基于可靠率的改进的LDPC码BF译码算法

Modified LDPC BF Decoding Algorithm Based on Reliability Ratio

相对于低密度奇偶校验(LDPC)码置信传播(BP)译码o(n2)数量级的计算复杂度,比特翻转(BF)译码算法的计算复杂度只有o(n),然而其译码性能却有很大降级。为此,该文提出了一种改进的BF算法。该方法使用了可靠率来衡量所有参与同一校验的信息节点对校验没有满足的贡献,以较低的计算量增加为代价在译码中引入软信息的使用,从而使BF的性能有了较大提升。理论分析表明其复杂度为o(n),仿真结果表明,与加权的比特翻转译码算法比较,新算法在信噪比为7 dB时,误码率由10-3数量级改善为10-4。

Compared with belief-propagation decoding algorithm which has complexity class of o（n^2）, bit-flipping（BF） decoding algorithm for low density parity check （LDPC） codes has only complexity class of o（n）. However, the performance of BF algorithm is degraded. This paper presents a modified BF decoding algorithm, which uses reliability ratio as a weight of information node in unsalisfied parity checks so that the soft information is introduced in decoding, and the decoding performance is improved greatly with a little more computation. Analyses show the modified algorithm still has a complexity class of o（n）. Simulation results indicate that the error rate with 7dB SNR is improved from 10^-3 of the weighted bit-flipping decoding algorithm to 10^-4 of the modified algorithm.