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。 Aiming at the analysis and research of SCG (4, k) code construction method, a new construction method of LDPC code which is suitable for the improvement of optical communication system is proposed. Based on preserving the construction method of SCG (4, k), the proposed method adopts quasi-cyclic structure to make the generated codeword not suffer from short-loop interference and has good girth characteristics. Compared with the former SCG (4, k) code, the construction method has the advantages of saving storage space and reducing computational complexity in hardware implementation. The LDPC (3969, 3720) codes with the code rate of 93.7% are constructed by this method. Simulation results show that the net coding gain (NCG) of this code is 1.99dB higher than the classical RS (255,239) codes widely used in optical communication systems.