针对LDPC码(低密度奇偶校验码)的噪声门限问题,基于置信传播算法讨论密度进化算法的实现方法,通过对校验节点均值迭代公式的简化来确定门限值,简化算法降低了迭代运算的复杂度,减小了运算量.构造了3种不同次数分布的LDPC码,对其在高斯白噪声信道下噪声方差门限和信噪比门限进行了理论计算和仿真,并对结果进行了比较分析.研究结果表明,随着列重的增加,LDPC码的误码性能将变差,选择好的次数分布能获得优秀的误码性能,这对LDPC码进一步的应用研究具有指导意义.
To deal with the noise thresholds of LDPC codes,the density evolutionary algorithm based on belief propagation algorithm is discussed to determine the thresholds through simplifying the message iterative arithmetic on the means of the check nodes which can reduce the computing complexity and the amount of computation.Three different degree distribution LDPC codes have been constructed,and the theoretical calculation and simulation have been carried on to determine the noise variance thresholds and the SNR thresholds under AWGN channel,the results have been compared.It shows that with the increase of the column weight,the performance of LDPC codes becomes worse.Excellent performance can be obtained if we choose good numbers of degree distribution,that has guiding significance for further application research of LDPC codes.
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