WO2000047009A1

WO2000047009A1 - A method of defining a home zone of a cellular radio system

Info

Publication number: WO2000047009A1
Application number: PCT/FI2000/000062
Authority: WO
Inventors: Kimmo Aalto; Thomas Jul; Sören RIIS
Original assignee: Nokia Networks Oy
Priority date: 1999-02-01
Filing date: 2000-01-31
Publication date: 2000-08-10
Also published as: FI990183A; FI990183A0; AU2443200A

Abstract

The present invention relates to a cellular radio system comprising: a mobile services switching center (MSC), and a plurality of radio cells (BTS1-BTS3), each radio cell comprising means for establishing a communication path between the mobile services switching center and subscriber stations (MS, 1), located within the radio coverage area of the radio cell. In order to define a home zone for a subscriber station said system comprises a service positioning system (SPS) comprising means for providing a list of radio cells (BTS1-BTS3) as a response to location information (BTS3) fed into the service positioning system, said radio cells being located in the vicinity of a location (P) indicated by said location information, means for defining an initial home zone for a subscriber station (MS) to consist of the radio cells (BTS1-BTS3) included in said list provided by the service positioning system (SPS), monitoring means (IN) for monitoring the calls of said subscriber station (MS) and for storing into a memory means an identifier of the radio cell used for each such call, where the radio cell used for the call belongs to the initial home zone of the subscriber station (MS), and means for defining a home zone for said subscriber station to consist of the radio cells (BTS1, BTS3), which have their identifier stored in said memory means.

Description

A METHOD OF DEFINING A HOME ZONE OF A CELLULAR RADIO SYSTEM

The present invention relates to a solution for defining a home zone for a subscriber station of a cellular radio system. The subscriber station can be for instance a mobile telephone of a mobile communication system, such as the GSM system (Global System for Mobile communications), or for instance a WLL subscriber station (Wireless Local Loop) where a conventional telephone of a fixed telephone network is connected to a WLL-terminal which establishes a connection over a radio path between the telephone and a base station of the cellular radio system.

A home zone consists of a group of radio cells which cover, for instance, the geographical area in the vicinity of the home of the owner of the subscriber station. The information about the home zone of a specific subscriber station is stored into a register of the cellular radio system, such that the cellular radio system can find out whether or not the subscriber station is using a radio cell within its home zone when it is establishing a call. In a WLL-system, for instance, this information might be used to decide whether or not the call is allowed (the operator of a WLL system may wish to restrict the calls from a WLL subscriber station such that only calls from the home zone of the subscriber station are allowed). It is also possible, for instance in a GSM system, that the operator wishes to charge the calls of the subscriber station at different rates, depending on whether or not the call is made from the home zone or not (operators usually charge a call at a lower rate if the call is made from the home zone of the subscriber station). Usually the radio cells which are included in the home zone of a subscriber station are all neighboring cells whose radio coverage areas overlap with each other to some extent.

In known solutions a home zone has been defined for a given subscriber station in such a way that when the subscriber station is added to the system, an operator checks, e.g. by using a map, which radio cell is likely to cover best the geographical area which the user of the subscriber station wishes to select as the home zone. This radio cell and perhaps some of its neighboring cells are then defined as the home zone of the subscriber station.

The above mentioned prior art solution has, however, the drawback that the actual field strengths of the radio cells cannot be taken into consideration. The field strength of a radio cell may vary considerably within the radio cell, especially in urban areas where buildings interfere with the signal propagation. Thus the choosing of radio cells for the home zone may fail, if the cells are chosen exclusively on the basis of a map.

An object of the present invention is to provide a solution for defining a home zone for a subscriber station, which solution requires less time and resources, and which makes it possible to select the most appropriate radio cells with a greater accuracy than previously. This object is achieved with a method of defining a home zone for a subscriber station of a cellular radio system. Said method is characterized by the steps of: defining an initial home zone for said subscriber station based on location information supplied by the user of the subscriber station, said initial home zone consisting of a group of radio cells, monitoring the calls of said subscriber station and storing into a memory means an identifier of the radio cell used for each such call, where the radio cell used for the call belongs to said group of radio cells defined as the initial home zone of the subscriber station, and defining the home zone for said subscriber station to consist of the radio cells which have their identifier stored in said memory means.

