GB2484129A

GB2484129A - Communication device stores network information relating to geographic regions in to which the device is deemed likely to move

Info

Publication number: GB2484129A
Application number: GB1016474.7A
Authority: GB
Inventors: Fabrice Zappulla
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2010-09-30
Filing date: 2010-09-30
Publication date: 2012-04-04
Anticipated expiration: 2030-09-30
Also published as: GB201016474D0; GB2484129B

Abstract

A telecommunication system 20 is provided in which communication devices 3-1, 3-2, 3-3 selectively receive and store network information broadcast by a base station 5 over a beacon channel, e.g. cognitive pilot channel (CPC), based on the communication device's current position, speed and heading, and on route data relating to transport routes that are in the vicinity of the communication device 3-1, 3-2, 3-3. The network information relates to specific geographic localities, or meshes 10, and each communication device 3-1, 3-2, 3-3 stores network information from received messages if the network information relates to geographic regions 10 in to which the communication device 3-1, 3-2, 3-3 is deemed likely to move. Thus, the need for a communication device 3-1, 3-2, 3-3 to obtain and store network information from each sequential broadcast they are capable of receiving, which includes a large quantity of redundant information, is avoided.

Description

Communication System The present invention relates to a communications device, an associated method of communicating and software for controlling the communications device. The present invention relates, in particular, to a communications device that may communicate from within, and move between, a plurality of geographic regions.

Modern telecommunications networks comprise a composite radio environment in which a wide variety of telecommunications services are provided and in which a great diversity of radio access technologies and radio interfaces are available. In such an environment it is becoming increasingly important to optimise the use of radio resources to ensure, for example, that the most appropriate technology and frequency are used for a particular service.

In order to improve optimisation of radio resources it has been proposed to provide mobile terminals, and other communication devices in the communication network, with a so called cognitive' capability. This cognitive capability allows the communications devices to adapt to their local radio environment by changing their transmission/reception parameters appropriately to allow efficient communication, whilst avoiding interference with the devices of other users.

In one implementation of this technology a dedicated cognitive pilot' channel (CPC) is provided for broadcasting relevant network information (e.g. operators, radio access technologies, frequency ranges, etc.) local to each mobile terminal to allow that mobile terminal to adapt accordingly. To help achieve this, the information to be broadcast is organised according to the specific geographic locality to which it relates. Possible approaches for organising this information include a so called mesh-based' approach in which a wider geographic area in which the mobile terminal operates is divided into a relatively large number of small geographic regions or zones, referred to as meshes'. The CPC is then used to broadcast the network information for each respective mesh sequentially, over the wider geographic area. The mobile terminal can thus retrieve and store the network information relating to the mesh in which it is located in order to adapt to the local radio environment accordingly.

One potential issue with this method can be understood from the exemplary scenario illustrated in Figure 1, in which network information for a large number of meshes 10 is broadcast by a base station 5 in a sequence corresponding to the spiral arrow Z. As seen in Figure 1 the broadcast sequence for the CPC involves network information for a first mesh (Mesh-A') being transmitted before the network information for a second mesh (Mesh-B'). Thus, a mobile terminal that moves (in the direction indicated by arrow Y) from Mesh-B to Mesh-A (as indicated by arrow Y) just after receiving the network information for Mesh-B may have to wait for a large part of the broadcast cycle before the network information for Mesh-A is re-transmitted.

This issue may be compounded further should the mobile terminal then move rapidly to a third mesh (Mesh-C'), after the information for Mesh-C has been re-transmitted, but before the network information for Mesh-B has been re-transmitted. In this way the mobile terminal can effectively move against the tide' of the broadcast sequence Z thereby resulting in a relatively long period during which the mobile terminal does not have the information available to make effective use of its cognitive ability to adapt appropriately to its local radio environment.

In order to address this problem, mobile terminals having a cognitive capability can obtain and store the network information from each sequential broadcast they are capable of receiving successfully. However, this requires reception, extraction and storage of a relatively large quantity of redundant information that the mobile terminal will never require. The reception, extraction and storage of this redundant information consume power and valuable storage capacity and are therefore generally undesirable.

One object of the invention, therefore, is to provide an improved communications device, and an associated communication method, in which the above issues are alleviated. In particular, the present invention seeks to provide an improved communications device that may communicate from within, and move between, a plurality of geographic regions in which the above issues are mitigated.

According to one aspect of the invention there is provided a communications device for communication from within, and movement between, any of a plurality of geographic regions, the communications device comprising: means for identifying a subset of said plurality of geographic regions, which subset comprises at least one geographic region in to which the communications device is deemed more likely to move than other geographic regions that are not in said subset; means for receiving a plurality of messages, each message comprising information (e.g. network information) relating to a respective geographic region of said plurality of geographic regions; and means for extracting and storing the network information from the received messages in dependence on whether that geographic region is one of said subset of geographic regions.

The network information may be broadcast over a dedicated channel, for example a beacon channel such as a cognitive pilot channel (C PC) or the like.

