3GPP 23.501 v20.2.0 — the document's own text
5.49.5.3 Impact of MWAB mobility
Taught in 26. Relays, satellites, femtos and shared networks (The 5G system architecture, in depth).
The mobility of MWAB includes the MWAB-UE and the MWAB-gNB aspect:
- The mobility of the MWAB-UE reuses the exiting UE mobility procedures specified for normal UE, subject to constraints specified in TS 38.401 [42]..
- During mobility, a MWAB-gNB can obtain or apply a new configuration as specified in TS 38.401 [42] from the OAM server of MWAB Broadcasted PLMN/SNPN and, if any new AMF was provided as part of the new configuration, the MWAB-gNB (i.e. the new logical gNB as specified in TS 38.401 [42]) sets up the N2 connection with the new AMF and it (i.e. the old logical gNB as specified in TS 38.401 [42]) releases the N2 connection with any old AMF removed from the MWAB-gNB configuration.
NOTE: It is expected the MWAB-gNB removes the old configuration after the MWAB-gNB has completed the handover of the UEs in RRC_CONNECTED state.
- The MWAB-UE may request new or modify existing BH PDU Sessions for the corresponding N2, N3 and Xn interfaces, upon request from the MWAB-gNB as it moves in the network and the MWAB-gNB updates the TNL association as specified in clause 5.21.1 and TS 38.401 [42] to use the new TNL information associated with the new BH PDU Session(s) as needed.
- SSC mode 3 may be applied to the BH PDU Sessions to minimize traffic interruption when UPF re-allocation for these BH PDU Sessions is required during the MWAB mobility.
- When it is required to change AMF for the UEs served by the MWAB-gNB upon mobility of a MWAB into a new region, the TAC(s) and Cell ID(s) the MWAB-gNB announces also change (i.e. upon mobility, as specified in TS 38.401 [42], the new logical gNB announces TAC(s) and Cell ID(s) values different from the values announced by the old logical gNB). The MWAB-gNB, for UEs in RRC_CONNECTED mode, behaves as specified in TS 38.401 [42].
- To prevent handover of a MWAB-UE towards a target MWAB-gNB, the target MWAB-gNB (i.e. during Xn handover or during N2 HO after target AMF slice control as described in step 4 in clause 4.9.1.3.2 of TS 23.502 [3]) fails the handover as specified in TS 38.401 [42] because the dedicated slices for BH PDU sessions of the MWAB-UE are not supported by the target MWAB-gNB.