信噪比失配对LDPC码译码影响的分析  

Effects of the SNR Mismatch on Decoding the LDPC Codes

作　　者：张仲明[1] 许拔[1] 杨军[1] 张尔扬[1] 

机构地区：[1]国防科学技术大学电子科学与工程学院,湖南长沙410073

出　　处：《计算机工程与科学》2011年第3期167-171,共5页Computer Engineering & Science

摘　　要：在加性高斯白噪信道条件下,采用置信度传播算法对LDPC码进行译码,需要精确估计信道信噪比用于计算接收比特的后验概率消息作为译码器的输入。信噪比值的错误估计称为信噪比失配。本文研究加性高斯白噪信道条件下信噪比失配对LDPC码译码的影响。通过对置信度传播算法校验节点更新方程的近似得到一个以信噪比为自变量的校正因子函数,基于该函数得出信噪比欠估计对译码的影响比过估计更敏感的结论,计算机仿真验证了该结论。The decoding of the LDPC codes by the belief propagation （BP） algorithm for the additive white Gaussian noise （AWGN） channel requires an accurate estimation of the signal-to-noise ratio （SNR） for the computation of the a posteriori probabilities （APPs） of the received bits that serve as the decoder inputs. An erroneous estimation of SNR at the decoder is referred to as SNR mismatch. In this paper, we study the effects of the SNR mismatch on the bit error rate （BER） performance of the LDPC codes for the AWGN channel. The correct-factor function is achieved by approximating the check node update equation of the BP algorithm. It is concluded that the effect of SNR under-estimation on decoding is more sensitive than SNR over-estimation based on the correct-factor function. The simulation results also indicate the concision.

关 键 词：LDPC码 置信度传播算法 信噪比失配 

分 类 号：TN911[电子电信—通信与信息系统]