Section: 16.8.2.2 Network timing synchronization monitoring towards CN
Content: For NG-RAN timing synchronization monitoring support, the 5GC initiates RAN Timing Synchronisation Status (TSS) Reporting procedure to obtain the change of network timing synchronization status of gNBs. The gNB may receive RAN timing synchronization status information request from the AMF, see TS 23.501[ System architecture for the 5G System (5GS) ]  [3]. The RAN timing synchronization status information includes the gNB node-level information about timing synchronization operation status. The gNB timing synchronization status may comprise one or more of the following information elements: synchronization state, traceability to UTC, traceability to GNSS, clock frequency stability, clock accuracy, parent time source, as defined in Table 5.27.1.12-1 in TS 23.501[ System architecture for the 5G System (5GS) ]  [3]. Based on NG-RAN's capabilities of reporting timing synchronisation status, NG-RAN accepts or rejects the request from AMF. NG-RAN can be pre-configured with thresholds for attributes on timing synchronisation status reporting via OAM. When the thresholds are met or exceeded, events will be triggered and NG-RAN reports Timing Synchronization Status to AMF. For detailed procedure on the Timing Synchronization Status reporting, refer to TS 38.401[ NG-RAN; Architecture description ]  Clause 8.x.1 [4].