U.S. patent application number 14/529991 was filed with the patent office on 2015-06-11 for wide-area dynamic rfid system using uwb.
The applicant listed for this patent is ZEBRA ENTERPRISE SOLUTIONS CORP.. Invention is credited to Gideon Kaplan.
Application Number | 20150161423 14/529991 |
Document ID | / |
Family ID | 37900172 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150161423 |
Kind Code |
A1 |
Kaplan; Gideon |
June 11, 2015 |
WIDE-AREA DYNAMIC RFID SYSTEM USING UWB
Abstract
A wide area radio frequency identification (RFID) system
includes: a first RFID cell and a second RFID cell. The first RFID
cell and the second RFID cell each include a reader and tags. The
readers access the tags using ultra-wide band signaling. The RFID
cells each include: a communications interface operable to
communicate with a network operations center, and a communications
gateway which supports direct communications between RFID cells.
The method includes accessing the second RFID cell from the first
RFID cell, and the accessing is performed using the communications
gateway that can cover a range of at least five hundred meters.
Inventors: |
Kaplan; Gideon; (Kiryat Ono,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZEBRA ENTERPRISE SOLUTIONS CORP. |
OAKLAND |
CA |
US |
|
|
Family ID: |
37900172 |
Appl. No.: |
14/529991 |
Filed: |
October 31, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12066697 |
Aug 19, 2008 |
8896421 |
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PCT/IL2006/001138 |
Sep 28, 2006 |
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14529991 |
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60721986 |
Sep 30, 2005 |
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Current U.S.
Class: |
340/438 ;
340/505 |
Current CPC
Class: |
B60Q 9/00 20130101; G06K
7/10306 20130101; G08B 13/2402 20130101; G08B 13/24 20130101; G06K
7/10475 20130101; H04M 15/00 20130101 |
International
Class: |
G06K 7/10 20060101
G06K007/10; B60Q 9/00 20060101 B60Q009/00; G08B 13/24 20060101
G08B013/24 |
Claims
1. A wide area radio frequency identification (RFID) system
comprising: at least two RFID cells, wherein a first RFID cells
includes a first reader and a first plurality of tags and a second
RFID cell includes a second reader and a second plurality of tags,
wherein the first reader is configured to accesses the first
plurality of tags and the second reader is configured to access the
second plurality of tags; wherein the first RFID cell and the
second RFID cell include a communications gateway operable to
support direct communications between at least the first RFID cell
and the second RFID cell; wherein, via the communications gateways
of the first RFID cell and the second RFID cell, the first reader
of the first RFID cell is configured to query data from, or write
data to, a tag within the second plurality of tags of the second
RFID cell; wherein the second RFID cell is configured to receive a
security alarm from the first RFID cell via the direct
communications that is arranged over a range of at least five
hundred meters.
2. (canceled)
3. The wide area RFID system, according to claim 1, wherein at
least one of said at least two RFID cells is located in a mobile
vehicle.
4. The wide area RFID system, according to claim 1, wherein said
ultra-wide band signaling is operable to determine respective
locations of the tags and to store said respective locations.
5. The wide area RFID system, according to claim 1, wherein said
communications gateway includes a cellular telephone communications
interface.
6. The wide area RFID system, according to claim 1, wherein said
communications gateway includes a cellular telephone operatively
attached to the at least one reader.
7. The wide area RFID system, according to claim 1, wherein said
communications gateway is operatively attached to a communications
link selected from the group of communications technologies
consisting of: cellular communications, terrestrial radio
communications, satellite communications, point-to-point microwave
communications, infrared free space point-to-point communications,
and free space point-to-point optical communications.
8. The wide area RFID system, according to claim 1, wherein the
tags are attached to objects included in materiel of an
organization, wherein said objects are managed by a materiel
management application accessible through the network operations
center.
9. A method for communicating between a first RFID cell and a
second RFID cell in a wide area radio frequency identification
(RFID) system. comprising: querying data from, or writing data to,
a tag within a second plurality of tags of the second RFID cell via
a communications gateway operable to support direct communications
between the first RFID cell and the second RFID cell, the querying
or writing being performed by a first reader; wherein the first
RFID cell includes the first reader and a first plurality of tags
and the second RFID cell includes a second reader and the second
plurality of tags, wherein the first reader accesses the first
plurality of tags using ultra-wide band signaling and the second
reader accesses the second plurality of tags using ultra-wide band
signaling; wherein the first RFID cell and the second RFID cell
each include communications gateways operable to support the direct
communications between the first RFID cell and the second RFID
cell; and wherein the second RFID cell is configured to receive a
security alarm from the first RFID cell via the direct
communications that is arranged over a range of at least five
hundred meters.
