WO2000072619A1

WO2000072619A1 - Method for managing the location of a mobile terminal in a cellular mobile radio network, cellular mobile radio network and mobile terminal

Info

Publication number: WO2000072619A1
Application number: PCT/DE2000/001606
Authority: WO
Inventors: Jens Biesterfeld; Klaus Jobmann
Original assignee: Universität Hannover
Priority date: 1999-05-22
Filing date: 2000-05-17
Publication date: 2000-11-30
Also published as: DE19923638A1; DE19923638C2

Abstract

The invention relates to the management of the location of a mobile terminal in a cellular mobile radio network, using an estimation method. The method determines the probable locations of the mobile terminal according to a fixed algorithm, based on a stored displacement pattern and manages these, to achieve a targeted signaling of the mobile terminal. The same estimation method is used by both a stationary device in the mobile radio network and also in parallel, by a device in the mobile terminal itself. The mobile terminal passively determines its actual location and compares this with the probable location which has been determined according to the estimation method. If there are deviations between the estimated and the actual location, corrective information is transmitted to the stationary device in the mobile radio network.

Description

Method for managing the location of a mobile terminal in a cellular mobile radio network, cellular mobile radio network and mobile terminal

The invention relates to a method for managing the location of a mobile terminal in a cellular mobile radio network according to the preamble of claim 1, a cellular mobile radio network according to the preamble of claim 7 and a mobile terminal according to the preamble of claim 11.

In the case of cellular mobile radio networks, it is important to know the locations of the mobile terminals in order to report an incoming call to the terminal as quickly as possible and without unnecessary load on the signaling channels of the mobile radio network.

For this purpose, static subscriber data and current stay data are stored in a database or several databases by means of a location management device. When there is an incoming call, the data of the mobile device required to find a subscriber is queried by a database query. If the current location area changes, when a predetermined limit between two location areas is exceeded, the new location area is determined by the mobile terminal and passed on to the location management facility of the mobile radio network, which then updates the database. The number of subscribers will increase in future mobile radio networks, which will be offset by a reduction in the size of the radio cells due to the limited capacity of the air interface between the mobile terminals and the radio stations. By increasing the subscriber density in connection with small cells, however, the signaling volume for the location management of the subscribers would increase disproportionately.

Until now, it was still possible to limit the signaling volume by not restricting residence areas, when a signal to update the residence area was sent from the mobile terminal to the mobile radio network, to individual cells, but rather by combining several adjacent cells. Within these areas, smaller search areas were formed, in which a connection request was sent in succession when an incoming call was received, so that the mobile terminal received the connection request at the latest after selection of the last search area and was able to report to the switching center with the identification of the current cell, to initiate the connection establishment.

However, the number of search areas within a stay area must be limited, so that in the worst case the time required to switch through a user connection does not become unreasonably long. However, this concept no longer does justice to the increasing number of participants, since constellations are possible that lead to an overload of the signaling capacity. Think of one here A large number of subscribers with mobile devices switched on, who travel on a train and, at the same time as they cross a border, send signals from one specified area to another to update the area.

It has already been proposed to make forecasts for future locations on the basis of movement patterns of the mobile terminal devices, which have been determined and stored based on past location determinations. If the participant shows stereotypical movement behavior, the prognosis is in good agreement with the actual location areas of the mobile terminal, so that an update when changing the location area can usually be dispensed with. In contrast, deviations from the stored movement pattern lead to incorrect forecasts and thus to a considerably longer time for the subscriber to search due to numerous unsuccessfully transmitted connection requests in search areas that cannot be received by the mobile terminal.

The invention has for its object to improve a method for location management of a mobile terminal in a cellular mobile radio network according to the preamble of claim 1 in such a way that the signaling volume is reduced and at the same time a current database for the location is ensured in the database responsible for this. This object is achieved in a method according to the preamble of claim 1 by the features specified in the characterizing part.

