针对SCG(4, k)码构造方法的分析与研究, 提出一种适用于光通信系统中改进的新颖低密度奇偶校验(LDPC)码构造方法。该方法在保留SCG(4, k)构造方法的基础上, 采用类似于准循环的构造形式, 使生成的码字不受短环干扰, 并具有良好的围长特性; 并且与改进前的SCG(4, k)码相比, 该构造方法具有硬件实现方面节省存储空间和降低计算复杂度等优点。采用该方法构造了码率为93.7%的LDPC(3969, 3720)码。仿真结果表明: 这种码的净编码增益(NCG)比广泛用于光通信系统中的经典RS(255, 239)码提高了1.99dB。

A novel construction method of low density parity (LDPC) code to be suitable for optical communication systems, based on the analysis and research of the construction method of Systematically Constructed Gallager(SCG)(4, k), was proposed. The novel construction method keeps the basic form of the construction method of SCG(4, k) and uses the similar structure of the Quasi-cyclic form, which makes the generated code avoid the interference of the short ring and have the good girth characteristics. Compared with common SCG (4, k) code, this novel construction method has such advantages as saving storage space and reducing computation complexity in the hardware realization. The LDPC(3969, 3720) code with 93.7% high code-rate is constructed by applying the novel construction method. The simulation analysis shows that the net coding gain(NCG) of the LDPC(3969, 3720) code is 1.99dB more than that of the classic RS(255, 239) widely used in optical communication systems.