7.1 Overview

24.5543GPPProximity-services (ProSe) in 5G System (5GS) protocol aspectsRelease 17Stage 3TS

This clause describes the procedures at the UE and between UEs, for 5G ProSe direct communication over PC5.

The UE shall support requirements for securing 5G ProSe direct communication over PC5.

The PC5 interface is selected based on the ProSe application to path preference mapping rules as specified in clause 5.2.4 before 5G ProSe direct communication.

For unicast mode 5G ProSe direct communication, the following data unit types are supported: IPv4, IPv6, Ethernet and Unstructured.

For broadcast and groupcast mode 5G ProSe communication, the following data unit types are supported: IPv4, IPv6, Ethernet, Unstructured and Address Resolution Protocol (see RFC 826 [32]).

5G ProSe direct communication over NR-PC5 supports broadcast mode, groupcast mode and unicast mode. If the upper layer of the UE indicates the mode of communication, the UE shall set the mode of communication based on the request of the upper layer. Otherwise, the UE shall set the mode of communication based on the mapping rules between the 5G ProSe identifiers and the default mode of communication defined in clause 5.2.4.

NOTE: Further details about whether broadcast, unicast or groupcast can be used over PC5 are described in 3GPP TS 23.304 [3] clause 5.3.

The UE may use the PC5 DRX mechanism to perform 5G ProSe direct communication over PC5 interface for broadcast mode and groupcast mode when the UE is not served by NG-RAN as specified in clause 5.2.4. For transmitting and receiving direct communication request messages (i.e. the PROSE DIRECT LINK ESTABLISHMENT REQUEST message), the default PC5 DRX configuration is used (see 3GPP TS 38.300 [21]).