基于时频域卡尔曼滤波的CO-OFDM系统相位噪声补偿算法

发布时间：2018-07-02 22:11

本文选题：光通信 + 相干光正交频分复用　；参考：《光学学报》2017年09期

【摘要】：针对基于高阶正交幅度调制(QAM)的大线宽相干光正交频分复用(CO-OFDM)系统,提出了一种基于时域和频域卡尔曼滤波(KF)联合估计的相位噪声补偿算法。所提算法在发射端插入时域训练符号和导频序列,在接收端基于训练符号进行频域卡尔曼滤波后得到信道估计值,进行时域扩展卡尔曼滤波(EKF)后得到相位噪声粗略估计值。时域相位噪声估计值为复数值,为获得较好的补偿效果,根据导频序列数目将每个OFDM符号分割为若干个亚符号。在导频序列处进行时域EKF,通过在每个亚符号最后一个导频处进行线性插值,得到每个采样点的相位噪声粗略估计值。对粗略相位噪声补偿后的频域数据进行预判决,并对时域相位噪声进行精细补偿。采用所提算法对传输速率为50Gbit·s-1、传输距离为100km的CO-OFDM系统进行了数值模拟,结果表明所提算法与其他方法相比取得了较好的补偿效果。对于激光器线宽为1 MHz(16QAM)和800kHz(32QAM)的CO-OFDM系统,误码率可达前向纠错上限。
[Abstract]:For large linewidth coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems based on high order orthogonal amplitude modulation (QAM), a phase noise compensation algorithm based on time domain and frequency domain Kalman filtering (KF) joint estimation is proposed. The proposed algorithm inserts time-domain training symbols and pilot sequences at the transmitter, obtains channel estimates after the frequency-domain Kalman filtering based on the training symbols at the receiver, and obtains rough estimates of the phase noise by using the time-domain extended Kalman filter (EKF). The estimation of phase noise in time domain is complex. In order to obtain better compensation effect, each OFDM symbol is divided into several sub-symbols according to the number of pilot sequences. The time domain EKF is carried out at the pilot sequence. By linear interpolation at the last pilot of each sub-symbol, the rough estimation of the phase noise at each sampling point is obtained. The frequency domain data after rough phase noise compensation are pre-determined and the time domain phase noise is compensated fine. The proposed algorithm is used to simulate the CO-OFDM system with a transmission rate of 50Gbit s-1 and a transmission distance of 100km. The results show that the proposed algorithm has better compensation effect than other methods. For CO-OFDM systems with 1 MHz (16QAM) and 800kHz (32QAM) linewidths, the error rate can reach the upper limit of forward error correction.
【作者单位】：浙江工业大学健行学院;浙江工业大学信息工程学院;上海交通大学区域光纤通信网与新型光通信系统国家重点实验室;
【基金】：国家自然科学基金(60907032,61675184,61675183) 浙江省自然科学基金(LY16F050009) 上海交通大学区域光纤通信网与新型光通信系统国家重点实验室开放基金(2016GZKF0JT004)
【分类号】：TN929.1

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