from the
HBSD to the location system, such information may be solicited from
the location system to the HBSD, in the form of a request/response
message scheme, using for example, a data-under-voice technique. In
such cases the SSP provides a data connection with the location
system 142 via the PSTN. The home base station may interact with
the mobile station in the same manner as a cordless telephone
transceiver interacts with a cordless telephone, when the mobile
station is within an acceptable range.
[0427] The HBS module 6 in FIG. 1 outputs the Latitude and
Longitude location estimates to either the PSTN 124 or to the
Internet 468, depending upon the source of the originating location
request.
Distributed Antenna Module
[0428] Upon receipt of one or more data ensemble messages from the
signal processing subsystem 20 in FIG. 1, the distributed antenna
(DA) module 10 queries a previously populated distributed antenna
database to determine the locations of distributed antennas
associated with the measured DA antenna "pilot delays" so that the
detected signal measurement delay signal values received from the
mobile station receivers and base station receivers can be input to
the TOA/TDOA module. The TOA/TDOA module then utilizes the
radius-radius method, or time difference method, in order to
provide location estimates within the building or area containing
the distributed antennas.
Daisey Chaining Base Stations
[0429] As a practical matter it may be necessary in some network
conditions to add base stations in areas to permit improved
estimates to be achieved in wireless location. An aspect in this
invention includes daisy chaining communication circuits or
transport facilities between or among base stations, in order to
simplify the installation and operation of such base stations. Base
stations normally communicate with the mobile switch center using
T-carrier transport facilities, in order to carry voice and data
bearer traffic, and to transport bi-directional control signals.
However for various economic or other reasons it may not be
justifiable to install such transport facilities. At the base
station, by essentially originating a plurality of mobile telephone
calls using the data communications option, and terminating such
calls at the mobile switch center appropriately, the outputs of the
base station transport multiplex circuits are re-directed into the
data communication circuits normally intended for use by mobile
stations in establishing a data circuit communication call to the
network. Circuits at the mobile switch center used to terminate
these data calls, redirect the communication to those circuits
normally used to terminate the T-carrier facilities from the base
stations. In this manner, existing wireless channels can be used to
provide transport via this daisy-chaining method between certain
base stations and the mobile switch center, thus simplifying
connectivity in cases where the installation of transport
facilities would either be impossible or impractical.
Distance First Order Module (TOA/TDOA)
[0430] Particular distinctions over the current state of the art
include utilizing essentially the native electronics, antennas and
standards, and opposed to overlay solutions, supervisor functions
which control a hybrid set of techniques, including Time Of Arrival
(TOA), Time Difference of Arrival (TDOA) in both the forward and
reverse paths, pilot signal strengths, power control, mobile
stations (mobile station) state conditions, stochastic features of
environmental clutter, multipath detection and mitigation, and
robustness, supporting a variety of conditions including
degraded/faulty equipment, distributed and SMART antennas, various
registration modes, and various call processing conditions such as
soft, hard and idle hand-off conditions, location during the idle
state, traffic-bearing states, and location during cases of severe
multipath, such as that experienced in urban canyon environments,
as well as location in suburban and rural cases.
[0431] Since each base station is required to emit a constant
signal-strength pilot pseudo-noise (PN) sequence on the forward
link channel identified uniquely in a network system by a pilot
sequence offset and frequency assignment, it is possible to use the
pilot channels of active, candidate, neighboring and remaining sets
of pilots, associated with neighboring base stations, stored in the
mobile station, for TOA and TDOA measurements performed by the
mobile station.
[0432] Based on the arrival time measurement estimates and the
speed of propagation, ranges or range differences between the base
stations and the mobile station can be calculated. TOA and/or TDOA
measurements can then be input to either the radius-radius
multilateration or the time difference multilateration
algorithms.
[0433] By utilizing the known base station positions, location of
the mobile station can be determined. Since measurements and base
station positions can be sent either to the network or the mobile
station, location can be determined in either entity.
[0434] Since not all measurements can provide accurate location
results at all times and conditions, a variety of supervisory logic
processes can be invoked to resolve or litigate the problem
area.
[0435] As those familiar with the EIA/TIA IS-95 and T1P1/JTC CDMA
standards specifications know, mobile station call processing
consists of four states: [0436] 1. Initialization State--where the
mobile station selects and acquires a system, a network, and timing
information. This state consists of four substates: System
Determination, Pilot Channel Acquisition, Sync Channel Acquisition,
and Timing Change Substate; [0437] 2. Idle State--where the mobile
station monitors messages on the Paging Channel, and supports
procedures such as Message Acknowledgment, nine modes of
Registration, Idle Hand-off, Pilot Search, and response to Overhead
Information, such as System and Access Parameters (which include BS
Latitude and Longitude), mobile station Message Transmission
Operation (i.e., Data Burst) and Neighboring List messages; [0438]
3. System Access State--where the mobile station sends messages to
the base station on the Access Channel. This state consists of six
substates: Update Overhead, Origination Attempt, Page Response,
mobile station Order/Message Response, Registration Access; Message
Transmission Operation/Data Burst); [0439] 4. Mobile station
Control on the Traffic Channel State--where the mobile station
communicates with the primary base station using the forward and
Reverse Traffic Channels. This state consists of five substates: TC
initialization, Waiting for Order, Waiting for mobile station
Answer, Conversation (which includes hand-off procedures and
earliest arriving usable multipath components of pilots), and
Release.
[0440] At power-up an IS-95 or T1P1 PCS CDMA compliant mobile
station enters Initialization State, as described in IS-95, section
6.6.1. During the System Determination substate, the mobile station
refers to its internal memory to acquire preferences for system
carrier (A or B), or the preferred carrier at 1.8-2.0 GHz, and for
other types of service, including advanced mobile phone service, or
AMPS, as well as narrow band advanced mobile phone service, or
NAMPS.
[0441] A CDMA-preferred mobile station then transfers to the Pilot
Acquisition Substate. The mobile station tunes to the CDMA Channel
number equal to CDMACH.sub.s then sets its Walsh code (always W0)
for the Pilot channel where it begins searching for pilot energy,
in terms of energy per bit, per spectral density.
[0442] Once a sufficiently strong (as defined by the T_ADD
threshold parameter) pilot channel has been identified within
T.sub.20m seconds, the mobile station enters the Sync Channel
Acquisition Substate, where the mobile station receives a Sync
channel Message that includes, among other information, system time
and the unique PN offset index for that particular BS. In the
Timing Change substate, the mobile station adjusts its internal
timing to match the BS's CDMA system time. At the completion of the
Timing Change substate, the mobile station is completely
synchronized to the CDMA system's BS time.
[0443] After satisfactory synchronization the mobile station then
enters the stable Idle State, where the paging channel begins to be
monitored.
[0444] At this point at least two alternatives are possible: [0445]
1. Perform Location determination without consumption of
user-perceived air time via the introduction of a new call
processing state, or [0446] 2. Perform Location determination via
the traffic channel (requires air time)
[0447] In cases where Distributed Antennas (DAs), and/or Home Base
Stations (HBS) are used, each location of these devices can be sent
to the mobile station. There are at least three format-types
possible in conveying this type of location information in the
GeoLocation Message. First, a unique identifier can be assigned to
each DA/HBS, such as a fully distinguished name. An example of
location information could be: Within the USA, State of Colorado,
city of Denver, with Service Provider xyz, BS ID 129, Distributed
Antenna number 8. Or more compactly, the location string is
structured as, "USA.CO.DEN.xyz.129.DA8". Secondly, an
easy-to-understand human style data message can be sent, such as,
"You are near the 30th floor of the Sears Tower building". Third,
data values for Latitude, Longitude, and possibly altitude and
accuracy could be sent from the BS or Location Center to the mobile
station/LU. In order to be most easily useful to and end-user, in
the first and third cases, a database would be needed within the
mobile station or a Personal Digital Assistant device, which
performs a translation of numerical data into a form useful for
human understanding.
[0448] The mobile station thus maintains a list of location pilot
offsets, where the list is ranked based on a weighted combination
of received signal energy and BS location. The mobile station
selects the best candidate BSs for location estimate purposes,
which may be slightly different from the Active, candidate and
remaining lists.
[0449] Additionally the mobile station may send a Data_Burst
message back to the BS or Location Center, informing that no other
Pilot Channels were detected. This "negative" Venn diagram
information may be useful with various heuristics for location
estimate deduction, for example, to note where the mobile station
is not located.
[0450] It is the difference of system time values (as opposed to
their absolute values) that is important. Note that for purposes of
location, any communication back to a BS 122 would require
re-synchronizing onto that BS's system time. Although not specified
in either IS-95 or T1P1/JTC's PCS CDMA standards, most mobile
station manufacturers build correlators with resolutions of
approximately 1/8 PN chip, which is about 125 nanoseconds (nS). A
location equipped mobile station will provide +/-125 nS. accuracy,
which is about +/-125 feet.
