基于自适应步长ICA的CO-OFDM系统的偏振效应均衡研究

提出一种基于自适应步长独立成分分析(ICA)法的 信道均衡算法,用于相干光正交频分复用 (CO-OFDM)系统偏振效应的补偿。基于50Gbit/s 16QAM CO-OFDM系统,偏振效应严重影响其系统传输性 能。接收端在完成系统公共相位误差(CPE)补偿后,用本文所提 算法对系统偏振效应进行 盲均衡,根据每次迭代中信道频响分离矩阵的变化量自适应调整迭代步长,然后进行 盲相互干扰(ICI)相位噪声 补偿。仿真结果表明,本文算法的系统性能补偿效果接近于差分群延迟(DGD) 为零时 的系统性能,从而证明本文算法可以有效补偿偏振效应对高速光CO-OFDM系统 性能的 劣化。与固定步长ICA算法相比,本文算法能够极大地提高了迭代算法的收敛速度,极大 地降低了算法复杂度。

Polarization effect equlization scheme using independent component analysis with adaptive variable step in CO-OFDM system

In this paper,by means of the independent component analysis (ICA) wi th adaptive variable step,a novel channel equalization scheme is proposed in order to perform polari zation effect equalization in coherent optical orthogonal-frequency-division-multiplexing (CO-OFDM) system .In 50Gbit/s CO-OFDM system with 16quadrature amplitude modulation (QAM),the system performance is degrade d seriously by the polarization effect.At the receiver,after performing blind common phase error (CPE) compensation,the ICA with adaptive variable step is implemented to reduce the influence from polar ization effect.In the algorithm,the inversion of each subcarrier channel frequency response is estimated by u sing adaptive iterative step,which depends on the variation of the channel matrix after each iteration.Next,the b lind inter-carrier interference (ICI) phase noise compensation is carried out at the receiver.It is proved by the simulation results that the ada ptive ICA method shares the same performance with only blind phase noise algorithm at DGD =0(differential group delay).And it is also demonstrated that the adaptive ICA algorithm can be used to reduce the s ystem performance degradation from the polarization effect.Compared with the ICA with constant iterative step,its convergence rate is also improved considerably,and the adaptive method reduces the computational complexity great ly.