基于最大余弦比的LDPC码闭集识别

Closed Set Identification of LDPC Codes Based on Maximum Cosine Ratio

为改善低信噪比条件下LDPC码闭集识别的性能,本文提出了一种基于最大余弦比的软判决识别算法。该算法在分析了最大均值似然比算法存在的问题的基础上,利用LDPC码的编码结构特点,将识别过程归结为二元域中线性关系的检测问题;同时引入能够有效表征线性编码约束关系成立可能性大小的余弦检验函数,基于正确校验矩阵与错误校验矩阵下的余弦检验函数统计特性不同的事实,将两种情况下的余弦比作为编码器判定依据,从而实现低信噪比下LDPC码闭集的有效识别。仿真结果表明,在信噪比为0 dB条件下,算法能够可靠识别出常用的IEEE802.16e协议中LDPC码,同时与现有算法相比,算法性能提升近1 dB。

In order to improve the performance of LDPC code closed-set recognition with low signal-to-noise ratio,this paper proposes a soft decision recognition algorithm based on maximum cosine ratio.Based on the analysis of the problems of the maximum mean likelihood ratio algorithm,the algorithm uses the coding structure characteristics of the LDPC code to reduce the recognition process to the detection problem of the linear relationship in the binary domain;At the same time,a cosine test function that can effectively characterize the possibility of the establishment of linear coding constraints is introduced,based on the fact that the statistical characteristics of the cosine test function under the correct check matrix and the error check matrix are different,and use the cosine ratio in both cases as the basis for encoder determination,thereby achieving low signal-to-noise ratio effective identification of closed sets of LDPC codes.The simulation results show that the algorithm can reliably identify the commonly used LDPC codes in IEEE802.16e protocol under the condition of 0 dB signal-to-noise ratio.At the same time,the performance of the algorithm is improved by nearly 1 dB compared with the existing algorithm.