[0451] The mobile station or location entity can process the
arrival time estimates in at least two ways. first the mobile
station may difference the measurements (preferred) to form
time-difference-of-arrivals (TDOA); or second, the mobile station
may determine absolute time-of-arrival (TOA) by solving for the
clock bias between the mobile station and other CDMA system time
reports. TOA requires very well calibrated BS system clocks among
each other.
[0452] The following procedure illustrates significant capabilities
hidden in the CDMA standards, which provide a substantial enabling
base with which to provide the measurements and data for this
inventions' location methods.
[0453] First the BS sends the Neighbor List Update Message,
containing a complete list of the neighboring pilot PN sequence
offset indices (i.e., via the NGHBR_PN field) associated with
candidate BSs in the area, with which the mobile station could
possibly scan for detecting usable earliest arriving neighboring
useable BS multipath components. This list should typically be a
complete list, as opposed to the presumed candidate subset. If the
mobile station is not already in the Traffic/Conversation State, it
could invoke this state by calling a dialable telephone number in
the network, e.g., a designed "Quiet Line" This approach also
allows a billing record to be generated according to routine
wireless telephony practice. If the network is to determine
location, then the network pages the mobile station 140, connecting
the mobile station to a Quiet LineNoice message upon mobile station
answer. Note that it may be desirable to suppress the mobile
station ringer sounding for certain location applications. Other
methods may also be possible.
[0454] During installation, each BS 122 in a particular area is
provisioned with the locations of all possible neighboring BSs in
its area. The BSs 122 use this information to populate a list of
all Latitudes and Longitudes which can be sent to the LUs, using
the Neighbor List Update message. Second, assuming that the mobile
station does not currently have this data or if unknown, then the
BS shall send a series of Mobile Station Registered Messages, each
message containing the latitude and Longitude values (i.e., the
BASE_LAT and BASE_LONG fields) associated with a neighboring BS
pilot PN offset sent with the first message. Note that the
constants N.sub.6m, Supported Traffic Channel Candidate Active Set
size, normally set to 6, and N.sub.7m, Supported Traffic Channel
Candidate Set size, normally set to 5, and N.sub.8m, the Minimum
Supported Neighbor Set size, normally set to 20, should be
sufficient for most location purposes, however these constants
could be changed if the need arises.
[0455] Third, the BS saves the current T_ADD and T_DROP values in
the BS memory, associated with the In-Traffic LU, and sends the
In-Traffic System Parameters Message, which includes reduced T_ADD
and T_DROP parameter values, useable for location purposes. The
value for T_ADD would typically be set to a value near the lower
end of the IS-98 specification, possibly below the 80 dB dynamic
range requirement, close to (but not including) the thermal noise
power level of the LU receiver. Note that if the LU is using
restricted battery, e.g., a portable, then the time for keeping
T_ADD and T_DROP at a low value for location estimates purposes,
should be kept short to delay adverse consequences, such as
increased current drain and noise.
[0456] Reduced T_ADD and T_DROP values sent to the mobile station
will cause the LU to scan all conceivable neighboring BS pilots
provided to it by the BS, and to measure the strengths of each
received pilot, and to determine the pilot arrival time for each
pilot offset. Note that the signal strengths now measured may not
be sufficient for carrying traffic, but may be sufficient for
location purposes.
[0457] Assuming the network is to determine location, then the
mobile station reports the arrival time, PILOT_ARRIVAL, for each
pilot reported to the base station. According to the standard the
arrival time is measured relative to the mobile station's time
reference (which was previously determined from the active BS), in
units of PN chips (1/2288) microseconds, or about 814 nanoseconds,
as follows:
PILOT_PN-PHASE=(PILOT_ARRIVAL+(64.times.PILOT_PN))mod 2.sup.15,
[0458] where PILOT_PN is the PN sequence offset index of the pilot
associated with the BS pilot indices in the neighbor list.
[0459] In order to achieve location accuracy estimates on the order
of a few hundred feet (or nanoseconds) a higher resolution than 1
PN chip is required. Although not specified directly in IS-95, most
mobile manufacturers use correlators with resolutions of
approximately 1/8 PN chip, or about 102 nS (suggesting that if no
other systemic errors are present, about 102 feet of error is
expected). Note that the search window size SRCH_WIN_A.sub.r for
each pilot may need to be increased if there are substantial delays
experienced from the environment. It is desirable for the mobile
station to report the second and third arrival time (or the second
and third fingers), and their relative signal strengths,
corresponding to each detectable Pilot Channel.
[0460] If more than one PILOT_ARRIVAL is available then a basic
TDOA multilateration algorithm may be invoked, at either the LU, or
the network. In the network case, the active BS 122 must send a
Pilot Request Order for Pilot Measurement Request Order (ORDER code
010001), which causes the mobile station 140 to forward its
measurements to the BS (and consequently the network, as
appropriate).
[0461] At this point a minimally sufficient number of measurements
are available to perform a location estimate. Thus the BS should
restore the original T_ADD and T_DROP values (previously saved in
the BS memory) to the mobile station, via the In-Traffic System
Parameters Message.
[0462] Additional information may be desirable, such as the active
BS' TOA measurement, as well as associated BS measurements of the
mobile station's TOA to their BS location. This added information
may be sent to the mobile station if the mobile station is to
perform location, via the Data Burst Message on the Forward Traffic
Channel. Since 26 combinations of data burst types have been
reserved for future use in the standard, dedication of several
combinations could be used to telemeter location-related data. In
cases where duplicate ranging or other information is available,
various supervisor techniques mentioned elsewhere in this document,
could be used to refine the location estimate.
[0463] Once the location estimate has been performed, any number of
means could be used to provide the results to the end user.
[0464] The IS-95 and J-STD-008 CDMA specifications require that BSs
should be synchronized to within +/-3 microseconds of CDMA system
time and shall be synchronized to within +/-10 microseconds. This
invention disclosure method assumes the cost of GPS receivers is
relatively small, thus time calibration at a more precise
calibration level at each location BS is recommended to be used by
using the very accurate GPS time parameters. Preferably the
absolute error deviation among surrounding or neighboring base
stations should be less than 800 nanoseconds, however in most cases
this should not be a fixed requirement, but rather a preference. In
cases where absolute BS timing is prohibitively expensive, then the
"Forced Hand-off" method discussed below can be used to overcome
the preferred, or strict absolute BS timing requirements.
[0465] Three methods have been currently identified. Some of these
techniques apply to other air interface types as well. [0466] 1.
Use the first finger at BS (Absolute Ranging), and if detectable,
invoke a "Forced Hand-off" between the mobile station and a
neighboring BS, for a time sufficient to complete signal
measurements between a mobile station transmitter and a BS
receiver, and if possible, between a BS transmitter and a mobile
station receiver, which gives access to as many BS's as can be
detected either by the mobile station receiver or the surrounding
BS receivers. [0467] 2. Use the first finger at mobile station
(Differential Ranging) to obtain differential time readings of
pilot channel from mobile station [0468] 3. Use the Pilot Power
Level Measurements and Ground Clutter (Stochastic information)
[0469] Now in the general case where three or more BSs can either
determine TDOA and/or the mobile station can telemeter such data to
the location entity within the network, repeat this method for
BS.sub.2 and BS.sub.3, and BS.sub.3 and BS.sub.1, in order to
determine the remaining curves, thus yielding location within a 2D
space. In the case of 3D geometry (such as a multi-story building
with multi-floor pico BS cells), the process must be repeated a
fourth time in order to determine altitude.
TABLE-US-00012 MATLAB MathWorks code to implement the above
algorithms follows: clear;hold off; j = sqrt(-1); step_size = 0.03;
# Set up BS variables theta = pi/3*ones(3,1); D = 10*ones(3,1);
z(1) = 0; z(2) = D(1); z(3) = D(3)*exp(-j*theta(1)); # Define the
distance parameters d = [0 6.4 -6.8]'; location1 = [ ]; location2 =
[ ]; location3 = [ ]; # Iterate and solve for the location with
respect to the first BS (at (0,0) ) t2 = -pi:0.05:0.05; for t1 =
-pi/3:0.05:0.05, t1 = t1+0.001; r1 =
1./(exp(j*t1)-exp(j*t2)).*(D(1)-d(1)*exp(j*t2)); r2 =
1./(exp(j*t1)-exp(j*t2)).*(D(1)-d(1)*exp(j*t1)); temp = arg(r1);
index = find(abs(temp) == min(abs(temp))); location1 =
[location1;r1(index)*exp(j*t1)]; end; for t1 = -pi/3:0.05:0.05 t1 =
t1+0.001; r1 = 1./(exp(j*t1)-exp(j*t2)).*(D(2)-d(2)*exp(j*t2)); r2
= 1./(exp(j*t1)-exp(j*t2)).*(D(2)-d(2)*exp(j*t1)); temp = arg(r1);
index = find(abs(temp) == min(abs(temp))); location2 =
[location2;r1(index)*exp(j*t1)]; end; for t1 = -pi/3:0.05:0.05 t1 =
t1+0.001; r1 = 1./(exp(j*t1)-exp(j*t2)).*(D(1)-d(3)*exp(j*t2)); r2
= 1./(exp(j*t1)-exp(j*t2)).*(D(1)-d(3)*exp(j*t1)); temp = arg(r1);
index = find(abs(temp) == min(abs(temp))); location3 =
[location3;r1(index)*exp(j*t1)]; end; location2 =
location2*exp(j*arg(z(3)-z(2))) + z(2); location3 =
location3*exp(j*arg(z(1)-z(3))) + z(3); set yrange [-10:1]; set
xrange [-1:11]; plot([z;z(1)]) hold on plot(location1)
plot(location2) plot(location3)
Wireless Location Data Collection
[0470] It is worthwhile to discuss techniques for both obtaining
the initial collection of verified location data, as well as how
additional location data can be obtained for updating the data in
this data base in a straightforward cost-effective manner.
