A reduced complexity decoding algorithm for NB-LDPC codes

Non-binary low-density parity-check (NB-LDPC) codes perform much better than their binary counterparts, when codeword length is moderate or high-order modulation is used. However, the implementation of a NB-LDPC decoder usually suffers from excessive hardware complexity and large memory requirement. Many new algorithms and decoding schedules have been introduced in recent literatures to reduce the decoding complexity in further. However, the complexity of current decoding algorithms for NB-LDPC codes is still high. In this paper, a two-extra-column trellis min-sum algorithm (TEC-TMSA) is proposed. The TEC-TMSA combines the two-extra-column method and the trellis min-sum algorithm in an intelligent way. Since only the minimum value of a row needs to be sorted out for configuration constructions, the computational complexity of the proposed TEC-TMSA is much lower than that of the TMSA. Furthermore, we develop a novel location-fixed selection scheme, which significantly decreases the number of required comparison operations in the TEC-TMSA with negligible performance loss.