10. (canceled)
11. The method, according to claim 9, wherein at least one of said
at least two RFID cells is located in a mobile vehicle.
12. (canceled)
13. The method, according to claim 9, wherein said accessing
includes a transmission from the first RFID cell, wherein said
transmission is selected from the group consisting of unicast,
multicast and broadcast transmissions.
14. (canceled)
15. (canceled)
16. (canceled)
17. The method, according to claim 9, wherein the second reader
maintains in storage a plurality of respective locations of the
second plurality of tags of the second RFID cell.
18. The wide area RFID system of claim 1, wherein the first reader
of the first RFID cell is configured to query data from, or write
data to, the tag within the second plurality of tags of the second
RFID cell in an instance in which the readers are prevented from
transmitting an alarm to the network operations center.
19. The wide area RFID system of claim 1, wherein the first RFID
cell or the second RFID cell is a personal area network (PAN).
20. The wide area RFID system of claim 1, wherein, using the
communications gateways of the first RFID cell and the second RFID
cell, the first reader of the first RFID cell is configured to
query data from and write data to a tag within the second plurality
of tags of the second RFID cell.
21. The wide area RFID system of claim 1, wherein at least one tag
within the second plurality of tags is not within range of the
first reader of the first RFID cell and the first reader of the
first RFID cell is configured to query data from, or write data to,
the at least one tag within the second plurality of tags via the
communications gateways of the first RFID cell and the second RFID
cell.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/066,697, filed Aug. 19, 2008, which is the National Stage of
International Application No. PCT/IL2006/001138, filed Sep. 28,
2006, which claims priority from U.S. Provisional Application Ser.
No. 60/721,986, filed on Sep. 30, 2005, the contents of which are
each incorporated by reference herein in their entirety.
TECHNICAL FIELD
[0002] The present invention relates to an RFID system including
readers and tags, using ultra-wide band (UWB) communications
between the readers and the tags, and the RFID system is managed
over a wide area between RFID cells separated over a wide area,
e.g., several kilometers or more. Specifically, the method includes
communications links operable between RFID/UWB cells for
transferring data between the cells.
BACKGROUND OF THE INVENTION
[0003] Radio Frequency IDentification (RFID) is a method of storing
and remotely retrieving data using devices called RFID tags. An
RFID tag is a small object that can be attached to a product,
animal, or person. RFID tags receive and respond to radio-frequency
queries from an RFID reader. RFID tags can be either active or
passive. Passive tags require no internal power source, whereas
active RFID tags have an internal power source, and typically have
longer range and larger memories than passive tags.
[0004] An RFID system includes several components including mobile
tags, tag readers, and application software. The RFID system
enables a query to be received by the mobile tag and the tag
responds with data. The data is received by an RFID reader and
processed according to the needs of a particular application. The
data transmitted by the tag may provide identification or location
information, or specifics about the product tagged, such as price,
color, date of purchase.
[0005] RF identification (RFID) systems are used to track objects,
animals and/or people in a large range of applications. As an
example, RFID is used to track books in a library. Security gates
include an RF transceiver as part of the RFID reader which detects
whether or not a book has been properly checked out of the library.
When the book returns, the tag attached to the book is detected and
an appropriate record is updated in the library system. In. another
application, RFID readers previously located in a warehouse are
used to identify certain objects (for example, on a track entering
the warehouse), or to find the location of certain objects, by
communicating with their tags and measuring the position of their
tags.
[0006] A RFID system employs tags on various objects and readers of
the tags in a given space. The main function of an RFID is to
enable identifying the objects and possibly reading and writing
data of the objects to and from the respective tags. Often the RFID
system allows tracking the location of the objects via the
respective tag location.
[0007] Ultra-wide band communications is particularly useful for
determining distance and location of RFID tags. PCT International
Patent Application Publication No. WO 2003/098528, (PCT Patent
Application No. PCT/IL2003/00358), entitled "Method and system for
distance determination of RF tags" is incorporated by reference for
all purposes as if fully set forth herein. PCT/IL2003/00358
discloses an RFID system having the capability of automatically
identifying unknown tags by sending a broadcast interrogation ultra
wide-band (UWB) message signal and receiving responses from tags
that receive the message signal.
