大气效应对相干光通信系统性能影响研究

发布时间：2018-09-03 16:12

【摘要】：相干光通信系统具有较高的接收灵敏度,可实现远距离和高码率的数据传输,是自由空间光通信技术的重要发展方向。然而,大气信道中湍流引起的折射率随机起伏,导致激光信号的振幅和相位发生随机波动,降低相干检测效率,影响通信系统的性能。系统地研究大气湍流对相干光通信系统性能的影响,探索抑制湍流效应、改善光通信系统性能的方法具有重要的理论意义和应用价值。此外,目前关于湍流对空间相干光通信性能影响的研究主要是基于平面波模型和单端探测方式,平面波模型无法体现光束半径对系统性能的影响。另外,光相干技术中的平衡探测是改善相干光通信系统性能的新技术。本文将开展基于平衡探测方式下的大气信道相干光通信系统性能的研究。本文系统地分析了湍流对基于平衡探测方式下的空间相干光通信系统性能的影响,其中信号光和本振光根据实际情况分别选择平面波模型和高斯光束模型。得出了在无湍流和有湍流影响下该模型中的信噪比概率密度分布函数及误码率计算表达式。在此基础上,针对近地水平传输链路,在无相位补偿和采用自适应相位补偿两种条件下,研究了光强闪烁指数和相位波动方差对系统误码率的影响;同时还分析了孔径平均效应对接收孔径直径的最优值的影响。数值计算了星地下行传输链路,孔径平均效应和天顶角对系统误码率的影响。本文最后基于实际测量的不同天气下的大气信道衰减系数,利用Optisystem软件,对空间相干光通信与非相干光通信系统性能进行了仿真,通过接收端的眼图分析比较了不同天气条件下两种通信方式的接收性能。
[Abstract]:Coherent optical communication system has high receiving sensitivity and can realize long distance and high bit rate data transmission. It is an important development direction of free space optical communication technology. However, the random fluctuation of refractive index caused by turbulence in atmospheric channel leads to random fluctuation of the amplitude and phase of laser signal, which reduces the efficiency of coherent detection and affects the performance of communication system. The effects of atmospheric turbulence on the performance of coherent optical communication systems are systematically studied. It is of great theoretical significance and practical value to explore the methods of suppressing turbulence effects and improving the performance of optical communication systems. In addition, the current research on the effect of turbulence on the performance of spatial coherent optical communication is mainly based on the plane wave model and single-ended detection mode. The plane wave model can not reflect the influence of beam radius on the performance of the system. In addition, balanced detection in optical coherence is a new technique to improve the performance of coherent optical communication system. In this paper, the performance of coherent optical communication system in atmospheric channel based on balanced detection is studied. The effect of turbulence on the performance of spatially coherent optical communication system based on balanced detection is systematically analyzed in this paper. The plane wave model and Gao Si beam model are selected according to the actual conditions of signal light and local oscillator light respectively. The probability density distribution function of signal-to-noise ratio and the expression of bit error rate in the model are obtained without and without the influence of turbulence. On this basis, the effects of intensity scintillation index and phase fluctuation variance on the bit error rate of the system are studied under the condition of no phase compensation and adaptive phase compensation for near-ground horizontal transmission link. At the same time, the influence of average aperture effect on the optimum value of the diameter of the receiving aperture is analyzed. The effects of satellite transmission link, average aperture effect and zenith angle on the bit error rate of the system are numerically calculated. Finally, based on the actual measured attenuation coefficient of atmospheric channel under different weather conditions, the performance of spatial coherent optical communication and incoherent optical communication system is simulated by using Optisystem software. The receiving performance of the two communication modes under different weather conditions is analyzed and compared by the eye diagram of the receiver.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

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