Section: 4.7.4.2 IAB-node Migration
Content: The IAB-node can migrate to a different parent node underneath the same IAB-donor-CU. The IAB-node continues providing access and backhaul service when migrating to a different parent node. The IAB-MT can also migrate to a different parent node underneath another IAB-donor-CU. In this case, the collocated IAB-DU and the IAB-DU(s) of its descendant node(s) retain F1 connectivity with the initial IAB-donor-CU. The IAB-MT of each descendant node and all the served UEs retain the RRC connectivity with the initial IAB-donor-CU. This migration is referred to as inter-donor partial migration. The IAB-node, whose IAB-MT migrates to the new IAB-donor-CU, is referred to as a boundary IAB-node. After inter-donor partial migration, the F1 traffic of the IAB-DU and its descendant nodes is routed via the BAP layer of the IAB topology to which the IAB-MT has migrated. Inter-donor partial migration is only supported for SA-mode. The intra-donor IAB-node migration procedure and inter-donor partial migration procedures are captured in TS 38.401[ NG-RAN; Architecture description ]  [4].