Another object of the present invention is to provide a cellular radio system where the method of the present invention can be utilized such that the operator can define home zones for subscribers with less efforts and with a greater accuracy than in previous systems. This object is achieved with a cellular radio system comprising: a mobile services switching center, and a plurality of radio cells, each radio cell comprising means for establishing a communication path between the mobile services switching center and subscriber stations located within the radio coverage area of the radio cell. The cellular radio system of the present invention is characterized in that the system comprises: a service positioning system comprising means for providing a list of radio cells as a response to location information fed to the service positioning system, said radio cells being located in the vicinity of a location indicated by said location information, means for defining an initial home zone for a subscriber station to consist of the radio cells included in said list provided by the service positioning system, monitoring means for monitoring the calls of said subscriber station and for storing into a memory means an identifier of the radio cell used for each such call, where the radio cell used for the call belongs to the initial home zone of the subscriber station, and means for defining a home zone for said subscriber station to consist of the radio cells, which have their identifier stored in said memory means. The invention is based on the idea that considerable advantages are obtained with a solution where the defining of the home zone is made in two different phases. In a first phase an initial home zone is defined for the subscriber station. The initial home zone can be defined to include a large number of radio cells. Any radio cell that is located in the vicinity of the location indicated by location information obtained from the subscriber can be included in the initial home zone. When the initial home zone is defined, the actual behavior of the subscriber station is monitored. During the monitoring period information indicating which of the radio cells included in the initial home zone are actually used in calls made from said subscriber station is obtained and stored into a memory means. Thus it is possible, in the second phase, to define a home zone for the subscriber station, such that only those radio cells of the initial home zone which have actually been used by the subscriber station, are included in the home zone of the subscriber station. The present invention thus provides a solution where an initial, large home zone is defined at the beginning, and later on the size of the home zone is reduced to include only the necessary radio cells.

The most significant advantages of the solution of the present invention are that the actual radio coverage of the radio cells can be taken into consideration when cells for the home zone are selected, that no extra radio cells need to be included in the home zone, that the definition of the home zone can be automatic, i.e. the network elements of the radio system can automatically carry out the selection of the radio cells for the home zone, so the user of a subscriber station does not notice that a home zone is being defined for the subscriber station.

In a preferred embodiment of the present invention the calls from the subscriber station are monitored until said subscriber station has made a predetermined number of outgoing calls from said initial home zone. Thus the subscriber station may be used without any restrictions during the monitoring phase, and only the calls made from the initial home zone are registered and taken into consideration when the home zone of the subscriber station is eventually defined.

In a second preferred embodiment of the present invention the location information can be obtained from the the subscriber's address. Thus it is sufficient that the operator enters the subscriber address for instance into a subscriber register after which the location information, such as the postal code of the subscriber, can be fed from the subscriber register into the service positioning system.

In another preferred embodiment the service positioning system comprises means for providing a geographical map, for instance on a display of a computer terminal. In this embodiment the location information can be fed into the service positioning system such that a pointing device is used to point at the location of the subscribers home on said map.

In still another preferred embodiment the location information is fed into the service positioning system when the subscriber makes an initial call with the subscriber station. In this embodiment the location information is obtained from the cell identity of the cell used for making the initial call.

The preferred embodiments of the method and the cellular radio system of the present invention are disclosed in the attached dependent claims 2 and 4 -9. In the following, the invention will be described in more detail by means of a preferred embodiment and with reference to the accompanying drawings, in which

Figure 1 shows a flow diagram of a preferred embodiment of the method of the invention, Figure 2 shows a block diagram of a preferred embodiment of the cellular radio system according to the present invention, and

Figure 3 shows a map provided by a service positioning system in a preferred embodiment of the present invention.

Figure 1 shows a flow diagram of a preferred embodiment of the method of the invention. The flow diagram of Figure 1 can be used for instance for defining a home zone for a subscriber unit MS of a GSM system (Global System for Mobile communications). The home zone can be defined for instance if a new subscriber station is taken into use in the system. The flow diagram of Figure 1 can also be used if a new radio cell has been added to the system, in which case it will be necessary to define new home zones for all subscriber stations which have their home zone located in the vicinity of the new radio cell.

In block A, location information is obtained for the subscriber station in question. There are at least three different ways to obtain the location information and feed it into the system: 1 ) The location information is obtained from the address of the subscriber. In this embodiment, the postal code of the subscriber's home address, for instance, is used to identify the location where the home zone should be located, and also to identify the identifier of a radio cell covering said location.

2) The location information is obtained by using a map where the coverage areas and the identifiers of the radio cells are indicated. In this embodiment the identifiers of the radio cells covering the location where the home zone should be located are obtained from the map. The address of the user of the subscriber unit is thus used to find the correct location on the map and then a radio cell identifier is read from the map.

3) The user of the subscriber unit is instructed to make an initial call from a location which should be covered by the home zone. The radio cell used for making the initial call can thus be identified by the cellular radio system. The subscriber may be instructed to make the initial call to a specific service number, for instance such that the system is able to identify the call as an initial call. Alternatively, the subscriber may be instructed that he has to make his first call from the geographical location which should be covered by the home zone. In block B, an initial home zone is defined for the subscriber unit based on the obtained location information. All radio cells located in the vicinity of the location indicated by the location information are included in the initial home zone. The number of radio cells in the initial home zone should be large in order to ensure that all possible radio cells that might be needed in the home zone are included.

