一种基于距离图的QC-LDPC构造算法

An algorithm of QC-LDPC construction based on distance graph

针对随机法构造的LDPC码结构性差,不易于硬件实现等问题,设计了一种基于距离图的QC-LDPC码构造算法。它有两种实现方式--顺序搜索方式和随机搜索方式,其码长、码率、圈长等参数可以根据实际需要设定,灵活性较好。仿真结果表明:随机搜索方式构造的QC-LDPC码性能明显优于顺序搜索方式,并且与PEG构造的随机码性能相当。与随机构造法相比,文中的搜索算法构造速度更快,并且所构造的码具有准循环特性,易于硬件实现。

According to the fact that the random constructions of LDPC codes are lack of structure and difficult to be implemented in hardware, an algorithm of QC-LDPC codes based on distance graph is designed. There are two ways to produce the codes-sequential search and random search. They can produce flexible QC-LDPC codes by setting the parameters such as code length, rates and girth according to requirement. The simulation shows that： the QC-LDPC codes constructed by random search perform better than those obtained using sequential search and have equivalent BER performance with PEG codes. Compared with random construction, the proposed algorithms is faster, and can obtain quasi-cyclic codes which are easy to be implemented in hardware.