A Full-rate Cooperative Transmission Scheme Using Precoding and Distributed Space-Time Coding

摘要

A full-rate wireless transmission scheme based on multiple half-duplex relays is proposed. To the best of our knowledge, we are the first to adopt DF (DF, Decode and Forward) mode into relay decoding strategy in this topic. Our motivation is that DF mode can reduce the noise among source and relay nodes effectively. We use prevailing linear constellation precoding process at the source node but design coding strategy with DSTC (DSTC, Distributed SpaceTime Coding) at each relay node. Thus the "Short Broad Effect" caused by the imbalance of error performance between odd time slot and even time slot can be solved. Two precoding matrixes are given out, which occupies low complexity. Meanwhile, the design principle of an easy operated DSTC matrix which matches the precoding matrix is proposed. The analysis on all possible situation of decoding is presented, which proves that full diversity gain can be achieved through easy operated matrixes compared to previous work. Simulation results also indicate that the scheme proposed obtains lower BER than the multi-relay NAF (NAF, Non-orthogonal AF) scheme in the SNR range of the real system.