Enhanced delta-based layered decoding of WiMAX QC-LDPC codes

Rovini, et al., have proposed a delta-based layered decoding algorithm to mitigate the latency constraint imposed by the layered decoding algorithm on QC-LDPC codes whose adjacent block rows overlap. We apply their algorithm and the low-complexity offset-based Min-Sum check equation to the decoding of the codes specified in WiMAX. The performance is simulated for two representative hardware pipeline depths, showing a maximal 0.13-dB performance loss, with respect to the ideal latency-free layered decoding algorithm, for a block error rate of 10^-2 in 15 iterations and a pipeline depth of eight. We further develop a systematic procedure to arrange the processing order of the block rows and block columns of a given QC parity check matrix, reducing the aforementioned performance loss to 0.03 dB at no extra hardware cost. The procedure can be applied to any QC-LDPC codes for any given pipeline depths.