In block C, the monitoring of the subscriber station is started. During the monitoring phase the system monitors all outgoing calls from the subscriber unit. If it is detected in block D that the radio cell used for a call belongs to the initial home zone of the subscriber unit in question, the cell identifier is stored into a memory means in block E.

In block F, a check is made in order to find out if a predetermined number of radio cell identifiers has been stored into the memory means. If the predetermined limit value has been reached, then block G is entered.

In block G, a home zone is defined for the subscriber station, such that the home zone includes those radio cells whose identifiers have been stored into the memory means. The size of the initial home zone has thus been reduced such that the (final) home zone includes only those radio cells which actually have been used by the subscriber station.

Figure 2 shows a block diagram of a preferred embodiment of the cellular radio system according to the present invention. The cellular radio system of Figure 2 can be for instance a GSM system, which is used both by ordinary mobile telephones MS and WLL subscriber units 1. The WLL subscriber unit 1 of Figure 2 consists of a WLL terminal that provides a communication path between the cellular radio system and an ordinary telephone. The cellular radio system of Figure 2 includes a mobile services switching center MSC, a base station controller BSC, and base stations BTS1 and BTS2. The cellular radio system of Figure 2 further comprises a Home Location Register HLR and a Visitor Location Register VLR for storing subscriber data. The cellular radio system of the invention shown in Figure 2 is provided with a Subscriber Positioning System SPS and an IN (Intelligent Network) server, which can be used when a home zone is defined for one of the subscriber units. The SPS receives information about the radio coverage areas of the cellular radio system from the Network Planning System NPS, which is a part of the Network Management System NPS in the embodiment of Figure 2. The Network Planning System NPS in Figure 2 includes information about the actual radio coverage areas of the different radio cells. This information may be based on measurement results, for instance. The NPS also contains information about the radio cell identifiers and the location of the different radio cells.

The SPS also receives address information from a Geographic Information System GIS. The Geographic Information System GIS is also a part of the Network Management System NMS in the embodiment of Figure 2. The SPS comprises means for combining the information obtained from the GIS and the NPS, together with location information fed into the SPS in order to provide a list of radio cells located in the vicinity of the location indicated by the location information. This can be done in at least three alternative ways. 1) The operator enters a new subscriber station MS into the system. This means that the subscriber data, which includes the address of the subscriber, is fed into a register for storing subscriber data. The address is retrieved from said register and fed into the SPS. The SPS uses the information obtained from the GIS to obtain, for instance, the coordinates of the address. The SPS then uses the coordinates to obtain a list of radio cells which according to the NPS are located in the vicinity of said coordinates. Thus a list of radio cells is obtained.

2) When a new subscriber station MS is entered into the system, the operator activates the SPS over a computer terminal. The SPS then provides a map on the display of said terminal based on information obtained from the GIS. Also the radio cells and their coverage areas are shown on said map. The information about the radio cells is obtained from the NPS. Thus the operator will have a map like the one shown in Figure 3 on the display of his terminal. After this the operator uses a pointing device, such as a mouse for instance, to indicate the home of the subscriber on said map. The location P in Figure 3 is thus entered into the SPS as location information for the subscriber station. The SPS is then able to determine that radio cells BTS1 , BTS2 and BTS3 are located in the vicinity of the location P, and said radio cells are thus included in the list of radio cells provided by the SPS.

3) The data about a new subscriber station MS is fed into the system, and the subscriber is instructed to make an initial call from his home, for instance to a predetermined service number. When the subscriber station MS makes the call to the service number, the radio cell identifier is retrieved from the system to the SPS. The SPS observes that the radio cell BTS3 has been used for the call. The SPS system is then able to determine from the information in the GIS and NPS that the radio cells BTS1 and BTS2 are also located in the vicinity of the location indicated by the location information (the identifier of the radio cell BTS3). The SPS therefore provides a list of the radio cells BTS1 , BTS2 and BTS3.

After the SPS has provided the list of the radio cells BTS1-BTS3, the SPS stores the list as an initial home zone into the IN server. From that moment the IN server begins to monitor the calls of the subscriber station MS. During the monitoring phase, the IN server stores the identifier of the used radio cell into a memory means each time the IN server discovers that the subscriber station MS has made a call from its initial home zone. When a predetermined number of identifiers is stored into said memory means then a home zone is defined to consist of those radio cells whose identifiers are stored into said memory means. In practice this means that the size of the initial home zone is reduced, the "final" home zone only including those radio cells of the initial home zone that actually have been used by the subscriber station MS during the monitoring phase. In the case of Figure 3, the final home zone of the subscriber station may include the radio cells BTS1 and BTS3 that cover best the location P.