[0471] Regarding both the obtaining of the initial collection of
verified location data as well as gathering data updates, it is
believed that some of this data can be obtained from the initial
and continued engineering of the base station infrastructure by the
wireless telephony service provider(s) in the radio coverage area.
Additional verified location data can be obtained by trained
technicians driving and/or walking certain areas and periodically,
at each of a plurality of locations: (a) determining a location
estimate (using, for example, GPS if possible and/or offsets from
GPS readings); and (b) using an mobile station 140 at the location
to generate location data communication with the wireless base
station infrastructure.
[0472] Alternatively, it is a novel aspect of the present invention
that a straightforward method and system for gathering verified
location data has been discovered, wherein a conventional mobile
station 140 can be used without any additional electronics or
circuit modifications. One embodiment of this method and system
utilizes the personnel of businesses that travel predetermined
routes through the radio coverage area (e.g., a delivery and/or
pickup service) to generate such data using a conventional mobile
station 140 while traversing their routes through the radio
coverage area. One example of such personnel is the postal workers,
and in particular, the mail carriers having predetermined (likely
repetitive) routes for mail pickup and/or delivery at predetermined
sites (denoted hereinafter as "mail pickup/delivery sites" or
simply "mail sites"). By having such mail carriers each carry a
conventional mobile station 140 and periodically generate location
data communication with the wireless base station infrastructure at
mail sites along their routes, additional verified location data
can be added to a Location Data Base (not shown) cost
effectively.
[0473] To describe how this can be performed, a brief description
of further features available in a typical mobile station 140 is
needed. At least some modules of mobile station 140 have the
following capabilities: [0474] (27.2.1) a unique mobile station 140
identification number; in fact, every mobile station 140 must have
such a number (its telephone number); [0475] (27.2.2) the mobile
station 140 has a display and a display memory for presenting
stored data records having telephone numbers and related data to a
user. Further, some portion of each data record is annotation and
some portion is able to be transmitted to the wireless base station
network. In particular, the mobile station 140 is able to store and
recall data records of sufficient size such that each data record
may include the following information for a corresponding mail
pickup/delivery site along a mail route: (a) an address or other
textual description data (e.g., an English-like description) of the
mail pickup/delivery site; (b) a predetermined telephone number;
and (c) a numerical code (denoted the "site code" hereinafter)
associated with the mail pickup/delivery site, wherein the site
code is at least unique within a set of site codes corresponding to
the mail sites on the mail route. In one embodiment, the memory may
store 99 or more such data records, and the display is scrollable
through the data records; [0476] (27.2.3) the mobile station 140
can have its display memory updated from either an RS232 port
residing on the mobile station, or from an over-the-air activation
capability of the wireless network; [0477] (27.2.4) the mobile
station 140 has a pause feature, wherein a telephone number can be
dialed, and after some predetermined number of seconds, additional
predetermined data can be transmitted either through additional
explicit user request (e.g., a "hard pause"), or automatically
(e.g., a "soft pause"). Moreover, the additional predetermined data
can reside in the display memory.
[0478] Assuming these features, the following steps can be
performed for acquiring additional verified location data: [0479]
(27.3.1) For (at least some of the) postal carriers having
predetermined routes of addresses or locations visited, the postal
carriers are each provided with an mobile station 140 having the
capabilities described in (27.2.1) through (27.2.4) above, wherein
the memory in each provided mobile station has a corresponding list
of data records for the addresses visited on the route of the
postal carrier having the mobile station. Moreover, each such list
has the data records in the same sequence as the postal carrier
visits the corresponding mail sites, and each data record includes
the information as in (27.2.2) for a corresponding mail site the
postal carrier visits on his/her mail route. More precisely, each
of the data records has: (a) a description of the address or
location of its corresponding mail pickup/delivery site, (b) a
telephone number for dialing a data collection system for the
location center 142 (or, alternatively, a reference to a memory
area in the mobile station having this telephone number since it is
likely to be the same number for most data records), and (c) a site
code for the mail pickup/delivery site that is to be transmitted
after a predetermined soft pause time-out. Note that the
corresponding list of data records for a particular postal route
may be downloaded from, for example, a computer at a post office
(via the RS232 port of the mobile station 140), or alternatively,
the list may be provided to the mobile station 140 by an
over-the-air activation. Further, there are various embodiments of
over-the-air activation that may be utilized by the present
invention. In one embodiment, the postal carrier dials a particular
telephone number associated with data collection system and
identifies both him/herself by his/her personal identification
number (PIN), and the postal route (via a route identifying code).
Subsequently, the mail pickup and delivery sites along the
identified route are downloaded into the memory of the mobile
station 140 via wireless signals to the mobile station 140.
However, additional over-the-air techniques are also within the
scope of the present invention such as: [0480] (a) If the postal
carrier's route is already associated with the carrier's PIN for
over-the-air activation, then the carrier may only need to enter
his/her PIN. [0481] (b) If the mobile station 140 is already
associated with a particular route, then the carrier may only need
to activate the mobile station 140, or alternatively, enter his/her
PIN for obtaining an over-the-air download of the route. [0482] (c)
Regardless of how the initial download of mail sites is provided to
the mobile station 140, it is also an aspect of the present
invention that if there are more mail sites on a route than there
is sufficient memory to store corresponding data records in the
mobile station, then the data records may be downloaded in
successive segments. For example, if there are 150 mail sites on a
particular route and storage for only 99 data records in the mobile
station, then in one embodiment, a first segment of 98 data records
for the first 98 mail pickup/delivery sites on the route are
downloaded together with a 99th data record for transmitting an
encoding requesting a download of the next 52 data records for the
remaining mail sites. (Alternatively, the data collection system
may monitor mobile station 140 requests and automatically detect
the last location capture request of a downloaded segment, and
subsequently automatically download the next segment of mail site
data records). Accordingly, when the data records of the first
segment have been utilized, a second segment may be downloaded into
the mobile station 140. Moreover, at the end of the last segment,
the data collection system may cause the first segment for the
route to be automatically downloaded into the mobile station 140 in
preparation for the next traversal of the route. [0483] (27.3.2)
Given that a download into the mobile station 140 of (at least a
portion of) the data for a postal route has occurred, the postal
carrier traversing the route then iteratively scrolls to the next
data record on the list stored in the mobile station as he/she
visits each corresponding mail pickup/delivery site, and activates
the corresponding data record. That is, the following steps are
performed at each mail pickup/delivery site: [0484] (a) As the
postal carrier arrives at each mail pickup/delivery site, he or she
checks the scrollable mobile station 140 display to assure that the
address or location of the mail pickup/delivery site is described
by the data record in the portion of the mobile station display for
activating associated data record instructions. [0485] (b) The
postal carrier then merely presses a button (typically a "send"
button) on the mobile station 140 for concurrently dialing the
telephone number of the data collection system, and initiating the
timer for the soft pause (in the mobile station 140) associated
with the site code for the mail pickup/delivery site currently
being visited. [0486] (c) Given that the soft pause is of
sufficient length to allow for the data collection system call to
be setup, the mobile station 140 then transmits the site code for
the present mail pickup/delivery site. [0487] (d) Upon receiving
the telephone number of the mobile station 140 (via automatic
number identification (AIN)), and the site code, the data
collection system then performs the following steps: [0488] (d1) A
retrieval of an identifier identifying the route (route id). Note
this may be accomplished by using the telephone number of the
mobile station. That is, when the data collection system first
detects that the mobile station 140 is to be used on a particular
route, the telephone number of the mobile station and the route id
may be associated in a data base so that the route id can be
retrieved using the telephone number of the mobile station. [0489]
(d2) A retrieval of a location representation (e.g., latitude,
longitude, and possibly height) of the mail pickup/delivery site
identified by the combination of the route id and the site code is
performed by accessing a data base having, for each mail site, the
following associated data items: the route id for the mail site,
the site code, the mail site address (or location description), and
the mail site location representation (e.g., latitude, longitude,
possibly height). [0490] (d3) A request to the location center 142
is issued indicating that the location data for the mobile station
140 (resulting from, e.g., the call being maintained between the
mobile station and the data collection system) is to be retrieved
from the wireless network, temporarily saved, and a location
estimate for the mobile station is to be performed. Accordingly,
the data collection system request to the location center 142 the
following: [0491] (i) the telephone number of the mobile station
140; [0492] (ii) the retrieved location of the mobile station 140
according to the route id and site code; [0493] (iii) a request for
the location center 142 to perform a location estimate on the
mobile station 140 and return the location estimate to the data
collection system; [0494] (iv) a request that the location center
142 retain the location for the mobile station 140 and associate
with it the location of the mobile station 140 received from the
data collection system.
