中文摘要：

基于行列约束条件提出适用于光通信系统中一种新颖的高码率与码长的Qc—LDPC码构造方法。该方法可在取得较好纠错性能的同时降低编码复杂度。并利用该方法构造出一种适用于光通信系统的非规则QC—LDPC（3591，3351）码。仿真分析表明：在BER为10^-7时，该QC—LDPC（3591，3351）码的净编码增益分别比ITU-TG．975中RS（255，239）码和ITU-TG．975．1中LDPC（32640，30592）码提高2．13dB和1．32dB；且比用SCG方法构造的LDPC（3969。3720）码和利用有限域乘群方法构造的规则QC—LDPC（5334,4955）码提高0．66dB和0．40dB，因而该QC—LDPC码新颖构造方法的纠错性能优越并在光通信系统中具有较好的应用前景。

英文摘要：

A novel construction method of Quasi-Cyclic Low-Density Parity-Check（QC-LDPC） codes with the higher code-rate and code-length for optical communications, based on row-column constraint condition, is proposed. The construction method can gain the better error-correction performance and reduce the encoding complexity. A irregular QC-LDPC（3951,3351） code to be suitable for optical communication systems is constructed by applying this construction method. The simulation results show that at the bit error rate（BER） of 10-7, the net encoding gain（NCG） of the irregular QC-LDPC（3591,3351） code is respectively 2.13dB and 1.32dB more than those of the classic RS（255,239） in ITU-T G.975 and LDPC（32640,30592） in ITU-T G.975.1, and respectively 0.66dB and 0.40dB more than those of the SCG-LDPC（3969,3720） code constructed by the systematically-constructed-Gallager（SCG） construction method and the regular QC-LDPC（5334,4962） code constructed by the finite field muhiplicative group method. Therefore, this novel construction method for the QC-LDPC code has the more excellent error-correction performance and the better application prospect in optical communication systems.