6.2 Procedures for Service Authorization and Provisioning to UE

23.3043GPPProximity based Services (ProSe) in the 5G System (5GS)Release 17TS

6.2.1 General

The procedures for service authorization and provisioning to UE may be initiated by the PCF (as described in clause 6.2.2), by the UE (as described in clause 6.2.4), or by the AF (as described in clause 6.2.5).

6.2.2 PCF based Service Authorization and Provisioning to UE

For PCF based Service Authorization and Provisioning to UE, the Registration procedures as defined in clause 4.2.2.2 of TS 23.502 [5], UE Policy Association Establishment procedure as defined in clause 4.16.11 of TS 23.502 [5] and UE Policy Association Modification procedure as defined in clause 4.16.12 of TS 23.502 [5] apply with the following additions:

– If the UE indicates 5G ProSe Capability in the Registration Request message and if the UE is authorized to use 5G ProSe service based on subscription data, the AMF selects the PCF which supports 5G ProSe Policy/Parameter provisioning as described in clause 6.2.3 and establishes a UE policy association with the PCF for 5G ProSe Policy/Parameter delivery.

– If the UE supports one of 5G ProSe capabilities and it does not have valid 5G ProSe policy/parameters, the UE includes the UE Policy Container with indicating the 5G ProSe Policy Provisioning Request during registration procedure. The UE may also include UE capabilities as defined in clause 4.3.1 in the 5G ProSe Policy Provisioning Request and PCF may determine the ProSe Policy/Parameters for the UE based on received UE capabilities.

– If the UE indicates the 5G ProSe Policy Provisioning Request in the UE Policy Container, the PCF determines whether to provision 5G ProSe Policy/parameters to the UE, as specified in clause 6.1.2.2.2 of TS 23.503 [9], and the PCF provides the 5G ProSe Policy/parameters (see clause 5.1.2.1, clause 5.1.3.1 and clause 5.1.4.1) to the UE by using the procedure as defined in clause 4.2.4.3 "UE Configuration Update procedure for transparent UE Policy Delivery" in TS 23.502 [5].

The PCF may update the 5G ProSe Policy/parameters to the UE in following conditions:

– UE Mobility, e.g. UE moves from one PLMN to another PLMN. This is achieved by using the procedure of UE Policy Association Modification initiated by the AMF, as defined in clause 4.16.12.1 of TS 23.502 [5].

– When there is a subscription change in the list of PLMNs where the UE is authorized to perform 5G ProSe services. This is achieved by using UE Policy Association Modification initiated by the PCF procedure as defined in clause 4.16.12.2 of TS 23.502 [5].

– When there is a change of service specific parameter (including path selection policy) as described in clause 6.2.5 (performing the procedure in clause 4.15.6.7 of TS 23.502 [5]).

– When the timer associated with some Policy/parameter expires.

– When the UE determines that the ProSe Policy/parameter(s) is invalid and performs UE triggered Policy Provisioning procedure to the PCF.

If the serving PLMN is removed from the list of PLMNs in the service authorization parameters, the service authorization is revoked in the UE.

When the UE is roaming, the change of subscription resulting in updates of the service authorization parameters are transferred to the UE by H-PCF via V-PCF.

The UE may perform UE triggered Policy Provisioning procedure to the PCF as specified in clause 6.2.4 when the UE determines the 5G ProSe Policy/Parameter is invalid (e.g. Policy/Parameter is outdated, missing or invalid).

When the UE disables a ProSe capability, the PCF may stop updating the corresponding ProSe Policy/parameter(s) and when the UE enables a ProSe capability the PCF may need to provide or update the corresponding ProSe Policy/parameter(s).

When a 5G ProSe Layer-3 Remote UE is accessing to 5GC via a 5G ProSe Layer-3 UE-to-Network Relay without involving N3IWF, the PCF based provisioning and update of 5G ProSe Policy/parameters to the 5G ProSe Layer-3 Remote UE are not supported.

6.2.3 PCF discovery

PCF discovery and selection mechanism defined in clause 6.3.7.1 of TS 23.501 [4] applies with the following addition to enable a PCF instance is selected for 5G ProSe service and for UE:

– Based on the indication from the UE and/or UE subscription data during the Registration procedure as specified in clause 6.5.2, the AMF may include the 5G ProSe Capability indication in the Nnrf_NFDiscovery_Request message as the optional input parameter. If provided, the NRF takes the information into account for discovering the PCF instance.

6.2.4 Procedure for UE triggered ProSe Policy provisioning

The UE triggered Policy Provisioning procedure is initiated by the UE to request ProSe Policy/Parameter from the PCF when UE determines the 5G ProSe Policy/Parameter is invalid in the following cases:

– if the validity timer indicated in the 5G ProSe Policy/Parameter expires;

– if there are no valid parameters, e.g. for the 5G ProSe Identifier a UE wants to use, for current area, or due to abnormal situation.

Figure 6.2.4-1: UE triggered 5G ProSe Policy provisioning procedure

1. The UE sends the UL NAS TRANSPORT message carrying the UE Policy Container (UE Policy Provisioning Request to request 5G ProSe policies) to the AMF.

2. The AMF sends Namf_Communication_N1MessageNotify request to the PCF including the UE Policy Container received from UE.

3. The PCF receives UE Policy Container which indicates UE Policy Provisioning Request to request 5G ProSe policies. If the 5G ProSe policies are authorized based on AMF input, the PCF performs the UE Policy delivery procedure as defined in clause 4.2.4.3 of TS 23.502 [5].

6.2.5 AF-based service parameter provisioning for ProSe over control plane

For 5G ProSe service parameter provisioning (i.e. creating, updating and deleting), the procedure defined in clause 4.15.6.7 of TS 23.502 [5] is performed with the following considerations:

– The AF in TS 23.502 [5] is considered as ProSe Application Server in this specification.

– Service Description indicates 5G ProSe service domain information.

– Service Parameters include parameters for 5G ProSe Direct Discovery and 5G ProSe Direct Communications. The detailed information on the parameters is described in clause 5.1.2.1 and clause 5.1.3.1.

– Service Parameters for 5G ProSe UE-to-Network Relay Discovery and 5G ProSe UE-to-Network Relay Communications. The detailed information on the parameters is described in clause 5.1.4.1.

NOTE: It is assumed that the ProSe service domain information is set based on the Service Level Agreement with the operator.