误码条件下LDPC码参数的盲估计

针对非合作信号处理中LDPC码（Low-Density Parity-Check）的盲识别问题,提出了一种容错能力较强的开集识别算法.该算法通过对码字矩阵进行高斯约旦消元找到汉明重量较小的"相关列",并根据"相关列"中所包含的约束关系求得LDPC码的校验向量,然后剔除"相关列"中为"1"位置对应的错误码字.若根据高斯约旦消元求校验向量和剔除错误码字进行迭代无法得到更多校验向量,则对得到的这些校验向量进行稀疏化,再进行译码纠错.最后,综合利用校验向量的求解,错误码字的剔除,校验向量稀疏化,LDPC码译码进行迭代,实现LDPC码校验矩阵的有效重建.仿真结果表明,对于IEEE 802.16e标准中的（576,288）LDPC码,在误比特率为0.0022时,本文算法仍可以达到较好的识别效果.

A Method for Blind Recognition of LDPC Codes in a Noisy Environment

A strong fault tolerance algorithm was proposed for LDPC (Low-Density Parity-Check) code reconstruction without a candidate set in a non-cooperative context.The algorithm uses Gauss Jordan elimination to find related columns with low Hamming weight and obtains the parity-check vector of LDPC codes according to the constraint relationship contained in the related column.Then the error code corresponding to the "1" position in the related column is removed.If the iteration according to Gauss Jordan elimination and the removing of error code can not get more parity-check vectors,then it makes these resulting parity-check vectors to be sparse and uses the sparse vectors to error correction.Finally,it reconstructs LDPC parity-check matrix effectively by making comprehensive use of parity-check vector solution,error code elimination,parity-check matrix sparsity and LDPC codes decoding to iterate.Simulation results show that,for the (576,288) LDPC codes in IEEE 802.16e standard,the proposed algorithm can provide good performance even when the bit error rate is 0.0022.