MOBILE COMMUNICATION SYSTEM, MOBILE AND POSITION REGISTERING METHOD

PROBLEM TO BE SOLVED: To decrease a generation of position registration request when changing a size of a position registration area which registers position of a mobile in a mobile communication system, a mobile and a position registering method. SOLUTION: A mobile communication system has a base station which communicates with mobiles MS1, MS2 and MS3, and a network containing a subscriber database. The network is structured by a plurality of hierarchies (hierarchies 1 to 4) by a logic node (for example, logic 1, logic A, logic a, logic (1)), and inter-range position information is formed by combining addresses of the logic nodes corresponding to each hierarchy, and position registration area information indicating a size of a position registration area according to validity/invalidity of the address of the logic node corresponding to each hierarchy is formed and is transmitted by annexing it to report information. The mobile comprises a means for storing the received inter-range position information and position registration information based on position registration area information in a memory, and for comparing the inter-range position information and position registration information with the inter-range position information and position registration area information of the report information, thereby sending a position registration request when everything is different.