Improved Log-BP Algorithm Based on GDL for M-ary APSK Modulated LDPC Code

Based on Generalized Distributive Law (GDL), improved belief propagation (BP) algorithm in logarithm domain for M-ary APSK modulated Low-density parity-check (LDPC) code which can get a better tradeoff between error performance and decoding complexity is proposed. Also the Min-Sum approximation of the improved log-BP algorithm is deduced. Simulation shows that the improved log-BP and Min-Sum algorithms achieve a better bit error rate(BER) compared with the corresponding binary algorithms when decoding a short frame 16APSK modulated LDPC code based on DVB-S2 standard.