6.2.29 TSCTSF

The Time Sensitive Communication and Time Synchronization Function (TSCTSF) supports the following functionality:

• Associating the time synchronization service request (see clause 5.27.1.8) from the NF consumer to the AF sessions with the PCF (the session between the PCF and TSCTSF).
• Controlling time synchronization service request from the NF consumer, (g)PTP-based time distribution and ASTI-based time distribution based on subscription data. The TSCTSF may be pre-configured with one or several PTP instance configurations. For each PTP instance configuration, it may contain:
• a reference to the PTP instance configuration.
• PTP profile.
• PTP domain.
• Detecting and reporting time synchronization service status based on NG-RAN and UPF/NW-TT timing synchronization status information and reporting status updates.
• Managing the DS-TT and NW-TT via exchange of PMIC and UMIC as described in Annex K.
• Detecting availability of 5GS Bridge/Router information (including user plane node ID that applies also for IP type PDU Sessions) as reported by PCF for both Ethernet and IP type PDU Sessions (including the need to (un)subscribe 5GS Bridge/Router information Notification from PCF).
• Creating the TSC Assistance Container based on individual traffic pattern parameters from the NEF/AF or DetNet controller and providing it to the PCF.
• Determining the Requested PDB by subtracting the UE-DS-TT Residence Time from the Requested 5GS Delay provided by the NEF/AF or DetNet controller and providing the determined Requested PDB to the PCF.
• Discovering the AMFs serving the list of TA(s) that comprise the spatial validity condition from the NRF or AMFs serving the UE(s) from the UDM and subscribing to the discovered AMF(s) to receive notifications about presence of the UE in an Area of Interest.
• Discovering the AMF(s) serving a UE or a list of TA(s) and subscribing to gNB's node-level timing synchronization status.
• Obtaining gNB's and UPF's node-level timing synchronization status information as defined in clause 5.27.1.12.
• Determining the spatial validity condition from the requested coverage area by the NEF/AF and enforcing time synchronization service for the requested coverage area.
• Support for RAN feedback for BAT offset and adjusted periodicity as defined in clause 5.27.2.5.
• In the case of support of integration with IETF Deterministic Networking (as depicted in clauses 4.4.8.4 and 5.28.5), acting as a stateful translator function between a DetNet controller and 5G System Network Functions and Procedures, including the NW-TT. This includes exposing the information about the 5GS router to the DetNet controller and mapping 5GS router configuration parameters provided by the DetNet controller to 5G System parameters. The details are defined in clause 5.28.5.