A.1 Monitoring of UL and DL user plane latency in NG-RAN
28.5523GPP5G performance measurementsManagement and orchestrationRelease 18TS
Satisfying low latency expectations for 5G services, such as URLLC, is one of the key tasks for the operator to meet service performance expectations. As the performance in UL and DL differs, it is important for operators to be able to monitor the UL and DL user plane latencies separately. With performance measurements allowing the operator to obtain or derive the UL and DL user plane latency information separately, the operators can pinpoint the services performance problems to specific problems in UL or DL.
The DL IP latency monitoring in NG-RAN refers to the transmission within gNB of IP packets arriving when there is no other prior data to be transmitted to the same UE in the gNB.
The average DL latency needs to be measured to give an general indication of the latency performance; further more the latency distributions (into bins with latency ranges) need to be measured, to tell the occurrences about the packets with each certain range of latency and better reflect the user experience.
Different network slices may have different requirements on the delay, so the delay needs to be measured for each S-NSSAI.
To further pinpoint performance problem detected, separate counters may be provided per mapped 5QI (which are particularly useful when the mapped 5QI is used by few services and users and the packet size does not vary much).