In the solution according to the invention, too, it is initially assumed that the determination of the location area of a mobile terminal is determined by an estimation method based on a stored movement pattern. Signaling when the location is changed can then be dispensed with if the actual location is included in the forecast. As a result, a large proportion of the signaling volume can already be saved for the total number of registered terminals. However, in order to avoid a possibly lengthy search of the mobile terminal if the location area deviates from the forecast, correction information is transmitted in the event of deviations of the actual location from the estimated location so that the estimated location corresponds to the current location again. In order to be able to transmit this correction information in a targeted manner, it is necessary to determine the deviation of the actual location from the estimated one.

The inventive idea for solving this problem consists in making the same estimate in the forecast of the location area as the facility for location management of the mobile radio network also makes in parallel in the mobile terminal in question. The mobile terminal can then compare its own location with the forecast and only then initiates the transmission corrective information if there is a deviation from the estimated location area.

The solution according to the invention does not lead to a reduction in the signaling volume for each individual subscriber in the same way, since it depends on the individual user behavior how large the deviations of the mobility from the stored movement pattern are, but overall the signaling volume is reduced across all subscribers, with at none of the participants experience inappropriately long search times in the event of incoming calls.

According to a further development, the correction information can include the actual location. This ensures in any case that an incoming call can be directed to the mobile device. If the actual location area falls into an additionally stored movement pattern, the estimation process can then be continued with this movement pattern in the further forecast.

Alternatively or additionally, the correction information can also include an updated movement pattern. On the one hand, this can serve to update the movement patterns for the estimation, on the other hand, it can also refine the prognosis of the current determination of the residence and thus reduce the number of other necessary correction information. The movement pattern can include time, state or speed dependent location information or a sub-combination of these. When evaluating all of this information, the prediction accuracy is significantly increased and the number of necessary correction information is thereby reduced.

The passive determination of the location area of the mobile terminal can be carried out by evaluating field strengths and / or phase positions of the transmissions of the receivable head-end station and their identifiers.

In this way, directions of movement can already be determined, the information content of which go beyond the mere change of the area of stay from one to the other and thereby help to improve the accuracy of the forecast.

A further improvement can consist in the passive determination of the location area of the mobile terminal by a position determination system, such as the GPS system, which is independent of the mobile radio network.

The invention further relates to a cellular mobile radio network according to the preamble of claim 7. In this regard, it is based on the object of improving a cellular mobile radio network in such a way that the signaling volume is reduced and at the same time an up-to-date database for the location area is ensured in the database responsible for this. This object is achieved in a cellular mobile radio network according to the preamble of claim 7 by the features specified in the characterizing part of this claim. Further developments and advantageous refinements result from claims 8 to 10. The explanations for claims 1 to 4 apply to the mode of operation and advantages of the features contained in these claims.

Finally, the invention relates to a mobile terminal according to the preamble of claim 11. In this regard, it is based on the task of improving a mobile terminal in such a way that the signaling volume is reduced and at the same time an up-to-date database for the area m of the database responsible for it is ensured becomes.

This object is achieved in a mobile terminal according to the preamble of claim 11 by the features specified in the characterizing part of this claim. Further developments and advantageous refinements result from sι.ch from claims 12 to 16. The explanations for claims 1 to 6 apply to the mode of operation and advantages of the features contained in these claims.

The invention is explained below on the basis of an exemplary embodiment which is illustrated in the drawing.

The drawing shows: 1 is a schematic representation of part of a cellular mobile radio network with location and search areas,

2 shows a schematic representation of devices of a cellular mobile radio network with a sketch of the route search,

3 shows a schematic representation of devices of a cellular mobile radio network with a sketch of the signaling when the stay area is updated,

4 shows a schematic representation of devices of a cellular mobile radio network with a sketch of the signaling when a connection request is sent,

5 is a flow chart for determining and updating the location according to the invention,

FIG. 6 shows a schematic representation of devices of a cellular mobile radio network modified with respect to FIG. 2 with a sketch of the location determination according to the invention and

FIG. 7 shows a schematic representation of a part of a cellular mobile radio network with search areas according to the invention, modified in comparison with FIG. 1.

The following explanations, which refer to the "Global System for Mobile Communication" GSM, also include the international terms and their abbreviations. tongues used. The latter are also partially included in the drawings to maintain the overview.

