LOCATION UPDATING IN THE CELLULAR RADIO NETWORK

Abstract: The invention relates to a cellular radio network and a mobile radio station. At least part of the mobile stations (MS) are capable of moving, except in a primary network, in at least one other network (BCPN1-2, DCPN1-2) having a location area configuration different from that of the primary network. By means of the invention, the user may prevent manually all location updatings and location updating attempts between the different networks and thus temporarily "lock" the use of the mobile station within a particular network. Not even a location updating attempt into a "foreign network" is made. It is up to the user of the mobile station (MS) to decide when he activates the registration function. The locking function remains activated until deactivation by the user. Subsequent to the deactivation, location updatings between the networks are performed in a normal manner.

Description: Location updating in the cellular radio network Field of the Invention The invention relates to a cellular radio net- work and especially to an improved location updating in cellular networks. Background of the Invention Base stations of a cellular radio network broadcast information of themselves and their envi¬ ronment continuously. Such network configuration in¬ formation may contain for instance a location area identifier, a base station identifier, a base station type identifier and a so-called neighbouring cell information. When being currently registered to a base station of a particular cell, a mobile station also monitors the quality of the transmission of the base stations indicated by the neighbouring cell in¬ formation of the current base station and moves to some of these base stations, if the field strength of the present base station becomes lower. The cellular network knows the location of the mobile station usu¬ ally with an accuracy of a so-called location area, to which belongs a suitable number of predetermined cells with their base stations. The location area information sent by the base station indicates to the mobile station to which location area the base sta¬ tion belongs. When the mobile station moves to an¬ other cell within the same location area, no location updating is needed in the cellular network. On the other hand, upon observing on the basis of location area information a change of location area when mov¬ ing to a coverage area of a new base station, the mobile station initiates a location updating by send- ing a location updating request to the cellular net- work. As a consequence of this location updating re¬ quest, the cellular network stores the new location area of the mobile station in subscriber registers. In future, it is conceivable that both public cellular networks maintained by different operators and several kinds of private Customer Premises Net¬ works (CPN) are utilized, such as for instance Busi¬ ness Customer Premises Networks (BCPN), Domestic Cus¬ tomer Premises Networks (DCPN) and Mobile Customer Premises Networks (MCPN). In such a situation, it would be preferable for the service of the networks that a mobile station would be capable of registering automatically or manually to these different net¬ works. The public cellular networks and the CPNs would have separate location area structures. The amount of location updatings would be high in such an environment, with the user moving from one place to another. In particular areas of the network, for in¬ stance at the edges of a private cellular network, signals of the other networks are so strong that a mobile station may try to initiate the location up¬ datings to an external network. Such location updat¬ ings are unnecessary and annoying when the user wishes to remain registered within the area of a par- ticular network, irrespective of received signal level, for instance. Moreover, unnecessary location updatings and location updating attempts cause an un¬ reasonable increase of the signalling load of the network. Disclosure of the Invention The object of the present invention is to re¬ duce unnecessary location updatings and location up¬ dating attempts and thereby unnecessary signalling in a cellular radio network having a plurality of sub- networks. According to one aspect of the invention, a cellular radio network, comprising a primary network having a first location area configuration, mobile radio stations capable of moving in the primary net¬ work from one location area to another, a mobile sta¬ tion starting a location updating procedure in the cellular network each time a changeover from one lo¬ cation area of the primary network to another is ob- served, is characterized in that at least part of the mobile stations are capable of moving, except in the primary network, in at least one other network having a second location area configuration differing from said first location area configuration, and that the mobile radio station comprises means, which, when activated by the user, temporarily prevent the mobile radio station from initiating location updatings to other networks from the network used at the time of activation. Another aspect of the invention is a mobile radio station for a cellular radio network, compris¬ ing a primary network having a first location area configuration, the