Accordingly, the communications device is able to avoid (or at least minimise) the extraction and storage of redundant information whilst minimising the risk that the communications device will enter a geographic region (e.g. a mesh) for which it does not have up-to-date information immediately available in its internal storage.

For example, the information relating to a particular geographic region may be extracted and stored if that geographic region is determined to be a geographic region into which said communications device is likely to move. Extraction of the information relating to a particular geographic region may be avoided if that geographic region is not determined to be a geographic region into which said communications device is likely to move.

The geographic regions may form part of a coverage area (e.g. a cell) of a base station. The base station may transmit the received messages for the plurality of geographic regions in accordance with a (predefined) broadcast sequence.

The plurality of messages may be transmitted, by another communication device, as part of a sequence of such messages, for example, each comprising network information relating to a respective geographic region. The receiving means may be operable to receive (or not receive) a message from said sequence of messages, in dependence on whether (or not) the geographic region to which that message relates is one of said identified subset of geographic regions. Thus the network information may be stored in dependence on whether that geographic region is one of said subset of geographic regions.

The communications device may further comprise means for retrieving sequence information identifying the order in which said sequence of messages are transmitted, for example in association with information identifying the geographic region to which each message relates. The receiving means may be operable to determine whether (or not) to receive a message from said sequence of messages in dependence on whether (or not) the sequence information indicates that the geographic region to which that message relates is one of said identified subset of geographic regions.

The extracting and storing means may be operable to extract, from a received message, information for identifying the geographic region to which the received message relates. The extracting and storing means may be operable to determine whether (or not) to store network information carried by said received message in dependence on whether (or not) said extracted information for identifying the geographic region to which the received message relates indicates that the received message relates to a geographic region in the subset. The extracting and storing means may be operable to store said network information relating to a geographic region in dependence on the result of the determination. Thus, the network information relating to a geographic region may be stored in dependence on whether that geographic region is one of said subset of geographic regions.

The communications device may comprise means for identifying relative movement comprising, for example, a direction in which said communications device is moving.

The identifying means may be operable to include geographic regions in said subset based on their proximity to the geographic region in which the communications device is currently located. The identifying means may be operable to include geographic regions in said subset based on information representing a relative movement of the communications device. The identifying means may be operable to include geographic regions in said subset based on information representing a potential route that the communications device may take.

The direction determining means may comprise, for example, a compass, a gyroscope, or the like. The direction determining means may, for example, comprise a device for determining the direction relative to the communications network (e.g relative to a base station), for example based on signal strength or the like.

The communications device may comprise means for estimating a speed in which said communications device is moving. The identifying means may be operable to include geographic regions in said subset based on said speed estimated by said speed estimating means.

The communications device may comprise means for identifying at least one potential route that a carrier of said communications device may take.

The network information relating to a geographic region may comprise information relating to a radio environment prevailing in the geographic region to which the network information relates. The network information relating to a geographic region may comprises information for enabling the communications device to make a communications decision relating to a radio environment prevailing in the geographic region to which the network information relates based on the network information.

The identifying means may be operable to identify which of said plurality of geographic regions to include in said subset based on where said communications device is determined to be likely to move to within a predetermined period of time in the future.

According to another aspect of the invention, there is provided a method performed by a communications device that is capable of communication from within, and movement between, any of a plurality of geographic regions, the method comprising: identifying a subset of said plurality of geographic regions, which subset comprises at least one geographic region that said communications device is deemed more likely to move to than to other geographic regions that are not in said subset; receiving a plurality of messages, each message comprising network information relating to a respective geographic region of said plurality of geographic regions; and extracting and storing the information relating to a geographic region from a received message in dependence on whether that geographic region is one of said subset of geographic regions.

According to another aspect of the invention, there is provided a communications device for communication in a communication system in which a plurality of messages are broadcast, by another communication device, as part of a broadcast sequence of such messages, the communications device comprising: means for identifying a subset of said sequence of messages, which subset comprises messages which said mobile device is to receive; means for obtaining information identifying the order in which said messages are broadcast; means for selectively receiving messages of said sequence of messages, in dependence on whether or not said messages are in said subset of messages, based on said information identifying the order in which said messages are broadcast.

According to another aspect of the invention, there is provided a method performed by a mobile communications device for communication in a communication system in which a plurality of messages are broadcast, by another communication device, as part of a broadcast sequence of such messages, the method comprising: identifying a subset of said sequence of messages, which subset comprises messages which said mobile device is to receive; obtaining information identifying the order in which said messages are broadcast; selectively receiving messages of said sequence of messages, in dependence on whether or not said messages are in said subset of messages, based on said information identifying the order in which said messages are broadcast.

A preferable embodiment of the invention also provides a computer program and a computer program product for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

A preferable embodiment of the invention also provides a signal embodying a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, a method of transmitting such a signal, and a computer product having an operating system which supports a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

A preferable embodiment of the invention extends to methods and/or apparatus substantially as herein described with reference to the accompanying drawings.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa.

Furthermore, features implemented in hardware may generally be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.

