一种改进的光偏分复用16-QAM系统盲解复用算法的研究  

Research on a modified blind polarization de-multiplexing method in the optical PDM-16-QAM system with digital coherent receivers

作　　者：童程[1] 邸雪静[1] 张晓光[1] 席丽霞[1] 

机构地区：[1]北京邮电大学信息光子学与光通信国家重点实验室,北京100876

出　　处：《光电子．激光》2013年第4期704-709,共6页Journal of Optoelectronics·Laser

基　　金：北邮青年创新专项基金(BUPT2011RC009);深圳市科学与技术基础研究基金(JC201105191003A)资助项目

摘　　要：在高速光纤偏分复用(PDM)16进制正交幅度调制(QAM)相干光通信系统中,偏分解复用算法是分离偏振信息和进行信号补偿的关键技术。针对传统盲解复用的恒模算法(CMA)易于陷入奇异性和独立成分分析(ICA)算法收敛性能一般的问题,本文提出了一种改进型ICA(MICA)算法。算法基于给出的一种全新收敛测量方法,通过计算补偿后信号点与理想星座点的距离,自适应的改变学习速率,达到了更好的误码率(BER)性能。在20Gbaud/s的PDM-16-QAW系统上的仿真结果表明,与传统CMA法相比,本文提出的算法完全消除了奇异性问题,与是否存在偏振相关损耗(PDL)无关。此外,算法还能在前向纠错编码门限上提供高达1dB的光信噪比(OS-NR)提升,并在收敛速率和精确度上都得到了提升。In the high-speed optical polarization division multiplexed 16 quadrature amplitude modulation （PDM-16-QAM） communication system with coherent detection,the polarization de-multiplexing algorithm is an essential technique that takes care of separating the information in polarization domain and compensating the Stochastic distortion. The widely used method in this area is the classic constant modulus algorithm （CMA） ,but it suffers from the singularity problem that the output converges to the same source. Independent component analysis （ICA） is a new way to solve this problem without singularity problem,but it performs not well in 16-QAM modulation system. Thus we propose the modified ICA （MICA） method to improve the convergence performance of ICA. Taking the distance between the com- pensated signal and the ideal constellation point as the convergence measurement, the algorithm adaptive- ly changes the learning rate to optimize the convergence. The performance of the algorithm is numerically tested in a 20G baud/s PDM-16-QAM simulation system with coherent detection. The simulation results show that the proposed algorithm can eliminate the singularity pi：oblem with or without polarization-de- pendent loss. Besides,it offers 1 dB optical signal-to-noise ratio （OSNR） improvement at the forward error correction （FEC） bit error rate （BER） threshold. The convergence measurements show that the proposed algorithm has advantages in both convergence speed and precision over the other two methods.

关 键 词：光通信 相干接收机 偏分复用(PDM) 独立成分分析(ICA) 自适应步长 

分 类 号：TN929.11[电子电信—通信与信息系统]