基于幅度相位联合校正算法的8-QAM自由空间相干光通信

Coherent Free-space Optical Communication with 8-QAM Modulation Using Joint Algorithm of Amplitude Compensation and Digital Phase Recovery

提出了基于幅度相位联合校正算法的8阶正交幅度调制(8-QAM)自由空间相干光通信方案。与传统的自由空间光通信方案相比,本文提出的方案不仅无需信道状态信息(CSI)就可以实现对原信号的高精度还原,同时还具有较高的光谱效率。仿真实验表明,当接收端与发射端的频偏f 0=20 MHz、激光器联合线宽Δf=10 kHz、信噪比为20 dB时,该方案在归一化大气闪烁标准差σ=0.25、归一化相位噪声方差σΦ^2=0.07的对数正态湍流信道条件下,其误码率(BER)与未采用联合校正算法的8-QAM系统相比低4个量级。

Coherent free-space optical communication with 8-quadrature amplitude modulation(8-QAM)using joint algorithm of amplitude compensation and digital phase recovery is proposed.Compared with traditional free-space optical communication schemes,the scheme we proposed not only can restore the signal without requiring the knowledge of instantaneous channel state information,but also has higher spectral efficiency.Numerical studies show that the bit error rate of the proposed system is four orders of magnitude lower than that of the 8-QAM system without joint algorithm,when the frequency offset f 0=20 MHz between the receiver and the transmitter,the lasers joint linewidthΔf=10 kHz,and the signal-to-noise ratio is 20 dB for a lognormal turbulence channel withσ=0.25 and phase noise with σΦ^2=0.07.