Section: 6.4.7 Signalling procedure for periodic local authentication
Content: The following procedure is used by the RNC to periodically perform a local authentication. At the same time, the amount of data sent during the RRC connection is periodically checked by the RNC and the UE. The RNC is monitoring the COUNT-C value associated to each radio bearer. The procedure is triggered whenever any of these values reaches a critical checking value. The granularity of these checking values and the values themselves are defined by the visited network. All messages in the procedure are integrity protected. Figure 15a: RNC periodic local authentication procedure 1. When a checking value is reached (e.g. the value in some fixed bit position in the hyperframe number is changed), a Counter Check message is sent by the RNC. The Counter Check message contains the most significant parts of the COUNT-C values (which reflect amount of data sent and received) from each active radio bearer. 2. The UE compares the COUNT-C values received in the Counter Check message with the values of its radio bearers. Different UE COUNT-C values are included within the Counter Check Response message. 3. If the RNC receives a counter check response message that does not contain any COUNT-C values, the procedure ends. If the RNC receives a counter check response that contains one or several COUNT-C values, the RNC may release the connection.