Section: 4.7.5 Mobile IAB 4.7.5.1 General
Content: Mobile IAB introduces the mobile IAB-node, which is a RAN node that provides NR access links to UEs and an NR backhaul link to a parent node, and that can conduct physical mobility across the RAN area. The mobile IAB-node includes a mobile IAB-MT and a mobile IAB-DU. Mobile IAB supports the same functionality as IAB unless explicitly specified. The following enhancements/restrictions only apply to mobile IAB: The mobile IAB-node uses the mobile IAB-node authorization procedure defined in TS 38.401[ NG-RAN; Architecture description ]  [4] and the MBSR authorization procedure defined in TS 23.501[ System architecture for the 5G System (5GS) ]  [3]. A RAN node operating as a mobile IAB-node shall not concurrently operate as an IAB-node. During network integration, the RAN node shall indicate whether it intends to operate as a mobile IAB-node or as an IAB-node via an indicator in the RRCSetupComplete message. The parent node indicates support for mobile IAB-nodes by broadcasting a mobile-IAB-specific indicator in SIB1. The mobile IAB-node shall not have descendent nodes. A mobile-IAB cell shall therefore not broadcast any indication that it is a suitable parent node for IAB-nodes or mobile IAB-nodes. The cell of a mobile IAB-DU may indicate to UEs via a SIB1 indicator that it is a mobile-IAB cell. The mobile IAB-node uses the mobile IAB-node network integration procedure as defined in TS 38.401[ NG-RAN; Architecture description ]  [4]. The mobile IAB-MT can perform the mobile IAB-MT migration procedures via Xn handover and/or via NG handover as defined in TS 38.401[ NG-RAN; Architecture description ]  [4]. The mobile IAB-MT can also perform the mobile IAB-node recovery procedure as defined in TS 38.401[ NG-RAN; Architecture description ]  [4]. The mobile IAB-node can perform the mobile IAB-DU migration procedure, where a new logical mobile IAB-DU is established on the mobile IAB-node and the initial logical mobile IAB-DU is released some time later. During this procedure, the UEs connected via the mobile IAB-node are handed over from the initial logical mobile IAB-DU, referred to as the source logical mobile IAB-DU, to the new logical mobile IAB-DU, referred to as the target logical mobile IAB-DU. The details of this procedure are defined in TS 38.401[ NG-RAN; Architecture description ]  [4]. Enhancements related to BAP for mobile IAB-DU migration are defined in TS 38.340[ NR; Backhaul Adaptation Protocol (BAP) specification ]  [31]. When a RAN node is operating as a mobile IAB node, dual connectivity for this node is not supported.