A Multiple-Voting-Based Decoding Algorithm for Nonbinary LDPC-Coded Modulation Systems

We propose a multiple-voting-based joint detection-decoding algorithm for nonbinary low-density parity-check (LDPC)-coded modulation systems. This algorithm is inspired from the reliability-based JDD algorithm for nonbinary LDPC-coded modulation systems, that has been proposed recently, in which the accumulated reliability of symbols based on one-step majority-logic decoding algorithm and the Chase-like local list decoding algorithm are used. However, the reliability-based JDD algorithm still has a significant performance degradation of at least 1 dB with low column weight (d_v≤4). In order to reduce the performance degradation with low column weight, the proposed algorithm allows unfixed number of variable nodes to pass two symbols to the associated check node, in contrast with the reliability-based JDD algorithm, which allows only one variable node to pass two symbols to check node, when updating variable-to-check messages. Moreover, the votes are weighted differently according to the components of the list in the check-sum computation. Simulations show that the proposed algorithm yields better performance with low column weight, while still maintaining the low complexity feature.