CIPHERING KEYS FOR DIFFERENT CELLULAR COMMUNICATION NETWORKS

摘要

Handover is implemented between different cellular communication networks (2,4) without the network being handed over to having to retrieve a new ciphering key before communication service is provided. An encryption algorithm (40) and ciphering key (50) independent of the individual networks (2,4) may be provided. Alternatively, a ciphering key for the new network may be included in the handover message. In a further alternative, encryption takes place before and after, but not during, the handover procedure. These procedures tend to provide an advantage of a reduction in handover delay, potentially leading to fewer dropeed calls and improved quality of service.