A novel low complexity space-time coding schemes for underwater acoustic communications

Underwater acoustic (UWA) channels exhibit time-varying fading statistics, thus a coded modulation scheme optimally designed for a specific model (e.g., Rayleigh fading) will perform poorly when the channel statistics change. Exploiting diversity via coded modulation is a robust approach to improve the reliability of the acoustic link in a variety of channel conditions. Herein, protocols coupled with space-time block code(STBC) strategies are proposed and analyzed for underwater communication. In this paper, we consider a time-reversal space-time block code (STBC) with rotated factors(RFTR-STBC) which extend a tranditional STBC scheme to a underwater communication scenario. We formulate its algebraic structure and propose a systematic method for its construction. Based on time-reversal scheme,we presented a new stratgy of STBC known as the block orthogonal STBCs (BOSTBCs), which exploited the time-reversal matrix with the rotated factor to restructure the new coded matrix.Analyzing both simulated and experimental data, the following results are confirmed: the proposed coding scheme yield a lower error rate when spatial diversity is very limited. On the other hand, the decoding complexity of the scheme show a better reduction performance than tranditional OSTBC schemes.