[0495] Regarding step (iii), the location estimate may also include
the steps temporarily increasing the mobile station transmitter
power level [0496] (27.3.3) Subsequently, given that the location
center 142 performs as requested, when the data collection system
receives the mobile station 140 location estimate from the location
center, the data collection system first associates the returned
mobile station location estimate with the corresponding data
collection system information regarding the mobile station, and
secondly, performs "reasonability" tests on the information
received from the mobile station 140 for detecting, filtering
and/or alerting systems and personnel whenever the postal carrier
appears to be transmitting (via the mobile station 140) from a
location different from what the route id and site code indicate.
The following are examples of such reasonability tests: [0497] (a)
If a threshold number of postal carrier transmittals disagree with
the location center 142 estimate by a predetermined distance
(likely dependent upon area type), then tag these particular
transmittals as problematic and mark all transmittals from the
mobile station 140 as suspect for "distance" inaccuracies. [0498]
(b) If there is less than a threshold amount of time between
certain postal carrier transmittals, then tag these particular
transmittals as problematic and mark all transmittals from the
mobile station 140 as suspect for "time" inaccuracies. [0499] (c)
If an expected statistical deviation between a sampling of the
postal carrier transmittals and the location estimates from the
location center 142 vary by more than a threshold amount, then tag
these particular transmittals as problematic and mark all
transmittals from the mobile station 140 as suspect for
"statistical" inaccuracies. [0500] (d) If an expected statistical
deviation between a sampling of the times of the postal carrier
transmittals and an expected timing between these transmittals vary
by more than a threshold amount, then tag these particular
transmittals as problematic and mark all transmittals from the
mobile station 140 as suspect for "statistical" inaccuracies.
[0501] (27.3.4) When suspect or problematic mobile station location
information is detected (e.g., incorrect site code) in step
(27.3.3), the data collection system may perform any of the
following actions: [0502] (a) Alert the postal carrier of
problematic and/or suspected inaccuracies in real time, after a
certain number of transmittals or at a later time. Note that such
alerts as well as positive feedback at the end of the postal
carrier's route (or segments thereof) may be advantageous in that
it likely inhibits the postal carrier from experimenting with
transmittals from locations that are purposefully inaccurate, but
at the same time provides sufficiently timely feedback to encourage
a conscientious postal carrier. [0503] (b) Alert the Postal Service
of perceived discrepancies in the mobile station 140 transmittals
by the postal carrier. [0504] (c) Dispatch location center
technicians to the area to transmit duplicate signals. [0505]
(27.3.5) If the transmittal(s) from the mobile station 140 are not
suspect, then the data collection system communicates with the
location center 142 for requesting that each location received from
the mobile station 140 be stored with its corresponding retrieved
location (obtained in step (d2)) as a verified location value in
the Location Data Base (not shown). Alternatively, if the
transmittals from the mobile station 140 are suspect, then the data
collection system may communicate with the location center 142 for
requesting that at least some of the location data from the mobile
station 140 be discarded.
[0506] Note that a similar or identical procedure to the steps
immediately above may be applied with other services/workers such
as courier services, delivery services, meter readers, street
sweepers, and bus drivers having predetermined routes.
Additional Modules to Increase Location Hypothesis Accuracy
[0507] The following modules may be provided in various embodiments
of the present invention, and in particular, as part of the
location engine 139. Further modules and description directed to
the location center 142 and its functionality, the location engine
139, various location enhancing techniques, and various additional
embodiments are provided in U.S. Provisional Patent Application
having Ser. No. 60/044,821, filed Apr. 25, 1997, by Dupray, Karr,
and LeBlanc from which the present application claims priority, and
which is fully incorporated herein by reference.
Path Comparison Module
[0508] The Path Comparison Module implements the following
strategy: the confidence of a particular location hypothesis is be
increased (decreased) if it is (not) predicting a path that lies
along a known transportation pathway (and the speed of the target
MS is sufficiently high). For instance, if a time series of target
MS location hypotheses for a given FOM is predicting a path of the
target MS that lies along an interstate highway, the confidence of
the currently active location hypothesis for this FOM should, in
general, be increased. Thus, at a high level the following steps
may be performed: [0509] (a) For each FOM having a currently active
location hypothesis in a Run-time Location Hypothesis Storage Area,
determine a recent "path" obtained from a time series of location
hypotheses for the FOM. This computation for the "path" is
performed by stringing together successive "center of area" (COA)
or centroid values determined from the most pertinent target MS
location estimate in each location hypothesis (recall that each
location hypothesis may have a plurality of target MS area
estimates with one being the most pertinent). The information is
stored in, for example, a matrix of values wherein one dimension of
the matrix identifies the FOM and the a second dimension of the
matrix represents a series of COA path values. Of course, some
entries in the matrix may be undefined. [0510] (b) Compare each
path obtained in (a) against known transportation pathways in an
area containing the path. A value, path_match(i), representing to
what extent the path matches any known transportation pathway is
computed. Such values are used later in a computation for adjusting
the confidence of each corresponding currently active location
hypothesis.
Velocity/Acceleration Calculation Module
[0511] The Velocity/Acceleration Calculation Module computes
velocity and/or acceleration estimates for the target MS using
currently active location hypotheses and previous location
hypothesis estimates of the target MS. In one embodiment, for each
FOM having a currently active location hypothesis (with positive
confidences) and a sufficient number of previous (reasonably
recent) target MS location hypotheses, a velocity and/or
acceleration may be calculated. In an alternative embodiment, such
a velocity and/or acceleration may be calculated using the
currently active location hypotheses and one or more recent "most
likely" locations of the target MS output by the Location Center.
If the estimated velocity and/or acceleration corresponding to a
currently active location hypothesis is reasonable for the region,
then its confidence value is incremented; if not, then its
confidence is decremented. The algorithm may be summarized as
follows: [0512] (a) Approximate speed and/or acceleration estimates
for currently active target MS location hypotheses may be provided
using path information related to the currently active location
hypotheses and previous target MS location estimates in a manner
similar to the description of the Path Comparison Module.
Accordingly, a single confidence adjustment number may be
determined for each currently active location hypothesis for
indicating the extent to which its corresponding velocity and/or
acceleration calculations are reasonable for its particular target
MS location estimate. This calculation is performed by retrieving
information from an Area Characteristics Data Base. Since each
location hypothesis includes timestamp data indicating when the MS
location signals were received from the target MS, the velocity
and/or acceleration associated with a path for a currently active
location hypothesis can be straightforwardly approximated.
Accordingly, a confidence adjustment value, vel_ok(i), indicating a
likelihood that the velocity calculated for the i.sup.th currently
active location hypothesis (having adequate corresponding path
information) may be appropriate for the environmental
characteristics of the location hypothesis' target MS location
estimate. Thus, if the target MS location estimate includes a
portion of an interstate highway, then an appropriate velocity
might correspond to a speed of up to 100 miles per hour, whereas if
the target MS location estimate includes only rural dirt roads and
tomato patches, then a likely speed might be no more than 30 miles
per hour with an maximum speed of 60 miles per hour (assuming
favorable environmental characteristics such as weather). Note that
a list of such environmental characteristics may include such
factors as: area type, time of day, season. Further note that more
unpredictable environmental characteristics such as traffic flow
patterns, weather (e.g., clear, raining, snowing, etc.) may also be
included, values for these latter characteristics coming from an
Environmental Data Base which receives and maintains information on
such unpredictable characteristics. Also note that a similar
confidence adjustment value, acc_ok(i), may be provided for
currently active location hypotheses, wherein the confidence
adjustment is related to the appropriateness of the acceleration
estimate of the target MS.
Attribute Comparison Module
[0513] The Attribute Comparison Module compares attribute values
for location hypotheses generated from different FOMs, and
determines if the confidence of certain of the currently active
location hypotheses should be increased due to a similarity in
related values for the attribute. That is, for an attribute A, an
attribute value for A derived from a set S.sub.FOM[1] of one or
more location hypotheses generated by one FOM, FOM[1], is compared
with another attribute value for A derived from a set S.sub.FOM2 of
one or more location hypotheses generated by a different FOM,
FOM[2] for determining if these attribute values cluster (i.e., are
sufficiently close to one another) so that a currently active
location hypothesis in S.sub.FOM[1] and a currently active location
hypothesis in S.sub.FOM2 should have their confidences increased.
