CO-OFDM系统中分块拉格朗日插值的CKF相位噪声补偿算法  

CKF Phase Noise Compensation Algorithm of Block Lagrangian Interpolation for CO-OFDM Systems

作　　者：袁建国[1] 李阳旭 左智航 Yuan Jianguo;Li Yangxu;Zuo Zhihang(Chongqing Key Laboratory of Photoelectronic Information Sensing and Transmitting Technology,Chongqing University of Posts and Telecommunications,Chongqing 400065,China)

机构地区：[1]重庆邮电大学光电信息感测与传输技术重庆市重点实验室,重庆400065

出　　处：《光学学报》2022年第16期29-35,共7页Acta Optica Sinica

基　　金：国家自然科学基金(61971079);重庆市研究生科研创新项目(CYS21319)。

摘　　要：针对相干光正交频分复用(CO-OFDM)系统中相位噪声造成的严重影响,提出了一种基于次符号进行分块二阶拉格朗日插值(BSSLI)的容积卡尔曼滤波(CKF)的相位噪声补偿算法。该算法先利用导频估计的时域OFDM符号相位噪声值进行第一次二阶拉格朗日插值(SLI),得到相位噪声粗略估计值,再将每个OFDM符号在时域分割成若干个次符号,将每个次符号的估计值作为它中间采样点的估计值进行第二次SLI,从而在提高时间分辨率的同时提升补偿精度,最后利用CKF对残余的相位噪声进行补偿。仿真结果表明:该算法在16阶正交振幅调制(16QAM)下,激光线宽为800 kHz时,其误码率(BER)接近于10^(-7)且降低了错误平层;该算法在32阶正交振幅调制(32QAM)下,激光线宽为800 kHz时,其BER达到10^(-3)以下;本文算法相较于线性插值与子符号光相位噪声补偿(LI-SCPEC)算法和基于拉格朗日插值的扩展卡尔曼滤波(LRI-EKF)算法补偿效果更优,有效改善了系统的性能。A cubature Kalman filter(CKF)phase noise compensation algorithm of the block sub-symbol second-order Lagrangian interpolation(BSSLI)is proposed to reduce the serious influence caused by phase noise in the coherent optical orthogonal frequency division multiplexing(CO-OFDM)system.The algorithm first uses the phase noise value of the time-domain OFDM symbol estimated by the pilot to perform the first second-order Lagrangian interpolation(SLI)and obtain a rough estimation of the phase noise,and then divides each OFDM symbol into several sub-symbols in the time domain.The estimated value of each sub-symbol is used as the estimated value of its intermediate sampling point to perform the second SLI,thus both the time resolution and the compensation accuracy are improved,and finally the CKF is used to compensate the residual phase noise.The simulation results show that:for 16 order orthogonal amplitude modulation(16QAM)and the laser linewidth of 800 kHz,the bit error rate(BER)of the algorithm can be close to 10^(-7) and the error floor is reduced;for 32 order orthogonal amplitude modulation(32QAM)and the laser linewidth of 800 kHz,the BER of the algorithm can reach below 10^(-3).Furthermore,compared with the linearly interpolated sub-symbol optical phase noise compensation scheme(LI-SCPEC)algorithm and the Lagrange interpolation based extended Kalman filter(LRI-EKF)algorithm,the proposed algorithm can better compensate the phase noise.Therefore,it can effectively improve the performance of the CO-OFDM system.

关 键 词：光通信 相干光正交频分复用 相位噪声 二阶拉格朗日插值 容积卡尔曼滤波 

分 类 号：TN913.7[电子电信—通信与信息系统]