U.S. patent number RE42,435 [Application Number 12/343,706] was granted by the patent office on 2011-06-07 for wireless location determining device.
This patent grant is currently assigned to Daak Wireless Fund L.L.C.. Invention is credited to Daniel A. Katz.
United States Patent |
RE42,435 |
Katz |
June 7, 2011 |
**Please see images for:
( Certificate of Correction ) ** |
Wireless location determining device
Abstract
The present invention discloses a system and a method to locate
moving objects, such as people, pets and vehicles, over a wide
area, by attaching small wireless devices, such as Bluetooth
transceivers, to said objects and determining the location of said
devices. The location of said wireless devices is determined by
achieving ad-hoc short range wireless connectivity between said
devices and communication devices such as Bluetooth enabled mobile
phones that pass by, where said latter communication devices can be
located by other means, such as GPS or network-based
techniques.
Inventors: |
Katz; Daniel A. (Kiryat Ono,
IL) |
Assignee: |
Daak Wireless Fund L.L.C.
(Wilmington, DE)
|
Family
ID: |
35542050 |
Appl.
No.: |
12/343,706 |
Filed: |
December 24, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
10710379 |
Jul 6, 2004 |
7155238 |
Dec 26, 2006 |
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Current U.S.
Class: |
455/456.1;
455/41.2; 455/456.2; 342/357.55; 455/457; 455/432.1;
340/539.13 |
Current CPC
Class: |
G01S
5/0289 (20130101); G01S 13/82 (20130101); H04W
64/00 (20130101) |
Current International
Class: |
H04W
24/00 (20090101) |
Field of
Search: |
;455/456.1-457,404.2,41.1-41.2,432.1,435.2,550.1,558,522.1,428,12.1
;370/331,338 ;342/357.06,357.09,357.1
;340/358.13,826.36,10.1,10.52,426.2 ;701/200,213 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Afshar; Kamran
Claims
The invention claimed is:
1. A communication system for determining geographical location of
roaming objects in a vicinity of a plurality of communication
devices, comprising: a) a communication network, consisting of at
least said plurality of communication devices, said plurality of
communication devices configured to communicate with other
communication devices over said communication network, and
establishing a short range wireless communication with other
wireless devices in the vicinity of said plurality of communication
devices, said communication network is configured for obtaining the
geographical location of said plurality of communication devices
and transmitting data representing said geographical location to a
destination, over said communication network; b) a wireless tag,
attached to each of said roaming objects, being a wireless device,
in which a unique data is stored, said tag is configured for
communicating with said plurality of communication devices via said
short range and transmitting said unique data to said destination
through said plurality of communication devices and over said
communication network, wherein said tag comprises: a) a short-range
wireless transceiver for communicating with said plurality of
communication devices being in the vicinity of said tag; b) a
memory for storing the unique data; and c) a control circuitry for
controlling the communication between said tag and said
communication device; and c) a control center being linked to said
destination, for receiving said unique data from said tag and for
using said unique data and the location of the plurality of
communication devices, through which said unique data is
transmitted, for determining and displaying the geographical
location of said tag, wherein the control center communicates with
the plurality of communication devices for the presence of tags in
their vicinity, according to at least one of the following
parameters: a tag's identification; time at which said unique data
is transmitted; a geographical region; identification of said
plurality of communication devices and a trigger signal generated
at the tag or input to the tag.
2. A system according to claim 1, in which each said plurality of
communication devices comprises: a) a short-range wireless
transceiver for communicating with one or more wireless tags being
in the vicinity of said plurality of communication devices; b) a
memory for storing multiple unique data transmissions from the same
tag, and/or said unique data transmissions from different tags; c)
circuitry for transmitting said data to the destination, over the
communication network; and d) a control circuitry for controlling
the communication between said plurality of communication devices
and said tags and the transmission of said unique data over said
communication network.
3. A system according to claim 1, in which each said plurality of
communication devices further comprises: a) location determining
circuitry for determining the geographical location of said
communication devices; and b) circuitry for transmitting data
representing said location to the destination.
4. A system according to claim 1, wherein the data representing the
location of the plurality of communication devices or the data
provided by the tag are affiliated into the control signals that
are transmitted from said plurality of communication devices over
the communication network.
5. A system according to claim 3, wherein the data representing the
location of the plurality of communication device is determined by
utilizing satellite signals received from a navigation system
.[.such as.]..Iadd., wherein the navigation system comprises one of
.Iaddend.Global Positioning System (GPS).[.or.]..Iadd.,
.Iaddend.Galileo.Iadd., .Iaddend.or GLONASS.
6. A system according to claim 1, wherein the communication network
is a cellular or mobile or wireless network.
7. A system according to claim 1, wherein the plurality of
communication devices are selected from the group: mobile
telephones; cellular telephones; wireless telephones; portable
computers; PDAs; WAN-LAN gateways or APs (Access Points); WAN-PAN
gateways or APs; LAN-PAN gateways or APs.
8. A system according to claim 1, wherein the communication between
the tag and the plurality of communication devices complies with a
communication standards selected from the group: Bluetooth; WiFi;
WiMax; HomeRF.
9. A system according to claim 1, wherein the data representing the
location of the plurality of communication devices is determined
either by the communication network or by the plurality of
communication devices or by a combination thereof.
10. A system according to claim 1, wherein the communication
between said tags and said plurality of communication devices is
established using unlicensed frequency band.
11. A system according to claim 1, wherein the time at which the
unique data is transmitted to said plurality of communication
devices, is recorded by the plurality of communication devices.
12. A system according to claim 1, wherein whenever the plurality
of communication device receives a new data signal and its
corresponding memory is full, the oldest data stored in said memory
is overwritten by said new data.
13. A system according to claim 1, wherein the utilization of said
plurality of communication devices for locating said tags does not
require the subscriber permission or wherein a subscriber that owns
or operates said plurality of communication device permits
utilizing said plurality of communication devices for locating said
tags.
14. A system according to claim 1, wherein the data representation
of the location of said tag is converted from geographic
coordinates to a corresponding physical address.
15. A system according to claim 1, wherein the initiation to
determine location of said tag comes from said tag and/or said
plurality of communication devices and/or said control center,
and/or an input to said tag and/or an input to said plurality of
communication devices and/or an input to said control center.
16. A system according to claim 1, wherein the communication
between said tag and said plurality of communication devices is
enabled during a specific period of time and/or when said plurality
of communication devices and/or said tag are part of a
predetermined sub group.
17. A system according to claim 1, wherein the location accuracy of
the tag is refined by obtaining a distance and/or a direction
information related to the relative position between the tag and
the plurality of communication devices.
