准循环LDPC好码设计

Journal of Systems Engineering and Electronics ›› 2009, Vol. 31 ›› Issue (5): 1011-1017.

准循环LDPC好码设计

肖扬¹, 徐丹²

1. 北京交通大学信息科学研究所, 北京, 100044;
2. 工业和信息化部软件与集成电路促进中心, 北京, 100038

收稿日期:2008-05-05 修回日期:2008-09-23 出版日期:2009-05-20 发布日期:2010-01-03
作者简介:肖扬(1955- ),男,教授,博士生导师,博士,主要研究方向为通信信号处理,多维系统理论,多维信号与信息处理.E-mail:yxiao@bjtu.edu.cn
基金资助:
国家自然科学基金(60572093);教育部博士点基金(20050004016)资助课题

Design of good quasi-cyclic LDPC codes

XIAO Yang¹, XU Dan²

1. Inst. of Information Science, Beijing Jiaotong Univ., Beijing 100044, China;
2. Software and Integrated Circuit Promotion Center, Ministry of Industry Information Technology, Beijing 100038, China

Received:2008-05-05 Revised:2008-09-23 Online:2009-05-20 Published:2010-01-03

摘要/Abstract

摘要： 现有准循环(QC)LDPC码的设计未考虑避免短环问题与校验矩阵的行相关问题.第一个问题使准循环LDPC码的误码率性能远低于随机LDPC码,第二个问题使得构造生成矩阵非常困难.为解决第一个问题,提出避免短环的准循环LDPC码的设计约束条件,根据四、六环检验结果调整校验矩阵中循环子矩阵的维数和移位因子.为解决第二个问题,提出一种不规则准循环LDPC码的设计方法,该方法将校验矩阵中的特定位置的子矩阵用零矩阵和循环矩阵置换,获得一非奇异方阵,用于构造生成矩阵.虽然在校验矩阵中采用双对角线子矩阵可解决校验矩阵的行相关问题,但是会产生低码重的码字,导致误码率性能不能随码长增加而提高.计算机仿真结果表明,设计的准循环LDPC码具有良好的误码率性能.

Abstract: The existing design of quasi-cyclic(QC) low-density parity-check(LDPC) codes has not considered the problems of short length girths and the rows' dependency.The first problem leads to the BER performance of QC LDPC codes to be much poorer than that of randomly constructed LDPC codes,while the second problem leads to the difficulty of construction of generator matrices from parity-check matrices.To solve the first problem,the constraint conditions for designing the QC LDPC codes are proposed,and the dimension and shift factors of the circulant matrices of the given sparse parity-check matrix are adjusted according to the test results of both girth 4 and girth 6.To solve the second problem,an approach of irregular QC LDPC codes is proposed.The proposed approach is to replace some sub-matrices by zero matrices and identity matrices at special positions in the given sparse parity-check matrix so as to get a nonsingular square matrix for the construction of the generator matrix.Though adopting bidiagonal submatrices in parity-check matrix can solve the rows' dependency problem,many code words with low weights will occur,which leads to the BER performance can not be better by increasing code lengths.Examples are provided for the proposed design of QC LDPC codes,and computer simulation results show that the proposed QC LDPC codes achieve good BER performance.

中图分类号:

肖扬, 徐丹. 准循环LDPC好码设计[J]. Journal of Systems Engineering and Electronics, 2009, 31(5): 1011-1017.

XIAO Yang, XU Dan. Design of good quasi-cyclic LDPC codes[J]. Journal of Systems Engineering and Electronics, 2009, 31(5): 1011-1017.

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