一类基于B_2(mod m)序列的准循环LDPC码  

A class of quasi-cyclic LDPC codes from B_2(mod m)sequences

作　　者：张国华[1,2] 王新梅[1] 

机构地区：[1]西安电子科技大学综合业务网理论及关键技术国家重点实验室,西安710071 [2]中国空间技术研究院西安分院,西安710100

出　　处：《中国科学：信息科学》2012年第3期343-351,共9页Scientia Sinica(Informationis)

基　　金：国家重点基础研究发展计划(批准号:2010CB328300);国家自然科学基金(批准号:61001130;61001131);高等学校学科创新引智计划(批准号:B08038)资助项目

摘　　要：基于B2(modm)序列,提出一种构造二元低密度奇偶校验(LDPC)码的新方法.这类编码的校验矩阵列重为3、行重为任意整数,并且具有准循环(QC)结构.校验矩阵对应的Tanner图围长至少为8,对应的最小距离至少为12.当m为素数时,提出一种减少8环的方法,使得Tanner图中4类可能的8环中两类被完全消除.仿真结果表明,m为素数时新LDPC码的译码性能优于渐进边增长(PEG)算法随机产生的(准)规则LDPC码.此外,提出一种基于邻域扩展搜索的启发式算法,利用该算法可以获得长度接近或达到上界的B2(modm)序列.A new class of binary low-density parity-check（LDPC）codes is proposed based on B2（mod m） sequences.The parity-check matrix of such a code has a column weight of three and a row weight of an arbitrary integer,and a quasi-cyclic structure.The parity-check matrix also has a girth at least 8,and corresponds to a code with minimal distance at least 12.When m is prime,an 8-cycles reduction method is presented to completely avoid the two types of 8-cycles within the total four types existed in the Tanner graph.Simulation results show that,for a prime integer m,the new LDPC code outperforms the random（quasi-）regular counterpart generated by the PEG algorithm.Finally,a heuristic algorithm based on a strategy called neighboring extension search is presented to search for the B2（mod m）sequences whose lengths approach or meet the upper bound.

关 键 词：低密度奇偶校验(LDPC)码 准循环(QC)码 循环置换矩阵 围长 迭代译码 

分 类 号：TN911.2[电子电信—通信与信息系统]