一种有效的LDPC码伪码字搜索算法

为了获得影响低密度奇偶校验码线性规划译码性能的伪码字，通过深入分析有害的Tanner子图中变量节点位置与线性规划译码器输入分量位置的对应关系，提出了二元对称信道下低密度奇偶校验码的一种有效的低重量伪码字搜索算法．通过对基于交替方向乘子法的线性规划译码器输入向量叠加偏置噪声，经过有限次迭代搜索后可快速收敛到低重量伪码字． 仿真结果表明，与现有伪码字搜索算法相比，所提出的方法能够更准确地找到大量中短码长规则和非规则低密度奇偶校验码的低重量伪码字．

Efficient pseudo-codeword search algorithm for LDPC codes

In order to obtain the pseudo-codewords which can decrease the linear programming (LP) decoding performance of low-density parity-check(LDPC) codes, an efficient algorithm for searching low-weight pseudo-codewords of LDPC codes is proposed on the binary symmetric channel by making a detailed analysis of the corresponding relationship between variable nodes in the harmful Tanner subgraphs and input components of LP decoders. The proposed algorithm can rapidly converge to low-weight pseudo-codewords of LDPC codes with finite iterations by biasing noises for the input vectors of the LP decoder based on the alternating direction method of multipliers. Simulation results show that the proposed approach can accurately find many low-weight pseudo-codewords of regular and irregular LDPC codes with a short or middle length compared with the existing pseudo-codeword search method.