The following Figure 4.2.3-1 shows the high level view of the non-roaming inter-PLMN architecture with service-based interfaces within the Control Plane. In this Figure, PLMN A is the HPLMN of UE A and PLMN B is the HPLMN of UE B.
Figure 4.2.3-2 shows the high level view of the roaming architecture with service-based interfaces within the Control Plane. In this Figure, UE A uses a subscription of PLMN A and UE B uses a subscription of PLMN B; UE A is roaming in PLMN C while UE B is not roaming.
The 5G System provides NEF services to enable communication between NFs in the PLMN and a ProSe Application Server. Figure 4.2.4-1 shows the high level view of AF-based service parameter provisioning for 5G ProSe communications. The ProSe Application Server may provide ProSe service parameters to the PLMN via NEF. The NEF stores the ProSe service parameters in the UDR.
The reference point between the ProSe application in the UE and in the ProSe Application Server. It is used to define application level signalling requirements. This reference point is not specified in this release of the specification.
PC3a:
The reference point between the UE and the 5G DDNMF. PC3a relies on 5GC user plane for transport (i.e. an "over IP" reference point). It is used to authorise 5G ProSe Direct Discovery request and perform allocation of ProSe Application Codes / ProSe Restricted Codes corresponding to ProSe Application Identities used for 5G ProSe Direct Discovery.
PC5:
The reference point between ProSe-enabled UEs used for control and user plane for 5G ProSe Direct Discovery, 5G ProSe Direct Communication, 5G ProSe UE-to-Network Relay and 5G ProSe UE-to-UE Relay.
PC8:
The reference point between the UE and the 5G ProSe Key Management Function (5G PKMF). The details are defined in TS 33.503.
Npc2:
The reference point between the ProSe Application Server and the 5G DDNMF. It is used to define the interaction between ProSe Application Server and 5G DDNMF for 5G ProSe Direct Discovery.
Npc4:
The reference point between the UDM and 5G DDNMF. It is used to provide subscription information in order to authorise 5G ProSe Direct Discovery request.
Npc6:
The reference point between the 5G DDNMF in the HPLMN and the 5G DDNMF in a Local PLMN (5G ProSe Direct Discovery). This reference point is used for HPLMN control of ProSe service authorization.
Npc7:
The reference point between the 5G DDNMF in the HPLMN and the 5G DDNMF in the VPLMN. It is used for HPLMN control of ProSe service authorization.
Npc8:
The reference point between the PCF and the 5G DDNMF. It is used to define the interactions between the 5G DDNMF and the PCF to e.g. get a PDUID from the PCF.
Npc9:
The reference point between the 5G PKMF of the 5G ProSe Remote UE and the 5G PKMF of the 5G ProSe UE-to-Network Relay and between the 5G PKMF of the 5G ProSe End UE and the 5G PKMF of the 5G ProSe UE-to-UE Relay. The details are defined in TS 33.503.
Npc10:
The reference point between the 5G PKMF and UDM. The details are specified in TS 33.503.
Npc11:
The reference point between the AUSF and Prose Anchor Function (PAnF). The details are specified in TS 33.503.
Npc12:
The reference point between the PAnF and UDM. The details are specified in TS 33.503.
Npc13:
The reference point between the SMF and PKMF. The details are specified in TS 33.503.
Npc14:
The reference point between the SMF and PAnF. The details are specified in TS 33.503.
Services provided by 5G DDNMF to manage inter-PLMN 5G ProSe Direct Discovery operations.
Npkmf:
Service provided by 5G PKMF to support inter-PLMN ProSe security management. The function of Npkmf is defined in TS 33.503.
In addition to the relevant services defined in TS 23.501 for the following service-based interfaces, in the case of ProSe Service, the services can be provided by corresponding NF are as follows:
Nudm:
Services provided by UDM are used to get 5G ProSe Service related subscription information to the AMF during Initial Registration procedure or UE Configuration Update (UCU) procedure to inform the AMF the subscription information has changed and to provide ProSe Service related subscription information to 5G DDNMF for the authorisation of 5G ProSe Direct Discovery requests. The subscription information is described in TS 23.502. Services provided by UDM may also be used by the 5G PKMF for relay service authorisation, see TS 33.503.
Npcf:
Services provided by H-PCF are used to provide 5G ProSe Service related parameters to V-PCF for the UE and NG-RAN in the roaming case and to enable the 5G DDNMF to get a PDUID or be notified of PDUID change.
Nudr:
Services provided by UDR are used to notify the PCF and the UDM of the update of the 5G ProSe Service related information as described in TS 23.502.
Nnef:
Services provided by NEF are used by the ProSe Application Server to update 5G ProSe Service related information of 5GC.
Namf:
Services provided by AMF are consumed by PCF to provide the 5G ProSe Service related parameters for the UE and the NG-RAN to the AMF and to enable the AMF create or update the UE context related to 5G ProSe service.
Nnrf:
Services provided by NRF are used to discover the PCF that supports 5G ProSe service and for 5G DDNMF in HPLMN to discover other 5G DDNMFs in VPLMN or local PLMN.
Naf:
Services provided by AF are consumed by the DDNMF to request authorization for Discovery Request. The AF may update the authorization information to revoke the Restricted ProSe Direct Discovery permission.