[0008] As known in the art of RFID systems, the readers are devices
which identify and store the data from the tags. The tags are
attached to assets or materiel being managed. A major goal of an
RFID system is to allow asset visibility to the organization and
improve the organization's efficiency in asset tracking within
different processes within the organization. The RFID system is a
useful tool to obtain resource and location information for
resource management or materiel management applications such as
computer resource management (CRM) or Enterprise Resource Planning
(ERP) applications running on interconnected computers within the
organization. Typically the readers of the RFID system collect data
originating in the tags, communicate and transfer the data with the
resource management applications.
[0009] An RFID system 10 of the prior art is shown in FIG. 1
including readers 101 communicating with tags 103. Readers 101 are
optionally connected to a conventional data switch 100 using
Ethernet (e.g., 100 BaseT) connections 105. RFID system 10
employing wide-band transmission can cover only limited areas, of
typical dimension no more than several hundred meters. This is
particularly the case for a RFID system employing ultra-wide band
(UWB) communications networks using impulse transmission or
otherwise complying with the definition of ultra wide (UWB) as
approved by the FCC, or other wide-band communication methods.
[0010] Wide-band, low data rate systems (including RFID systems)
fall under the category of personal area networks (PAN) and cover a
limited area. In some cases, the low data rate systems include
several readers that are used to cover the area, whereas tags 103
within this area can communicate with one or more readers 101
within the area. Information regarding tagged objects may be
relayed between different RFID tag cells, according to the prior
art from readers 101 through switch 100 to a wide area network such
as the Internet to a network operations center (not shown).
[0011] In numerous cases, there exists a need to cover a wide area
in which assets or objects may move. Due to the limited coverage
capability of an RFID system employing UWB, other communications
systems are required to achieve the coverage over the wide area. A
conventional method for covering a wide area is disclosed in US
application 20040203377 entitled, "Communication system for dynamic
management of a plurality of objects and method therefor". In US
patent application publication 20040203377, the objects are located
within a large coverage area, and communicate their information to
a central server. The objects may belong to dynamic groups
controlled by group controllers. Another representative prior art
reference is US patent application publication 2005/0248454
entitled "Marine Asset Security and Tracking System" as disclosed
by Hanson et. al. Hanson et. al disclose a system using radio
frequency identification (RFID) tags installed on containers.
Multiple RFID readers are required, e.g., on ship, which relay
information from the RFID tags to a site served installed on ship
or in port. The site server relays information regarding the
monitored containers via satellite link to a network operations
center (NOC).
[0012] However, in many cases a central server or network
operations center is not readily available either due to lack of
worldwide coverage or insufficient capacity. In other cases, such
as when the connection to a network operations center (NOCRO
requires the use of low earth orbit (LEO) satellites the satellite
communication connection is very expensive.
[0013] There is thus a need for, and it would be highly
advantageous to have a wide area dynamic RFID system using UWB
which does not always require the use of a central server nor a
network operations center (NOC) for communicating between one
RFID/UWB cell to another RFID/UWB cell.
[0014] Other Prior Art:
[0015] US patent application publication 20050208892, Kotola et
al., entitled "System and Method for remote service operation",
provides techniques for the management of information regarding
remote services. A remote service link is received across a
short-range wireless communications network. The remote services
may provide location-specific information regarding topics, such as
weather forecasts, local dining and shopping, maps, transit
schedules, etc. A mobile device may store and display information
that allows a user to initiate service sessions with various remote
service providers.
[0016] US patent application publication, 20050198208, S. Nystrom,
"Accessing data in a short-range wireless communication network"
describes a short-range communication system, including a
transponder and mobile reader device that integrates information
stored on a short range communications tag with information stored
remotely at an external network resource. The user of a
reader-associated device can access information stored on a
short-range communication tag and information stored remotely at a
network resource without incurring unnecessary delay. The system of
US20050198208 includes a short-range wireless communication tag.
The tag includes short-range wireless communication circuitry and a
memory unit in communication with the circuitry. The memory unit
stores local content information, e.g., Internet home page, and
commands for concurrently effecting retrieval of supplemental
content information, associated with the local content information
from a remote network resource while the local content information
is accessible to a remote wireless device.