1 shows a schematic representation of part of a cellular mobile radio network with subdivision into different areas. A mobile switching center (MSC) is connected to several radio stations (base transceiver station) BTS via radio station controls (base station controller) BSC. The BTS are assigned to the respective cells. A plurality of cells are used to determine areas within which the subscriber is searched, namely search areas (paging areas) PA and also to determine location areas (LA) on the other hand, if the limit is exceeded, the terminal sends a message to the user about the update of the location area Network sends. The volume of the signaling messages can be controlled within limits by the choice of the size of the search areas and location areas in connection with the number of associated cells and can thus be adapted by the network operator.

Two signaling messages were defined for the implementation of the areas in a cellular mobile radio network. In international parlance, the notification of the subscriber about a change of the stay area is called "location updating" LU and the notification of the subscriber when the connection request arrives is "paging".

2 shows a schematic representation of devices of a cellular mobile radio network with a sketch of the route before using the example of an incoming connection request from a landline. The route search is divided into two sections. In the first section the selected subscriber number is used for routing and in the second section a temporary number that depends on the current location. The following actions are carried out in detail, which are illustrated in FIG. 2. 1. A connection establishment request is directed to a switching center within the fixed network which aims to establish a connection to a mobile terminal (mobile station) MS. This connection request is forwarded to a mobile switching center (gateway mobile switching station) GMSC. 2. initiates the mobile switching center to request a location by calling the subscriber's internationally unique number (Mobile Subscriber ISDN Number) MSISDN at a home database in the GSM network (Home Location Register) HLR. In the home database there is a reference to the responsible visitor database in the GSM network (Visitor Location Register) VLR, which is called 3. via the internationally unique subscriber address (International Mobile Subscriber Identity) IMSI. The visitor database in whose administrative area the participant is currently responsible is responsible.

A temporary station number (Mobile Station Roaming Number) MSR is generated in the visitor database, which is 4. returned to the home database and 5. to the mobile switching center of the caller. With the help of this telephone number, the user connection is now switched to the destination switching center via static traffic routing tables as in the fixed network. The destination exchange requests 7. the visitor assigned to it The database now 8. Generates a search message. The temporary internal network address TMSI (Temporary Mobile Subscriber Identity) is generally used to address the terminal device, and 9. then calls the subscriber.

The subscriber then has the opportunity to report to the mobile switching center. If the subscriber answers within a certain time, 11. the user connection is switched through, otherwise the connection setup is interrupted.

As mentioned, different routing numbers are distinguished. On the one hand, this is the GSM number MSISDN, which the calling subscriber must know. The MSISDN is used as the directory number in the HLR. On the other hand, the subscriber is addressed within the network via the IM-SI, which is clearly assigned to the actual call number MSISDN in the HLR. After the first login, a temporary number TMSI is assigned to the air interface to protect the identity of the participant. This is changed each time the lounge area changes.

For calls from the digital fixed network, the first part of the routing in ISDN takes place via a gateway MSC GMSC until entry into the GSM network. The GMSC gets the route search information from the HLR to the location of the selected participant. It has a database and software that enables it to select the responsible HLR. The MSRN is a number that is used to establish a connection from the GMSC to the subscriber. visited MSC. This is temporarily assigned to a participant from a pool of numbers.

Location management in the GSM system consists of the following basic procedures:

a) First booking into the network with the IMSI, b) Change of the stay area, if necessary, periodic transmission of TMSI

Periodicity from 6 min. up to 24h or infinitely possible through network setting or broadcast

Periodic update if the databases need to be restored b) Switching the mobile station (Attach / Detach) IMSI on or off

IMSI Attach marks the participant in the VLR as an active message. IMSI Attach Request optional; in the broadcast the mobile station reports in an LA, in which the MS is already registered, e.g. B. after a brief switch-off of the MS

IMSI Detach marks the participant in the VLR as initative

IMSI Detach Indication message optional; in the broadcast, the mobile station sends SIM card before switching off or before removing the subscriber identification unit (Subscriber Identity Module), avoiding unnecessary paging c) Location cancellation from HLR to VLR for the purpose of changing the VLR after an LU d) Deregistration, which is currently not used

The course of an exemplary signaling connection is indicated for the location update LU in FIG. 3.

