Section: 6.8.2.1.2 State transition from RRC_CONNECTED to RRC_INACTIVE
Content: The gNB/ng-eNB shall send to the UE an RRCRelease with suspendConfig message that is ciphered and integrity protected in PDCP layer using a current AS security context. The gNB/ng-eNB shall include a fresh I-RNTI, and an NCC in that RRCRelease with suspendConfig message. The I-RNTI is used for context identification, and the UE ID part of the I-RNTI assigned by the gNB/ng-eNB shall be different in consecutive suspends of the same UE. This is to avoid tracking of UEs based on the I-RNTI. If the gNB/ng-eNB has a fresh and unused pair of {NCC, NH}, the gNB/ng-eNB shall include the NCC in the RRCRelease with suspendConfig message. Otherwise, the gNB/ng-eNB shall include the same NCC associated with the current KgNB in the RRCRelease with suspendConfig message. The NCC is used for AS security. The gNB/ng-eNB shall delete the current AS keys KRRCenc, KUPenc (if available), and KUPint (if available) after sending the RRCRelease with suspendConfig message to the UE, but shall keep the current AS key KRRCint. If the sent NCC value is fresh and belongs to an unused pair of {NCC, NH}, the gNB/ng-eNB shall save the pair of {NCC, NH} in the current UE AS security context and shall delete the current AS key KgNB. If the sent NCC value is equal to the NCC value associated with the current KgNB, the gNB/ng-eNB shall keep the current AS key KgNB and NCC. The gNB/ng-eNB shall store the sent I-RNTI together with the current UE context including the remainder of the AS security context. Upon receiving the RRC Release with suspendConfig message from the gNB/ng-eNB, the UE shall verify that the integrity of the received RRCRelease with suspendConfig message is correct by checking the PDCP MAC-I. If this verification is successful, then the UE shall take the received NCC value and save it as stored NCC with the current UE context. The UE shall delete the current AS keys KRRCenc, KUPenc (if available), and KUPint (if available), but keep the current AS key KRRCint key. If the stored NCC value is different from the NCC value associated with the current KgNB, the UE shall delete the current AS key KgNB. If the stored NCC is equal to the NCC value associated with the current KgNB, the UE shall keep the current AS key KgNB. The UE shall store the received I-RNTI together with the current UE context including the remainder of the AS security context, for the next state transition.