GB2387745A

GB2387745A - Sending location reports from a mobile transceiver at intervals inversely dependent on the distance from a target zone or cell

Info

Publication number: GB2387745A
Application number: GB0208633A
Authority: GB
Inventors: John Watson; Christopher David Pudney
Original assignee: Vodafone Ltd
Current assignee: Vodafone Ltd
Priority date: 2002-04-15
Filing date: 2002-04-15
Publication date: 2003-10-22
Anticipated expiration: 2022-04-15
Also published as: GB2387745B; GB0208633D0

Abstract

In a mobile telecommunications system, such as a 2G GSM or 3G UMTS network, boundary crossing routeing area update signals (RAUs) are produced as a selected mobile enters each of a plurality of routeing areas (RA1,RA2,RA3) to a target zone in the form of a cell (12) within a particular routeing area (RA3). As the terminal moves though each routeing area A towards the routeing area (RA3) in which the target zone (12) is located, it is arranged to produce periodic routeing area update signals (PRAUs) at a reporting frequency which increases as the terminal approaches the target zone C.

Description

LOCATION-DEPENDENT MOBILE TELECOMMUNICATIONS

SYSTEMS AND METHODS

The invention relates to location-dependent mobile telecommunications systems and methods. In embodiments of the invention to be described in more detail below, by way of example only, the changing location of a mobile radio transceiver is monitored. In a particular example, the mobile transceiver may be a mobile telephone handset in a cellular telephone or telecommunications network, but the invention is not limited in this way.

According to the invention, there is provided a location-dependent mobile telecommunications system, comprising a plurality of radio transceiver terminals which are mobile within a geographical region, means for selecting a particular target zone within the region for a specified one of the terminals, and control means for producing location reporting signals indicative of the position of the specified terminal within the region at a reporting frequency which increases as the terminal approaches the target zone. According to the invention, there is also provided a location-dependent mobile telecommunications method for use with a plurality of radio transceiver terminals which are mobile within a geographical region in which a particular target zone within the region is selected for a specified one of the terminals, and including the step of producing location reporting signals indicative of the position of the specified terrnina1 within the

region at a reporting frequency which increases as the terminal approaches the target zone. Location-dependent mobile telecommunications systems and methods according to the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 shows a public land mobile network (PLMN) and a mobile therein moving towards a target location; If) Figure 2 shows part of a 2G (Second Generation) GSM^cellular telecommunications network operating in accordance with one embodiment of the invention; Figure 3 is a flow chart for explaining the operation of the network shown in Figure 2; Figure 4 corresponds to Figure 2 but shows part of a 3G (Third Generation) cellular telecommunications network for explaining its operation in accordance with another embodiment of the invention.

The embodiments of the invention to be described in more detail below are concerned with the problem of determining when a particular mobile radio transceiver terminal arrives at a predetermined location - that is, within a predetermined target zone. The

mobile transceiver terminal may take any suitable form. In one particular example, the mobile transceiver is a mobile telephone handset, operating in a cellular telephone system, and carried by its user or carried in the user's car. In another example, the mobile transceiver is also operative within a cellular telecommunications network but in this case may be carried by and within a vehicle for transmitting and receiving data relevant to the operation of the vehicle and not normally user-accessible.

For many purposes, it is desirable to be able to detect when a particular mobile terminal reaches a particular target zone. In the case where the mobile terminal is a mobile telephone, commercial organizations may wish to provide localised information (advertising, for example) to particular mobile terminals when they have reached a particular target zone (adjacent to a particular commercial outlet, for example). In such cases, users may have given general authorization (in order to comply with data protection and privacy requirements) to one or more particular commercial organizations and can thus receive relevant localised commercial information whenever their mobile terminals come into particular target zones as specified by the commercial organizations. In another example, a user may themselves define particular target zones, requesting that they be informed when their mobile terminal has entered that defined target zone - so as, for example, to become informed when the destination of a railway or road journey has been reached. In the case of a mobile terminal which is incorporated into a vehicle and not normally user- accessible, the terminal may signal when the vehicle has reached one or more specified target zones for vehicle tracking and fleet management purposes or (when

used in combination with the registration number of the vehicle) for automating road tolling or parking charge purposes, for example.

In each of these cases, the system is required to Back the changing position of the mobile terminal so as to be able to detect when it reaches the target zone. In principle, though, the mobile terminal might not reach the target zone for a considerable period of time -

hours, days or weeks, for example. If the mobile terminal is caused to report its position at frequent intervals, this may therefore impose excessive signalling and data processing loads on the network. For example, a system reporting the entry into and exit from every cell through which the mobile terminal passes on its way to the target zone could produce significant signal overload, particularly because such updates would obviously have to include information relating to the identity of the particular cell.

