基于完备循环差集的type-Ⅱ QC-LDPC码的构造  

Construction of the type-Ⅱ QC-LDPC codes based on perfect complete cyclic difference families

作　　者：黄胜[1] 宋静 袁建国[1] HUANG Sheng;SONG Jing;YUAN Jianguo(Key Laboratory of Optical Communication and Networks,Chongqing University of Posts and Telecommunications,Chongqing 400065,China)

机构地区：[1]重庆邮电大学光通信及网络重点实验室,重庆400065

出　　处：《系统工程与电子技术》2018年第11期2586-2590,共5页Systems Engineering and Electronics

基　　金：国家自然科学基金(61371096;61571072);重庆市基础与前沿研究计划项(cstc2015jcyjA40015)资助课题

摘　　要：针对当前type-Ⅱ的准循环低密度奇偶校验(quasi-cyclic low-density parity check,QC-LDPC)码中仅含有权重为2的循环置换矩阵而引入短环,导致迭代译码性能下降的问题,基于完备循环差集给出了近似双对角结构的type-ⅡQC-LDPC码的设计方法,该方法构造的奇偶校验矩阵由零矩阵,权重为1的循环单位阵和权重为2的循环矩阵组成,不但围长至少为8,而且还保留了type-ⅡQC-LDPC码具有更高最小距离上界的优点,从而使译码时可快速收敛。仿真结果表明:构造的type-ⅡQC-LDPC码在加性高斯白噪声(additive white Gauss noise,AWGN)信道下,采用和积(sum-product algorithm,SPA)译码时,码字无明显的错误平层且具有良好的纠错性能。To deal with the short girth,which caused by the only weight-2 circulant permutation matrices in the current type-Ⅱquasi-cyclic low-density parity check(QC-LDPC)codes.A method of approximate double diagonal structure of the type-ⅡQC-LDPC codes based on perfect cyclic difference families(P-CDF)is proposed.The parity check matrices constructed by this method consist of zero matrices,weight-1 circulant permutation matrices and weight-2 permutation matrices,which not only keeps the girth at least 8,but also retains the advantages of type-ⅡQC-LDPC codes with a higher minimum distance upper bound,so that decoding can quickly converge.The simulation results show that the type-ⅡQC-LDPC codes have no obvious error-floor and good iterative decoding performance when decoded by the sum-product algorithm(SPA)under the additive white Gauss noise(AWGN)channel.

关 键 词：type-Ⅱ准循环低密度奇偶校验码 完备循环差集 围长 最小距离 

分 类 号：TN911.22[电子电信—通信与信息系统]