18. A system according to claim 1, wherein the roaming object is
selected from the following group: persons; animals; vehicles;
goods; mailed/delivered items; weapons; ammunition.
19. A system according to claim 1, wherein the location accuracy of
the tag is refined by extrapolation, when the transmission of the
unique data from the tag to the plurality of communication devices
and the determination of the location of the plurality of
communication devices are performed at different times.
20. A system according to claim 1, wherein the control center is a
communication device.
21. A system according to claim 1, wherein said tag and/or said
plurality of communication devices relay/retransmit data that
arrives from other tags and/or said plurality of communication
devices.
.Iadd.22. A communication system comprising: a communication device
including: a first processor configured to determine a location of
the communication device; and a first transceiver operatively
coupled to the first processor and configured to establish a short
range wireless communication link with a tag; and transmit the
location of the communication device and identity data
corresponding to the tag to a control center; the tag, wherein the
tag is associated with a roaming object, and further wherein the
tag includes: a second processor; a short-range wireless
transceiver operatively coupled to the second processor and
configured to communicate with the communication device; a memory
operatively coupled to the second processor and configured to store
the identity data corresponding to the tag; and control circuitry
operatively coupled to the second processor and configured to
control communication between the tag and the communication device;
and the control center, wherein the control center is configured
to: communicate with the communication device to determine whether
the communication device is in range of the tag, wherein the
determination is based at least in part on the identity data
corresponding to the tag; and determine, if the communication
device is in range of the tag, a geographical location of the tag
based at least in part on the location of the communication
device..Iaddend.
.Iadd.23. The communication system of claim 22, wherein the
communication device further comprises a global positioning system
(GPS) receiver for use in determining the location of the
communication device..Iaddend.
.Iadd.24. The communication system of claim 22, wherein the short
range wireless communication link is established over an unlicensed
frequency band..Iaddend.
.Iadd.25. The communication system of claim 22, wherein the first
processor is further configured to identify a time at which the
identity data is received by the communication device from the
tag..Iaddend.
.Iadd.26. The communication system of claim 25, wherein the first
transceiver is further configured to transmit the time at which the
identity data is received to the control center..Iaddend.
.Iadd.27. The communication system of claim 22, wherein the control
center is further configured to convert geographic coordinates of
the tag to a corresponding physical address..Iaddend.
.Iadd.28. The communication system of claim 22, wherein a decision
to determine the geographic location of the tag originates from the
control center or from an input to the control center..Iaddend.
.Iadd.29. The communication system of claim 22, wherein the short
range wireless communication link between the tag and the
communication device is enabled during one or more specific periods
of time..Iaddend.
.Iadd.30. The communication system of claim 22, wherein the
communication device and the tag are both members of a sub-group,
and further wherein the tag is configured to communicate only with
other members of the sub-group..Iaddend.
.Iadd.31. The communication system of claim 22, wherein the
geographic location of the tag is further based at least in part on
a distance between the tag and the communication
device..Iaddend.
.Iadd.32. The communication system of claim 22, wherein the
geographic location of the tag is further based at least in part on
a relative position of the tag with respect to the communication
device..Iaddend.
.Iadd.33. The communication system of claim 22, wherein the tag is
associated with a roaming object, and further wherein the roaming
object comprises a person, an animal, a vehicle, a weapon, or
mail..Iaddend.
.Iadd.34. A tag comprising: control circuitry configured to
activate an active mode in response to a trigger signal; a
transceiver operatively coupled to the control circuitry and
configured to, in response to activation of the active mode,
transmit identity data associated with the tag or an object to
which the tag is attached to a cellular telephone in a vicinity of
the tag, wherein, in response to receipt of the identity data, the
cellular telephone is configured to determine a location of the
cellular telephone and provide the location and the identity data
to a control center, and further wherein the identity data is
transmitted to the cellular telephone through one or more
short-range wireless signals; and a memory operatively coupled to
the control circuitry and configured to store the identity
data..Iaddend.
.Iadd.35. The tag of claim 34, further comprising a timer, wherein
the trigger signal originates at the tag based on expiration of the
timer..Iaddend.
.Iadd.36. The tag of claim 34, wherein the trigger signal is
received from an alarm system..Iaddend.
.Iadd.37. The tag of claim 34, wherein the control circuitry is
further configured to establish a short range wireless
communication link with the cellular telephone..Iaddend.
.Iadd.38. A communication device comprising: a transceiver
configured to receive a request to locate a tag from a control
center, wherein the request originates from the control center and
includes identity data corresponding to the tag; and a processor
operatively coupled to the transceiver and configured to establish,
in response to the request, a short range wireless communication
link with the tag if the tag is in range of the communication
device; determine a location of the communication device; and cause
the transceiver to provide the location of the communication device
to the control center if the tag is in range of the communication
device..Iaddend.
.Iadd.39. The communication device of claim 38, further comprising
a global positioning system (GPS) receiver for use in determining
the location of the communication device..Iaddend.
.Iadd.40. The communication device of claim 38, wherein the short
range wireless communication link between the tag and the
communication device is enabled during one or more specific periods
of time..Iaddend.
.Iadd.41. The communication device of claim 38, wherein the
processor is further configured to identify a time at which the
short-range wireless communication link is established with the
tag..Iaddend.
.Iadd.42. The communication device of claim 41, wherein the
transceiver is further configured to transmit the time to the
control center..Iaddend.
.Iadd.43. A method comprising: receiving identity data at a third
communication device from a first communication device, wherein the
identity data is associated with a tag or an object to which the
tag is attached, and further wherein the identity data originates
from the tag and is transmitted from the tag to the first
communication device in response to a trigger signal; receiving, at
the third communication device, a location of the first
communication device from the first communication device;
determining, at the third communication device, a geographic
location of the tag based at least in part on the identity data and
the location; and providing the geographic location of the tag to a
second communication device from the third communication device for
use by the second communication device in locating the
tag..Iaddend.
.Iadd.44. The method of claim 43, wherein the trigger signal
originates at the tag based on expiration of a timer..Iaddend.
.Iadd.45. The method of claim 43, wherein the geographic location
of the tag is further based at least in part on a distance between
the tag and the first communication device..Iaddend.
.Iadd.46. The method of claim 43, wherein the geographic location
of the tag is further based at least in part on a relative position
of the tag with respect to the first communication
device..Iaddend.
