A simple adaptive data link protocol for performance enhancement on networks with variable-quality links

The authors propose an automatic repeat request (ARQ) scheme in which either single or multiple (N) packet copies are transmitted, depending on the channel state. Channel state estimates are based on the receipt or absence of acknowledgements. When N packet copies are transmitted, code combining using majority voting on each packet is used to significantly improve performance. Throughput efficiency is calculated for send-and-wait (SW) flow control vs. channel error probability for various N values. The algorithm was implemented on a noisy, five-station intrabuilding power line data network at 1.2, 2.4, 4.8, and 9.6 kbit/ s. When this scheme was used, measured delay and throughput performance the LAN improved dramatically over that obtained using conventional SW ARQ.<
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