Proximity based Services (ProSe) in the 5G System (5GS)
The present document specifies the Stage 2 of the Proximity based Services (ProSe) features in 5GS. 5G ProSe features consist of: 5G ProSe Direct Discovery, 5G ProSe Direct Communication, 5G ProSe UE-to-Network Relay, 5G ProSe UE-to-UE Relay and 5G ProSe Intermediate UE-to-Network Relay.
5G ProSe Direct Discovery identifies that 5G ProSe-enabled UEs are in proximity using NR.
5G ProSe Direct Communication enables establishment of communication paths between two or more 5G ProSe-enabled UEs that are in direct communication range using NR.
5G ProSe UE-to-Network Relay enables indirect Layer-2 and Layer-3 single-hop communication and Layer-3 multi-hop communication between the 5G network and 5G ProSe-enabled UEs (e.g. for 5G ProSe-enabled UEs that are out of coverage of the network).
Editor's note: Support for Multi-hop Layer-2 UE-to-Network relaying will be aligned with RAN WGs' progress/decision.
5G ProSe UE-to-UE Relay enables indirect Layer-2 and Layer-3 single-hop communication and Layer-3 multi-hop communication between two 5G ProSe End UEs.
5G ProSe Intermediate UE-to-Network Relay enables Layer-3 multi-hop communication between a 5G Remote UE and a 5G ProSe UE-to-Network Relay.
Security aspects of ProSe in 5GS are defined in TS 33.503 [29].