利用ACE值构造QC-LDPC码

为进一步提升中短码长下准循环低密度奇偶校验(Quasi-cyclic Low-density Parity-check,QC-LDPC) 码的纠错性能，提出了一种综合短环数目和环连通性的QC-LDPC码构造方法。首先，采用Golomb规则构造QC-LDPC码，对基矩阵中的部分元素进行替换预处理，初步降低短环数目；其次，采用所提的利用近似环外信息度（Approximate Cycle Extrinsic message degree，ACE）的消环掩模算法来优化QC-LDPC码，使得掩模后的校验矩阵具有较大的ACE平均值，最终完成QC-LDPC码的构造。该构造方法简单、通用性强，在短环数目和连通性间进行了平衡。与只考虑减少短环数目、增大围长等方法相比，该方法构造的QC-LDPC码有更加优异的纠错性能。

Construction of QC-LDPC Codes with ACE Value

To further improve the performance of quasi-cyclic low-density parity-check(QC-LDPC) codes with short and medium lengths,a simple and versatile method is proposed to construct QC-LDPC codes by jointly optimizing the number and the connectivity of cycles.First,a replacement preprocessing algorithm is presented to effectively eliminate short cycles in QC-LDPC codes constructed by Golomb rule.Then,the masked matrix of irregular QC-LDPC code with a large approximate cycle extrinsic message degree(ACE) average is constructed by using the masking algorithm with ACE.Finally,a class of QC-LDPC codes can be constructed by such simple and universal method.Compared with other codes that only consider one certain index,the constructed QC-LDPC codes have excellent error correction performance.