A.19 Monitor of ARQ and HARQ performance

28.5523GPP5G performance measurementsManagement and orchestrationRelease 18TS

Reliable Packet Delivery is one of the important Performance factor for a better User experience. HARQ re-transmissions at the MAC layer ensure reliable packet delivery

In addition, RLC can be configured to operate in acknowledged mode for those applications that need very low packet drops and can tolerate a slightly higher delay from RLC re-transmissions.

If a MAC PDU is not delivered, HARQ takes care of re-transmitting (up to a maximum configurable number). If all the re-transmissions fail at MAC layer, and if RLC is configured to operate in acknowledged mode, RLC’s ARQ mechanism will take care of any residual packet errors.

It is important to:

a) Maintain the block error rate or packet error rate within tolerable limits.

b) Ensure that HARQ re-transmissions take care of most packet errors, instead of relying on RLC layer re-transmissions (which would increase the delay).

So, it is important to monitor the performance of these schemes.

HARQ Performance if viewed at MCS (Modulation Coded Scheme) can help in monitoring the MCS Performance also.