Mobile communications system and mobile station therefor

• US 6,363,255 B1
• Filed: 10/04/1999
• Issued: 03/26/2002
• Est. Priority Date: 10/26/1998
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kuwahara, Soichi
• Primary Examiner(s): Legree, Tracy
• Assistant Examiner(s): GELIN, JEAN ALLAND
• Application Number:
  US09/411,073
• Time in Patent Office: 904 Days
• Field of Search: 455/422, 455/423, 455/425, 455/432, 455/433, 455/434, 455/435, 455/436, 455/439, 455/440, 455/450, 455/452, 455/456-457, 455/458-464, 455/517, 455/519, 455/525, 455/459, 455/67.1, 455/556, 455/560, 455/575, 370/336, 370/335, 370/331
• US Class Current: 455/456.5
• CPC Class Codes: H04W 60/04 using triggered events
• CPC Class Codes: H04W 68/04 multi-step notification using statistical or historical mobility data
• CPC Class Codes: H04W 68/06 using multi-step notification by changing the notification area

Abstract

A mobile communications system having a mechanism to reduce the control message traffic in paging and location updating operations. Each mobile station receives from the nearest base station a notification message containing its base station ID. A location change counting unit detects a change in the mobile location by comparing two consecutive instances of the base station ID. It counts and records such location changes, together with the two base station IDs involved in each change. Based on the location change count values, a personal location area (PLA) setting unit defines personal location areas by grouping associated cells into one area. A PLA memory stores the defined personal location areas and relevant base station IDs. Each time a new base station ID is detected, a location change detector tests whether the presently registered personal location area is still valid. If it is no longer valid, a location registration unit searches the PLA memory for a new relevant personal location area. The location registration unit then sends a location updating message to notify the mobile switching center of the new personal location area and its relevant base station IDs.

Claims

1. A mobile communications system where base stations provide radio links for mobile stations in each cell and a mobile switching center controls connections between the mobile stations by switching circuits, the system comprising:

notification message reception means, disposed in each mobile station, for receiving a notification message from the nearest base station;

base station ID extracting means, disposed in each mobile station, for extracting a base station ID from the received notification message to identify which base station is sending the notification message;

location change counting means, disposed in each mobile station, for detecting location changes by comparing two consecutive instances of the base station IDs extracted by said base station ID extracting means, and counting the detected location changes separately for each pair of base station IDs involved in the changes;

personal location area (PLA) setting means, disposed in each mobile station, for defining personal location areas by grouping associated cells into one area, based on the location change count values obtained by said location change counting means;

.

PLA memory means, disposed in each mobile station, for storing records of the personal location areas defined by said PLA setting means, each of the records containing the base station IDs indicating which cells constitute each personal location area;

location change detecting means, disposed in each mobile station, for testing whether the personal location area registered at present is valid, each time said base station ID extracting means extracts a base station ID that is different from before;

location registration means, disposed in each mobile station and activated when said location change detecting means has detected that the registered personal location area is no longer valid, for searching said PLA memory means to retrieve one of the records of personal location areas that contains the extracted base station ID, and performing location registration by sending to the mobile switching center the retrieved personal location area and base station IDs relevant thereto;

PLA configuration data storage means, disposed in the mobile switching center, for storing records of the personal location area and relevant base station IDs received from each mobile station; and

paging means, disposed in the mobile switching center and responsive to an incoming call to one of the mobile stations, for searching said PLA configuration data storage means to retrieve one of the records that is relevant to the called mobile station, and paging the called mobile station through the base stations specified in the retrieved record.

2. The mobile communications system according to claim 1, wherein said personal location area setting means extracts such mobile station ID pairs that exhibit larger location change count values exceeding a predetermined threshold, and defining the personal location areas by grouping the mobile station ID pairs having a predetermined relationship.

3. The mobile communications system according to claim 1, wherein said location registration means performs location registration by using network default location areas that the system provides, if no relevant personal location area is found in said PLA memory means.

4. The mobile communications system according to claim 1, wherein:

each of the mobile stations comprises real-time clock means for providing date and time information, and

said PLA setting means refers to the date and time information provided by said real-time clock means to update the definitions of the personal location areas at predetermined intervals.

5. The mobile communications system according to claim 1, wherein:

said mobile switching center further comprises minimum/maximum number notification means for notifying the mobile stations of parameters specifying suitable size of each personal location area, the parameters including minimum and maximum numbers of cells to be grouped into one personal location area; and

said PLA setting means uses the minimum and maximum numbers of cells to define the personal location areas.

6. The mobile communications system according to claim 5, wherein:

said mobile switching means further comprises incoming call frequency memory means for counting incoming calls addressed to each individual mobile station; and

said minimum/maximum number notification means modifies the minimum and maximum numbers, referring to the count values provided by said incoming call frequency memory means, in such a way that the minimum number or maximum number for frequently-called mobile stations will be reduced by a predetermined number, while the minimum number or maximum number for infrequently-called mobile stations will be increased by another predetermined number.

7. The mobile communications system according to claim 5, wherein:

each of the mobile stations further comprises incoming call frequency memory means for counting incoming calls addressed thereto; and

said PLA setting means modifies minimum and maximum numbers of cells to be grouped, referring to count records provided by said incoming call frequency memory means, in such a way that the minimum number or maximum number for frequently-called mobile stations will be reduced by a predetermined number, while the minimum number or maximum number for infrequently-called mobile stations will be increased by another predetermined number.

8. The mobile communications system according to claim 1, wherein each of the mobile stations further comprises disabling means for disabling said location change counting means and said PLA setting means.

9. The mobile communications system according to claim 8, wherein each of the mobile stations further comprises overriding means for temporarily overriding said disabling means to make said location change counting means and said PLA setting means operate, and if a different personal location area is obtained during the temporary overriding, continuing to override said disabling means for a predetermined extended period.

10. The mobile communications system according to claim 1, wherein each of the mobile stations further comprises disabling means for disabling said location change counting means and said PLA setting means when said each mobile station is roaming.

11. The mobile communications system according to claim 1, wherein the mobile stations communicate with the mobile switching center by using CDMA techniques.

12. A mobile station for use in a mobile communications system where base stations provide radio links for mobile subscribers in each cell and a mobile switching center controls connections between the mobile subscribers by switching circuits, the mobile station comprising:

notification message reception means for receiving a notification message from the nearest base station;

base station ID extracting means for extracting a base station ID from the received notification message to identify which base station is sending the notification message;

location change counting means for detecting location changes by comparing two consecutive instances of the base station IDs extracted by said base station ID extracting means, and counting the detected location changes separately for each pair of base station IDs involved in the changes;

personal location area (PLA) setting means, disposed in each mobile station, for defining personal location areas by grouping associated cells into one area, based on the location change count values obtained by said location change counting means;

PLA memory means, disposed in each mobile station, for storing records of the personal location areas defined by said PLA setting means, each of the records containing the base station IDs indicating which cells constitute each personal location area;

location change detecting means for testing whether the personal location area registered at present is valid, each time said base station ID extracting means extracts a base station ID that is different from before; and

location registration means, disposed in each mobile station and activated when said location change detecting means has detected that the registered personal location area is no longer valid, for searching said PLA memory means to retrieve one of the records of personal location areas that contains the extracted base station ID, and performing location registration by sending to the mobile switching center the retrieved personal location area and base station IDs relevant thereto.