mobile radio station being capable of moving in the primary network from one location area to another and starting a location updating pro¬ cedure in the cellular network each time a changeover from one location area of the primary network to an¬ other is observed, characterized in that the mobile station is capable of moving, except in the primary network, in at least one other network having a sec¬ ond location area configuration differing from said first location area configuration, and that the mobile radio station comprises means, which, respon¬ sive to an activation by the user, temporarily pre- vent the mobile station from initiating location up- datings to other networks from the network used at the time of activation. By means of the invention, the user may, if de¬ sired, prevent manually all location updatings and location updating attempts between the different net¬ works and thus temporarily "lock" the use of a mobile station within a particular network area. The locking of location updatings between networks means that the user may move in the network selected by him from a location area to another, but location updatings from one -network to another (e.g. from a BCPN or DCPN to a public network or vice versa, or between public net¬ works) are not performed under any circumstances. Not even an attempt is made to update locations into a "foreign network". The user of the mobile station is entitled to decide when he activates a locking func¬ tion. For performing a locking function, the mobile station shall be capable of distinguishing the vari¬ ous networks from each other, which may occur for in- stance by means of a network-specific "locking code" sent by the base stations of the network, whereby all base stations of the same network send the same lock¬ ing code. Alternatively, a network identifier may be included in the information sent by the base stations already or it may be derived from that. With the locking function activated, the mobile station moni¬ tors a change of location area and starts updating the location, if the locking code or the network identifier remains unchanged, but does not perform location updating, if the locking code or the network identifier changes. The locking function remains ac¬ tivated until the user deactivates it, and after that all location updatings between the networks are per¬ formed in a normal manner. By means of the invention, unnecessary location updatings and location updating attempts between net¬ works are prevented and signalling resources and pro¬ cessing capacity of a cellular radio network are saved. A Brief Description of the Drawings The invention will be explained below by means of illustrative embodiments referring to the attached drawing, in which Figure 1 illustrates one cellular radio network according to the invention and Figure 2 is a general block diagram of one mobile station. A Detailed Description of the Invention The present invention may be applied in any cellular radio system, as for instance a digital GSM mobile telephone system, an NMT (Nordic Mobile Tele¬ phone), a DCT1800, a PCN (Personal Communication Net- work), a UMC (Universal Mobile Communication), a UMTS (Universal Mobile Telecommunication System), an FPLMTS (Future Public Land Mobile Telecommunications System), etc. As is well-known, the geographic area covered by a cellular radio network is divided into smaller separate radio areas, i.e. cells, in such a way that a Mobile Station MS, when being in a cell, communi¬ cates with the network via a fixed radio station po¬ sitioned in the cell, i.e. via a Base Station BS. The radio stations MS belonging to the system may roam freely in the system area from one cell to another. However, the cellular radio network maintains files of the location of the mobile station MS in order to be able to route calls terminating to the MS or to page it for some other reason. The cellular network typically knows the location of the MS with an ac¬ curacy of an area formed by one or a plurality of cells, which area is generally called location area. The base stations of a cellular network broad- cast continuity information of themselves and their surroundings, such as a Location Area Identifier (LAI), a Base Station Identifier (BSI), a Base Sta¬ tion Type Identifier (BSTI) and so-called neighbour¬ ing cell information. On the basis of the neighbour- ing cell information broadcast by respective base station BS, an MS registered to a cell knows the neighbouring cells the transmission of the base sta¬ tions of which the MS should monitor. With weakening field strength of the present base station BS, the MS is registered to the best of these monitored neigh¬ bouring base stations. On the basis of the location area identifier (LAI) of the base station, the MS knows to which location area the base station BS be¬ longs. If the MS observes a change of LAI simultane- ously with a change of base station BS, i.e. a change of location area is observed, the MS initiates loca¬ tion updating by sending a location updating request to the cellular network. If the location area does not change, the MS does not perform a location updat- ing. A location updating causes an updating of sub¬ scriber data in a subscriber register/subscriber reg¬ isters of a cellular network. In a GSM system, for