The invention will now be described by way of example only with reference to the attached figures in which: Figure 1 shows a simplified plan view of a coverage area for a base station; Figure 2 shows a simplified overview of a mobile telecommunication system; Figure 3 illustrates how network information is structured for transmission to individual meshes of the mobile telecommunication system of Figure 2; Figure 4 shows a simplified plan view of a coverage area for a base station of the mobile telecommunication system of Figure 2; Figure 5 shows a block schematic illustrating key components of a mobile telephone of the mobile telecommunication system of Figure 2; Figure 6 shows a block schematic illustrating key components of a base station of the mobile telecommunication system of Figure 2; and Figure 7 shows a flow diagram illustrating operation of the mobile telephone of Figure 5.

Overview Figures 2 to 4 show, in overview, a mobile (cellular) telecommunication system 20 including a plurality of mobile telephones 3-1, 3-2 and 3-3 (sometimes hereafter referred to as user equipment 3), and a base station 5 via which the mobile telephones 3 are able to connect into a wider communication network. Thus, users of mobile (cell) telephones 3, are able to communicate with one another and with other users (not shown) via the base station 5 and a core telephone network (not shown).

The base station 5 serves a cell comprising a coverage area 12 that is conceptually divided into a plurality of geographic regions 10 (herein referred to as meshes) between which a mobile telephone 3 in that cell may move (as indicated by arrows Y- 1, Y-2, and Y-3).

In this embodiment, a mesh 10 may be defined as a region where certain radio electrical commonalities can be identified (e.g. a certain frequency that is detected with a power above a certain level in all the points of the mesh, or the like). Each mesh 10 is univocally defined by its geographic coordinates, and has a size that depends on the minimum spatial resolution where the radio electrical commonalities can be identified. In the Figures, the meshes are illustrated as being square, in practice they will of course have an irregular shape.

Each mesh 10 has a radio environment characterised by associated geographically related network information 25 stored at the network side. The network information typically comprises, for example: Location information 25(a) location information indicating the geographic coordinates of each mesh 10; Operator information 25(b) for each operator (of which there may be one or more) providing services in a respective mesh 10 including an operator identifier for uniquely identifying each operator; Radio Access Technology (RAT) information 25(c), for each operator, including information for identifying each available RAT (of which there may be one or more) for each operator and the RAT type (e.g. RAT_TYPE = GSM, UMTS, WiMAX, LTE, etc.); and Frequency range information 25(d) comprising information for identifying each frequency range (of which there may be one or more) used by each RAT.

The base station 5 regularly broadcasts the network information 25 to user equipment 3 in its coverage area 12 on a dedicated broadcast channel (herein referred to as a Cognitive Pilot Channel' -CPC, but also sometimes referred to a beacon' channel). The respective geographically related network information 25 is transmitted, for each mesh 10 in turn, in a broadcast sequence Z. In this embodiment, the broadcast sequence Z begins with the transmission of network information 25 relating to the meshes 10 closest to the base station 5. The broadcast sequence Z then continues with the transmission of network information 25 relating to the meshes 10 at greater distances from the base station 5, in a conceptual increasing spiral' sequence, until the network information 25 for every mesh 10 in the sequence has been broadcast.

As shown in Figure 3, for each mesh 10 in the broadcast sequence Z, the base station 5 transmits the location information 25(a) to allow the mesh 10 to which the network information 25 being broadcast relates, to be identified by user equipment 3 receiving it. Operator information 25(b) is transmitted for each operator (operator #1 to #m) in a list of operators serving the mesh 10 to which the broadcast network information 25 relates. For each operator, RAT information 25(c) is transmitted for each available RAT (RAT #1 to #j) for that operator and for each RAT, frequency range information 25(d) is transmitted for each frequency range (frequency range #1 to #n) available for that RAT.

Each mobile telephone 3 has the ability to receive information broadcast on the CPC and, accordingly, to receive the network information 25 transmitted by the base station 5. Each mobile telephone 3 also has a cognitive capability to make decisions on which operator, RAT and/or frequency range to use for communication with other user equipment 3 in order to optimise radio usage.

Accordingly, user equipment 3, in a particular mesh 10 is able to obtain the network information 25 for that mesh 10 from the broadcasts on the CPC, and to cognitively adapt to the prevailing radio environment in that mesh 10 based on the network information 25.

Referring to Figure 4, in this embodiment, each mobile telephone 3 is operable to identify a current' mesh 10-0 in which the mobile telephone 3 is currently located and, based on this information, to identify a number of candidate' meshes comprising meshes 10 into which the mobile telephone 3 has a reasonable probability of moving within an associated time period.

When identifying the candidate meshes, the mobile telephone 3 is capable of taking a variety of information into account in dependence on its availability including: The geographic proximity of a mesh 10 to the current mesh 10-0; Data representing the relative (recent) movement of the mobile telephone 3 including, for example, the direction of the movement; and/or Data representing possible future routes that the mobile telephone 3 may take including, for example, map data from a Global Positioning System (GPS) application.

If the only information that is available is proximity information (e.g. because the mobile telephone 3 is not moving), then the candidate meshes, identified by the mobile telephone 3 comprise neighbouring' meshes which are determined to be adjacent, or in relative close proximity, to the current mesh 10-0. These neighbouring meshes are illustrated in Figure 4, as being the meshes 10-1 within the large square 11-1.

