准循环低密度校验码的构造

Construction of Quasi-cyclic Low-density Parity-check Codes

文中提出了一种利用筛选算法寻找指数矩阵的新方法,其构造的准循环低密度校验码有两个主要的优点:一是可用简单线性移位寄存器完成编码;二是只需存储校验矩阵的指数矩阵,可节约很多存储空间。利用计算机能较快的搜索圈长为6,8,10,12的循环置换矩阵阶数的最小值p,搜出的这些p在理论上达到了Fossorier给出的最小下界。仿真结果表明构造的低密度校验码在加性高斯白噪声信道中BPSK调制下用和积迭代译码算法的误比特性能表现良好。

A new method for finding the exponent matrix is proposed, the codes based on it have two main advantages： low complexity shift register encoding and small size of memory. The minimum p with girth 6,8,10,12 can be easily searched, and the searched p theoretically reaches the lower bound given by Fossorier. Simulation results show that the constructed LDPC codes perform well with sum-product decoding algorithm （SPA）.