Figure 1 shows a PLAIN 10 in the form of a cellular network comprising a number of cells of which one is shown at 12. The mobile terminal MT is one of many mobile terminals within the network 10 which can move around the network, from cell to cell, and can communicate with each other and with other mobile and fixed terminals in other networks, via base stations respective to the cells, all in known fashion. It is assumed that the cell 12 represents a target zone which has been previously specified as such either by an external organisation (such as a commercial outlet), to which the user of the mobile terminal MT has given authorization, or may have been specified by the user of the mobile terminal. The system being described is intended to track the movement of the

mobile terminal MT, producing periodic signals dependent on its location, so as to be able to determine when the mobile terminal reaches the target cell 12.

The operation of the system, when the network 10 is a 2G GSM network will be explained in more detail with reference to Figure 2.

It is known in a 2G GSM network to divide the network up into routeing areas, such as RA1,RA2 and RA3 shown in Figure 2. leach such routeing area comprises a number of cells as shown diagrammatically within routeing area RA3 which also shows the target zone in the form of cell 12 (see Figure 1). When a mobile terminal enters a particular routeing area, this is signalled to the network together with the identity of the routeing area. Thus, boundary crossing routeing area update reporting signals are produced as shown at RAU1,RAU2 and RAU3 as the mobile enters routeing areas RA1,RA2 and RA3 respectively. In accordance with a feature of the embodiment being described, the mobile terminal also produces periodic routeing area update reporting signals, signalling its position within each routeing area as it moves within the area, the reporting frequency of such update signals being arranged to be inversely dependent on the distance of the current routeing area from the routeing area RA3 containing the target zone. RA1 is relatively distant from RA3 which includes the target zone 12 so that the reporting frequency ofthe periodic RAUs produced by the mobile terminal MT is set to a relatively low value while the mobile terminal is within routeing area RAT. In this example, therefore, MT produces a single PRAU as it passes through RAT, as shown at PRAU1.

It is now assumed that MT enters RA2 and produces the boundary crossing routeing area update signal RAU2. RA2 is closer to RA3, and MT is now set to produce periodic routeing area update signals at a higher reporting frequency. Thus, as shown in Figure 2, it is assumed that the mobile terminal MT produces two such periodic RAUs as shown at PRAU2 and PRAU3 as it crosses the routeing area Row. The mobile terminal then enters RA3 end produces boundary crossing routeing area update signal RAU3 upon entry into RA3. RA3 incorporates the target zone 12, of course, and the network now sets mobile terminal MT to produce periodic RAUs at a higher reporting frequency. As shown in Figure 2, such signals are shown at PRA1J4, PRAU5, PRAU6 and PRAU7.

In this way, the signalling and data processing load on the network is minimal when the mobile terminal MT is far away from the target zone because routeing area update signals are produced at very low reporting frequency. However, the reporting frequency of local area updates increases as the MT approaches.the target zone so that the network is alerted to the imminent arrival of the terminal at the target zone and can initiate the necessary informational action when the mobile terminal arrives there.

Although Figure 2 shows production of a single periodic RAU (PRAU1) from the mobile terminal when in RAT, two periodic RAUs (PRAU2 and PRAU3) when the mobile terminal is within RA2 and four periodic RAUs (PRAU4,PRAU5, PRAU6 and PRAU7) when the mobile terminal is within RA3, the number of periodic RAUs will not necessarily increase progressively in this fashion. Figure 2 assumes that the mobile

terminal is moving progressively across RAT, RA2 and RA3 towards the target zone 12.

In a practical example, the mobile terminal might remain within RA1 for a considerable amount of time, so that several periodic RAUs might be generated - though at relatively low reporting frequency (that is, with relatively long time intervals between them). It might then pass relatively rapidly pass RA2, perhaps producing only one or a few periodic RAUs - though with considerably shorter time intervals between them. Then, when it enters RA3, the time intervals between the periodic RAUs would be smaller still - and the number of such signals generated by the mobile terminal within RA3 would be dependent on the total time taken for it to move across RA3 to the target zone 12.

The system described with reference to Figure 2 is particularly advantageous for use with mobile terminals operating in packet mode such as a GPRS system (General Packet Radio System). For terminals in GPRS mode, the relevant base station can set the reporting frequency at which a particular selected mobile terminal is to produce routeing area update signals - that is, the base station can set different local area update reporting frequencies for each of the mobile terminals currently within the particular cell. When mobile terminals are operating in circuitswitched mode, their location reporting frequencies cannot normally be set individually - the base station can thus only operate to set all the circuit-switched mobile terminals within the cell to have the same location reporting frequency. Therefore, the advantage of the system described with reference to Figure 2 is primarily obtainable when the relevant mobile terminals are operating in GPRS mode.

The flow chart of Figure 3 illustrates the operations described with reference to Figure 2.

As shown at A, the system detects entry of a specified mobile terminal (e. g. mobile terminal MT) into a particular routeing area (e.g. RAT).

At B. the system determines the distance of this routeing area from the position of the target area 12. At C, the system instructs mobile terminal MT to adjust the reporting frequency of the periodic RAUs to a specified value inversely dependent on the distance of the current routeing area from the target area.

tom) Figure 4 shows the application of the system being described to a 3G or UNITS network.