If the relative movement information is available, then the mobile telephone 3 identifies its direction of movement (as indicated by arrow X) and uses this heading information to identify a smaller number of candidate meshes corresponding to the meshes into which the mobile telephone 3 is likely to enter, given the current heading. This smaller number of candidate meshes is illustrated in Figure 4 as being the meshes 10-2 within the smallersquare 11-2.

If the route data is available, then the mobile telephone 3 identifies potential routes that the mobile telephone 3 may take and then identifies route' meshes (illustrated in Figure 4 as the distributed cross-hatched meshes generally labelled 10-3) on or in close proximity to these potential routes to be candidate meshes. If the direction of the mobile telephone 3 can be determined then the potential routes can be narrowed down to the most likely routes, given the current direction of the mobile telephone 3, and the number of candidate meshes is reduced accordingly.

The mobile telephone 3, of this embodiment, stores the network information 25 for the identified candidate meshes but does not have to store the network information 25 (although it may choose to do so) broadcast by the base station 5 for other meshes 10 in the coverage area 12.

Thus, the mobile telephone 3 advantageously has the network information 25 it requires to adapt cognitively to the radio environment prevailing in the meshes into which it is likely to move whilst the amount of data (network information 25) that is stored on the mobile telephone 3 is minimised.

In this embodiment, the mobile telephone 3 also obtains and stores information representing the broadcast sequence Z and timing information to allow the mobile telephone 3 to determine precisely when information relating to a specific mesh 10 will be broadcast by the base station 5 (if information on the broadcast sequence Z and timing information is available). Thus, the mobile telephone 3 is able to synchronise with the broadcast sequence, to open a radio channel to listen on the CFC when it knows network information 25 relating to an identified candidate mesh will be broadcast, and to close the radio channel at other times when network information 25 relating to identified candidate meshes is not being broadcast.

Thus, the mobile telephone 3 is advantageously able to retrieve the network information 25 that it requires to adapt cognitively to the radio environment prevailing in the meshes into which it is likely to move whilst the power consumption required to do so is minimised.

Mobile Telephone Figure 5 is a functional block diagram of a mobile telephone 3 shown in Figure 2. As shown, the mobile telephone 3 has a transceiver circuit 23 that is operable to transmit signals to and to receive signals from the base station 5 via one or more antenna 30. The mobile telephone 3 has a controller 27 to control the operation of the mobile telephone 3. The controller 27 is associated with a memory 37 and is coupled to the transceiver circuit 23, to a user interface comprising a loudspeaker 29, a microphone 31, a display 33 and a keypad 35. The controller 27 is also coupled to a position indicator 28 and a direction indicator 32. Although not necessarily shown in Figure 5, the mobile telephone 3 has all the usual functionality of a cellular telephone and this may be provided by any one or any combination of hardware, software and firmware, as appropriate. Software may be pre-installed in the memory and/or may be downloaded via the telecommunications network or from a removable data storage device, for example.

The position indicator 28 of this embodiment comprises a global positioning system (GPS) module for providing data indicating the geographic position of the mobile telephone 28 using satellite positioning. The direction indicator 32 of this embodiment comprises a gyroscopic module for providing movement related data including data indicating the direction in which the mobile telephone 3 is moving at any given time (e.g. by reference to inertial or other such measurements).

The controller 27 is configured to control overall operation of the mobile telephone 3 by, in this embodiment, program instructions or software instructions stored within memory 37. As shown, these software instructions include, among other things, an operating system 39, a Cognitive Pilot Channel (CPC) reception module 40, a Cognitive Pilot Channel (CPC) transmission module 47, a movement data module 41, a geographic data module 42, a mesh data management module 43, and a radio environment adaptation module 45.

Also stored within memory 37, in this embodiment, is mesh data 49 comprising positional information identifying the geographic location of each mesh 10 in the coverage area 12 in conjunction with information identifying when the information for each mesh 10 is due to be transmitted in the broadcast sequence Z (where such broadcast sequence information is available). This mesh data 49 is derived from the broadcasts of network information 25, on the CPC, when the mobile telephone 3 first enters the coverage area 12. The mesh data 49 also includes information identifying the meshes determined to be the current mesh 10-0 or a candidate mesh and their associated network information 25.

The CPC reception module 40 controls reception of data being broadcast over the CPC. The CPC module 40 synch ronises reception of the network information 25, for each candidate mesh, with the broadcast sequence being used by the base station 5 (where information on the broadcast sequence is available). Accordingly, the CPC module 40 opens a channel for receiving network information 25 broadcast on the CPC for the meshes 10 determined to be candidate meshes (thanks to movement data module 41 and geographic data module 42 in conjunction with mesh data management module 43, as described in more detail below) and closes the reception channel to avoid receiving network information 25 broadcast on the CPC for other meshes 10. The CPC transmission module 47 controls transmission of data over the cPc.

The movement data module 41 handles data provided by the direction indicator 32 and generates direction data representing the direction in which the mobile telephone 3 is moving.

