一种利用大衍数列构造多码率原模图QC-LDPC码的方法

A Construction Method of Multi-Code-Rate Protograph QC-LDPC Codes Using Dayan Sequence

针对准循环低密度奇偶校验(Quasi-Cyclic Low-Density Parity-Check,QC-LDPC)码存在码长码率不能灵活选择的问题,提出了一种基于大衍数列构造多码率的原模图QC-LDPC码的新颖方法,该方法利用计算机搜索算法得到原模图基矩阵,然后基于大衍数列的循环移位矩阵对原模图基矩阵进行循环扩展,以此得到校验矩阵。该方法构造的校验矩阵围长至少为6,只需要简单的移位寄存器就可以实现编码,并且具有良好的纠错性能。仿真结果表明,在误码率(Bit Error Rate,BER)为10^(-6)时,所构造的码率为0.5的P-DY-QC-LDPC(4000,2000)码和码率为0.75的P-DY-QC-LDPC(4000,3000)码与同码率近似码长的其他码型相比较,其净编码增益均有一定提高。

To solve the problem that quasi-cyclic low-density parity-check（QC-LDPC）codes cannot be flexibly selected,a cyclic-shift matrix based on da yan sequences was used to extend the protograph basic matrix,and a novel method was constructecd for multi-rate QCLDPC codes.The method uses computer searching algorithm to obtain the protograph basic matrix,and then applies cyclic-shift matrix to extend it to obtain the check matrix.The check matrix constructed by this method has a girth of at least 6,and only a simple shift register is needed to achieve coding,and a good error correction performance is realzied.Simulation results show that the constructed P-DY-QC-LDPC（4000,2000）code with the code-rate of 0.5 and PDY-QC-LDPC（4000,3000）code with the code-rate of 0.75,compared with other codes with the same code-rate and approximate code-length,both can improve the net coding gain at the bit error rate of 10^-6.