Mobility Restrictions restrict service access of an 5G-RG depending on RG location.
For a 5G-RG connecting over NG-RAN, the Mobility Restriction functionality as described in TS 23.501, clause 220.127.116.11
For an 5G-RG connecting over wireline access, the Mobility Restriction functionality is described in this clause.
Mobility restrictions do not apply to scenarios with FN-BRG.
Since access to 5GC for FN-BRG subscriptions are identified by a SUPI determined from the GLI as described in clause 4.7.3
and clause 4.7.8
. Such subscriptions are by definition restricted to a specific location.
For FN-CRG subscriptions, HFC Node ID is used to identify the location of FN-CRG, thus service area restrictions for the FN-CRG can be identified by an HFC_Node ID, or by a list of HFC_Node ID.
Mobility Restrictions for wireline access consists of Forbidden Area and Service Area Restrictions, as described in the following clauses.
In a Forbidden Area, the 5G-RG, based on subscription, is not permitted by the 5GC to initiate any communication with the 5GC for this PLMN.
The UDM stores the Forbidden Area for wireline access in the same way as for 3GPP access, with the following differences:
For subscriptions for 5G-BRG, GLI is used to describe the Forbidden Area.
For subscriptions for 5G-CRG and FN-CRG, HFC Node IDs are used to describe the Forbidden Area (instead of TA).
The Forbidden Area in UDM can be encoded as a "white list" indicating the non-forbidden area. In this case all GLI or HFC_Node ID values not included in the list are considered forbidden.
The use of "white list" is to ensure an efficient Forbidden Area definition if only a small set of GLI / HFC Node ID values are not forbidden.
Forbidden Area is enforced by AMF, based on subscription data and the location information received from W-AGF. The AMF rejects a Registration Request from a 5G-RG or the W-AGF acting on behalf of a FN-CRG in a Forbidden Area with a suitable cause code. The 5G-RG behaviour depends on the network response (cause code from AMF) that informs the RG that communication is forbidden.
The subscription data in the UDM for a 5G-BRG includes a Service Area Restriction which may contain either Allowed or Non-Allowed Areas specified by using explicit GLI(s) and/or other geographical information (e.g., longitude/latitude, zip code, etc.).
The subscription data in the UDM for a 5G-CRG and FN-CRG includes a Service Area Restriction which may contain either Allowed or Non-Allowed Areas specified by using explicit HFC Node IDs and/or other geographical information (e.g., longitude/latitude, zip code, etc.).
The geographical information used to specify allowed or non-allowed area is only managed in the network, and the network will map it to a list of GLI(s) or HFC Node IDs before sending Service Area Restriction information to the PCF.
The UDM stores the Service Area Restrictions for the 5G-RG or FN-CRG as part of the subscription data. The PCF in the serving network may (e.g. due to varying conditions such as 5G-RG's location, time and date) further adjust Service Area Restrictions of a 5G-RG, either by expanding an allowed area or by reducing a non-allowed area. The UDM and the PCF may update the Service Area Restrictions of a 5G-RG or a FN-CRG at any time.
During registration, if the Service Area Restrictions of the 5G-RG or FN-CRG is not present in the AMF, the AMF fetches from the UDM the Service Area Restrictions of the 5G-RG or FN-CRG that may be further adjusted by the PCF. The serving AMF shall enforce the Service Area Restrictions of a 5G-RG and a FN-CRG. The AMF receives the location information (GLI, HFC Node IDs) where the RG is connected from the W-AGF via N2.
The network does not send any Allowed Area or Non-Allowed Area to the 5G-RG for wireline access. If the 5G-RG initiates communication in an Allowed Area, the network accepts the communication as allowed by the subscription. If the 5G-RG initiates Service Request or SM signalling in a Non-Allowed Area, the AMF rejects the request with a suitable cause code indicating that the 5G-RG/W-AGF should not retry Service Request and SM signalling while being connected to the same line.
Upon change of serving AMF due to mobility, the old AMF may provide the new AMF with the Service Area Restrictions of the 5G-RG that may be further adjusted by the PCF.