An adaptive two-copy delayed SR-ARQ for satellite channels with shadowing

The paper focuses on improving performance of land mobile satellite channels (LMSC) at high band (K or EHF band), where shadowing is the primary impediment to reliable data transmission. Compared with multipath fading, shadowing exists on a longer time scale. Hence interleaving to combat shadowing introduces unacceptably large decoding delay. Here we propose an adaptive two-copy delayed SR-ARQ scheme whereby two copies of a packet are sent - the second with a delay relative to the first - in every transmission or retransmission. Closed-form expressions for mean transmission time, success probability, and residual loss probability are provided and simulation is used to validate the analysis. Furthermore, the issue of optimizing delay is addressed as well, and a simple yet effective strategy is suggested to support TCP traffic. By simulation, we compare the proposal with the normal SR-ARQ scheme in terms of TCP end-to-end throughput, and show great performance improvement achieved by our method.