.Iadd.47. A method comprising: receiving a request to locate a tag
from a control center, wherein the request originates from the
control center and includes identity data corresponding to the tag;
establishing, in response to the request, a short range wireless
communication link with the tag if the tag is in range of a
communication device; determining a location of the communication
device; and providing the location of the communication device to
the control center if the tag is in range of the communication
device..Iaddend.
.Iadd.48. The method of claim 47, further comprising providing the
identity data to the control center..Iaddend.
.Iadd.49. The method of claim 47, further comprising: determining a
distance between the tag and the first communication device; and
providing the distance to the control center..Iaddend.
.Iadd.50. The method of claim 47, further comprising providing a
time at which the short-range wireless communication link is
established to the control center..Iaddend.
.Iadd.51. A method comprising: activating an active mode in
response to a trigger signal at a tag; establishing, in response to
activation of the active mode, a short-range communication link
with a communication device in a vicinity of the tag; and
transmitting identity data associated with the tag to the
communication device, wherein, in response to receipt of the
identity data, the communication device is configured to determine
a location of the communication device and provide the location and
the identity data to a control center..Iaddend.
.Iadd.52. The method of claim 51, wherein the trigger signal
originates at the tag based on expiration of a timer..Iaddend.
.Iadd.53. The method of claim 51, wherein the trigger signal is
received by the tag from an alarm system..Iaddend.
.Iadd.54. The communication system of claim 22, wherein the control
circuitry causes the tag to enter an inactive mode to conserve
power when the tag is not communicating with the communication
device..Iaddend.
.Iadd.55. The tag of claim 34, wherein the control circuitry causes
the tag to enter an inactive mode to conserve power when the tag is
not communicating with the communication device..Iaddend.
.Iadd.56. The method of claim 51, further comprising entering an
inactive mode to conserve power when the tag is not in
communication with the communication device..Iaddend.
.Iadd.57. A tangible, non-transitory computer-readable medium
having instructions stored thereon, the instructions comprising
instructions for: receiving identity data at a third communication
device from a first communication device, wherein the identity data
is associated with a tag or an object to which the tag is attached,
and further wherein the identity data originates from the tag and
is transmitted from the tag to the first communication device in
response to a trigger signal; receiving, at the third communication
device, a location of the first communication device from the first
communication device; determining, at the third communication
device, a geographic location of the tag based at least in part on
the identity data and the location; and providing the geographic
location of the tag to a second communication device from the third
communication device for use by the second communication device in
locating the tag..Iaddend.
.Iadd.58. The computer-readable medium of claim 57, wherein the
trigger signal originates at the tag based on expiration of a
timer..Iaddend.
.Iadd.59. The computer-readable medium of claim 57, wherein the
geographic location of the tag is further based at least in part on
a distance between the tag and the first communication
device..Iaddend.
.Iadd.60. The computer-readable medium of claim 57, wherein the
geographic location of the tag is further based at least in part on
a relative position of the tag with respect to the first
communication device..Iaddend.
.Iadd.61. A tangible, non-transitory computer-readable medium
having instructions stored thereon, the instructions comprising
instructions for: receiving a request to locate a tag from a
control center, wherein the request originates from the control
center and includes identity data corresponding to the tag;
establishing, in response to the request, a short range wireless
communication link with the tag if the tag is in range of a
communication device; determining a location of the communication
device; and providing the location of the communication device to
the control center if the tag is in range of the communication
device..Iaddend.
.Iadd.62. The computer-readable medium of claim 61, further
comprising instructions for providing the identity data to the
control center..Iaddend.
.Iadd.63. The computer-readable medium of claim 61, further
comprising instructions for: determining a distance between the tag
and the first communication device; and providing the distance to
the control center..Iaddend.
.Iadd.64. The computer-readable medium of claim 61, further
comprising instructions for providing a time at which the
short-range wireless communication link is established to the
control center..Iaddend.
.Iadd.65. A tangible, non-transitory computer-readable medium
having instructions stored thereon, the instructions comprising
instructions for: activating an active mode in response to a
trigger signal at a tag; establishing, in response to activation of
the active mode, a short-range communication link with a
communication device in a vicinity of the tag; and transmitting
identity data associated with the tag to the communication device,
wherein, in response to receipt of the identity data, the
communication device is configured to determine a location of the
communication device and provide the location and the identity data
to a control center..Iaddend.
.Iadd.66. The computer-readable medium of claim 65, wherein the
trigger signal originates at the tag based on expiration of a
timer..Iaddend.
.Iadd.67. The computer-readable medium of claim 65, wherein the
trigger steal is received by the tag from an alarm
system..Iaddend.
.Iadd.68. The computer-readable medium of claim 65, further
comprising instructions for entering an inactive mode to conserve
power when the tag is not in communication with the communication
device..Iaddend.
Description
.Iadd.CROSS-REFERENCE TO RELATED APPLICATIONS.Iaddend.
.Iadd.This application is a Reissue Application of U.S. patent
application Ser. No. 10/710,379, filed Jul. 6, 2004, now U.S. Pat.
No. 7,155,238, granted Dec. 26, 2006..Iaddend.
BACKGROUND OF INVENTION
Moveable or roaming objects, including persons and animals, may be
required, for various reasons, to be located by a third party or
system, from a remote location. Examples for such needs may include
persons in distress, particularly children, adults or handicapped
people that require assistance, lost pets, stolen vehicles to be
restored and transported assets to be tracked on their way.
A conventional technique for locating roaming objects from remote
location(s), involves utilizing wireless devices that are attached
to these objects, in advance, and a radio network capable of
communicating with these wireless devices and transmitting signals
from which their location may be interpreted by a remote receiver.
The communication channels in such network may comprise wireless
and wireline elements, and the components of the network/system may
be terrestrial, extraterrestrial airborne and space-borne. In some
cases, this wireless location network serves also for
telecommunications ("telecom") of generic information, such as
voice, data or video signals.
One particular framework for wireless location is promoted by the
U.S. Federal Communications Commission (FCC), in order to locate
cellular handsets operated by people in emergency situations. This
plan is known as the "E911" act, an augmentation to the "911"
service (a service that is provided in the U.S.A.), designed to
handle distress calls, either from fixed or from mobile phones.
Currently, the 911 service is capable of locating fixed phones,
while in the future it is planed to be capable of locating mobile
phones as well, for the same purpose of emergency assistance. For
further information, see: http://www.fcc.gov/e911/ and also CFR
(Code of Federal Regulations) Title 47, Volume 2, Parts 20 to 39,
[Revised as of Oct. 1, 1999] PART 20-COMMERCIAL MOBILE RADIO
SERVICES--Sec. 20.18-911 Service.
