Section: A.8 Monitor of ARQ and HARQ performance
Content: Reliable Packet Delivery is one of the important Performance factor for a better User experience. HARQ retransmissions 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 retransmissions. If a MAC PDU is not delivered, HARQ takes care of retransmitting (upto a maximum configurable number). If all the retransmissions 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 retransmissions take care of most packet errors, instead of relying on RLC layer retransmissions (which would increase the delay). So, it is important to monitor the performance of these schemes. ARQ Performance if viewed at QCI level can help in monitoring the distribution for each of the services. HARQ Performance if viewed at MCS (Modulation Coded Scheme) can help in monitoring the MCS Performance also.