Research On Influence Of Turbulence Effect On Laser Communication Performance

Research on laser communication technology at home and abroad has never stopped.Since some or all of the laser communications are in the atmosphere,the atmosphere is one of the main factors that cannot be ignored.Atmosphere will produce various attenuations in the communication system.The effects of atmospheric turbulence on the laser communication system cannot be ignored.Atmospheric turbulence will cause random changes in the refractive index of the atmosphere,resulting in many phenomena such as beam expansion,beam drift,and light intensity flicker.Among them,the degree of influence of light intensity flicker is quite obvious.These phenomena can increase the bit error rate of the communication system,thereby degrading the performance of the laser communication system.This forced us to carry out in-depth analysis and research,and then improve and improve the performance of laser communication systems.This paper first analyzes the effect of turbulence on the propagation of laser beams in atmospheric turbulence.Then,by analyzing the statistical characteristics of turbulence,several power law spectrum models and structural constants,it was found that the K-spectrum does not exactly coincide with the actual atmospheric turbulence in the troposphere and the stratosphere,so a more realistic altitude-related model is established.The three-layer height spectrum.Under weak turbulence conditions,based on the three-layer height spectrum,the flicker coefficients of the plane wave and the spherical wave in the oblique link are analyzed and compared with the flicker coefficient derived from the K-spectrum,and the turbulence caused by the three-layer height spectrum description is found.The light intensity is more pronounced.Then,the error rate of the communication system in the lognormal(LN)channel is analyzed,and the influence of different zenith angles and different optical wavelengths on the communication system is quantitatively analyzed.The conclusion is that the bit error rate rises as the wavelength becomes smaller and the zenith angle increases.Based on this,a flicker coefficient model of Gaussian wave in weak turbulence is established based on three-layer height spectrum,and the error rate under different conditions is studied using the expression of bit error rate under LN channel fading.Quantitative analysis of the effects of finite beam radii on the flicker coefficient and bit error rate in the uplink and downlink,and concluded that the downlink BER does not change with the radius of the beam,while the uplink has the lowest BER.The optimum waist radius.The study is performed continuously under different exponential conditions with different atmospheric heights.Compared with the previous studies,the turbulence coefficient model is not exactly the same as the previous one.