DEFINITIONS
[0017] The term "ultra-wide band" (UWB) as used herein is defined
(by FCC and ITU-R) in terms of a transmission from an antenna for
which the emitted signal bandwidth exceeds the lesser of 500 MHz or
20% center frequency. Ultra-wide band (UWB) communication
technology employs discrete pulses of electromagnetic energy that
are emitted at, for example, picosecond to microsecond intervals.
For this reason, ultra-wide band is often called "impulse radio." A
UWB pulse is a single electromagnetic burst of energy. A UWB pulse
can be either a single positive burst of electromagnetic energy, or
a single negative burst of electromagnetic energy, or series of
pulses. Each pulse in a pulse-based UWB system occupies the entire
UWB bandwidth, e.g., 3.1 to 10.6 GHz. thus having relative immunity
to multipath fading (but not to intersymbol interference), unlike
carrier-based systems that are subject to both deep fades and
intersymbol interference.
[0018] Ref: http://en.wikipedia.org/wilci/Ultra_wide band.
[0019] The terms "cell" or "RFID cell" as used herein is an RFID
network using ultra wide band signaling over a limited area,
typically up to a few hundred meters in dimension.
[0020] The terms "personal area network" (PAN) and "RFID cell" are
used herein interchangeably.
[0021] The term "wide area" in the context of the present
invention, refers to an area with typical dimensions of at least
five hundred meters up to several kilometers or more. Coverage need
not be contiguous over the wide area but rather only within the
RFID cells in which the assets or tagged objects are located.
[0022] The terms "direct" or "directly" referring to communications
between RFID cells without communicating through a network
operations center.
[0023] The term "materiel" as used herein refers to the equipment
and supplies in military and commercial supply chain management. In
a military context, the term "materiel" relates to the specific
needs of an army to complete a specific mission. Materiel in the
context of commercial distribution includes items being transported
by the services of or as the products of the business.
[0024] Integrated Digital Enhanced Network (iDEN) is a mobile
telecommunications technology, developed by Motorola, which
provides benefits of a trunked radio and a cellular telephone. iDEN
places more users in a given spectral space, compared to analog
cellular and two-way radio systems, by using speech compression and
time division multiple access (TDMA). Notably, iDEN is designed to
operate on narrow Specialized Mobile Radio (SMR) spectrum, rather
than cellular frequencies. This necessitates the use of time
division duplex, since SMR frequencies are unpaired. Up to six
communication channels share a 25 kHz space; where analog two-way
systems place only one channel in 12.5 kHz.
[0025] (Ref:
http://en.wikipedia.org/wiki/Integrated_Digital_Enhanced_Network)
SUMMARY OF THE INVENTION
[0026] According to the present invention there is provided a wide
area radio frequency identification (RFID) system including RFID
cells. The RFID cells include readers and tags. The readers access
the tags using ultra-wide band signaling. The RFID cells each
include a communications interface operable to communicate with a
network operations center, and a communications gateway operable to
support direct communications between the RFID cells. The direct
communications is over a range of at least five hundred meters.
Typically, one or more of the RFID cells are located in a mobile
vehicle. The ultra-wide band signaling is preferably operable to
determine respective locations of the tags and to store the
respective locations. The communications gateway preferably
includes a cellular telephone communications interface and a
cellular telephone operatively attached to or integrated with the
reader. The communications gateway is operatively attached to a
communications link using a communications technologies such as
cellular communications, terrestrial radio communications,
satellite communications, point-to-point microwave communications,
infrared free space point-to-point communications, and free space
point-to-point optical communications. The tags are attached to
objects included in materiel of an organization, The objects are
managed by a materiel management application accessible through the
network operations center.
[0027] According to the present invention there is provided a
method in a wide area radio frequency identification (RFID) system.
The system includes a first RFID cell and a second RFID cell. The
first RFID cell and the second RFID cell each include a reader and
tags. The readers access the tags using ultra-wide band signaling.