Several methods are known in the art for wirelessly determining the
location of roaming devices. One known group of methods is based on
dedicated Telecom networks or dedicated segments of a Telecom
network. These methods are usually referred to as "network based",
i.e., they employ a wide area array of antennas and transceivers
coupled together, such that a roaming wireless device can be
located whenever being contained within the area that is covered by
said antennas. Such methods usually require minimal modifications
in the communication devices the location of which is to be
determined by this network.
The latter methods are further subdivided into "sub-methods". One
such sub-method measures the Angle of Arrival (AOA) of a signal
emitted by a roaming wireless device, received at least at two of
the network's antennas. Knowing the location of these antennas and
the AOA of the received signal, the location of the roaming
wireless device can be derived by trigonometric calculations.
Another sub-method measures the Time of Arrival (TOA) of a signal
emitted by the roaming wireless device, received at least at three
of the network's antennas. Knowing the location of these antennas
and the TOA of the received signal, the location of the roaming
wireless device can be derived. The TOA method is based on
spherical radio navigation, i.e., the geometric locus of points
having a same range from a fixed point is a sphere surface, the
fixed point of which is its center. In case of TOA, the fixed
points are the receiving network's antennas and the range is
[TOA.times.C] for each receiving antenna, wherein "C" is the
velocity of light or electromagnetic waves. The location of the
roaming device is calculated as one of the two points, defined by
the crossing sector of all three sphere surfaces (the crossing
sector of two spherical surfaces is a circle, and this circle
crosses a third sphere surface at two points). Sometimes, a fourth
antenna is used to remove this ambiguity or to compensate for clock
discrepancies.
The Global Positioning System (GPS), as described hereinafter, is
based on a TOA method as well. In addition, if the roaming device
is known to be essentially on the ground (e.g., mounted in a car),
the earth globe, with proper topography, can be used as an
additional reference "sphere" to refine the TOA calculations. This
approach is especially useful for GPS navigating vessels,
particularly in oceans, where the altitude is constant (i.e., is
the sea level).
One useful variation of TOA is TDOA (Time Difference Of Arrival),
where a difference in time of arrival of one transmitted signal is
measured at two different receivers. This method was originally
developed for radio navigation systems as LORAN-C and OMEGA,
however slightly different--the time difference between two
signals, transmitted synchronously from two remote sites, is
measured at the LORAN-C or OMEGA receiver. Both variations of TDOA
are based on hyperbolic radio navigation, i.e., the geometric locus
of points that have a common difference in range from two fixed
points is a hyperbola. In TDOA, as in TOA and GPS, time
measurements provide range estimation ("pseudorange"), since
[time.times.C=range]. In order to determine the actual location of
a moveable device by TDOA, at least three reference antennas are
required, to provide two hyperbolas that cross each other at one
point, being the required actual location. For further information,
see the book "AMERICAN PRACTICAL NAVIGATOR" by N. Bowditch, Pub.
No. 9, volume 1, part eight (ELECTRONICS AND NAVIGATION), published
by the DEFENSE MAPPING AGENCY HYDROGRAPHIC CENTER, USA DoD.
An exemplary system that utilizes TDOA and AOA methods for location
determination is Sigma-5000 TDOA-AOA, which has been developed by
"SigmaOne" (Rehovot science park, Israel). See also
www.sigma-1.com/index_flash.htm. However, network-based methods for
wireless location determination, require a dedicated infrastructure
of antennas and transceivers, which is costly and takes substantial
time to deploy.
Another known group of methods for wirelessly determining the
location of roaming devices is based on self-location capabilities
incorporated in the Telecom end unit (e.g., a wireless "handset"
device). The unit location can be measured at the unit itself by
utilizing corresponding sensors, embedded in the unit. Then, a
signal representing this location is transmitted wirelessly over
the network to a place where it is required. These methods are
usually referred to as "handset based".
One handset based sub-method uses a GPS receiver embedded in a
mobile Telecom unit. A GPS receiver measures its position by
processing signals received from navigation satellites, launched by
the U.S. Department Of Defense (DOD). Signals from at least 4
satellites are required to reach the antenna of the GPS receiver,
in order to allow calculating its location. GPS technology is based
on a TOA method, however slightly different--multiple transmissions
are received at a single receiver. Due to clock discrepancies
between satellites and GPS receivers, at least four in-view
satellites are required in order to determine a GPS position (only
three are required if the altitude is known, as in case of ocean
navigation).
The GPS geographic position is expressed in latitude and longitude
coordinates, in addition to altitude above sea level. GPS uses the
World Geodetic System defined in 1984 ("WGS-84"). Though there are
about 100 different local grids in use by cartographers in
different parts of the world, in addition to different map
projections, WGS-84 coordinates can be converted to any other
reference grid.
GPS receivers have two different versions, military (P code) and
civilian (C/A code). After the removal of the intentional
degradation--"Selective Availability" (S/A) from the GPS signals, a
C/A code GPS receiver can typically achieve an accuracy of better
than 50 meters (rms). This position, practically expressed in about
10 bytes, can easily be transmitted over the network, by the same
Telecom unit that contains the GPS receiver, to a place where it is
required. For further information one might reference the web site
www.trimble.com/gps/.
Examples for such prior art technologies are products of "SiRF"
(California, U.S.A.) Particularly, those following SiRF's
handset-based SiRFstar TM architectures SiRFstarI and SiRFstarII.
For further information one might reference the web site
www.sirf.com/.
Other prior art systems introduce capabilities for short-range
wireless connectivity in cellular handsets and mobile computers.
This type of connectivity is normally required for forming wLANs
(wireless Local Area Networks) or wPANs (wireless Personal Area
Networks), while the primary cellular network is usually referred
as wWAN (wireless Wide Area Network). Usually, wLANs support faster
data rates and larger transmission distances than wPANs. The
typical state of the art of a wLAN transmitter range is about 500
meters, while a wPAN transmitter range is typically 10-100 meters.
One specific standard for wLANs is IEEE 802. 11. WPANs typically
replace short communication cables, supporting wireless handset
peripherals, such as a keyboard, screen/display, headset, speaker
and microphone, or data communications between a cellular handset
and a Personal Digital Assistance (PDA), e.g., for updating a
telephone list. One of the standards for short-range wireless
connectivity (wPAN) is "Bluetooth" ("BT"), originally defined by
Ericsson, Sweden, which utilizes wireless digital connectivity over
the 2.4 GHz unlicensed band, using frequency hopping spread
spectrum modulation, at 721 Kbps (revision 1.1). No line of sight
is required between a transmitter and a receiver and the typical
communication range is 10-100 meters, depending on which
transmission class, chosen from one of the three available classes
of maximum RF power, is in use: 1 mw (class 3), 10 mw (class 2) or
100 mw (class 1). Several schemes of power saving, error
correction, authentication and encryption are included in the BT
standard. Each BT device is assigned a unique 48 bits ID. BT
devices form ad hoc "piconets", even among devices that have no
previous coordination, with up to 8 peer devices, one of which is
considered a master device. Basically, the unit that initiates the
connection is defined as master of the piconet. However, these
roles can be switched over. For further details, one might
reference the web site www.Bluetooth.com.
