A HARQ scheme for combating burst-errors due to power control gaps 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 round-trip propagation delay will cause power control gaps when the channel transits from a good state to a bad state, resulting in long (large-scale) burst-errors. A novel hybrid ARQ (HARQ) scheme is proposed to combat this kind of burst error. Based on the iterative SOVA (soft-output Viterbi algorithm) decoder, the proposed scheme utilizes the side information of the turbo decoder to derive the average reliability of the desired packet. When the average reliability 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 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 in a severe Markov satellite channel, which is especially suitable for traffic having strict delay requirement and moderate BER requirement