Mobile communications system and mobile station therefor

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and activated when said location change detecting means has detected that the registered personal location area is no longer valid, for searching said PLA memory means to retrieve one of the records of personal location areas that contains the extracted base station ID, and performing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.