In the 3G network, registration areas (UMTS Registration Areas or URAs) are defined, and arranged in an hierarchical stack of successively smaller size. Thus, a very large-

sized URA is shown at URA 1 a which encompasses progressively smallersized URAs shown atURA lb,URA lcandURA id. In operation ofthe3Gnetwork,a particular mobile may be registered with URA la - for example, when in a sparsely populated rural area. If it then moves into more populated areas, it may be successively transferred into registration with URA lb, URA lo and URA id. The identity, and thus the size, of the URA with which the mobile is currently registered can therefore be used to determine the location reporting frequency. Thus, when the mobile is registered with URA la, its location reporting frequency can be low, increasing to a medium reporting frequency when it becomes registered with URA lb and to a high reporting frequency when it becomes registered in URA 1 c. When the mobile terminal becomes registered with URA

id, the location reporting frequency can be increased still further and, for example, the mobile terminal can be set to send a location reporting update upon each movement from one cell within URA 1 d to another cell therein.

Thus, when the mobile terminal 10 becomes registered with each URA, it produces a URA update signal identifying the URA, as shown at URAU1, URAU2, URAU3 and URAU4. While the mobile terminal is registered within a particular URA, it will produce periodic URA update signals as shown at PURAU1 to PURA10 in Figure 4 at a frequency which increases as the mobile terminal 10 moves from URAla to URAld. Again, of course, the number of PURAUs which are produced while the mobile terminal is in a particular URA depends not only on the reporting frequency set for this particular URA but also on the time which the mobile terminal spends within this URA.

Although the target zone has been described above as being a cell of a cellular telecommunications network, it could instead be part of a cell or could be larger than a single cell.

Claims

A location-dependent mobile telecommunications system, comprising a plurality of radio transceiver terminals which are mobile within a geographical region, means for selecting a particular target zone within the region for a specified one of the terminals, and conko1 means for producing location reporting signals indicative of the position of the specified terminal within the region at a reporting frequency which increases as the terminal approaches the target zone.
2. A system according to claim 1, in the form of a cellular mobile telecommunications system and in which the target zone is a particular cell of the system.
3. A system according to claim 2, in which the geographical region is arranged in a plurality of routeing areas each comprising a respective plurality of the cells, and in which the control means is responsive to the distance of the routeing area within which the specified terminal is currently located for setting the terminal to produce the location reporting signals at a reporting frequency inversely dependent on the distance of that routeing area from the routeing area which includes the target zone.
4. A system according to claim 3, in the form of a GSM system.
5. system according to claim 4, in which the specified terminal is operative in the

packet mode.
6. A system according to claim 2, in which the geographical region is arranged in a plurality of routeing areas each comprising a plurality of cells, the routeing areas having progressively greater geographical size and each of them (except the largest-sized one) being geographically encompassed within the next larger-sized one of them, each mobile terminal within the geographical area of the largest-sized one of the areas being registered with a particular one of the areas, and in which the control means sets the specified one of the terminals to produce the location reporting signals at a reporting frequency dependent on the particular one of the routeing areas with which the mobile terminal is currently registered.

camp
7. A system according to claim 6, organised as a 3G or UNITS system.
8. A location-dependent mobile telecommunications method for use with a plurality of radio transceiver terminals which are mobile within a geographical region, in which a particular target zone within the region is selected for a specified one of the terminals, and including the step of producing location reporting signals indicative of the position of the specified terminal within the region at a reporting frequency which increases as the terminal approaches the target zone.
9. A method according to claim 8, for use with a cellular mobile telecommunications

system and in which the target zone is a particular cell of the system.
10. A method according to claim 9, in which the geographical region is arranged in a plurality of routeing areas each comprising a respective plurality ofthe cells, and in which the specified terminal is set to produce the location reporting signals at a reporting frequency inversely dependent on the distance ofthe routeing area in which it is currently located from the location area which includes the target zone.
1 1. A method according to claim 10, in which the telecommunications system is in the lore) form of a GSM^system.
12. A method according to claim 11, in which the specified terminal is operative in the packet mode.
13. A method according to claim 9, in which the geographical region is arranged in a plurality of routeing areas each comprising a plurality of the cells, the routeing areas having progressively greater geographical size and each of them (except the largest-sized one) being geographically encompassed within the next larger-sized area, each mobile terminal within the geographical area of the largest-sized one of the areas being registered with a particular one of the areas, and in which the specified one of the terminals is set to produce the location reporting signals at a reporting frequency dependent on the particular one ofthe routeing areas with which the mobile terminal is currently registered.
14. A method according to claim 13, in which the telecommunications system is (M) organised as a 3G or UNITS system.
15. A location-dependent mobile telecommunication system, substantially as described with reference to Figures 1 to 3 of the accompanying drawings.
16. A Location-dependent mobile telecommunication system, substantially as described with reference to Figure 4 of the accompanying drawings.
17. A location-dependent mobile telecommunication method, substantially as described with reference to Figures 1 to 3 of the accompanying drawings.
18. A location-dependent mobile telecommunication method, substantially as described with reference to Figure 4 of the accompanying drawings.