Blockage mitigation in adaptive rate land mobile satellite links using cooperative ARQ

In this paper, we consider efficient communication over land mobile satellite channels (LMSC) based on a cooperative automatic repeat request (ARQ) strategy. Specifically, we propose a cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer with cooperative truncated ARQ protocol at the data link layer. We first derive a closed form expression for the spectral efficiency in this setting. Aiming at maximizing this performance measure, we then optimize an AMC scheme which directly satisfies a prescribed packet loss rate constraint at the data-link layer. The results indicate that utilizing cooperative diversity to mitigate channel blockage in a LMSC, noticeably enhances the spectral efficiency compared with the system that employs only AMC at the physical layer. Moreover, the proposed combining scheme outperforms the fixed rate cooperative ARQ when the transmission rates at the source and relay are chosen based on channel statistics.