The geographic data module 42 handles data provided by the position indicator 28 and to identify the current location of the mobile telephone 3 from that data. The geographic data module 42 also stores map data for use in conjunction with the position indicator 28, for route finding and other navigational tasks. The geographic data module 42 is operable to co-operate with the movement data module 41, and the mesh data management module 43, to interactively generate route data representing likely future routes that the mobile telephone 3 will take, given the current location of the mobile telephone, and the direction that the mobile telephone 3 is currently moving.

The mesh data management module 43 manages the extraction and storage of network information 25 broadcast using the CPC, and received under the control of the CPC reception module 40. The mesh data management module 43 is also operable to identify the candidate meshes into which the mobile telephone 3 is likely to move, from the current mesh 10-0 (either directly or indirectly), in the relatively near future (e.g. within a particular time period), based on data from the movement data module 41 and the geographic data module 42. The mesh data management module 43 identifies the current mesh 10-0 in which the mobile telephone 3 is located from the mobile telephone's current location, as identified by the geographic data module 42, and from the mesh data 49. The mesh data management module 43 also determines which meshes 10 should be classified as candidate meshes, as described above, based on the location of the current mesh 10-0, any available direction data, and any available route data for the wider geographical area in which the current mesh 10-0 is located.

The radio environment adaptation module 45 evaluates the characteristics of the prevailing radio environment (operators, RAT's, frequency ranges, etc.) from the network information 25 for the current mesh 10-0 in which the mobile telephone 3 is located. The radio environment adaptation module 44 controls the adaptation of the mobile telephone 3 to the prevailing radio environment by performing discovery procedures (including measurements) in a limited set of frequency bands based on the network information 25 broadcast on the CPC, and by selecting a suitable network to connect to, or to handover to.

Base Station Figure 6 shows a functional block diagram of the base station 5 shown in Figure 2.

As shown, the base station 5 has a transceiver circuit 51 to transmit signals to and to receive signals from the mobile telephones 3 via one or more antenna 53, a network interface 55 to transmit signals to and receive signals from the core network. The base station 5 has a controller 57 to control the operation of the base station. The controller 57 is associated with a memory 59. Although not necessarily shown in Figure 6, the base station 5 will of course have all the usual functionality of a cellular telephone network base station and this may be provided by any one or any combination of hardware, software and firmware, as appropriate. Software may be pre-installed in the memory 59 and/or may be downloaded via the telecommunications network or from a removable data storage device, for example.

The controller 57 is configured to control overall operation of the base station 5 by, in this example, program instructions or software instructions stored within memory 59.

As shown, these software instructions include, among other things, an operating system 61, a CPC transmission module 63 and a CPC reception module 65. Also stored within memory 59, is mesh data 67 comprising respective network information for each mesh.

The CPC transmission module 63 controls broadcast of data such as the network information 25 over the CPC. The CPC transmission module 63 manages the timing of the respective network information broadcasts, for each mesh 10 in turn, in synchronisation with a pre-defined broadcast sequence.

The CPC reception module 65 controls reception of data being sent by a mobile telephone 3, or another base station.

Operation Figure 7 is a flow diagram illustrating operation of the mobile telephone 3 of Figure 4 to determine which meshes 10 should be classed as candidate meshes.

Referring to the process shown in Figure 7, when a mobile telephone 3 moves into a particular mesh 10, the mesh data management module 43 identifies the location of the current mesh (SlO) and identifies the neighbouring meshes 10-1 (S12) to be (potential) candidate meshes. If direction data is available (514) the mesh data management module 43 filters the identified potential candidate meshes by removing meshes 10 into which the mobile telephone 3 is unlikely to move, given the current direction of travel (S15) leaving only direction filtered meshes 10-2 as candidate meshes. Otherwise, if direction data is not available, all the neighbouring meshes identified at 512 are considered to be candidate meshes. Information representing the identified candidate meshes is then stored as mesh data 49 (S 16). If map data is available (S18) the mesh data management module 43, in co-operation with the geographic data module 42, identifies possible future routes which the mobile telephone 3 may take (S20). The mesh data management module 43 then adds meshes 10-3 on (or proximate to) the possible future routes to the previously identified candidate meshes (S22) stored as mesh data 49..

The mobile telephone 3 then obtains and stores network information 25 for the identified candidate meshes only without obtaining and storing network information for the other meshes 10 in the coverage area 12 (S24).

Thus, the mobile telephone 3 advantageously has the network information 25 it requires to adapt cognitively to the radio environment prevailing in the meshes into which it is likely to move whilst the amount of data stored on the mobile telephone 3 is minimised. The mobile telephone 3 is also advantageously able to switch its radio on to receive the network information 25 that it requires to adapt cognitively to the radio environment prevailing in the meshes into which it is likely to move whilst saving power by switching it off when network information 25 is being broadcast for othermesheslO.

Modifications and Alternatives A number of detailed embodiments have been described above. As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above embodiments whilst still benefiting from the inventions embodied therein.

