Section: 4.9.3 Signalling procedures
Content: NR RRC signalling is utilized to configure the NCR-MT to receive side control information from a gNB, which is used by the NCR-Fwd to determine whether and how to amplify-and-forward RF signals. If the side control configuration is removed, the NCR-Fwd ceases its amplifying-and-forwarding function. When the NCR-MT is in RRC_CONNECTED state, the NCR-Fwd may amplify-and-forward RF signals based on the side control information received from the gNB. The NCR-MT does not support RRM measurements in RRC_CONNECTED. When the NCR-MT transitions from RRC_CONNECTED state to RRC_INACTIVE state, the NCR-Fwd may continue to amplify-and-forward RF signals in accordance with the last side control information received from the gNB. When the NCR-MT is in RRC_INACTIVE state, the NCR-Fwd ceases to amplify-and-forward RF signals if no suitable cell is detected, or if the NCR-MT selects a different cell than the last serving cell on which side control configuration was received. When an NCR-MT in RRC_INACTIVE state determines degradation of the NCR-Fwd backhaul link beam, then the NCR-Fwd should cease amplifying-and-forwarding RF signals, and the NCR-MT should attempt to resume its RRC connection (with cause value mo-Signalling). The criteria to evaluate backhaul beam degradation are left to the NCR-node implementation. When the NCR-MT transitions from RRC_CONNECTED state to RRC_IDLE, the NCR-Fwd ceases any amplifying-and-forwarding of RF signals. How an NCR-MT transitions back from RRC_IDLE state to RRC_CONNECTED state is left to NCR-node or network implementation. An NCR-MT can detect RLF on the control link as specified in TS 38.331[ NR; Radio Resource Control (RRC); Protocol specification ]  clause 5.3.10 [12]. When RLF is detected, the NCR-MT performs the RRC re-establishment procedure as specified in TS 38.331[ NR; Radio Resource Control (RRC); Protocol specification ]  [12]. During the RRC re-establishment procedure, the NCR-Fwd ceases to amplify-and-forward RF signals. After successfully performing the RRC re-establishment procedure, the NCR-MT waits for the new side control configuration for the NCR-Fwd to resume the amplifying-and-forwarding of RF signals. An NCR-MT can also perform Beam Failure Detection (BFD) and Beam Failure Recovery (BFR) as described in clause 9.2.8. Once the NCR-MT detects beam failure in the control link, the NCR-Fwd should cease amplifying-and-forwarding RF signals until BFR is completed.