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详细研究了Gamma-Gamma湍流信道大气闪烁、信道衰落及瞄准误差对差分相移键控(DPSK)相干光通信系统误码性能、信道容量和中断概率等指标的影响。自由空间光通信(FSO)系统采用基于马赫-曾德尔调制器(MZM)和马赫-曾德尔干涉仪(MZI)的DPSK调制/解调结构,通过广义超几何方法分析推导出有关平均误码率、平均信道容量和中断概率的闭合表达式并简化分析。在Matlab平台下进行模拟仿真,实验结果表明,系统的平均误码率和平均信道容量随湍流程度的增强而减弱;信道容量的提升可以通过增加带宽或减小抖动方差实现;当瞄准误差过大时导致中断概率增大,严重影响系统的通信性能。
The effects of Gamma-Gamma turbulence channel air flicker, channel fading and aiming error on the BER performance, channel capacity and interrupt probability of DPSK coherent optical communication system are studied in detail. The free space optical communication (FSO) system uses the DPSK modulation / demodulation structure based on Mach-Zehnder modulator (MZM) and Mach-Zehnder interferometer (MZI) to derive the average bit error rate , The closed-form expression of the average channel capacity and the outage probability, and simplifies the analysis. Simulation results show that the average bit error rate (BER) and average channel capacity of the system are weakened with the increase of turbulence degree. The improvement of channel capacity can be achieved by increasing the bandwidth or reducing the jitter variance. When the aiming error is too large When the interrupt probability increases, seriously affecting the system’s communication performance.