Section: 5.3.7 RRC connection re-establishment 5.3.7.1 General
Content: Figure 5.3.7.1-1: RRC connection re-establishment, successful Figure 5.3.7.1-2: RRC re-establishment, fallback to RRC establishment, successful The purpose of this procedure is to re-establish the RRC connection. A UE in RRC_CONNECTED, for which AS security has been activated with SRB2 and at least one DRB/multicast MRB setup or, for IAB and NCR, SRB2, may initiate the procedure in order to continue the RRC connection. The connection re-establishment succeeds if the network is able to find and verify a valid UE context or, if the UE context cannot be retrieved, and the network responds with an RRCSetup according to clause 5.3.3.4. The network applies the procedure e.g as follows: - When AS security has been activated and the network retrieves or verifies the UE context: - to re-activate AS security without changing algorithms; - to re-establish and resume the SRB1; - When UE is re-establishing an RRC connection, and the network is not able to retrieve or verify the UE context: - to discard the stored AS Context and release all RBs and BH RLC channels and Uu Relay RLC channels; - to fallback to establish a new RRC connection. If AS security has not been activated, the UE shall not initiate the procedure but instead moves to RRC_IDLE directly, with release cause 'other'. If AS security has been activated, but SRB2 and at least one DRB or multicast MRB or, for IAB and NCR, SRB2, are not setup, the UE does not initiate the procedure but instead moves to RRC_IDLE directly, with release cause 'RRC connection failure'.