Currently, state of the art of BT technology allows the
implementation of almost a full BT digital radio, including RF and
baseband circuitry, in a smaller than 10.times.10 mm chip size. For
example, see Cambridge Silicon Radio (CSR) "bcO1" chip, Philips
"PCD 87750" or Ericsson's "PBA 3131" radio chip.
Since BT chips are also low power consumers, typically 100 mw in
active mode (receive or transmit--class 3) and about 1 mw in
standby mode ("page scan" or "inquiry scan" or "park"), they fit
battery operation, and particularly designed to be embedded in
cellular handsets and portable computers.
Several models of BT-enabled cellular handsets have already been
introduced to the market, as "Ericsson R520", "Nokia 6310" and
"Motorola Timeport 270c".
U.S. Pat. No. 6,246,376 discloses a method for refining GPS
positioning by data provided over a Bluetooth (BT) connection, or
by the BT received signal. This method might be utilized, for
example, for measuring azimuth. A cellular handset is utilized,
which includes a GPS receiver, a BT radio and additional navigation
circuitry, for example a "north-finder"/compass. Such handset
calculates its position by GPS, while utilizing also the received
BT data signal. However, handset-based wireless location devices
are expensive, consume a considerable amount of power, are
relatively big in size and radiate substantial RF power.
There is another group of known methods for wireless location,
which is based on a combination of network and handset based
capabilities. Such methods are usually referred to as "hybrid
solutions". For example, WO/0150151 discloses a way for locating
cellular handsets that include a GPS receiver. The data received by
the GPS receiver is enhanced, particularly when satellites are
blocked, by providing positioning data by nearby Bluetooth base
stations.
Many wireless location systems are deployed and expected to be
further deployed in the future, particularly systems to locate
cellular handsets over cellular networks. The urge for the
deployment is driven by Federal and state regulations, as well as
by the need for location based commercial services.
All the methods described above have not yet provided satisfactory
solutions to the problem of wirelessly determining the location of
small, inexpensive and low power roaming devices, over a wide area,
without requiring a dedicated infrastructure.
It is an object of the present invention to provide a system and
method for wirelessly determining the location of devices, by
leveraging the location determining capability of conventional
positioning systems, such as those used to locate cellular
handsets, to determine the location of a different type of wireless
devices, smaller and cheaper, by wirelessly linking between both
types of devices.
It is another object of the present invention to provide a system
and a method for wirelessly determining the location of devices, by
utilizing existing and widespread active Telecom units
("communication devices"), such as mobile telephones, to be used as
gateways or access points for a second tier of wireless devices,
forming a large and dense mobile communication infrastructure for
said wireless devices, over a wide area.
It is still another object of the present invention to provide a
system and a method for wirelessly determining the location of
devices, by utilizing the existing infrastructure of a
communication network having positioning capabilities.
It is yet another object of the present invention to provide a
system and method for wirelessly determining the location of
roaming objects in an area covered by a Telecom network, by using
location determining devices which are small, inexpensive and
having low power consumption.
It is yet another object of the present invention to provide a
system and method for wirelessly determining the location of
roaming objects in an area covered by a Telecom network, by using
location determining devices, which emit low RF radiation and
reduce potential risk to their carriers.
It is yet another object of the present invention to provide a
system and method for wirelessly determining the location of
roaming objects in an area covered by a Telecom network, by using
location determining devices which do not require human
interface/intervention.
It is yet another object of the present invention to provide a
system and method for wirelessly determining the location of
roaming devices, in an area covered by a Telecom network, that
minimizes the amount of data that should be transmitted over the
Telecom network.
Other objects and advantages of the invention will become apparent
as the description proceeds.
SUMMARY OF INVENTION
The invention is directed to a system for determining the
geographical location of roaming objects (such as persons, animals,
vehicles, goods, mailed/delivered items ammunition and weapons),
that comprises: a) a communication network, consisting of at least
a plurality of communication devices, each of which having wireless
and/or wireline communication capability with other communication
devices over said communication network, wherein at least one of
said communication devices is mobile (e.g. a cellular/mobile
network), and of establishing wireless communication (e.g.,
according to Bluetooth or IEEE 802.11) with other wireless devices
in the vicinity of said communication device, said communication
network being capable of obtaining the geographical location of
said communication devices and transmitting data representing said
geographical location to a destination, over said communication
network; b) a wireless tag, attached to each of said roaming
objects, being a wireless device, in which a unique data is stored,
said tag being capable of communicating with one or more
communication devices and transmitting said unique data to said
destination through said communication device(s) and over said
communication network; and c) a control center (which may be a
communication device) being, or linked to, said destination, for
receiving said unique data from said tag and for using said unique
data and the location of the communication device, through which
said unique data is transmitted, for determining/displaying or
forwarding the geographical location of said tag.
Preferably, each communication device comprises: a) a short-range
wireless transceiver for communicating with one or more wireless
tag(s) being in the vicinity of the communication device; b) a
memory for storing multiple unique data transmissions from the same
tag, and/or unique data transmissions from different tags; c)
circuitry for transmitting the data to the destination, over the
communication network; and d) a control circuitry for controlling
the communication between the communication device and tags and the
transmission of the unique data over the communication network.
Each communication device may further comprise location determining
circuitry for determining the geographical location of the
communication device (e.g. a GPS receiver) and circuitry for
transmitting data representing the location to the destination.
Preferably, the tag comprises: a) a short-range wireless
transceiver for communicating with one or more communication
devices being in the vicinity of the tag; b) a memory for storing
the unique data; and c) a control circuitry for controlling the
communication between the tag and the communication device.
The data representing the location of the communication device may
be determined either by the wireless communication network or by
the communication device or by a combination thereof, and may be
affiliated into the control signals that are transmitted from the
communication device over the communication network, or transmitted
as a user's message (e.g., Short Message Service [SMS] or General
Packet Radio Services [GPRS]).
Preferably, the communication between tags and communication
devices is established using unlicensed frequency band, around 2.4
GHz and power of transmissions, which is less than 100 mW. The tag
preferably operates in its power save inactive mode, when
communication is not required with communication device(s).
