LDPC码在相干光通信下的性能分析与研究

Analysis on the performance of LDPC codes under coherent optical communication

对于相干光通信系统,相位噪声成为影响系统性能的重要因素之一,并严重影响LDPC码(低密度奇偶校验码)软译码的性能。仿真结果表明,在16QAM调制方式下,500kHz线宽的激光器相位噪声将导致1.5dB的性能损失。为了降低相位噪声的影响,提出了一种基于相位噪声估计值修正LLR(对数似然比信息)的方法。经仿真验证,该LLR修正方法能够挽回0.5dB的译码性能损失。

For coherent optical fiber communication systems,phase-noise become one of the most factor that degrade decoding performance.The simulation results show that for 16QAM coherent optical communication systems the phase-noise of 500kHz Laser linewidth cause 1.5dB performance lose.To reduce the impact of phase noise,this paper also presents a revised phase-noise estimate based on LLR（log-likelihood ratio information） method.After simulation,the LLR correction decoding method can restore 0.5dB performance loss.