instance, the cellular network contains at least a Home Location Register HLR, Visitors Location Regis¬ ters VLR, mobile telephone exchanges MSC and Base Station Controllers BSC, which are connected to the base stations BS of the network. Subscriber location area data are stored in a Visitors Location Register VLR, the number of these registers being typically one per each mobile telephone exchange. The HLR knows the VLR in the area of which the subscriber is cur¬ rently located. As for this, the structure and opera¬ tion of the GSM system are described in more detail in Finnish Patent 921074, for example. Figure 1 presents a cellular radio network ac¬ cording to the invention, comprising a so-called pub¬ lic primary network and Customer Premises Networks (CPN) of several kinds, such as for instance Business Customer Premises Networks (BCPN), Domestic Customer Premises Networks (DCPN) and Mobile Customer Premises Networks (MCPN). For the sake of clarity, Figure 1 shows only two BCPNs and two DCPNs, the areas and base stations BS of which are illustrated by broken lines, and a group of primary network base stations BS around these CPNs. The public cellular network, i.e. the primary network, may be a conventional mo¬ bile telephone network, which offers the same ser¬ vices to all customers within the operating area of the entire cellular network. The CPNs again may be any other cellular networks situated in the area of the primary network or bounded by the primary network at its edges. Such CPNs are typically private, for instance business or corporation systems, and their radio coverage areas cover a relatively local area, e.g. a building site, a building or part thereof, such as one floor or office. Such CPNs may also be called small, sub, local or complementary networks, depending on their configuration and relation to the primary network in each particular case. As to the invention, the configuration of these other networks is not essential, if only at least part of the sub¬ scribers are able to use both the primary network and at least one CPN. As stated earlier, the primary network and each CPN have separate location area structures, i.e. se¬ parate location areas. From this follows that the number of location updatings increases considerably in this kind of network environment with a mobile station MS moving from one place to another. Part of the location updatings and location updating attempts are unnecessary and undesired for the user and in¬ crease the signalling load of the network without cause. In particular areas of the network, for in- stance at the edge of a private network, signals of other networks are so strong that the MS may try to perform a location updating to an external network. Such location updatings are unnecessary and annoying when the user desires to remain registered in the area of a particular network irrespective of the re¬ ceived signal level or other criteria. The user may, if he desires, prevent manually all location updat¬ ings and location updating attempts between the dif¬ ferent networks and thus lock the use of the mobile station MS temporarily within the area of a parti¬ cular network. The locking prevents location updat¬ ings between the networks so that the MS may roam in a selected network from a location area to another, but location updatings from one network to another (e.g. from a BCPN or DCPN to a public network or vice versa, or between two public networks or between two private networks) are not performed under any cir¬ cumstances. Not even an attempt is made to update the location to a "foreign network". The user of the mobile station MS is entitled to decide when he activates the locking function of location updating. The user may wish to remain in a particular network for instance for charging reasons in order to be able to utilize special services of- fered by this particular network or to prevent un- necessary location updatings. The locking is acti¬ vated manually e.g. by means of a key function or a function code, if the mobile station MS is provided with a particular function code for such a locking function. To perform the locking function, the MS shall be capable of distinguishing the different networks from each other, which can be carried out for in¬ stance in such a manner that the base stations BS of the cellular network broadcast, except the identifi¬ ers LAI, BSI, BSTI etc. mentioned earlier, also a network-specific "locking code". Thus all base sta¬ tions of the same network broadcast the same locking code. In Figure 1 for instance, the base stations BS of the public primary network send a locking code (1000), the BCPN- sends a locking code (0111), the BCPN 2 sends a locking code (1001), the DCP^ sends a locking code (0101) and the DCPN 2 sends a locking code (1111). Another alternative is that the information broadcasted by the base stations BS contains the identifier of that network to which the base station belongs or said identifier may be derived from the broadcasted information. Such an identifier may be formed for instance by means of the Base Station Identifier BSI and the Base Station Type Identifier BSTI. When the user activates, preferably manually, the locking function of location updating of an MS, the MS stores the locking code sent by the current BS or the identifier