信噪比失配对LDPC码译码影响的分析

张仲明，许拔，杨军，张尔扬

doi:10.3969/j.issn.1007130X.2011.

计算机工程与科学 >

2011 , Vol. 33 >Issue 3: 167 - 171

DOI: https://doi.org/10.3969/j.issn.1007130X.2011.

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信噪比失配对LDPC码译码影响的分析

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(国防科学技术大学电子科学与工程学院,湖南长沙 410073)

张仲明(1980)，男，浙江浦江人,博士生，研究方向为高效信道编码和高速数据传输。许拔(1981),男，湖南汨罗人，博士生，研究方向为高效信道编码和高速数据传输。杨军(1977)，男，博士，研究方向为通信信道编码和高速调制解调技术。张尔扬(1941)，男，浙江宁波人,教授，博士生导师，研究方向为军用无线通信与网络技术、软件无线电、空间通信与组网。

收稿日期: 2009-01-05

修回日期: 2009-10-21

网络出版日期: 2011-03-25

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Effects of the SNR Mismatch on Decoding the LDPC Codes

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(School of Electronics Science and Engineering,National University of Defense Technology,Changsha 410073,China)

Received date: 2009-01-05

Revised date: 2009-10-21

Online published: 2011-03-25

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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。

关键词： LDPC码; 置信度传播算法; 信噪比失配

本文引用格式

张仲明，许拔，杨军，张尔扬 . 信噪比失配对LDPC码译码影响的分析[J]. 计算机工程与科学, 2011 , 33(3) : 167 -171 . DOI: 10.3969/j.issn.1007130X.2011.

Abstract

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 conclsion.

Key words： LDPC codes;belief propagation algorithm;SNR mismatch

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