Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2001-03-29
2004-08-03
Cumming, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C435S009000, C701S001000
Reexamination Certificate
active
06771972
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a distributed search method for finding lost assets.
BACKGROUND OF THE INVENTION
Communication infrastructures suitable for mobile users (in particular, though not exclusively, Public Land Mobile Networks, PLMN, in the form of cellular radio infrastructures) have now become widely adopted. Whilst the primary driver has been mobile telephony, the desire to implement mobile data-based services over these infrastructures, has led to the rapid development of data-capable bearer services across such infrastructures. This has opened up the possibility of many Internet-based services being available to mobile users.
Data-capable bearer services can be provided, for example, by a Short Message Service (SMS), by using a voice traffic circuit for data, or by using specialised data facilities such as provided by GPRS for GSM PLMNs (GPRS—General Packet Radio Service—enables IP (or X.25) packet data to be sent through the PLMN and full details of GPRS can be found in the ETSI, European Telecommunications Standards Institute, GSM 03.60 specification).
A number of technologies also exist for the short range wireless communication of information to and between mobile devices. These technologies include infra-red based technologies and low-power radio technologies (including, in particular, the recent “Bluetooth” short range wireless standard). Depending on the technology implementation, differing types of message propagation will be enabled including asynchronous message broadcast, and multicast and point-to-point duplex connections established after coordination and negotiation between communicating devices.
The increasingly widespread deployment of the foregoing technologies in mobile devices has led to an increased interest in ways of determining the location of mobile devices, primarily with a view either to providing user-location information to emergency services or to enabling the provision of location-aware information services. A number of methods exist for determining the location of a mobile user as represented by an associated mobile equipment. Some of these methods, such as the use of a GPS (global positioning system) system described below relation to
FIG. 1
, result in the user knowing their location thereby enabling them to transmit it to a location-aware service they are interested in receiving; other of the methods, such as the use of a PLMN location server described below in relation to
FIG. 2
, result in the user's location becoming known to a network entity from where it can be supplied directly to a location-aware service (generally only with the consent of the user concerned).
More particularly, on the left-hand side of
FIG. 1
, a mobile entity
11
A is provided with a standard GPS module and is capable of determining the location of entity
11
A by picking up signals from satellites
12
. The entity
11
A can then supply this location when requesting, in request
61
, a location-aware service from service system
40
. The right-hand side of
FIG. 1
depicts, in relation to mobile entity
11
B, two ways in which assistance can be provided to the entity in deriving location from GPS satellites. Firstly, a PLMN
10
can be provided with fixed GPS receivers
13
that each continuously keep track of the satellites
12
visible from the receiver and pass information in messages
63
to local mobile entities
11
B as to where to look for these satellites and estimated signal arrival times; this enables the mobile entities
11
B to substantially reduce acquisition time for the satellites and increase accuracy of measurement. Secondly, as an alternative enhancement, the processing load on the mobile entity
11
B can be reduced and encoded jitter removed using the services of network entity
14
(in or accessible through PLMN
10
). Once the mobile unit
11
B has determined its location, it can pass this information in request
65
when invoking a location-aware service provided by service system
40
.
FIG. 2
depicts two general approaches to location determination from signals present in a cellular radio infrastructure. First, it can be noted that in general both the mobile entity and the network will know the identity of the cell in which the mobile entity currently resides, this information being provided as part of the normal operation of the system. (Although in a system such as GSM, the network may only store current location to a resolution of a collection of cells known as a “location area”, the actual current cell ID will generally be derivable from monitoring the signals exchanged between the BSC
14
and the mobile entity). Beyond current basic cell ID, it is possible to get a more accurate fix by measuring timing and/or directional parameters between the mobile entity and multiple BTSs
15
, these measurement being done either in the network or the mobile entity (see, for example, International Application WO 99/04582 that describes various techniques for effecting location determination in the mobile and WO 99/55114 that describes location determination by the mobile network in response to requests made by location-aware applications to a mobile location center—server—of the mobile network).
The left-hand half of
FIG. 2
depicts the case of location determination being done in the mobile entity
11
C by, for example, making Observed Time Difference (OTD) measurements with respect to signals from BTSs (Base Transceiver Stations)
15
and calculating location using a knowledge of BTS locations. The location data is subsequently appended to a service request
66
sent to service system
40
in respect of a location aware service. The calculation load on mobile entity
110
could be reduced and the need for the mobile to know BTS locations avoided, by having a network entity do some of the work. The right-hand half of
FIG. 2
depicts the case of location determination being done in the network, for example, by making Timing Advance measurements for three BTSs
15
and using these measurements to derive location (this derivation typically being done in a unit associated with BSC, Base Station Controller,
16
). The resultant location data is passed to a location server
17
from where it can be made available to authorised services. When the mobile entity
11
D of
FIG. 5
wishes to invoke a location-aware service available on service system
40
, it sends a request
69
including an authorisation token and its ID (possible embedded in the token) to the service system
40
; the service system then uses the authorisation token to obtain the current location of the mobile entity
11
D from the location server
17
. The service system
40
can be pre-authorised to access the location server
17
.
The possibility of using the locatability of mobile devices to provide security systems has been proposed. Thus U.S. Pat. No. 5,712,679 describes a vehicle security system in which a vehicle is provided with a locatable portable electronic camera which, when triggered by unauthorized activity, takes a picture and stores it with location data; at the same time it sends the picture and location data back to a remote receiver where the location data is displayed on a map display and the picture on a TV display.
It has also been proposed to geographically route messages to mobile devices. The paper “Geographic Addressing, Routing and Resource Discovery with GPS” (Tomasz Imielinski and Julio C. Navas; Computer Science Department, Rutgers, The State University Piscataway, N.J.) describes various geographic routing applications including geographic email, geographic broadcasting, and geographically directed multicasting, for example, to all police cars in a specified area.
It is an object of the present invention to provide a distributed search method for finding lost assets that utilizes certain capabilities of mobile devices equipped both with mobile radio communication means and short-range wireless transceivers.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a method of se
Crouch Simon E.
McDonnell James Thomas Edward
Waters John Deryk
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