大气湍流影响星地激光通信误码率建模与仿真分析

发布时间：2018-03-04 23:07

本文选题：星地激光通信　切入点：大气湍流　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：与传统的微波通信相比,激光通信具有带宽宽、传输速率快、安全保密性好等优点,已成为近年来的研究热点。但是在星地激光通信链路中,湍流造成的折射率随机变化会引起接收端的光强起伏和相位起伏,会导致系统信噪比降低,误码率升高。因此,研究大气湍流如何影响星地激光通信的误码率具有重要意义。实验方法研究该问题周期长、费用高,而通过理论分析往往因为参数众多不能取得精确的结果,因此本文采用建模仿真的方法进行研究。本文重点阐述大气光学湍流影响高斯信号光束整层大气传输的模型和数值仿真算法。并就相干BPSK或非相干OOK探测方式下,包含或不包含自适应光学校正系统条件下的大气湍流影响星地激光下行链路误码率问题进行了的仿真分析。将高斯光束以一定的天顶角从地球同步轨道卫星处出发经过真空传输和大气传输到达地面站点接收端。本文采用等Rytov方差的方法对大气湍流廓线模型下的大气湍流进行分层,利用快速傅立叶变换的相位屏生成算法在每一层湍流中间插入一个随机相位屏,令光束在32个相位屏之间分段传输得到接收端的光束复振幅。然后,利用平面波的闪烁指数和光强概率密度对高斯光束传输结果进行检验。最后分别推导了非相干OOK调制和相干BPSK调制的光通信系统误码率模型,将星地激光下行传输结果带入误码率模型得到大气湍流对系统误码率的影响。同时,还利用Zernike多项式相位补偿分析了自适应光学系统的对通信性能的提高作用。本文建立起来的星地光通信误码率仿真模型对星地激光通信系统的研制具有参考价值,可以为通信系统探测方式、调制方式、收发装置的设计提供重要的理论依据。因此本文的研究成果具有重要的指导意义和参考价值。
[Abstract]:Compared with traditional microwave communication, laser communication has many advantages, such as wide bandwidth, fast transmission rate, good security and secrecy, etc. It has become a research hotspot in recent years. The random change of refractive index caused by turbulence will cause the light intensity fluctuation and phase fluctuation at the receiving end, which will reduce the SNR of the system and increase the bit error rate. It is of great significance to study how atmospheric turbulence affects the bit error rate of satellite-to-ground laser communication. The experimental method has the advantages of long period and high cost, but the theoretical analysis is often unable to obtain accurate results because of the large number of parameters. In this paper, the modeling and simulation methods are used to study the effects of atmospheric optical turbulence on the atmospheric propagation of Gao Si signal in the whole layer. In this paper, the model and numerical simulation algorithm for the atmospheric propagation of Gao Si signal in the whole layer are described. In the case of coherent BPSK or incoherent OOK detection, Simulation analysis of the effect of atmospheric turbulence on bit error rate in satellite-ground laser downlink with or without adaptive optical correction system is carried out. The Gao Si beam is emitted from geosynchronous orbit satellite at a certain zenith angle. In this paper, the atmospheric turbulence under the atmospheric turbulence profile model is stratified by using the method of equal Rytov variance. A random phase screen is inserted in the middle of each layer of turbulence by using the phase screen generation algorithm of fast Fourier transform, so that the beam propagates between 32 phase screens to obtain the complex amplitude of the beam at the receiving end. The transmission results of Gao Si beam are verified by using the flicker exponent of plane wave and the probability density of light intensity. Finally, the error rate models of incoherent OOK modulation and coherent BPSK modulation are derived, respectively. The effect of atmospheric turbulence on the error rate of the system is obtained by bringing the results of satellite and ground laser downlink transmission into the BER model. At the same time, The Zernike polynomial phase compensation is also used to analyze the effect of adaptive optical system on improving the communication performance. The simulation model of bit error rate (BER) for satellite-to-ground optical communication is established in this paper, which has reference value for the development of satellite-to-ground laser communication system. It can provide important theoretical basis for the design of detection mode, modulation mode and transceiver device of communication system, so the research results of this paper have important guiding significance and reference value.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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