为了满足光通信系统对纠错码高码率、低误码率的要求, 基于伽罗华域中域的特征提出了一种结构简单、易于编码并且可以有效避免四环的QC-LDPC(准循环低密度奇偶校验)码的新构造方法。并运用该方法构造了适用于光通信系统的FC-QC-LDPC(基于域特征的QC-LDPC)(3969,3729)码。仿真结果表明, 在误码率=10-7时, 所构造的码率为0.937的FC-QC-LDPC(3969,3729)码的NCG (净编码增益)比QC-LDPC(4288,4020)码提高了约0.15 dB, 比Linshu-QC-LDPC(3780,3542)码和经典的RS(255,239)码的NCG分别提高了约0.35和2.1 dB。此外, 所构造的码的性能与Mackay码的性能相当。因而其纠错性能更强, 更适用于高速长距离光通信系统。

In order to meet the requirements of optical communication systems for high code rate and low bit error rate of error-correction codes, we present a novel construction method for QC-LDPC codes on the basis of the nature of the field characteristics of Galois field, which is simple in structure, easy to be encoded and can effectively avoid the girth 4 effectively, and use this method to construct an FC-QC-LDPC (3969,3729) code that is suitable for optical communication systems. The simulation results show that when the BER=10-7, the Net Coding Gain (NCG) of the constructed FC-QC-LDPC (3969,3729) code with the code rate of 0.937 is about 0.15 dB higher than that of the QC-LDPC (4288,4020) code, and about 0.35 dB and 2.1 dB higher than those of the Linshu-QC-LDPC (3780,3542) code and the classical RS (255,239) code respectively. In addition, its performance is about the same as that of Mackay code but has stronger error-correcting performance. So it is more suitable for high-rate long-haul optical communication systems.