Section: 8.9.10.1 IAB-node orderly release
Content: For orderly release, the IAB-donor-CU can remove the F1 interface connection to the IAB-DU without releasing the IAB-MT. If the IAB-MT needs to be released, IAB-MT will perform the deregistration procedure. If both F1 interface and IAB-MT need to be released, the IAB-donor-CU should remove the F1 interface to the IAB-DU before it releases the collocated IAB-MT. The deregistration procedure is the same as the UE deregistration procedure. The IAB-donor-CU hands over the UEs or child IAB-nodes currently connected to the IAB-node’s cell(s) to another cell(s), or releases the UEs and may stop accepting incoming handovers or connections to the IAB-node that is about to be released. The IAB-donor-CU may also update/release the BH RLC channels in the intermediate hops. At this point, the F1 interface will be released and the corresponding SCTP associations will be removed.