The unique data may be related to the tag's ID and/or to the time
at which the unique data is transmitted. The time, at which the
unique data is transmitted to communication devices, may be
recorded by the communication devices. Whenever a new data signal
is received by the communication device and its corresponding
memory is full, the oldest data stored in the memory may be
over-written by the new data.
Preferably, the control center interrogates the communication
devices for the presence of tags in their vicinity, according to
the tag ID, the time, the geographical region, or the ID of
communication devices, or any combination thereof.
In one aspect, a subscriber that owns or operates a communication
device permits utilizing the communication device for locating
tags. The subscriber may be paid or otherwise benefit from
utilizing his/her communication device for locating tags.
Alternatively, communication devices will perform these functions
as part of the basic mobile system and not require subscriber
permission.
The data representation of the location of tag(s) may be converted
from geographic coordinates to a corresponding physical
address.
The wireless communication between the tag and the communication
device may be initiated by each one of them, or by the control
center, for determining a tag location. Alternatively, the location
process may be initiated by a signal that is input to the tag by a
device that is external to the communication network.
Communication between the tag and the communication device may be
enabled only during specific periods of time, and/or when the
communication device and/or the tag are part of a predetermined sub
group.
The location accuracy of the tag may be refined by obtaining
distance and/or direction information related to the relative
position between the tag and the communication device, or by
extrapolation, when the transmission of the unique data from the
tag to the communication device and the determination of the
location of the communication device are performed at different
times.
The invention is also directed to a wireless tag, attached to a
roaming object, for determining the geographical location of the
roaming object, the tag being capable of communicating with one or
more communication devices being part of a communication network,
said communication network being capable of obtaining the
geographical location of said communication devices and
transmitting data representing said geographical location to a
destination, over said communication network, said tag being
capable of transmitting, through communication device(s) and over
the communication network, a unique data to a destination, at which
the geographical location of the tag is determined using the unique
data and the location of the communication device, through which
the unique data is transmitted, wherein at least one of the
communication devices is mobile.
The invention is also directed to a communication device being part
of a communication network that comprises other communication
devices, said communication network being capable of obtaining the
geographical location of said communication devices and
transmitting data representing said geographical location to a
destination, over said communication network, said communication
devices being capable of communicating with each other and with the
communication device, for determining the geographical location of
a roaming object by determining the geographical location of a
wireless tag, attached to the roaming object, the communication
device being capable of communicating with the tag and
transmitting, over the communication network, a unique data that is
received from the tag to a destination, at which the geographical
location of the tag is determined using the unique data and the
location of the communication device, wherein at least one of the,
or the other communication devices is mobile.
The invention is further directed to a method for determining the
geographical location of roaming objects. A communication network
that consists of at least a plurality of communication devices is
provided, each of which having wireless and/or wireline
communication capability with other communication devices over the
communication network, such that at least one of the communication
devices is mobile, and of establishing wireless communication with
other wireless devices in the vicinity of the communication device,
the communication network being capable of obtaining the
geographical location of the communication devices and transmitting
data representing said geographical location to a destination, over
the communication network. A wireless tag being a wireless device,
in which a unique data is stored, is attached to each of the
roaming objects. The tag is allowed to communicate with one or more
communication devices and to transmit the unique data to the
destination through the communication device(s) and over the
communication network. The unique data from the tag is received in
a control center being, or linked to, the destination and the
geographical location of the tag is determined using the unique
data and the location of the communication device, through which
the unique data is transmitted.
BRIEF DESCRIPTION OF DRAWINGS
The above and other characteristics and advantages of the invention
will be better understood through the following illustrative and
non-limitative detailed description of preferred embodiments
thereof, with reference to the appended drawings, wherein:
FIG. 1 illustrates a general system for determining the location of
roaming devices in an area covered by a communication network
(hereinafter referred to as "Telecom network") according to a
preferred embodiment of the invention;
FIG. 2 illustrates the major components of a communication device
(hereinafter referred to as TU) according to a preferred embodiment
of the invention;
FIG. 2 102b also illustrates the major components of a tag, the
wireless locatable unit, according to a preferred embodiment;
and
FIG. 3 illustrates in more details the communication network, shown
in FIG. 1, according to a preferred embodiment of the
invention.
DETAILED DESCRIPTION
FIG. 1 is a block diagram of a system for determining the
geographical location of roaming objects, in an area covered by a
communication network (hereinafter referred to as "Telecom
network"), according to a preferred embodiment of the invention.
The system consists of at least one wireless tag 101, attached to a
roaming object, in which a unique data is stored, a plurality of
communication devices (hereinafter referred to as TUs, only one TU:
102 is shown), a wireless communication network 103 and a control
center (i.e., LS: 104). Whenever required, the data stored in
wireless tag 101 is transmitted to a destination (which may be, or
may be linked to, control center 104),, trough TU 102 and over
communication network 103. TU 102 and tag 101 obtain a short-range
wireless transceiver (shown in FIG. 2), for communicating with each
other. Preferably, communication network 103 is a cellular/mobile
phone network and TU 102 is a cellular phone handset with an
embedded GPS receiver and embedded Bluetooth ("BT") short-range
radio (shown in FIG. 102). Alternatively, TU 102 may be a mobile
telephone, a portable computer, an Access Point/gateway or a PDA.
Wireless tag 101 is essentially a BT-based radio (as shown in FIG.
2 102b) powered by a power supply, preferably a small-sized battery
(not shown). Alternatively, the communication between tag 101 and
TU 102 may comply with communication standard IEEE 802.11 or, WiFi,
WiMax or HomeRF. Control center LS 104 is a server computer,
connected to communication network 103. The geographical location
of TU 102 is determined by utilizing conventional
technologies/methods (e.g., GPS). Therefore, the location of
wireless tag 101, when in the vicinity of TU 102 and when a
short-range wireless connectivity is achieved between them, can be
determined. The data representative of the location of TU 102 may
be determined by communication network 103, by TU 102, or by a
combination thereof.
Attempts to establish a wireless connection between a wireless tag
and a TU may be carried out either by the tag or by the TU; i.e., a
tag may transmit inquiring/paging/seeking signals in order to
interrogate for the presence of nearby TUs, and vice versa.
