Research of Optimal Decoding Algorithm Based on Belief Propagation

In this paper, the decoding algorithm of Low-Density Parity-Check (LDPC) codes is analyzed, and a new decoding algorithm based on the belief propagation (BP) algorithm to eliminate the influence of cycles in the factor graph is proposed. In the traditional BP algorithm, the cycles of factor graph will send message back to its source, and this will decrease the decoding performance. The new algorithm records each cycles path and length of each node, and cuts off the path by which message is propagated when the message will come back. It can advance the decoding performance by protect the message of good quality be propagated as widely as possible. The results of simulation show that the performance of new algorithm is not worse than that of traditional BP algorithm in the low SNR channel and the new algorithm significantly outperform traditional BP algorithm in good channel condition.