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在自由空间光通信(FSO)中,由系统设计以及大气湍流所引起的光强闪烁和相位起伏会造成圆偏振控制误差,这严重影响圆偏振位移键控(CPol SK)通信系统的性能。因此,基于Gamma-Gamma大气信道模型,在较全面考虑光强起伏、相位噪声和圆偏振控制误差三个参数的基础上,建立了CPol SK系统信道的数学统计模型,推导了平均信道容量的闭合表达式,仿真研究了误码率在连续相位噪声下的性能以及三个参数对信道容量的影响。结果表明,光强起伏的增强和相位噪声的增大均会导致CPol SK系统性能的劣化,而提高平均信噪比在一定程度上能够改善系统性能。特别地,当圆偏振控制误差大于8°时,CPol SK系统的平均信道容量显著下降。
In free space optical communications (FSO), flicker and phase fluctuations caused by system design and atmospheric turbulence can result in circularly polarized control errors that seriously affect the performance of a CPol SK communications system. Therefore, based on Gamma-Gamma atmospheric channel model, mathematical statistics model of CPol SK system channel is established on the basis of comprehensive consideration of three parameters of light intensity fluctuation, phase noise and circular polarization control error, and the closure of average channel capacity is deduced The simulation results show the performance of the bit error rate under continuous phase noise and the influence of three parameters on the channel capacity. The results show that both the increase of light intensity and the increase of phase noise can lead to the degradation of CPol SK system performance, while improving the average signal to noise ratio can improve the system performance to a certain extent. In particular, when the circular polarization control error is greater than 8 °, the average channel capacity of the CPol SK system drops significantly.