针对光传输系统的特点与要求, 基于有限域提出了一种新颖的扩展非规则重复累积准循环低密度奇偶校验码(eIRA-QC-LDPC)构造方法, 该构造方法可根据实际需要灵活地调整码长码率, 利用此方法构造了一种码率为0.937的novel-eIRA-QC-LDPC(4599,4307)码。仿真结果表明: 在误码率(BER)为10-7且码率均为0.937的情况下, 该novel-eIRA-QC-LDPC(4599,4307)码比ITU-T G.975中RS(255,239)码和ITU-T G.975.1中LDPC(32640,30592)码的净编码增益(NCG)分别改善了约2.13和1.33dB, 比用SCG构造方法构造的SCG-eIRA-LDPC(3717,3481)码和基于阵列码构造方法构造的Array-eIRA-QC-LDPC(4560,4275)码的净编码增益分别提高了约0.24和0.41dB, 距离香农限约1.07dB。因而该构造方法所构造的eIRA-QC-LDPC码具有更好的纠错性能, 更适合高速长距离的光传输系统。

A novel construction method of the extended irregular repeat-accumulate quasi-cyclic low density parity check(eIRA-QC-LDPC) code, based on finite field, is proposed according to the characteristics and requirements of optical transmission systems. This construction method can flexibly adjust the code-length and code-rate according to the actual demand. A novel-eIRA-QC-LDPC(4599,4307) code is constructed by applying the proposed construction method. The simulation results show that at the bit error rate(BER) of 10-7 and the same code-rate of 0.937, the net coding gain(NCG) of the constructed novel-eIRA-QC-LDPC(4599,4307) code is 2.13dB more than that of RS(255,239) code in ITU-T G.975, and 1.33dB more than that of the LDPC(32640,30592) code in ITU-T G.975.1, and 0.24dB and 0.41dB more than those of the SCG-eIRA-LDPC(3717,3481) code constructed by the systematically constructed gallager(SCG) construction method and the array-eIRA-QC-LDPC(4560,4275) code constructed by the construction method of the array LDPC code and 1.07dB away from the Shannon limit. Therefore, the eIRA-QC-LDPC code constructed by the proposed construction method has better error-correction performance and is more suitable for high-speed long-haul optical transmission systems.