CO-OFDM 系统中基于线性预处理的新相位噪声抑制算法

针对相干光正交频分复用（coherent optical orthogonal frequency division multiplexing，CO-OFDM）系统中相位噪声引起的载波间干扰（inter-carrier interference，ICI）问题，提出了一种基于线性预处理的新判决反馈相位噪声抑制算法。该新算法改进了线性预处理部分，利用循环前缀与OFDM符号固有的相关性，在时域进行简单的线性组合运算，充分利用了OFDM符号中冗余信息。仿真分析表明，在激光器线宽为200 kHz且误码率（bit error rate， BER）为10－4时，与判决反馈相位噪声抑制算法和一次迭代的判决反馈相位噪声抑制算法相比，该新算法BER曲线的信噪比（signal to noise ratio，SNR）分别改善了3 dB和1 dB，有效地降低由ICI引起的错误平层。

Novel phase noise suppression algorithm based on the linear preprocessing in CO-OFDM systems

A novel decision feedback phase noise suppression algorithm based on the linear preprocessing is proposed according to the Inter-Carrier Interference ( ICI) problem caused by the phase noise in the coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. The novel algorithm has improved the linear preprocessing, the inherent correlation between the cyclic prefix and the OFDM symbol is applied to make a simple linear combination operation in time domain, and the novel algorithm can make full use of the redundant information in the OFDM symbol. The simulation analysis shows that the signal to noise ratio (SNR) of the BER curve of the novel algorithm, compared with the decision feedback phase noise suppression algorithm and an iteration of the decision feedback phase noise suppression algorithm, can respectively be improved 3 dB and 1 dB when the bit error rate (BER) is of 10 - 4 and the laser line width is of 200 kHz.Therefore, the proposed algorithm can effectively reduce the error floor caused by the ICI.