For example, the attribute may be a "target MS path data"
attribute, wherein a value for the attribute is an estimated target
MS path derived from location hypotheses generated by a fixed FOM
over some (recent) time period. Alternatively, the attribute might
be, for example, one of a velocity and/or acceleration, wherein a
value for the attribute is a velocity and/or acceleration derived
from location hypotheses generated by a fixed FOM over some
(recent) time period.
[0514] In a general context, the Attribute Comparison Module
operates according to the following premise: [0515] (37.1) for each
of two or more currently active location hypotheses (with positive
confidences) if: [0516] (a) each of these currently active location
hypotheses, H, was initially generated by a corresponding different
FOM.sub.H; [0517] (b) for a given MS estimate attribute and each
such currently active location hypothesis, H, there is a
corresponding value for the attribute (e.g., the attribute value
might be an MS path estimate, or alternatively an MS estimated
velocity, or an MS estimated acceleration) wherein the attribute
value is derived without using a FOM different from FOM.sub.H, and;
[0518] (c) the derived attribute values cluster sufficiently
well,
[0519] then each of these currently active location hypotheses, H,
will have their corresponding confidences increased. That is, these
confidences will be increased by a confidence adjustment value or
delta.
[0520] Note that the phrase "cluster sufficiently well" above may
have a number of technical embodiments, including performing
various cluster analysis techniques wherein any clusters (according
to some statistic) must satisfy a system set threshold for the
members of the cluster being close enough to one another. Further,
upon determining the (any) location hypotheses satisfying (37.1),
there are various techniques that may be used in determining a
change or delta in confidences to be applied. For example, in one
embodiment, an initial default confidence delta that may be
utilized is: if "cf" denotes the confidence of such a currently
active location hypothesis satisfying (37.1), then an increased
confidence that still remains in the interval [0, 1.0] may be:
cf+[(1-cf)/(1+cf)].sup.2, or, cf*[1.0+cf.sup.n], n.=>2, or,
cf*[a constant having a system tuned parameter as a factor]. That
is, the confidence deltas for these examples are:
[(1-cf)/(1+cf)].sup.2 (an additive delta), and, [1.0+cf.sup.n] (a
multiplicative delta), and a constant. Additionally, note that it
is within the scope of the present invention to also provide such
confidence deltas (additive deltas or multiplicative deltas) with
factors related to the number of such location hypotheses in the
cluster.
[0521] Moreover, note that it is an aspect of the present invention
to provide an adaptive mechanism for automatically determining
performance enhancing changes in confidence adjustment values such
as the confidence deltas for the present module. That is, such
changes are determined by applying an adaptive mechanism, such as a
genetic algorithm, to a collection of "system parameters"
(including parameters specifying confidence adjustment values as
well as system parameters) in order to enhance performance of the
present invention. More particularly, such an adaptive mechanism
may repeatedly perform the following steps: [0522] (a) modify such
system parameters; [0523] (b) consequently activate an
instantiation of the Location Center (having the modified system
parameters) to process, as input, a series of MS signal location
data that has been archived together with data corresponding to a
verified MS location from which signal location data was
transmitted (e.g., such data as is stored in a Data Base); and
[0524] (c) then determine if the modifications to the system
parameters enhanced Location Center performance in comparison to
previous performances.
[0525] Assuming this module adjusts confidences of currently active
location hypotheses according to one or more of the attributes:
target MS path data, target MS velocity, and target MS
acceleration, the computation for this module may be summarized in
the following steps: [0526] (a) Determine if any of the currently
active location hypotheses satisfy the premise (37.1) for the
attribute. Note that in making this determination, average
distances and average standard deviations for the paths (velocities
and/or accelerations) corresponding to currently active location
hypotheses may be computed. [0527] (b) For each currently active
location hypothesis (wherein "i" uniquely identifies the location
hypothesis) selected to have its confidence increased, a confidence
adjustment value, path_similar(i) (alternatively,
velocity_similar(i) and/or acceleration_similar(i)), is computed
indicating the extent to which the attribute value matches another
attribute value being predicted by another FOM.
[0528] Note that such confidence adjustment values are used later
in the calculation of an aggregate confidence adjustment to
particular currently active location hypotheses.
Extrapolation Module
[0529] The Extrapolation Module works on the following premise: if
for a currently active location hypothesis there is sufficient
previous related information regarding estimates of the target MS
(e.g., from the same FOM or from using a "most likely" previous
target MS estimate output by the Location Center), then an
extrapolation may be performed for predicting future target MS
locations that can be compared with new location hypotheses. Note
that interpolation routines (e.g., conventional algorithms such as
Lagrange or Newton polynomials) may be used to determine an
equation that approximates a target MS path corresponding to a
currently active location hypothesis.
[0530] Subsequently, such an extrapolation equation may be used to
compute a future target MS location. For further information
regarding such interpolation schemes, the following reference is
incorporated herein by reference: Mathews, 1992, Numerical methods
for mathematics, science, and engineering. Englewood Cliffs, N.J.:
Prentice Hall.
[0531] Accordingly, if a new currently active location hypothesis
is received, then the target MS location estimate of the new
location hypothesis may be compared with the predicted location.
Consequently, a confidence adjustment value can be determined
according to how well if the location hypothesis "i". That is, this
confidence adjustment value will be larger as the new MS estimate
and the predicted estimate become closer together.
[0532] Note that in one embodiment of the present invention, such
predictions are based solely on previous target MS location
estimates output by Location Center. Thus, in such an embodiment,
substantially every currently active location hypothesis can be
provided with a confidence adjustment value by this module once a
sufficient number of previous target MS location estimates have
been output. Accordingly, a value, extrapolation_chk(i), that
represents how accurately the new currently active location
hypothesis (identified here by "i") matches the predicted location
is determined.
Analytical Reasoner Controller
[0533] Given one or more currently active location hypotheses for
the same target MS input to a controller (denoted the Analytical
Reasoner Controller herein), this controller activates, for each
such input location hypothesis, the other submodules (denoted
hereinafter as "adjustment submodules") with this location
hypothesis. Subsequently, the Analytical Reasoner Controller
receives an output confidence adjustment value computed by each
adjustment submodule for adjusting the confidence of this location
hypothesis. Note that each adjustment submodule determines: [0534]
(a) whether the adjustment submodule may appropriately compute a
confidence adjustment value for the location hypothesis supplied by
the controller. (For example, in some cases there may not be a
sufficient number of location hypotheses in a time series from a
fixed FOM.); [0535] (b) if appropriate, then the adjustment
submodule computes a non-zero confidence adjustment value that is
returned to the Analytical Reasoner Controller.
[0536] Subsequently, the controller uses the output from the
adjustment submodules to compute an aggregate confidence adjustment
for the corresponding location hypothesis. In one particular
embodiment of the present invention, values for the eight types of
confidence adjustment values (described in sections above) are
output to the present controller for computing an aggregate
confidence adjustment value for adjusting the confidence of the
currently active location hypothesis presently being analyzed. As
an example of how such confidence adjustment values may be
utilized, assuming a currently active location hypothesis is
identified by "i", the outputs from the above described adjustment
submodules may be more fully described as:
TABLE-US-00013 path_match(i) 1 if there are sufficient previous
(and recent) location hypotheses for the same target MS as "i" that
have been generated by the same FOM that generated "i", and, the
target MS location estimates provided by the location hypothesis
"i" and the previous location hypotheses follow a known
transportation pathway. 0 otherwise. vel_ok(i) 1 if the velocity
calculated for the i.sup.th currently active location hypothesis
(assuming adequate corresponding path information) is typical for
the area (and the current environmental characteristics) of this
location hypothesis' target MS location estimate; 0.2 if the
velocity calculated for the i.sup.th currently active location
hypothesis is near a maximum for the area (and the current
environmental characteristics) of this location hypothesis' target
MS location estimate; 0 if the velocity calculated is above the
maximum. acc_ok(i) 1 if the acceleration calculated for the
i.sup.th currently active location hypothesis (assuming adequate
corresponding path information) is typical for the area (and the
current environmental characteristics) of this location hypothesis'
target MS location estimate; 0.2 if the acceleration calculated for
the i.sup.th currently active location hypothesis is near a maximum
for the area (and the current environmental characteristics) of
this location hypothesis' target MS location estimate; 0 if the
acceleration calculated is above the maximum. similar_path(i) 1 if
the location hypothesis "i" satisfies (37.1) for the target MS path
data attribute; 0 otherwise. velocity_similar(i) 1 if the location
hypothesis "i" satisfies (37.1) for the target MS velocity
attribute; 0 otherwise. acceleration_similar(i) 1 if the location
hypothesis "i" satisfies (37.1) for the target MS acceleration
attribute; 0 otherwise. extrapolation_chk(i) 1 if the location
hypothesis "i" is "near" a previously predicted MS location for the
target MS; 0 otherwise.
[0537] Additionally, for each of the above confidence adjustments,
there is a corresponding Location Center system settable parameter
whose value may be determined by repeated activation of an
Adaptation Engine. Accordingly, for each of the confidence
adjustment types, T, above, there is a corresponding system
settable parameter, "alpha_T", that is tunable by the Adaptation
Engine. Accordingly, the following high level program segment
illustrates the aggregate confidence adjustment value computed by
the Analytical Reasoner Controller.
