一种改进的多进制LDPC码的译码算法

An Updating Decoding Algorithm of Non-binary LDPC Codes

提出了一种多进制LDPC码基于EMS的改进算法,从译码效率的角度分析计算复杂度。利用变量节点的可靠程度随迭代次数的增加而增加的特点,采用每个变量节点的非法校验值结合变量节点的最大伪后验概率来判断变量节点的可靠性,通过判断准则让一部分节点提前终止迭代,减少迭代过程中不必要的校验节点和变量节点的更新,从而降低复杂度,提高译码效率。对该算法在高斯白噪声信道,基于GF(4)有限域,码率0.5的规则LDPC码(8 192,3,6)进行了仿真,结果显示:改进的EMS译码算法相对传统的EMS译码算法,在误码性能上的损失极小(当误码率10-4时,信噪比损失大约0.05 dB),而且随着信道条件的改善,这种损失进一步减少,但计算复杂度大大降低,译码效率大大提高。

This paper presents an improved decoding algorithm of non-binary LDPC codes based on the Expanded Min-Sum algorithm,analyzes the complexity of the algorithm in decoding efficiency.According to the fact that the reliability of variable note is increased with the increase of the iterative number,the reliability of the variable notes is estimated by the maximum post probability of variable notes and illegal parity-check values.By the estimation rule,the iterative calculations or some variable notes are stopped,the number of calculation for updating variable and parity-check notes is reduced,thus the decoding complexity is decreased and the decoding efficiency is improved.A simulation is made using regular non-binary LDPC codes under White Gaussian Noise channel based on GF（4）,the result shows that the performance decreases by about 0.05 dB when BER（Bit Error Rate） is,but the decoding complexity is reduced and the decoding efficiency is improved significantly.