As soon as a mobile terminal exceeds the limit of a location area, which can be determined by monitoring the identifiers of the receivable radio stations, the terminal sends a message to update the location (location update). The mobile switching center then transfers the updated location area LA to the visitor database, which then transmits an entry about the updated location LOC to the home database.

Now there is a query for the entry of the participant data, then. after authentication and encryption of a reply, a confirmation to enter the participant data and finally a message from the home database to the visitor database that the update of the location has been entered. This information is now passed on from the visitor database to the mobile device via the mobile switching parts. In connection with this, a new temporary subscriber address (Temporary Mobile Subscriber Identity) TMSI is assigned. As soon as the mobile device has received this new subscriber address, a Confirmation transmitted back, which then goes from the mobile switching center to the visitor database.

In the case of registration after switching on, the same procedure is used as for the stay update. If the mobile terminal is already known in the visitor database, no signaling is exchanged with the home database.

The sequence of the signaling connection for paging is shown in FIG. 4.

The visitor database sends a signaling protocol (Base Station Subsystem Management Part (BSSMAP)) to all radio station controls BSCs with the IMSI or TMSI and the cell list via the responsible mobile switching center. The radio station controls then send radio station-specific control calls (radio subsystem management) RSM paging "to the radio stations BTS. Finally, the radio stations BTS send calls to the mobile terminal PAGING REQUEST on the specified radio channel for paging channel (PCH).

Fig. 5 shows a flow diagram of the steps which are carried out in the location management according to the invention.

In a first phase, the observation phase, movement data of the participant are recorded and compressed into movement profiles. Here, a static procedure with fixed, network-wide specifications is used for residence management Location and search areas used as it is currently used in the GSM network. A terminal sends a location update message if it exceeds a radio cell boundary, which at the same time represents the boundary of a location area.

Once enough data has been recorded to predict the location, the training phase begins. In the training phase, the estimation method used is trained with the recorded movement data so that a prediction can be made. The amount of data required and their accuracy depend on the forecasting method used. The training phase takes up a very short amount of time compared to the observation phase.

The prediction phase follows the training phase. In the prediction phase, in the event of an incoming call, the estimation method used is used to obtain estimates for the current location of the subscriber. The location is only calculated in the network in the event of an incoming call. In the terminal, on the other hand, which has the same data as the network, the location is calculated in the idle state each time the radio cell is changed. If the current location is not included in the result of the prediction, the terminal sends a location update message to the network. In the case of call operation, it is not necessary to update the location because the subscriber communicates with the network via the radio link and the whereabouts are known.

If the location cannot be predicted over a longer period of time, the location management method of the observation phase is used and a post-training phase may begin. A post-training phase becomes necessary if the participant has changed his movement habits in the long term.

FIG. 6 shows a schematic illustration of devices of a cellular mobile radio network modified with respect to FIG. 2 with a sketch of the determination of the location according to the invention. In contrast to FIG. 3, the home database does not ask the visitor database in a third step, but rather in a mobility computer which has been trained according to an algorithm on the basis of the movement data observed and is now performing a prediction. The subsequent search for the responsible mobile switching center and the calling of the subscriber can also be carried out with or without the involvement of the visitor database. The response of the subscriber is transmitted either to the home database or to the visitor database, depending on which database has sent the search message in question. Furthermore, the user connection is only established when the subscriber has registered.

A computer of the same type as the mobility computer determines the location in each terminal using the same algorithm. However, while the mobility calculator of the network as fixed device is activated only in the event of a connection establishment request, the internal computer of the terminal continuously predicts the location and compares it with the actual location. If there is a deviation, a location update is then transmitted to the mobility computer, similar to the description of FIG. 3. As a result, the mobility computer is able to specifically address the responsible mobile switching center with each connection establishment request and to have the subscriber called in the current search area.

Even if a participant behaves in accordance with his recorded local movement pattern, time tolerances are possible in which the individual recorded locations are reached during movement processes. It is within the scope of the invention that individual locations are assigned probabilities and are graded from the greatest to the lowest probability of the participants.