The RFID cells each include: a communications interface operable to
communicate with a network operations center (NOC), and a
communications gateway which supports direct communications between
RFID cells. The communication interface to the NOC and the
communication gateway, may be housed in the same device or in
different devices. The method includes accessing the second RFID
cell from the first RFID cell, and the accessing is performed using
the communications gateway over a range of at least five hundred
meters. Typically one or more of the RFID cells is located in a
mobile vehicle. An RFID cell is capable of receiving a security
alarm from another RFID cell. Transmissions from the RFID cell are
optionally unicast, multicast and/or broadcast transmissions. A
reader in one RFID cell can access a tag, of another RFID cell,
either by querying information from the tag; or by writing data to
the tag; or the reader in the RFID cell accesses another reader of
the other RFID cell. By virtue of ultra-wide band signaling, a
reader in one RFID cell preferably maintains in storage locations
of the tags in the RFID cell. The locations may be queried
typically by a reader from the other cell.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention is herein described, by way of example only,
with reference to the accompanying drawings, wherein:
[0029] FIG. 1 is a prior art drawing of a conventional RFID cell;
and
[0030] FIG. 2 is a drawing according to an embodiment of the
present invention of a wide area RFID system using UWB.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] The present invention is of a system and method of providing
a wide area dynamic RFID system using UWB. Specifically, the system
and method includes multiple RFID systems using ultra wide band
(UWB) signaling between readers and tags 103 and information
regarding tagged objects is transferred over relatively large
distances between multiple RFID systems using communications links.
A wide area RFID/UWB network is thus achieved which is preferably
managed in a similar way to a single RFID cell. The communication
links which allow mesh connectivity between RFID cells may be
achieved using a cellular network, a satellite network, terrestrial
radio, or point-to-point links such as microwave, infrared or
optical links.
[0032] The principles and operation of a system and method of
providing a wide area dynamic RFID system using UWB, according to
the present invention, may be better understood with reference to
the drawings and the accompanying description.
[0033] Before explaining embodiments of the invention in detail, it
is to be understood that the invention is not limited in its
application to the details of design and the arrangement of the
components set forth in the following description or illustrated in
the drawings. The invention is capable of other embodiments or of
being practiced or carried out in various ways. Also, it is to be
understood that the phraseology and terminology employed herein is
for the purpose of description and should not be regarded as
limiting.
[0034] By way of introduction, a principal intention of the present
invention is to provide a wide area RFID network in which RFID
cells are separated by large distances, e.g., several kilometers
and information transfers between RFID cells using communications
links between RFID cells. The information transfer between the RFID
cells is performed using the communications links between the cells
particularly when the central server or network operations center
(NOC) is unavailable, e.g., no cellular coverage, or otherwise
undesirable, e.g., too costly for frequent updates such as in the
case of using a low Earth orbit satellite network. Another
intention of some embodiments of the present invention is to reduce
management overhead by managing the wide area RFID network much in
the same way as if it were a single RFID cell. The wide area RFID
network, according to embodiments of the present invention,
maintains accurate location information regarding organizational or
corporate assets i.e., tagged objects, using communications links
between the cells. The wide area RFID network updates location
information of the tagged objects, preferably only as required,
e.g., once per day or upon query through the network operations
center to the enterprise resource management application. In this
way, communications using the network operations center is
minimized. Another intention of embodiments of the present
invention is to increase security since multiple communications
links need to be jammed to prevent the reader from transmitting an
alarm.
[0035] The wide area RFID network, according to different
embodiments of the present invention may include static RFID cells
such as in a warehouse, or mobile RFID cells which include tagged
objects in a truck, container, ship or airplane or a combination of
mobile and static RFID cells. Similarly; the readers in different
embodiments of the present invention may be immobile within a
warehouse, at a vehicle entrance or docking points; or the readers
may be mobile within trucks, ships, airplane and other vehicles. In
other embodiments, different mobile cells may become sufficiently
close, e.g. within 100 meters, to overlap and the tags of one cell
may be accessed by the reader of another cell nearby using UWB
signaling and synchronization.
[0036] Referring now to the drawings, FIG. 2 illustrates
schematically a wide area dynamic RFID system 20 using UWB,
according to embodiments of the present invention. Wide area RFID
system 20 includes multiple RFID cells or PANS 11. In each PAN 11
there is gateway device 201 which connects to other cells 11 via
connections 203. Gateway device 201 may be integrated with UWB
reader 101 of the RFID system 10. Gateway device 201, is preferably
accessible by query from network operations center 207 when a
conventional WAN connection 205 is available. Gateway device 201
may be used to access readers 101 in the same cell 11, particularly
when reader 101 is not accessible for some reason using
conventional UWB signaling. In some embodiments of the present
invention, gateway 201 is a mobile telephone such as cellular,
e.g., GSM, telephone or iDEN, since iDEN doesn't require a nearby
base station to establish communications. In some embodiments of
the present invention, UWB reader 101 is built into the same
housing as the mobile telephone, enabling full RFID functionality
within cell 11. Gateway device 201 and connection 203 may use any
known type of communications known in the art including radio, free
space point-to-point microwave, infrared or optical links.