However, in order to facilitate the understanding of the operation
of the system, it is assumed that tags, such as tag 101, try to
establish a wireless connection with TUs, such as TU 102,
periodically, and TUs continuously monitor, and respond to, such
inquiries. Since the nature of the communication between a tag and
a TU is of short range, and assuming that tag 101 and TU 102 are
close enough to each other for a sufficient period of time, a
wireless link 105 is established and digital data is transmitted
from tag 101 to TU 102. Preferably, tag-TU wireless connection 105
compiles with the Bluetooth standard, power class 2, typically
covering a distance of 10 meters. Therefore, tag 101 must be
located essentially within this range from TU 102, for several
seconds, in order to allow successful determination of its
location. Communication link 106 may be either wireline or
wireless, or a combination thereof, for allowing communication with
other components of the network, such as other TUs (i.e. similar to
TU 102) and LS 104. Preferably, communication link 105 and
communication link 106 utilize different frequency bands in order
to avoid communication interference. Preferably, no prior knowledge
of each other or synchronization ("pairing") is required between
tags and TUs for establishing communication link 105, as long as
they both comply with the same communication standard (e.g. BT
standard), which supports ad hoc connections. In other words, as
long as some commercial and procedural issues are set (perhaps a
specific profile for location service is defined in future versions
of BT standard) link 105 could be established between a tag that
roams around the world (e.g. embedded in a letter), and BT-enabled
cellular devices that are encountered on its way. Communication
link 105 may be based on unlicensed frequency band, due to its
short-range nature, particularly, on a frequency band around 2.4
GHz.
According to one aspect of the invention, tag 101 normally remains
in a "power-save inactive" (i.e. "Standby") mode while no
communication is required with TUs. However, a corresponding
trigger signal (not shown) may switch it to active mode, to enable
establishing BT connection 105 with any TU 102 in the vicinity of
tag 101. The triggering signal may be prompted inside the tag, by a
timer contained within the tag, or can be initiated from an
external source, such as an alarm system. Once link 105 is
established, the tag's ID is transmitted to the TU, with other
optional data, such as the tag's battery status. Tag 101 remains in
its active mode for a certain period of time, trying to establish a
connection as many as N times, and, then, switches back to
power-save mode. This policy is carried out in order to save the
tag's battery power, but also to save "airtime" over the Telecom
network. There is a trade-off in determining the parameter N: a
high value increases the probability to determine the tag's
location, but a low value saves tag's and TU's power and airtime
over the network. At the TU, the tag's report may be recorded in a
memory or storage array, or immediately relayed to LS 104. TU is
preferably a cellular handset featured with a GPS receiver, so the
handset's position at the time that the tag reported its ID is
monitored and the control center that receives both the tag's ID
and nearby TU location, can report the tag's location.
According to the preferred embodiment of the invention, LS 104 is a
server allowing to locate tags of interest. Upon receiving a
request from a client to locate a specific tag, at least one
parameter from the group of {Tag ID; TIME; Geographical Region; TU
ID} is used in the interrogation message/signal that is transmitted
over the network, seeking TUs that are (or recently were, or will
be) in contact with tags, according to said input parameters. The
corresponding TUs transmit back the relevant data/records, to LS
104, then LS 104 reports to the client the results of this
interrogation i.e., the current, or the last known, location of the
tag, including the time that corresponds to this location. LS
server 104 retrieves the tag's geographic coordinates (i.e.,
latitude and longitude) and using proper software
(GIS--Geographical Information System) and digital maps, convert
geographic coordinates into a corresponding physical address, being
more friendly to the client.
FIG. 2 illustrates the building blocks of TU 102 (see FIG. 1). TU
102 comprises a cellular handset 102c, into which GPS receiver 102a
and basic BT radio transceiver 102b are integrated, according to
the preferred embodiment of the invention. GPS receiver 102a allows
determining the location of TU 102, and BT radio 102b is a
short-range radio that is utilized as a radio interface between
cellular handset 102c and a nearby tag (not shown, but is
illustrated in FIG. 2 102b) for allowing receiving a corresponding
data signal from the nearby tag. The content of the data signal is
related to the ID number/code of the tag and, optionally, to
additional data, such as an input from an external alarm system
(not shown).
Cellular handset 102c plus BT radio 102b form a BT-enabled cellular
phone, which is implemented, for example, in the following
commercial devices: "Ericsson R520", "Nokia 6310" and "Motorola
Timeport 270c". In order to implement a TU according to the present
invention, a GPS receiver should be added to the BT-enabled phone,
such as 102a. FIG. 2 depicts a specific GPS module: GPS-MS1E, a
product of u-blox from Switzerland. The GPS-MS1E module is based on
the set of electronic chips SiRFstar/LX.TM. made by SiRF from
U.S.A.
Alternatively, OEM GPS receiver 102a can be from Trimble USA (e.g.
"Lassen LP GPS" or "SVeeEight Plus GPS.TM. module"--see
http://www.trimble.com/oem.html) or u-blox from Switzerland (e.g.
GPS-PS1E or GPS-MS1E, see
http://www.u-blox.ch/gps/gps-ps1e/index.html) or SiRF USA (e.g.
SiRFstarI or SiRFstarII, see
http://www.sirf.com/products.html).
Preferably, the internal interface between the circuitry of handset
102c and GPS receiver 102a is an RS-232 interface. However any
other serial or parallel interface can be utilized.
Another option is utilizing a TU unit that is based on a cellular
handset, which already includes an original "built-in" GPS
receiver, such as made by SiRF USA (e.g. SiRFstarI or SiRFstarII,
see http://www.sirf.com/products.html), and add a BT radio. The
embedded BT radio is, for example, a CSRs BC01M2 module. In this
option, the additional BT module may be preferably interfaced over
a serial RS-232 link, or any other serial or parallel
interface.
It is assumed that the CPU of handset 102c is capable of
controlling BT radio 102b and GPS receiver 102a, in addition to its
original tasks as a cellular phone. In order to carry out its new
tasks, a proper software module is affiliated into handset 102c;
i.e., into the integrated TU, to enable a position fix by GPS 102a,
as well as the communication with nearby tag(s), through BT radio
102b.
Whenever BT radio 102b receives a data signal from a nearby tag
(not shown), the corresponding data is temporarily stored in Flash
memory 201, or, alternatively, in a different memory (not shown)
that is embedded in the integrated cellular handset 102.
Still referring to FIG. 2, Bluetooth communication means 102b is
embedded into tag 101 (shown in FIG. 1), and a similar one into TU
102, for interfacing cell phone handset 102c, according to a
preferred embodiment of the invention. BT 102b is based on an
Integrated Circuit (IC) manufactured by Cambridge Silicon Radio
(CSR)--bc01 or bc01M or bc02, a 2.4 GHz antenna and powered by a
3-volts source, possibly a battery. Normally, bc01 chips require an
external Erasable Programmable Read Only Memory (EPROM), preferably
Flash EPROM, while bc01M or bc02 might utilize an optional EEPROM.
