USER AUTHENTICATION METHOD FOR MULTIPLE LONG-DISTANCE COMMUNICATION NETWORK AND SYSTEM

PROBLEM TO BE SOLVED: To authenticate a user's terminal through one long-distance communication network such a digital PLMN and a satellite network by accessing an authentication center through a selected network. SOLUTION: An IMSI is sent to a PLMN 9 via a satellite 3a and an MD-ISI and an NASS, and further sent to an HLR and an authentication center AuC in order to authenticate a user's terminal UT1 which uses an SPDN. The IMSI is collated in a memory of the AuC, and if it is authenticated, an individual RAND value is generated, algorithms A3/A8 operate to the RAND and Ki, generate an SRES and a KC, and they are sent from the AuC to the NASS. The value of the RAND is returned to the terminal UT1, and corresponding SRES' value is generated and returned to the NASS. The values of the SRES and SRES' are compared, and if they are identical, the user's terminal is authenticated for the use that uses the SPDN.