An adaptive hybrid-ARQ scheme combating burst-errors caused by power control lag in Ka-band LEO satellite systems

When power control is employed in a Ka-band LEO satellite system featured with a Markov channel, the long loop lag induces power control gaps during channel state transition, which results in long (large-scale) burst errors. To combat it, a novel hybrid ARQ scheme is proposed in this paper, in which the side information of the turbo decoder is utilized to derive the average reliability LLR_l of the desired frame based on the iterative SOVA decoding algorithm. When LLR_l is below the specified threshold, a Go-Back-N ARQ protocol is launched. With this scheme, the large-scale burst errors are effectively detected and corrected by the retransmission; the small-scale burst errors are filtered out for the interleaving and FEC coding to correct. The simulation results show that this scheme can achieve good BER performance with small cost in throughput and delay for Ka-band Markov satellite channels.