[0037] In each PAN 11 of wide area RFID system 20, network topology
and Media Access Control (MAC) protocols may be similar to those
specified by IEEE 802.15.4 standard, or any other suitable
protocol.
[0038] According to embodiments of the present invention, operation
of wide area RFID network 20 using RFID operates using an
innovative protocol. Wide area RFID network 20 protocol between
RFID cells 11 preferably includes the following elements:
[0039] A message (and response message) for identifying all objects
in cell `n`;
[0040] A read of data from object `y` in cell number `n`;
[0041] Write operation of data `d` to object `x` in cell `n`;
[0042] Find location of object `z` in cell number `k`;
[0043] An outgoing (alert) message from one cell 11 to another cell
11 or to NOC 207: event `eee` occurred in element `w` of cell (or a
security event, out of list of prescribed events).
[0044] In wide area RFID network 20, `read` (object data or object
ID), `write` (object data) and `locate` (an object) have both a
local meaning (inside PAN 11) as well as a global meaning in wide
area RFID network 20. Reader 101 in one RFID cell 11 may transmit a
query for a tagged object in the same cell 11 or in another cell
11, by either an addressed unicast, multicast message or by a
broadcast message. Reader 101 may also write data to a tagged
object in local RFID cell 11 or in another RFID cell. Furthermore,
reader 101 may be required to find the location of a tagged object,
either in local RFID cell 11, or in another RFID cell 11 of
wide-area network 20. The absolute (e.g. geographic) location of
objects in any RFID cells 11, may be measured (such as using the
teachings of WO 2003/098528) if the absolute location of readers
101 is known. In the case of a immobile RFID cell 11, the location
of readers 101 is typically known a priori. Otherwise, the location
of readers 101 may be determined for instance using an attached
global positioning system (GPS). If the absolute location of reader
101 is not available, the location of a tagged object can be
specified based on a relative location of one or more readers 101.
In either case, the computation to determine location of tagged
objects is performed locally or remotely over the wide area RFID
network 20 using a centralized processing machine or server (not
shown) preferably co-located with one of gateways 201.
[0045] The usage of wide area RFID system 20 may be further
augmented for various combinations of local and global processes,
for example:
[0046] Wide area RFID system 20 may support additional mechanisms
of information transfer e.g., video transmission to the Network
Operation Center 207, e.g., for emergency situations triggered by
the occurrence of a local event. Wide area RFID system 20 may be
used to synchronize processes in different PANs 11 very close to
real time, e.g. by updating records, such as shipment dates or
destinations written on tagged objects in one PAN 11, in response
to an event in another PAN 11 or in response to the command of
materiel management application.
[0047] When gateway 201 is a cellular telephone integrated with UWB
reader 101, the cellular telephone has a network identification, is
manually operable through a conventional keypad, or automatically
places calls to NOC 207 or other gateways or responds to calls from
NOC 207 or other gateways 201.
[0048] One application of the present invention is in the military
theater. Typically, modem armies are required to maintain and
secure weapon inventories. An RFID/UWB cell 11 is located in each
weapons warehouse or truck carrying weapons. If one military unit
requires weaponry from a second unit, a multicast (or broadcast)
query may be placed over communications links 203 to locate the
required weaponry from neighboring cells 11 of other military
units.
[0049] In another application of the present invention, a
telecommunications company in a modem city has several trucks with
replacement parts, e.g., switches or circuit boards. One technician
may require a replacement part which is not available on his truck.
The technician performs a multicast query over communications links
10, to perform an inventory search in neighboring cells 11, e.g.
trucks to locate the required part a nearby cell 11.
[0050] As such, those skilled in the art will appreciate that the
conception, upon which this disclosure is based, may readily be
utilized as a basis for the designing of other structures, methods
and systems for carrying out the several purposes of the present
invention. It is important, therefore, that the claims be regarded
as including such equivalent constructions insofar as they do not
depart from the spirit and scope of the present invention.
[0051] While the invention has been described with respect to a
limited number of embodiments, it will be appreciated that many
variations, modifications and other applications of the invention
may be made.
* * * * *
References