of the network in a memory. In Fig¬ ure 1 for instance, the MS locked to the BS of the BCPN 2 stores the locking code (1001 ) of said network in the activation situation. To facilitate the proce- dure of being locked to a correct network, the net- work used at present may be indicated by the MS to the user in a suitable manner, e.g. by presenting the name of the network on the display, by means of par¬ ticular indicator lights, etc. When the MS after this moves in the area of the BCPN 2 , it still observes the information sent by other networks, e.g. the primary network and the base sta¬ tions BS of the BCPNi. The MS monitors in a normal manner the quality of signals sent by the neighbour- ing base stations BS and selects, when the field strength of the present base station becomes weaker, on the basis of predetermined criteria a new base station to which it might register to. If the Loca¬ tion Area Identifier LAI received from the new base station BS is the same as that of the present base station, the location area does not change and a base station handover may be performed normally. If the MS observes that the location area identifier received from the new base station differs from the location area identifier LAI of the present base station BS, i.e. it observes a change of location area, the MS does not start updating the location immediately, but compares the stored locking code/network identifier at first with the locking code/network identifier received from the new base station ' . If the stored locking code/network identifier and the received locking code/network identifier are identical, the MS initiates the location updating, because the area in question is still the same network area to which the location updating is locked. If the stored locking code/network identifier differs from the received locking code/network identifier, the MS identifies the new base station BS as a base station of a "for¬ eign network" and the location updating is not ini- tiated. In Figure 1 for instance, the locking of lo- cation updating is activated by MS in the network BSPN 2 , and consequently, the MS performs a location updating when it moves from a base station to another within the BCPN 2 , but does not under any circumstances perform a location updating for instance via the base stations of the primary network (locking code 1000) or the base stations of the BCPN X (locking code 0111), since they have different locking codes. The locking function may be a voluntary func- tion, which is not necessarily supported by all net¬ works, and for this reason, they do not broadcast any locking code at all. In such a situation the MS, in which the locking of location updating is activated, interpretes the missing locking code as a different code and does not initiate the location updating. If a location updating is prevented according to the invention at some base station, the MS remains registered to the present base station or selects by means of specific criteria the next best base station and takes the measures according to the invention also for this new base station. The locking of location updating remains acti¬ vated, until the user deactivates it. After the deac¬ tivation of the locking, all location updating at- tempts also between different networks are performed in a conventional manner. When comparing the above alternative manners of implementation, the use of locking code may be con¬ sidered more limited, because it lengthens messages sent by the base station BS and a locking code cannot actually be used for other purposes. For the MS, it may be the more uncomplicated alternative. Another case, in which the network indentifier can be derived from the base station identifier BSI, for instance, is preferable, because the base station identifier is generally utilized for other functions as well and is thus sent anyway. The cellular network is thus not supposed to have any new functionality, but the im¬ plementation of the locking function depends on the functionality of the mobile station MS only. For the MS, this alternative may be more complicated. How¬ ever, the function according to the invention can be implemented in both cases also in mobile terminals available at present by relatively minor changes in software. Figure 2 shows a general block diagram of one mobile station MS, to which the invention may be ap¬ plied. The MS comprises a transceiver 21 connected to an antenna 27, in which transceiver the receiver is connected via digital-analog and base frequency cir¬ cuits 23 to a loudspeaker 25 and in which the trans¬ mitter is connected via analog-digital converter and base frequency circuits 24 to a microphone 26. The operation of the MS is controlled by a microprocessor 22 processing the signalling sent and received by the transceiver. A user interface comprises a display 28 and a keyboard 29, which are connected to the micro¬ processor 22. The invention may be realized by chang¬ ing the software of the microprocessor 22 in such a way that it performs the inventive functions de¬ scribed above. The figure and the description associated with it are only intended to illustrate the present inven¬ tion. As to the details, the cellular radio network according to the invention may vary within the scope and spirit of the attached claims.

