A SIMPLE PACKET RETRANSMISSION STRATEGY FOR THROUGHPUT AND DELAY ENHANCEMENT ON POWER-LINE COMMUNICATION CHANNELS

A new, simple, and effective communication protocol is developed and e valuated for use on power line distribution networks. The protocol inv olves retransmission of unacknowledged packets, which are sent in eith er single or multiple (N) copies in accordance with estimates of commu nication link quality. Multiple packet copies can be code combined at the receiver, using majority voting on each bit position, to reduce pa cket error rates. Adaptive link quality estimates are based on the rec eipt or absence of positive acknowledgements. Information throughput e fficiency is calculated and N optimized in terms of system variables. Performance benefits of code combining are clearly demonstrated. The a lgorithm was implemented and tested using a five-station intrabuilding power line communications network operating at 1.2, 2.4, 4.8 and 9.6 kbit/s data rate. Substantial throughput and delay improvement occurre d on poor quality links, without degrading performance on good links.