7 shows a schematic representation of a part of a cellular mobile radio network with search areas according to the invention modified in comparison with FIG. 1. The search areas are no longer statically defined, but are recalculated each time a connection is established to the mobile device. Individual cells that are not geographically contiguous can also be notified. In order to limit the signaling volume in the case of different probabilities of the locations, the search areas can sequentially descend from the largest to the smallest probability selected and the participant called there. FIG. 7 shows here how the search areas comprising individual cells are called out in succession in the first, second and third attempts. A notification is of course not required if the participant already reports after the first notification.

Claims

13 patent claims

1. A method for managing the location of a mobile terminal in a cellular mobile radio network by means of an estimation method which, based on a predetermined algorithm, determines the probable whereabouts based on a stored movement pattern of the mobile terminal and manages it for targeted signaling of the mobile terminal, characterized in that the same estimation method is used by both a stationary device of the mobile radio network and, in parallel, a device of the mobile terminal itself is used in such a way that the mobile terminal passively determines its actual location and compares the estimated location determined using the estimation method with the actual location and that the mobile terminal in the event of deviations correction information to the stationary device of the mobile between the estimated expected locations and the actual location radio network transmitted.

2. The method according to claim 1, characterized in that the correction information comprises the actual location.

3. The method according to claim 1 or 2, characterized in that the correction information comprises an updated movement pattern.

4. The method according to any one of claims 1 to 3, characterized in that the movement pattern comprises time, state, speed-dependent location information or a sub-combination of these.

5. The method according to any one of claims 1 to 4, characterized in that the passive determination of the location area of the mobile terminal is carried out by evaluating the field strengths and / or phase positions of the transmissions of the receivable radio stations and their identifiers.

6. The method according to any one of claims 1 to 5, characterized in that the passive determination of the location of the mobile terminal by a position determination system independent of the mobile network, such as the GPS system is carried out.

7. Cellular mobile radio network, which comprises stationary facilities for location management, of mobile terminals, which use an estimation method according to a defined algorithm to determine the probable locations due to stored movement patterns of registered mobile terminals and to manage the targeted signaling of the mobile terminals, characterized in that the stationary facility for location management in the event of deviations in the estimated expected locations of a terminal from the actual location receives correction information which is transmitted from the terminal concerned to the mobile radio network and which is thereby generated is that the same estimation method is also used in parallel by a device of the mobile terminals themselves, that the mobile terminals passively determine their actual location and compare the estimated whereabouts determined using the estimation method with the actual location and the correction information in the event of deviations between the estimated probable locations and generate and send the actual location.

8. Cellular cellular network according to claim 7, characterized in that the correction information includes the actual locations.

9. Cellular cellular network according to claim 7 or 8, characterized in that the correction information comprises updated movement patterns.

10. Cellular mobile radio network according to one of claims 7 to 9, characterized in that the movement pattern includes time, state, speed-dependent location information or sub-combinations thereof.

11. A mobile terminal for a cellular mobile radio network with a facility for managing the location of mobile terminals, the facility for managing the location using an estimation method which, based on a defined algorithm based on stored movement patterns of the mobile terminals, determines their likely locations and for targeted signaling of the mobile terminals. te managed, characterized in that the mobile terminal comprises a device in which the same estimation method is used in parallel as in the facility for location management, that the mobile terminal further comprises a device for the passive determination of its actual location and according to the estimation method compares the estimated location with the actual location and that the mobile terminal comprises a device which, in the event of deviations between the estimated location and the actual location, generates correction information and transmits it to the stationary device of the mobile radio network.

12. Mobile terminal according to claim 11, characterized in that the correction information comprises the actual whereabouts.

13. Mobile terminal according to claim 11 or 12, characterized in that the correction information comprises an updated movement pattern.

14. Mobile terminal according to one of claims 11 to 13, characterized in that the movement pattern includes time-, state-, speed-dependent location information or a sub-combination of these.

15. Mobile terminal according to one of claims 11 to 14, characterized in that the device for passively determining the location area, the field strengths and / or Evaluates the phase of the transmissions of the receivable radio stations and their identifiers.

16. Mobile terminal according to one of claims 11 to 15, characterized in that the device for the passive determination of the location area uses a position determination system which is independent of the mobile radio network, such as the GPS system.