Improved Partial Retransmission Hard-Decision Message-Passing ARQ

The proposed improvement on hard-decision message-passing (hMP-ARQ) method can verify correct symbols when there is a group of common error symbols in a pair of check nodes. This leads to a better performance than the existing hMP-ARQ. At symbol error probability (Ps) of 0.2, the average numbers of frames for successful transmission were reduced to only 42% and 46% of the existing hMP-ARQ for (45,30) and (60,30) codes respectively. With lower complexity, it even performs better than block Vector Symbol Decoding ARQ (BVSD-ARQ) for a (60,30) LDPC code and Ps < 0.175. Thus, it is a good choice for partial retransmission ARQ.