Claims: Claims: 1. A cellular radio network comprising a primary network having a first location area configuration, mobile radio stations (MS) capable of moving in the primary network from one location area to an¬ other, a mobile station starting a location updating procedure in the cellular network each time a change- over from one location area of the primary network to another is observed, c h a r a c t e r i z e d in that at least part of the mobile stations (MS) are capable of moving, except in the primary network, in at least one other network (BCPN1-2, DCPN1-2) having a second location area configuration differing from said first location area configuration, and that the mobile radio station (MS) comprises means (22), which, when activated by the user, temporarily prevent the mobile radio station from initiating lo¬ cation updatings to other networks from the network used at the time of activation. 2. A cellular radio network according to claim 1, c h a r a c t e r i z e d in that said at least one other network comprises at least one complemen¬ tary network (BCPN1-2, DCPN1-2) having a second loca¬ tion area configuration differing from said first location area configuration, and that the mobile radio stations (MS) are capable of moving in the pri- mary network and said at least one complementary net¬ work (BCPN1-2, DCPN1-2) and between them. 3. A cellular radio network according to claim 1 or 2, c h a r a c t e r i z e d in that the base stations (BS) of the primary network and the base stations (BS) of said at least one other network (BCPN1-2, DCPN1-2) send network configuration infor¬ mation, and that a network identifier is contained in or derived from said network configuration informa¬ tion and that a mobile station (MS) is capable of distinguishing the location areas of the primary net¬ work and said at least one other network from each other by means of said network identifier. 4. A cellular radio network according to claim 1, c h a r a c t e r i z e d in that means (22) for preventing location updating are responsive to a manual activation by the user for storing a network identifier of the current network in a memory, the means (22) for preventing location updating are responsive to an observation of a change of loca¬ tion area for comparing the stored network identifier with a network indentifier received in the network configuration information from the base station of the new location area and a) for allowing location updating if the net¬ work identifiers are identical, b) for preventing location updating if the net¬ work identifiers are different. 5. A cellular radio network according to claim 1, c h a r a c t e r i z e d in that a transmission of the base stations (BS) of the primary network con¬ tains a first locking code and a transmission of the base stations (BS) of said at least one other network (BCPN1-2, DCPN1-2) contains a second locking code, and that said preventing means (22) of the mobile station (MS) are capable of distinguishing the loca¬ tion areas of the primary network and said at least one other network from each other by means of said locking codes. 6. A cellular radio network according to claim 5, c h a r a c t e r i z e d in that the means (22) for preventing location updating are responsive to a manual activation by the user for storing the locking code sent by the present network in a memory, the means (22) for preventing location updating are responsive to an observation of a change of loca¬ tion area for comparing the stored locking code with a locking code received from the base station of the new location area and a) for allowing location updating if the lock¬ ing codes are identical, b) for preventing location updating if the locking codes are different or the base station of the new location area sends no locking code at all. 7. A cellular radio system according to claim 1, c h a r a c t e r i z e d in that with the means (22) for preventing location updating unactivated, the mobile station (MS) initiates a location updating procedure each time when it moves from one location area to another. 8. A mobile radio station (MS) for a cellular radio network comprising a primary network having a first location area configuration, the mobile radio station (MS) being capable of moving in the primary network from one location area to another and start¬ ing a location updating procedure in the cellular network each time a changeover from one location area of the primary network to another is observed, c h a r a c t e r i z e d in that the mobile station (MS) is capable of moving, except in the primary network, in at least one other network (BCPN1-2, DCPN1-2) having a second location area configuration differing from said first location area configuration, and that the mobile radio station (MS) comprises means (22), which, responsive to an activation by the user, temporarily prevent the mobile station from initiat¬ ing location updatings to other networks from the network used at the time of activation. 9. A mobile radio station according to claim 8, c h a r a c t e r i z e d in that the means (22) for preventing location updating are capable of distin¬ guishing the location areas of the different networks from each other by means of different locking codes sent by the base stations of the primary network and said at least one other network, the means (22) for preventing location updating are responsive to a manual activation by the user for storing a locking code sent by the present network in a memory, and that the means (22) for preventing location updating are responsive to an observation of a change of loca¬ tion area for comparing the stored locking code with a locking code received from the base station of the new location area and a) for allowing location updating if the lock¬ ing codes are identical, b) for preventing location updating if the locking codes are different or the base station of the new location area sends no locking code at all. 10. A mobile radio station according to claim 8, c h a r a c t e r i z e d in that the mobile radio station (MS) is capable of distinguishing the location areas of the primary net¬ work and said at least one other network (BCPN1-2, DCPN1-2) from each other by means of a network iden¬ tifier contained in or derived from the network con¬ figuration information sent by the base stations (BS), the means (22) for preventing location updating are responsive to an activation by the user for stor¬ ing the identifier of the present network in a memory, and that the means (22) for preventing location updating are responsive to an observation of a change of loca¬ tion area for comparing the stored network identifier with a network identifier received from the network configuration information sent the base station of the new location area and a) for allowing location updating if the net¬ work identifiers are identical, b) for preventing location updating if the net¬ work identifiers are different.

Inventors: KAUPPI HANNA-MARIA, KAUPPI, HANNA-MARIA
Applicants: KAUPPI HANNA MARIA, NOKIA TELECOMMUNICATIONS OY
Application year: 1993
Main classification: H04B7
IPC codes: H04W8, H04W12, H04W60