TABLE-US-00014 target_MS_loc_hyps <--- get all currently active
location hypotheses, H, identifying the present target; for each
currently active location hypothesis, hyp(i), from
target_MS_loc_hyps do { for each of the confidence adjustment
submodules, CA, do activate CA with hyp(i) as input; /* now compute
the aggregate confidence adjustment using the output from the
confidence adjustment submodules. */ aggregate_adjustment(i)
<--- alpha_path_match * path_match(i) + alpha_velocity *
vel_ok(i) + alpha_path_similar * path_similar(i) +
alpha_velocity_similar * velocity_similar(i) +
alpha_acceleration_similar* acceleration_similar(i) +
alpha_extrapolation * extrapolation_chk(i); hyp(i).confidence
<--- hyp(i).confidence + aggregate_adjustment(i); }
Wireless Location Applications
[0538] After having determined wireless location from a base
technology perspective, several applications are detailed below,
which provide the results of the location information to a variety
of users in various channels and presentation schemes, for a number
of useful reasons and under various conditions. The following
applications are addressed: (1.) providing wireless location to the
originator or another, using either the digital air interface voice
channel or a wireline channel, and an automatic call distributor;
(2.) providing wireless location to the originator, or another,
using either the digital air interface voice channel or a wireline
channel, and a hunt group associated with the central office or a
PBS group; (3.) providing wireless location to the originator or
another, using either the digital air interface text paging, or
short message service communications channel; (4.) providing
wireless location to the originator or another, using the Internet,
and in one embodiment, using netcasting or "Push" technology; (5.)
selective group, multicast individualized directions with optional
Conferencing; (6.) rental car inventory control and dispatch; (7.)
vocalized directions and tracking; (8.) wireless location and court
ruling/criminal incarceration validation; (9.) flexible delivery of
wireless location information to public safety answering points;
(10.) trigger-based inventory and tracking; (11.) group, e.g.,
family, safety and conditional notification; (12.) wireless
location-based retail/merchandising services; (13.) location-based
home/office/vehicle security management; (13.)
infrastructure-supported wireless location using hand-actuated
directional finding; (14.) infrastructure-supported intelligent
traffic and highway management; (15.) Parametric-driven intelligent
agent-based location services. Each of these wireless location
applications is discussed in detail below.
Providing Wireless Location Using an ACD Application
[0539] Referring to FIG. 36, a user (the initiating caller)
desiring the location of a target mobile station 140a, such as a
user at a telephone station 162 which is in communication with a
tandem switch 489 or a user of an mobile station 140b, or any other
telephone station user, such as a computer program, dials a
publicly dialable telephone number which terminates on the
automatic call distributor 546 (ACD), associated with the location
center 142. If the caller originated the call from a mobile station
140b, then the call is processed via a base station 122b to a
mobile switch center 112a. The mobile switch center 112a recognizes
that the call is to be routed to the PSTN 124 via an interoffice
trunk interface 600. The PSTN 124 completes the call to the ACD
546, via a trunk group interface 500. Note that the initiating
caller could access the ACD 546 in any number of ways, including
various Inter-LATA Carriers 492, via the public switched telephone
network (PSTN) 124. The ACD 546 includes a plurality of telephone
network interface cards 508 which provide telephony channel
associated signaling functions, such as pulse dialing and
detection, automatic number identification, winking, flash,
off-hook voice synthesized answer, dual tone multi frequency (DTMF)
detection, system intercept tones (i.e., busy, no-answer,
out-of-service), disconnected, call progress, answer machine
detection, text-to-speech and automatic speech recognition. Note
that some of these functions may be implemented with associated
digital signal processing cards connected to the network cards via
an internal bus system. An assigned telephone network interface
card 508 detects the incoming call, provides an off-hook (answer
signal) to the calling party, then provides a text to speech (TTS)
message, via an assigned text-to-speech card 512 indicating the
nature of the call to the user, collects the automatic number
identification information if available (or optionally prompts the
caller for this information), then proceeds to collect the mobile
identification number (MIN) to be located. MIN collection, which is
provided by the initiating caller through keypad signaling tones,
can be achieved in several methods. In one case the network card
508 can request a TTS message via text-to-speech card 512, which
prompts the initiator to key in the MIN number by keypad DTMF
signals, or an automatic speech recognition system can be used to
collect the MIN digits. After the MIN digits have been collected, a
location request message is sent to a location application 146. The
location application 146, in concert with location application
interface 14 (more particularly, L-API-Loc 135, see FIG. 36), in
the location system 142, is in communication with the location
engine 139. Note that the location engine 139 includes the signal
processing subsystem 20, and one or more location estimate modules,
i.e., DA module 10, TOA/TDOA module 8 or HBS module 6. The location
engine 139 initiates a series of messages, using the location
application programming interface (L-API-MSC 136) to the mobile
switch center 112a. The location application programming interface
136 then communicates with one or more mobile switch centers 112b,
to determine whether or not the mobile station 140a to be located
can be located. Conditions affecting the locateability of the
mobile station 140a include, for example: the mobile station 140a
being powered off, the mobile station 140a not being in
communication range, the mobile station 140a roaming state not
being known, the mobile station 140a not being provisioned for
service, and related conditions. If the mobile station 140a cannot
be located then an appropriate error response message is provided
to the initiating caller, via e-mail, using the web server 464 in
communications with the Internet 468 via an Internet access channel
472 or alternatively the error response message may be sent to a
text to speech card 512, which is in communications with the
initiating caller via the telephone interface card 508 and the ACD
546, which is in communication via telephony interface circuits 500
to the PSTN 124.
[0540] Note that in cases where rendering location estimate
information is required on the Internet, the web server 464 can
include the provision of a digital certificate key, thus enabling a
secure, encrypted communication channel between the location web
server 464 and the receiving client. One such digital encryption
key capability is a web server provided by Netscape Communications,
Inc. and a digital certificate key provided by Verisign, Inc. both
located in the state of California, U.S.A.
[0541] The PSTN 124 completes routing of the response message to
the initiating caller via routine telephony principles, as one
skilled in the art will understand. Otherwise the mobile station
140a is located using methods described in greater detail elsewhere
herein. At a high level, the mobile switch center 112a is in
communication with the appropriate base stations 122, and provides
the location system 142 with the necessary signal and data results
to enable a location estimation to be performed by the location
engine 139. Once the location has been determined by the location
engine 139 in terms of Latitude, Longitude and optionally height if
known (in the form of a text string), the result is provided by to
the initiator by inputting the location text string to a
text-to-speech card 512, which in turn is in communication with the
assigned telephone interface card 508, via the automatic control
distributor 546, for completing the communication path and
providing the location response back to the initiating user via the
telephone interface 500 to the PSTN 124, and from the PSTN 124 to
the initiating user.
[0542] Alternatively the location results from the location
application 146 (e.g., FIGS. 37 and 38) could be provided to the
initiating caller or Internet user via a web server 464 in
communication with the Internet 468, via an Internet access channel
472 and a firewall 474 (e.g., FIG. 36). In another embodiment, the
location results determined by the location application 146 may be
presented in terms of street addresses, neighborhood areas,
building names, and related means familiar to human users. The
alternative location result can be achieved by previously storing a
relationship between location descriptors familiar to humans and
Latitude and Longitude range values in a map database 538 (FIG.
36). During the location request, the location application 146
accesses the map database 538, providing it with the Latitude and
Longitude information in the form of a primary key which is then
used to retrieve the location descriptor familiar to humans. Note
that to those skilled in the art, the map database 538 and
associated messaging between the map database 538 and the location
application 146 can be implemented in any number of techniques. A
straightforward approach includes defining a logical and physical
data model using a relational database and designer environment,
such as "ORACLE 2000" for the design and development, using a
relational database, such as the "ORACLE 7.3" database.
[0543] In an alternative embodiment, the location application 146
may be internal to the location system 142 (e.g. FIG. 37), as one
skilled in the art will understand.
Providing Wireless Location Via Hunt Groups Application
[0544] Referring to FIGS. 37 and 38, a user--the initiating caller,
such as a mobile station 140a desiring the location of a mobile
station 140, signals to the primary base station 122g, in
connection with the mobile switch center 112 via transport
facilities 176. The mobile switch center 112 is connected to the
PSTN 124, via interoffice trunks 600. The initiating user dials a
publicly dialable telephone number which is then routed through an
end office 496, to a telephone interface card 508, via a telephone
hunt group 500. The hunt group 500 provides a telephony connection
to the interface card 247 associated with the location system 142.
