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 QCLDPC 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 PDY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.