4.27 Mobile base station relay support

A 5GS can support a MBSR-UE and a UE accessing to MBSR (see clause 5.35A of 3GPP TS 23.501 [8]). This clause describes NAS-specific aspects of the 5GS features to support the authorization of the MBSR-UE, and the control of the UE access via MBSR.

The AMF authorizes the UE's request to act as a MBSR based on the subscription information. The AMF can indicate to the MBSR-UE that it is allowed or not allowed to operate as MBSR during registration procedure as specified in clause 5.5.1.2.

Enhanced CAG information can be used for the control of UE's access via MBSR. CAG identifier is used to control the access of UE via MBSR. The 5GCN supports the UE access control based on the PLMND ID and CAG identifier broadcast by the MBSR and the CAG-ID authorized based on "Allowed CAG list" in the PLMN's entry of "CAG information list" stored in the UE. Time validity information can be provided to the UE together with the CAG identifier for accessing to MBSR in order to control that UE not accessing the MBSR cell outside of the time validity information. For the UE not supporting CAG functionality, the 5GCN can control the access of the UE with managing the forbidden tracking area.