The hunt group trunk interface 500 is provided from an end office
telephone switch 496. Note that the initiating caller could access
the telephony interface card 508, via hunt group trunk interface
500 in any number of ways, including an InterLATA Carrier 492, via
the public switched telephone network (PSTN) 124. The hunt group
trunk interface 500 is in communication with a plurality of
telephone interface cards 508. The interface cards 508 provide
telephony channel associated signaling functions, such as pulse
dialing and detection, automatic number identification, winking,
flash, off-hook voice synthesized answer, dual tone multi frequency
(DTMF) detection, system intercept tones (i.e., busy, no-answer,
out-of-service), disconnected, call progress, answer machine
detection, text-to-speech and automatic speech recognition. An
assigned network interface card 508 detects the incoming call,
provides an off-hook (answer signal) to the calling party, then
provides a text to speech (TTS) message indicating the nature of
the call to the user, collects the automatic number identification
information if available (or optionally prompts the caller for this
information), then proceeds to collect the mobile identification
number (MIN) to be located. MIN collection can be achieved in
several methods. In one case the network card 508 can request a TTS
message, generated by a voice synthesizer or text to speech card
512, which prompts the initiator to key in the MIN number by keypad
tone signals, or an automatic speech recognition system can be used
to collect the MIN digits. After the MIN digits have been
collected, a location request message is sent to an application 146
in the location system 142. The application 146 in location system
142 initiates a series of messages to the mobile switch center 112,
and optionally to the home location register 460, to determine
whether or not the mobile station 140 to be located can be located.
If the mobile station 140 cannot be located then an appropriate
error response message is provided to the initiating caller, via
e-mail, test to speech card 512, web server 464 in communications
with the public Internet 468, or similar means. Alternatively the
last known location can be provided, along with the time and date
stamp of the last location, including an explanation that the
current location is not attainable. Otherwise the mobile station
140 is located using methods described in greater detail elsewhere
in this patent. At a high level, the mobile switch center 112 is in
communication with the appropriate base stations 122g and 122h, and
provides the location system 142 with the necessary signal and data
results to enable a location estimation to be performed by the
location system 142. Once the location has been determined by the
location system 142 in terms of Latitude, Longitude and optionally
height if known (in the form of a text string), the result is
provided back to the initiator by inputting the location text
string to a text-to-speech card 512, in communication with the
assigned telephone interface card 508. The interface card 508 then
provides the audible, synthesized message containing the location
estimate to the initiating caller. Alternatively the location
results could be provided to the initiating caller via a web server
464 in communication with the Public Internet 468, using standard
client request-response Internet protocols and technology, location
system 142 access to a geographical information system or other
mapping system could also be used to further enhance the user
understanding of the location on a map or similar graphical
display.
Providing Wireless Location Via Text Paging Application
[0545] Referring to FIG. 38, a user (the initiating caller)
desiring the location of an mobile station 140, such as a wireless
user using mobile station 140 who has text paging service
provisioned, dials a publicly dialable telephone number, carried to
the PSTN 124 which terminates on an end office 496 based hunt group
interface 500, which in turn is in communication with the location
system 142. The mobile switch center 112, local tandem 317 and
interLATA Carrier tandem 362 are in communication with the PSTN
124, as those skilled in the art will understand. Note that the
initiating caller could also be a wireline user with an ordinary
telephone station 162 in communication with a local tandem 489,
connected to the PSTN 124. The initiating location request user
could access the telephony interface cards 512 via the hunt group
500. In other embodiments, including various Inter-LATA Carriers
492, via the public switched telephone network (PSTN) 124. The hunt
group interface 500 is in communication with a plurality of
telephone network interface cards 512, which are in communication
with the location application 146. The telephone interface cards
512 provide telephony channel associated signaling functions, such
as pulse dialing and detection, automatic number identification,
winking, flash, off-hook voice synthesized answer, dual tone multi
frequency (DTMF) detection, system intercept tones (i.e., busy,
no-answer, out-of-service), disconnected, call progress, answer
machine detection, text-to-speech and automatic speech recognition.
Note that some of these functions may be implemented with
associated digital signal processing cards connected to the network
cards via an internal bus system. An assigned telephony interface
card 508 detects the incoming call, provides an off-hook (answer
signal) to the calling party, then provides, if appropriate, a text
to speech (TTS) message indicating the nature of the call to the
user, collects the automatic number identification information if
available (or optionally prompts the caller for this information),
then proceeds to collect the mobile identification number (MIN) to
be located by sending a location request message to an application
146 in the location system 142. The mobile station MIN collection,
provided through the communications channel established, is sent by
the initiating caller through keypad signaling tones. This MIN
collection process can be achieved in several methods. In one case
the telephony interface card 512 can request a text-to-speech
message, generated by a text-to-speech card 512, which prompts the
initiator to key in the MIN number by keypad tone signals. In
another case an automatic speech recognition system can be used to
collect the MIN digits. In either case, after the MIN digits have
been collected, a location request message is sent to the location
system 142. The location system 142 initiates a series of messages
to the mobile switch center 112, via the location applications
programming interface (L-API-MSC 136), and optionally to the home
location register 460, to determine whether or not the mobile
station 140 to be located can in fact be located. Alternatively the
last known location can be provided, along with the time and date
stamp of the last location, including an explanation that the
current location is not attainable. Conditions regarding the
locateability of a mobile station include, for example: mobile
station 140 powered off, mobile station not in communication range,
mobile station roaming state not known, mobile station 140 not
provisioned for service, and related conditions. If the mobile
station 140 cannot be located then an appropriate error response
message is provided to the initiating caller, via the service node
(SN) 107 for short messaging service (SMS). The service node is in
communication with the location system 142 using a common text
paging interface 108. The service node 107 accepts the location
text paging message from the location system 142 and communicates a
request to page the initiating caller via a typical signaling
system 7 link for paging purposes, to the mobile switch center 112.
The mobile switch center 112 forwards the location text page
information to the initiating caller via the appropriate base
stations, to the initiating mobile station caller. Otherwise the
mobile station 140 is located using methods described in greater
detail elsewhere in this patent. At a high level, the mobile switch
center 112 is in communication with the appropriate base stations,
and provides the location system 142 with the necessary signal and
data results to enable a location estimation to be performed by the
location system 142. Once the location has been determined by the
location system 142 in terms of Latitude, Longitude and optionally
height if known (in the form of a text string). The location result
is provided to the initiator by inputting the location text string
to the service node 107 for short messaging service (SMS). The
service node 107 is in communication with the location system 142
using a common text paging interface 108. The service node 107
accepts the location text paging message from the location system
142 and communicates a request to page the initiating caller via a
typical signaling system 7 link 105 for paging purposes, to the
mobile switch center 112. The mobile switch center 112 forwards the
location text page information to the initiating caller via the
appropriate-base stations 122a or 122b (not shown in FIG. 38), to
the initiating caller, via a text-to-speech card 512, in
communication with the assigned telephone interface card 508.
Providing Wireless Location Using Internet Push Technology
Application
[0546] Referring to FIG. 39, a user (the initiating user) desiring
the location of an mobile station 140, who has a push technology
tuner 484 associated with the user's client workstation 482,
selects the location channel in the area, and further specifies the
mobile station(s) 140 to be located, with what frequency should the
location estimate be provided, and other related parameters, such
as billing information. The user's client workstation 482 is in
communication with the Internet, optionally via an encrypted
communications channel (e.g. channel 490) using, for example,
Netscape's SSL 3 encryption/decryption technology. A push
transmitter 472, connected to the Internet 468 via a web server
464, detects the client workstation 482 user's request. The
transmitter 472 requests location update information for specified
mobile identification numbers through a firewall 474 and a
publisher 478, in communication with a location channel application
429 in the location system 142. The location system 142 initiates
location requests for all mobile station mobile identification
numbers for which location information has been subscribed to, then
provides the location results to the location channel application
429.
[0547] The location system 142 initiates a series of messages to
the mobile switch center 112, via the location applications
programming interface (L-API-MSC 136), and optionally to the home
location register (HLR) 460, to determine whether or not the mobile
station 140 or others, to be located can in fact be located.
Alternatively the last known location can be provided, along with
the time and date stamp of the last location, including an
explanation that current location is not attainable. Conditions
regarding the locateability of a mobile station 140 include, for
example: mobile station 140 powered off, mobile station not in
communication range, mobile station 140 roaming state not known,
mobile station 140 not provisioned for service, and related
conditions. If the mobile station 140 cannot be located then an
appropriate error response message is provided to the initiating
client workstation 482, via the push technology components location
channel application 429, publisher 478, firewall 474, transmitter
472, web server 464, public Internet 468, to the client workstation
482. A similar communication mechanism is used to provide the
client's workstation 482 with attained location information.
[0548] Note that the location channel 429 could in fact provide a
collection of mobile station 140 mobile identification numbers for
location purposes that are grouped by a particular market and/or
customer organization segment. for example, location channel number
1 could provide enhanced wireless 9-1-1 service to specific public
safety answering points, channel number 2 could provide periodic
wireless location information of a fleet of taxi cabs belonging to
a particular company, to their dispatch operator, channel 3 could
provide wireless location to a control center of a military
organization, channel 4 could provide wireless location information
of vehicles carrying hazardous materials, to a control center, and
so forth.