One may refer to the web site http://www.csr.com/ for further
information. A more general view can be found at
http://www.bluetooth.com/, including a list of alternative
products.
FIG. 3 illustrates a general communication network 300, which
comprises a plurality of base stations 301, cellular phone handsets
TU, such as TU 302, a plurality of satellites, such as 303 and
location center (or "Location Server"--LS) 304. Whenever required,
LS 304 launches an interrogation signal by communication path 305
and over network 300, seeking a tag 306 having a specific ID. The
signal is received by TU 302 via either one of base stations 301,
with, or without, utilizing satellite 303.
The principles described hereinabove may be utilized in various
ways. For example, roaming objects may be persons, animals,
vehicles, goods, mailed/delivered items, ammunition and weapons.
Additionally, the communication link between tags and TUs may be
enabled during specific periods of time. It is also possible to
relate to a sub group of tags and/or a sub group of TUs.
According to one aspect of the invention, a client connects, from a
fixed or mobile computer or other I/O device as mobile phone or
PDA, to the Location Server (LS), and inputs a password/code
related to the ID of the tag, the location of which is to be
determined/found. The LS then automatically initiates an
interrogation session by launching/transmitting a corresponding
interrogation signal, and after receiving an answer message from
the corresponding TU, the LS reports the requested tag's location
to the client. According to another approach, clients may call the
LS operator over the phone, asking for locating a specific tag. The
LS operator then initiates an interrogation session and reports
back the interrogation results to the client(s).
According to one aspect of the invention, the trigger for
establishing a communication between the tag and a TU comes from an
external device (e.g. an alarm system or sensor) interfacing the
tag, in order to save the tag's battery power.
According to another embodiment of the invention, the accuracy of
the tag location can be refined by obtaining the distance and/or
direction information related to the relative position between the
tag and the corresponding TUs. If either the TU or the tag can
assess the range or direction to the opposite device by other
methods (e.g. methods for calculating the range between two
BT-based units), this assessment may be processed in order to
refine the tag's location (which otherwise is assessed as the
nearby TU location). An additional refinement can be achieved by
extrapolating the TU's position in case when the transmission from
the tag to the TU and the determination of the location of the TU
are performed at different times.
According to one aspect of the invention, the tag is utilized for
determining the location of a child that was lost, for example, in
an amusing park. In this case, the child wears the tag as a
wristwatch and this tag does not initiate inquiries but
periodically monitors possible interrogation signals. Once the
person that escorted the child suspects that the child is lost,
he/she uses his cellular phone to contact a control center (e.g.,
an LS server), asking for a location service. Upon inputting the ID
of the child's tag, or any other password related unambiguously to
this tag, the control center broadcasts an interrogation signal
over the cellular network, interrogating for this tag.
Consequently, cellular phones try to establish a BT connection with
this specific tag, including phones of other people visiting this
park. Once a connection is established, the child's location is
determined and the control center calls back the child's escort and
reports the child's location, guiding him/her to the child,
preferably assisted by a digital map displayed on his/her mobile
phone.
According to one aspect of the invention, the LS is capable of
directing an interrogation signal to a (selected) specific limited
geographical region(s), wherein a specific tag (the location of
which is to be determined) is expected to be found (e.g. in an
amusing park), thereby avoiding disturbing other parts/areas of the
network to which this specific interrogation session is not
relevant. Failing to find the specific tag in a specific area, the
search for the tag might be selectively extended to other
areas.
According to another aspect of the invention, whenever an intruder
breaks into a vehicle to which a wireless tag is affixed, the
wireless tag is used for detecting the presence and the location of
the intruder by utilizing his own cell phone. In this case, the
car's alarm system integrates a wireless tag. Once the alarm system
detects that the car was been intruded unlawfully, it triggers the
tag, which in turn tries to establish a BT link with a nearby BT
enabled cellular phone. In case that the intruder carries such a
device, the tag transfers to the intruder's phone its ID and a
pre-defined message code that indicates the alarm status. Upon
interpreting the alarm code, the cellular phone transmits the data
to the LS, or to a linked control center, where appropriate
measures are taken. The control center is capable of keeping track
of the location of the car (and of the intruder, while driving the
car). If at some point the intruder leaves the car, his location
can be further tracked after he moves away from the car, while the
car's last known location is recorded at the place where the
intruder deserted it.
According to one aspect of the invention, communication is enabled
when the TU and/or the tag are part of a predetermined sub group.
For example, due to economical and/or security reasons, the army
may wish that tags, attached to military objects , such as weapons,
vehicles and soldiers will respond only to interrogation signals
that are transmitted from its authorized TUs.
According to another aspect of the invention, a "time window/gap"
may be added as a criterion for activating a tag report. For
example, it is supposed that a museum is open to the public at
specific working hours. A wireless tag is affixed to each
object/item that should be protected in the museum. At non-working
hours, tags try to establish a BT link with passing-by cellular
phones, excluding some predefined phones that belong to the museum
staff. These tags are registered in the control center, together
with the cell phone ID numbers of the employees. Thus, whenever a
non-listed BT enabled cellular phone passes by the protected
objects at non-working hours, a proper alarm message is transmitted
by the tag affixed to the object, by the passing-by phone, to the
control center.
According to another aspect of the invention, additional criteria
may be used to trigger a tag's report, as data resulting from
interaction between tags. For example, a wireless tag is utilized
for tracking (valuable) goods as they are transported from one
place to another. Such goods may be gasoline/oil/gas containers,
dangerous and/or precious chemicals, precious stones, diamonds,
money/bonds, weapons, gold/silver/platinum bars, electronic
equipment (e.g., television sets, computers, stereo radio, video
sets) etc. According to this aspect, a wireless tag is affixed to
the vehicle carrying the goods, as well as to each item/good
(wherever possible). As long as the tags attached to the
transported goods detect the vehicle tag, their state is defined as
normal. Once these tags cannot communicate with the vehicle tag,
over BT communication, this may lead to a conclusion that goods
have been stolen, and each tag is triggered to report its status
(and therefore, its location), using any passing-by BT enabled
cellular device as a gateway.
The above examples and description have of course been provided
only for the purpose of illustration, and are not intended to limit
the invention in any way. As will be appreciated by the skilled
person, the invention can be carried out in a great variety of
ways, employing more than one technique from those described above,
such as providing communication capabilities between tags, all
without exceeding the scope of the invention.
* * * * *
References