It will be appreciated that whilst, for simplicity, square meshes of identical dimension have been described other approaches may be used in which the meshes may be of different sizes and or shapes. Moreover, the size and/or shape of the geographic region defining a particular mesh may adaptive, for example the size and/or shape may be determined dynamically as network conditions/characteristics and/or other time varying factors fluctuate.

It will be further appreciated that the candidate meshes may comprise direct' meshes into which the mobile telephone 3 is likely to move directly from the current mesh 10- 0 and/or may comprise indirect' meshes into which the mobile telephone 3 is likely to move indirectly, from the current mesh 10-0, via other intermediate meshes 10.

Moreover, the neighbouring meshes 10-1 may comprise direct meshes and/or may comprise indirect meshes within a predefined (or possibly dynamically defined) proximity of the current mesh 10-0 (e.g. less than a particular distance away from, or within a particular geographic boundary around, the current mesh 10-0). The relative proximity of the neighbouring meshes 10-1 to the current mesh 10-0 (i.e. the number of meshes in square 11-1) may be dependent on the speed with which the mobile telephone 3 is moving. For example, whilst Figure 4 shows a 5 x 5 square 11-1 centred on the current mesh 10-0, if the mobile phone is moving relatively quickly the square 11-1 may comprise a greater number of meshes (e.g. a 7 x 7, 9 x 9 or even larger square; or the like depending on the shape of the meshes). Similarly, if the mobile phone is moving relatively slowly the square 11-1 may comprise fewer meshes (e.g. a 3 x 3 square depending on the shape of the meshes). The number of meshes classed as neighbouring meshes may also depend on the size of the meshes. For example, whilst Figure 4 shows a 5 x 5 square 11-1 centred on the current mesh 10-0, if the meshes are relatively small the square 11-1 may comprise a greater number of meshes (e.g. a 7 x 7, 9 x 9 or even larger square; or the like depending on the shape of the meshes). Similarly, if the meshes are relatively large the square 11-1 may comprise fewer meshes (e.g. a 3 x 3 square or the like depending on the shape of the meshes).

Whilst the relative movement data described for the above embodiment comprises direction data, a skilled person will understand that the relative movement data may alternatively or additionally comprise data representing the current or historic speed and/or acceleration of the mobile telephone 3. The route data may comprise historic route data including, for example: previous locations visited; previous routes taken; common (or popular) routes/locations; and/or the like. The route data may also comprise user defined routes/locations; auto-defined routes (e.g. a route proposed by a Global navigation satellite system (GNSS) device such as a GPS module); and/or the like. Accordingly, determination of candidate meshes may take account of the speed/acceleration of the mobile telephone to assess whether or not it is likely to enter a particular mesh within a predetermined time period. Moreover, determination of candidate meshes may be refined based on historic data about the typical journeys a user of the mobile telephone 3 has taken in the past, or may be refined based on a route that a user has requested a navigation tool to generate. The route data may be based on a determination that the user of the mobile telephone 3 is likely to be restricted to a particular transport routeway such as, for example, a major road (e.g. a motorway), a rail line, or the like.

If the direction data is unavailable and/or if the battery is low, then the mobile telephone 3 may determine that a search for potential routes is inappropriate (for example, because the search may consume too much power due to the relatively large scope of the search -i.e. for a full 360° sweep). In this case, the systematic route search shown in Figure 7 may be carried out subject to a decision on whether the route search is appropriate.

In addition to the basic information transmitted on the CPC, other information may be transmitted. Optionally, for example, terminal-dependent information may be transmitted such as maximum transmitted power levels allowed depending on e.g. whether the terminal is indoor or outdoor. Moreover, the information may include information on specific operator and/or radio access policies.

Where the memory available for storing network information 25 is limited, or power availability is low, the amount of data stored and/or power consumption may be reduced further by applying greater restrictions to the meshes 10 determined to be candidate meshes for example by assigning a priority to the candidate meshes.

Whilst the mobile telephone in the above embodiment has been described as having separate direction and position indicators 32, 28 for determining movement related information and geographic location related information respectively, the movement related and or positioning information may be derived from signals received from the base station 5. The mobile telephone 3 may determine movement related information and/or geographic location related information by performing calculations referenced to the known position of a plurality of base stations (e.g. base station triangulation using, time of flight, signal strength, or the like as an indicator of distance). Further, the movement related information may be calculated from data provided by the position indicator 28 location system such as a GPS rather than the mobile telephone 3 being provided with a separate internal gyroscope, compass, or other direction finding device.

The position indicator 28 and direction indicator 32 may comprise any suitable internal or external device. The position indicator may, for example, be adapted to use any suitable GNSS or other positioning technology such as GPS technology, The European Union's Galileo technology, China's COMPASS technology, Japan's Quasi-Zenith Satellite System (QZSS) technology, or the like. Moreover, positioning information may be derived from cellular network positioning instead of, or to enhance, positioning using a GNSS device or other such device. The direction indicator 32 may, for example, comprise an electronic compass based on magnetic direction finding or radio direction finding. However, it is generally advantageous for the direction data produced by the direction indicator 32 to represent direction of movement, rather than simply a direction in which the mobile telephone 3 is oriented, since the mobile telephone 3 will often be oriented in a direction that is different to that in which the mobile telephone is moving.