The cellular radio system of the present invention also offers the possibility to automatically redefine the home zones of a subscriber station, for instance, in order to take into account the effects of a new radio cell. This can be done for instance such that a new initial home zone is defined for the subscriber station to consist of all radio cells of the previous (final) home zone and of any radio cells located in the vicinity of the previous home zone. Then a new monitoring phase is entered, and after said new monitoring phase, a new home zone can be defined to consist of the radio cells of said initial home zone that have been used during the monitoring phase. Figure 3 shows a map provided by a service positioning system

SPS in a preferred embodiment of the present invention. In this embodiment the SPS receives the information needed for producing a map from a Geographic Information System GIS. Also address information may be included in the information which is fed from the GIS into the SPS. The SPS also receives information about the radio cell coverage areas from the Network Planning system NMS of the cellular radio system. Thus the SPS is able to produce a map, as indicated in Figure 3, including both objects in the environment, such as houses, mountains and lakes, and information about the field strengths of the different radio cells. This makes it possible to identify the radio cells which are located, for instance, in the vicinity of the subscriber's home in order to define an initial home zone for the subscriber station used by said subscriber.

It should be understood that the above description and the enclosed drawings are only intended to illustrate the present invention by way of examples. Thus it is possible, for instance, that instead of using the IN server for monitoring the subscriber station and the SPS to control the defining of a home zone, some other network elements of the cellular radio system may be used for these purposes when a home zone is defined for a subscriber station. Also other variations and modifications can be made to the above described solution without departing from the scope and spirit of the invention as disclosed in the attached claims.

Claims

Claims:

1. A method of defining a home zone for a subscriber station of a cellular radio system, c h a r a c t e r i z e d b y the steps of: defining an initial home zone for said subscriber station based on location information supplied by the user of the subscriber station, said initial home zone consisting of a group of radio cells, monitoring the calls of said subscriber station and storing into a memory means an identifier of the radio cell used for each such call, where the radio cell used for the call belongs to said group of radio cells defined as the initial home zone of the subscriber station, and defining the home zone for said subscriber station to consist of the radio cells which have their identifier stored in said memory means.

2. A method according to claim ^ c h a r a c t e r i z e d in that the calls of said subscriber station are monitored until said subscriber station has made a predetermined number of outgoing calls from said initial home zone.

3. A cellular radio system comprising: a mobile services switching center (MSC), and a plurality of radio cells (BTS1-BTS3), each radio cell comprising means for establishing a communication path between the mobile services switching center and subscriber stations (MS, 1) located within the radio coverage area of the radio cell, c h a r a c t e r i z e d in that the system comprises: a service positioning system (SPS) comprising means for providing a list of radio cells (BTS1-BTS3) as a response to location information (BTS3) fed to the service positioning system, said radio cells being located in the vicinity of a location (P) indicated by said location information, means for defining an initial home zone for a subscriber station (MS) to consist of the radio cells (BTS1-BTS3) included in said list provided by the service positioning system (SPS), monitoring means (IN) for monitoring the calls of said subscriber station (MS) and for storing into a memory means an identifier of the radio cell used for each such call, where the radio cell used for the call belongs to the initial home zone of the subscriber station (MS), and means for defining a home zone for said subscriber station to consist of the radio cells (BTS1, BTS3), which have their identifier stored in said memory means.

4. A cellular radio system according to claim 3, characterized in that said means for defining the home zone are adapted to define the home zone for said subscriber station (MS) when said subscriber station (MS) has made a predetermined number of calls from radio cells that belong to the initial home zone of the subscriber station.

5. A cellular radio system according to claim 3 or 4, characterized in that said service positioning system (SPS) comprises: means for receiving information regarding the radio coverage areas of the radio cells from a network planning system (NPS), means for receiving address information from a geographic information system (GIS), and processing means for combining the information obtained from said network planning system (NPS) and geographic information system (GIS) in order to obtain a list of radio cells (BTS1-BTS3) as a response to location information fed into said service positioning system.

6. A cellular radio system according to any one of claims 3 to 5, characterized in that said location information fed into the service positioning system consists of information obtained from the subscriber's address.

7. A cellular radio system according to any one of claims 3 to 5, characterized in that said service positioning system comprises means for providing a geographical map, and that said location information is fed into the service positioning system by pointing at a location on said geographical map with a pointing device.

8. A cellular radio system according to claim 7, characterized in that the radio cell identities and the field strengths of the radio cells at different locations are indicated on said geographical map.

9. A cellular radio system according to any one of claims 3 to 5, characterized in that that said monitoring means (IN) are adapted to monitor an initial call made by said subscriber station (MS) and to register the cell identity of the radio cell (BTS3) used for said initial call, and that said location information fed into the service positioning system (SPS) consists of said registered cell identity.