| 摘要 |
A method for protecting traffic in a radio access network connected to at least two core networks (CN). The method comprises maintaining a core-network-specific authen- tication protocol and a radio-bearer-specific ciphering process, and generating, for each ciphering process, a count parameter (C) comprising a cyclical sequence number (43) and a hyperframe number (HFN) which is incremented each time the cyclical sequence number (43) completes one cycle. For each core network or authentication protocol, a first radio bearer of a session is initialized (5-8) with a HFN exceeding the highest HFN used during the previous session. When a new radio bearer is established, the mobile station selects (5-10) the highest HFN used during the session for the core network in question, increments it (5-12) and uses it for initializing (5-14) the count parameter for the new radio bearer. At the end of a session, the mobile station stores (5-16) at least part (41) of the highest HFN used during the session. |