It will be appreciated that in some scenarios the sequence information Z may not be used to synchronise the reception of the network information with the broadcast sequence (either by design or because the information is temporarily unavailable or has been found to be inaccurate) and, accordingly, the mobile telephone 3 may not obtain and store information representing the broadcast sequence Z. Thus, whilst it is advantageous for the CPC reception module 40 to open and close the receiver channel in synchronisation with the broadcast sequence Z to optimise the associated power consumption, the CPC reception module 40 may, nevertheless, receive all CPC transmissions either by design or because broadcast sequence data is not available or has been discovered to be inaccurate. In this scenario, the mesh data management module 43 of the mobile telephone 3 may identify the mesh 10 to which each broadcast of network information 25 relates (e.g. from the location information 25(a)) and selectively extract and/or store the rest of the network information 25 in dependence on whether the identified mesh 10 is one that has been classified as a candidate mesh.

It will further be appreciated that whilst, in the above embodiment, the mobile telephone 3 is described as not storing network information 25 for other non-candidate' meshes there may be scenarios in which network information 25 for one, some or all of the non-candidate meshes may be stored for other reasons. For example, the broadcast network information 25 may represent delta' information comprising the differences between the information for a specific mesh 10 and the information for a reference mesh. In this scenario, the reference mesh may not be a candidate mesh but the information for it may, nevertheless, be stored on the mobile telephone 3 so that the mobile telephone 3 is able to derive the full network information 25 for the candidate meshes. Moreover, if candidate meshes cannot be identified, or doing so will consume too much battery power (especially if the battery power is low) then information on all meshes may be obtained and stored without identification of candidate meshes. This may be the case, for example, where the direction information is changing rapidly (and persistently) and/or where the number of possible routes is particularly high (e.g. over a 360° sweep of possible directions.

Although the application has been described with particular reference to CPC based systems the invention may be implemented in other similar systems and, in particular, in other beacon' type systems in which a dedicated beacon' channel is used for the transmission of data relating to different geographic areas.

It will be appreciated that whilst the candidate meshes may be identified in advance of the information relating to them being broadcast (e.g. as shown in Figure 7) the candidate meshes may be identified on-the-fly' (e.g. when (or shortly before) the information relating to that mesh is due to be broadcast). In this variation, the mobile telephone 3 may, for example, extract the location information from a received message and determine (e.g. from an on-the-fly comparison of the extracted information with route information and/or direction information) whether the mesh is a candidate mesh or not. Based on this on-the-fly comparison, the mobile telephone 3 may thus decide whether other information contained in the message should be extracted and/or stored.

In the above embodiment, a mobile telephone based telecommunications system was described. As those skilled in the art will appreciate, the signalling techniques described in the present application can be employed in other communications system. Other communications nodes or devices may include user devices such as, for example, personal digital assistants, laptop computers, web browsers, etc. As those skilled in the art will appreciate, it is not essential that the above described relay system be used for mobile communications devices. The system can be used to extend the coverage of base stations in a network having one or more fixed computing devices as well as or instead of the mobile communicating devices.

In the embodiment described above, the mobile telephone and the base station each include transceiver circuitry. Typically this circuitry will be formed by dedicated hardware circuits. However, in some embodiments, part of the transceiver circuitry may be implemented as software run by the corresponding controller.

In the above embodiments, a number of software modules were described. As those skilled in the art will appreciate, the software modules may be provided in compiled or un-compiled form and may be supplied to the base station or the mobile telephone as a signal over a computer network, or on a recording medium. Further, the functionality performed by part or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates the updating of the base stations and the mobile telephones in order to update their functionalities.

Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

Claims

Claims 1. A communications device for communication from within, and movement between, any of a plurality of geographic regions, the communications device comprising: means for identifying a subset of said plurality of geographic regions, which subset comprises at least one geographic region in to which the communications device is deemed more likely to move than other geographic regions that are not in said subset; means for receiving a plurality of messages, each message comprising network information relating to a respective geographic region of said plurality of geographic regions; and means for extracting and storing the network information from the received messages in dependence on whether that geographic region is one of said subset of geographic regions.
2. A communications device as claimed in claim 1, wherein said plurality of messages are transmitted, by another communication device, as part of a sequence of such messages each comprising network information relating to a respective geographic region; and wherein said receiving means is operable to either receive, or not receive, a message from said sequence of messages, in dependence on whether or not the geographic region to which that message relates is one of said identified subset of geographic regions; whereby said network information is stored in dependence on whether that geographic region is one of said subset of geographic regions.
3. A communications device as claimed in claim 2, further comprising means for retrieving sequence information identifying the order in which said sequence of messages are transmitted in association with information identifying the geographic region to which each message relates; and wherein said receiving means is operable to determine whether or not to receive a message from said sequence of messages in dependence on whether or not said sequence information indicates that the geographic region to which that message relates is one of said identified subset of geographic regions.
4. A communications device as claimed in claim I wherein said extracting and storing means is operable to extract, from a received message, information for identifying the geographic region to which the received message relates.
5. A communications device as claimed in claim 4 wherein said extracting and storing means is operable: to determine whether or not to store network information carried by said received message in dependence on whether or not said extracted information for identifying the geographic region to which the received message relates indicates that the received message relates to a geographic region in said subset; and to store said network information relating to a geographic region in dependence on the result of said determination whereby said network information relating to a geographic region is stored in dependence on whether that geographic region is one of said subset of geographic regions.
6. A communications device as claimed in any preceding claim wherein the identifying means is operable to include geographic regions in said subset based on their proximity to the geographic region in which the communications device is currently located.
7. A communications device as claimed in any preceding claim wherein the identifying means is operable to include geographic regions in said subset based on information representing a relative movement of the communications device.
8. A communications device as claimed in claim 7 wherein said information representing said relative movement of the communications device is provided by at least one of an electronic compass, a gyroscope, and/or means for providing a position of the communications device relative to a base station.
9. A communications device as claimed in any preceding claim wherein the identifying means is operable to include geographic regions in said subset based on information representing a potential route that the communications device may take.
10. A communications device as claimed claim 9 wherein said information representing a potential route is based on map data.
11. A communications device as claimed claim 9 or 10 wherein said information representing a potential route is based on information provided by a positioning system.
12. A communications device as claimed in any preceding claim wherein the identifying means is operable to include geographic regions in said subset based on historic information.
13. A communications device as claimed claim 12 wherein said historic information comprises at least one of: information identifying at least one geographic region previously visited; information identifying at least one route previously taken; and/or information identifying at least one direction previously taken.
14. A communications device as claimed in any preceding claim wherein the network information relating to a geographic region comprises information relating to a radio environment prevailing in the geographic region to which the network information relates.
15. A communications device as claimed in any preceding claim wherein a first said message comprises a first set of network information relating to a first geographic region, and a second said message comprises delta network information representing a difference between a second set of network information for a second geographic region and the first set of network information for the first geographic region.
16. A communications device as claimed in any preceding claim wherein a (or the) first set of network information relating to a (or the) first geographic region is stored by said extracting and storing means, and delta network information, representing a difference between a (or the) second set of network information for a (or the) second geographic region, and the first set of network information for the first geographic region, is stored for the first geographic region.
17. A communications device as claimed in claim 15 or 16 wherein the first said geographic region does not form pad of said subset of geographic regions.
18. A communications device as claimed in any preceding claim wherein the network information relating to a geographic region comprises information for enabling the communications device to make a communications decision relating to a radio environment prevailing in the geographic region to which the network information relates based on that network information.
19. A communications device for communication from within, and movement between, any of a plurality of geographic regions, the communications device comprising: a processor operable to identify a subset of said plurality of geographic regions, which subset comprises at least one geographic region in to which the communications device is deemed more likely to move than other geographic regions that are not in said subset; and a receiver operable to receive a plurality of messages, each message comprising network information relating to a respective geographic region of said plurality of geographic regions; wherein the processor is operable to extract and store the network information from the received messages in dependence on whether that geographic region is one of said subset of geographic regions.
20. A method performed by a communications device that is capable of communication from within, and movement between, any of a plurality of geographic regions, the method comprising: identifying a subset of said plurality of geographic regions, which subset comprises at least one geographic region that said communications device is deemed more likely to move to than to other geographic regions that are not in said subset; receiving a plurality of messages, each message comprising network information relating to a respective geographic region of said plurality of geographic regions; and extracting and storing the information relating to a geographic region from a received message in dependence on whether that geographic region is one of said subset of geographic regions.
21. A communications device for communication in a communication system in which a plurality of messages are broadcast, by another communication device, as part of a broadcast sequence of such messages, the communications device comprising: means for identifying a subset of said sequence of messages, which subset comprises messages which said mobile device is to receive; means for obtaining information identifying the order in which said messages are broadcast; and means for selectively receiving messages of said sequence of messages, in dependence on whether or not said messages are in said subset of messages, based on said information identifying the order in which said messages are broadcast.
22. A communications device for communication in a communication system in which a plurality of messages are broadcast, by another communication device, as part of a broadcast sequence of such messages, the communications device comprising: a processor operable to identify a subset of said sequence of messages, which subset comprises messages which said mobile device is to receive, and to obtain information identifying the order in which said messages are broadcast; and a receiver operable to selectively receive messages of said sequence of messages, in dependence on whether or not said messages are in said subset of messages, based on said information identifying the order in which said messages are broadcast.
23. A method performed by a mobile communications device for communication in a communication system in which a plurality of messages are broadcast, by another communication device, as part of a broadcast sequence of such messages, the method comprising: identifying a subset of said sequence of messages, which subset comprises messages which said mobile device is to receive; obtaining information identifying the order in which said messages are broadcast; selectively receiving messages of said sequence of messages, in dependence on whether or not said messages are in said subset of messages, based on said information identifying the order in which said messages are broadcast.
24. A computer program product comprising computer implementable instructions for causing a programmable computer device to become configured as the communications device of any of claims I to 19, 21 or 22, or to carry out a method according to claim 20 or 23.