4.15 Time synchronization and time sensitive communication

24.5013GPPNon-Access-Stratum (NAS) protocol for 5G System (5GS)Release 17Stage 3TS

4.15.1 General

A 5GS can support time synchronization and TSC (see 3GPP TS 23.501 [8], 3GPP TS 23.502 [9], and 3GPP TS 23.503 [10]). The clause describes NAS-specific aspects of the 5GS features to support time synchronization and TSC. Interworking with EPS is not supported for a PDU session for time synchronization or TSC.

4.15.2 Void

4.15.2.1 Void

4.15.2.2 Void

4.15.2.3 Void

4.15.3 Time synchronization

Two types of synchronization processes are supported by the 5GS: 5GS synchronization and (g)PTP domain synchronization (see 3GPP TS 23.501 [8]).

For 5GS synchronization, the lower layers provide the 5G internal system clock signalled via the NG-RAN (see 3GPP TS 38.331 [30]) and the UE forwards the 5G internal system clock to the DS-TT(s).

For (g)PTP domain synchronization, the UE supports forwarding (g)PTP messages (see 3GPP TS 23.501 [8], 3GPP TS 23.502 [9], and 3GPP TS 24.535 [19A]). For all (g)PTP domains associated with a PDU session:

a) if the UE receives (g)PTP message via the PDU session, the UE forwards the (g)PTP messages to the DS-TT associated with the PDU session; or

b) if the UE receives (g)PTP messages from the DS-TT associated with the PDU session, the UE forwards the (g)PTP messages via the PDU session.

4.15.4 User plane node management

A 5G system (5GS) can act as a user plane node of an external network (e.g. IEEE TSN bridge) or a 5GS can be independently used to enable TSC. For these purposes, information available at a UE is provided to the network and port management information containers are exchanged between a DS-TT and a TSN AF or a TSCTSF (see 3GPP TS 24.539 [19BA]).

During a UE-requested PDU session establishment procedure, if the UE supports transfer of port management information containers, then the UE indicates that transfer of port management information container is supported and the UE provides a DS-TT Ethernet port MAC address (if the PDU session type is Ethernet), port management information container, and a UE-DS-TT residence time (if available) to the network (see subclause 6.4.1.2).

Once the UE has successfully established a PDU session and the UE has indicated that transfer of port management information container is supported during the UE-requested PDU session establishment procedure (see subclause 6.4.1.2), then port management information containers are exchanged via a UE-requested PDU session modification procedure and a network-requested PDU session modification procedure (see subclauses 6.3.2 and 6.4.2). The UE receiving a port management information container from the network shall forward the port management information container to the DS-TT. The SMF receiving a port management information container from the UE shall operate as described in 3GPP TS 23.502 [9].