The following Figure 4.2.7.1-1 shows the high level reference architecture for 5G ProSe Layer-3 UE-to-Network Relay. In this Figure, the 5G ProSe Layer-3 UE-to-Network Relay may be in the HPLMN or a VPLMN.
The following Figure 4.2.7.1-2 shows the non-roaming reference architecture for 5G ProSe Layer-3 UE-to-Network Relay when N3IWF is supported. In this Figure, the PLMN A and PLMN B may be the same or different. When the 5G ProSe Layer-3 Remote UE may connect to NG-RAN directly to access PLMN B and in that case it would take the role of UE in the Figure. The N3IWF may be connected to Relay UE UPF via a Data Network.
The following Figure 4.2.7.1-3 shows the roaming reference architecture for 5G ProSe Layer-3 UE-to-Network Relay. In this Figure, the PLMN A and PLMN B may be the same or different and/or the PLMN A and PLMN C may be the same or different. The N3IWF may be connected to Relay UE UPF via a Data Network.
Figure 4.2.7.2-1 shows the 5G ProSe Layer-2 UE-to-Network Relay reference architecture. The 5G ProSe Layer-2 Remote UE and 5G ProSe Layer-2 UE-to-Network Relay may be served by the same or different PLMNs. If the serving PLMNs of the 5G ProSe Layer-2 Remote UE and the 5G ProSe Layer-2UE-to-Network Relay are different then NG-RAN is shared by the serving PLMNs, see the 5G MOCN architecture in clause 5.18 of TS 23.501.
Figure 4.2.8-1 shows the Layer-2 and Layer-3 5G ProSe UE-to-UE Relay reference architecture. The 5G ProSe End UEs communicate with each other via a 5G ProSe UE-to-UE Relay.