[0549] The location channel application 429 provides the location
results to the publisher 478, which provides a method of adding the
new location results to the transmitter 472, via firewall 474. The
firewall 474, provides protection services between certain systems
and the Internet 468, such as preventing malicious users from
accessing critical computing systems.
Selective Group, Multicast, Individualized Directions Conferencing
Application
[0550] The group multicast help, with individualized directions, is
an application wherein for members of a group that are authorized
and nearest a distressed caller, these members are given text
paging message instructions on how to drive or navigate, to reach
the initiating distressed caller. Alternatively optional voice
synthesis technology could be used to aid one or more members to
have spoken instruction giving directions and/or instructions for
each member, to help them reach the distressed caller.
[0551] Referring to FIG. 40, an individual having a mobile station
140 desires to make a distress call for help, or for some other
reason. The distressed caller with mobile station 140 dials a
special telephone number, received by base station 122, which then
sends the originating call setup request to the mobile switch
center 112. The mobile switch center 112 routes the originating
call through the PSTN 124 to an automatic call distributor (ACD)
546. The ACD 546 selects an available telephony interface circuit
508, which answers the call and provides introductory information
to the caller, such as a greeting message, progress of service,
etc., using a voice synthesizer circuit card 512. Note that
circuits 508 and 512 may be combined as voice response units. The
telephony interface circuit 508 collects the automatic number
identification information if available in the call setup message
or optionally prompts the caller for this information. This MIN
collection process can be achieved in several methods. In one case
the network telephony interface card 508 can request a TTS (text to
speech) message, generated by a voice synthesizer card 512, which
prompts the initiator to key in their MIN number by keypad tone
signals. In another case an automatic speech recognition system can
be used to collect the MIN digits. In either case after the MIN
digits have been collected, a location request message is sent to
the location system 142. The location system or location center
(LC) 142 initiates a series of messages to the mobile switch center
112, via the location applications programming interface
(L-API-MSC136), to determine whether or not the mobile station 140
to be located can in fact be located. If the mobile station 140
cannot be located then an appropriate error response message is
provided to the initiating caller. Otherwise the LC 142 determines
the caller's location via methods discussed elsewhere in this
patent. While this event is proceeding an application in the LS 142
references the initiating caller's location subscriber profile
database (not shown) to determine if the caller allows others to
locate him or her, and specifically which individuals are allowed
to be informed of the caller's location.
[0552] Assuming the caller allows location information to be sent
out to a select group, then the list of member's mobile station
identification numbers (MIN)s are extracted from the profile
database, and an application in the LC 142 initiates a series of
messages to the mobile switch center 112, via the location
applications programming interface (L-API-MSC 136), to determine
the locations of each of the users' mobile station mobile
identification numbers associated with the member list. Regarding
those mobile station mobile identification numbers nearest the
distress caller, each member's mobile station is dialed via a
control message sent from an application in the LC 142 to the
telephony interface card 508. A voice synthesizer card 512 or text
to speech circuit is also patched in the calling circuit path, to
announce the purpose of the automated call to each member. The ACD
546 initiates the call request to each member via the PSTN 124,
which connects to the mobile switch center 112, that ultimately
rings the member mobile station 140 and 148 via base stations 122.
An application in the LC 142 identifies a start and finish location
destination location for a member, based on his/her current
location as being the start location, and the finish location being
the distress caller's location at mobile station MIN. The
application in the LC 142 initiates a http or similar Internet
compatible protocol universal resource locator (URL) request via
the web server/client 530 to the public Internet 468, which
terminates on a maps, directions web server 534. One such URL known
to the authors is Lucent Technologies' http://www.mapsOnUs.com,
which is provided for public use. The map/directions server 534
queries the map base 536 via a directions algorithm, and returns to
the initiating http request, the location web server 530, with a
list of instructions to enable a user to navigate between a start
location and end location. Referring to FIG. 41, the information
shown in the columns labeled "Turn #", "Directions", "And Go",
and/or "Total Miles", can then be parsed from the http response
information. Referring now to FIG. 40, this information can then be
sent as a short text message, to the relevant mobile station 148 or
140 via the service node 107, using interface 105 to the mobile
switch center 112, and relevant base stations 122, assuming each
member mobile station has short message service provisioned. If
this is not the case, the service node 107 will inform the
application within the LS 142, which then initiates an alternative
method of sending the start-finish location navigation instructions
information via an appropriate voice synthesizer card 512 and
associated telephony interface card 508. The interface card 508
initiates an automated call to each appropriate member's mobile
station 148 and 140, via the telephony path including components
ACD 546 in communication with the PSTN 124, which is in
communication with the mobile switch center 112. The mobile switch
center 112 completes the routing of the automated call to the
appropriate mobile station 140 using base stations 122. The above
process is repeated for each nearby member's mobile station, thus
allowing all nearby members to be notified that the distressed
caller needs help, with navigation instructions to each member,
which enables the member to reach the distressed caller. Variations
of this application include putting each relevant party in
communication with each other via a conference call capability in
the ACD 546, with or without providing location information and/or
start-finish navigation instructions.
Rental Car Inventory, Tracking and Control Application
[0553] An application in the location system utilizes periodic
wireless location of appropriate rental cars, control circuits and
control communications within the rental car, and secured
transactions across the Internet, or similar means, in order to
provide various tracking and control functions. Such functions
allow rental car agencies to remotely control and operate their
rental cars in order to reduce operating costs such as storage and
maintenance, as well as provide additional conveniences and
services to rental car agency customers.
[0554] Referring to FIG. 42, a vehicle 578 containing various
sensors and actuators (not shown) used to, for example, lock and
unlock car doors, sense door position, keypad depressions, sense
the condition of the engine and various subsystems, such as brakes,
electrical subsystems, sense the amount of various fluid levels,
etc., is in communication with a vehicle-based local area network
572, which is in turn connected to a mobile station 140 containing
asynchronous data communications capability. The vehicle-based
local area network may optionally contain a computer (not shown)
for control and interfacing functions. The mobile station 140 is
always in communication, using the radio air interface with at
least one base station 122g, and possibly other base stations 122h.
The base stations 122g and 122h are in communication with the
mobile switch center 112 via transport facilities 176. The mobile
switch center 112 is in communication with the location system 142
and the public switched telephone network 124 via interoffice
trunks 600. In addition the mobile switch center 112 is also in
communication with the location system 142 via the location
system--mobile switch center physical interface 178. The physical
interface provides two-way connections to the location applications
programming interface (i.e., L-API-MSC 136), which is in
communication with a location engine 139, which performs wireless
location estimations for the mobile station, which is permanently
mounted in the vehicle 578. The location engine 139 represents key
components within the location system 142 which together comprise
the capability to perform wireless location estimations. The rental
car location application 146 is in communications with the location
engine 139 for purposes of initiating wireless location requests
regarding the mobile station 140, as well as for receiving wireless
location responses from the location engine 139. The application
146 is in communications with the automatic call distributor 546
for purposes of initiating and receiving telephone calls to and
from the public switch telephone network 124, via hunt group
interface 500. As one skilled in the art will appreciate, other
interfaces (not shown) beyond hunt groups 500, can alternatively be
used, such as ISDN interface circuits, T-carrier and the like. The
application 146 is in communication with a web server and client
464, which in turn is in communication with the Internet 468 via an
Internet access interface 472. As those in the art will understand,
an Internet access interface is typically provided by an Internet
service provider, also there are other methods which could be used
to complete the Internet connection. The rental car agency contains
a workstation or personal computer 582 with an Internet access
interface 472 to the Internet 468. The application 146 requests of
the location engine 139 to perform a location request periodically
regarding the mobile station 140, with the location response
information provided the web server and client, 464. For each
rental car or vehicle containing a mobile station 140, the
location, as well as various information about the rental car or
vehicle can be ascertained via the above described
infrastructure.
911 Application with Wireless Location of the Caller Reporting an
Incident
[0555] An application in the location system operates in
conjunction with an application in each public safety answering
point (PSAP) that together provides various call handling functions
to enable the PSAP to perform its work load efficiently and
effectively toward unique emergency events unique to a given
location. The application pair measures the number of emergency
9-1-1 wireless calls originating from a particular geographical
area or location. Upon exceeding a provisional threshold value "X",
the application pair traps the next incoming call from the same
location and provides a call screening function via a play
announcement and collect digits activity. This activity alerts the
originating caller that if their call relates to an incident at a
particular location, then they are the "X+1 th" caller who has
already notified the PSAP, and that no further caller discussion is
required. However, if the caller's intent does not relate to the
incident described above, then the caller is requested to press or
say "one", or some similar keypad number, which then is collected
and causes the caller to be re-routed to the next available PSAP
call taker. Alternatively if the originating caller does not
respond within a short time period, then the call is also re-routed
to the next available PSAP call taker. The voice announcement may
either be synthesized by a text-to-speech card, or an PSAP operator
may store a voice message which describes the incident at the
above-referenced location.
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References