Performance Analysis Of Atmospheric Channel In Wireless Laser Communication

Free-space optical communication (wireless laser communication) has stronganti-jamming capability, large information capacity and many other advantages, but theatmosphere is one of the most important factors affecting its transmission, the study ofwireless optical communication channel characteristics is essential.First, this paper studied the effects of various attenuation caused by atmosphericparticles, discussed separately the effect of atmospheric attenuation of lasertransmission in the troposphere, aerosols, clouds, rain, and atmospheric turbulence.Predict in the different wavelengths, laser energy attenuation with different visibilitycaused by fog. The results show that, Cloud attenuation is greater than the aerosolattenuation, and decrease with increased visibility quickly. Secondly, using the signal tonoise ratio and bit error rate mode of the communication system, and calculate andanalysis the signal to noise ratio and bit error rate in various circumstances, and usingmodulation and demodulation techniques to improve the performance of opticalcommunication systems,such as OOK、DPSK、PSK、PPM. That the use of PPMmodulation to improve system performance most advantages.Thirdly, The averagecapacity and outage probability of a PCB is calculated under the condition of differentcoherent length, aperture, on the horizontal and Earth-space path, respectively. Theresults of scintillation index show that the difference among plane, spherical, and beamwave are obvious from weak to moderate turbulence regime, at strong regime, theresults tend to saturation. Based on the Log-normal model in weak turbulent fadechannel and the Gamma-Gamma model from weak to strong turbulence fade channel,the average capacities for different initial Gaussian beam radius, partially coherentdegree beam are estimated, respectively. Finally, From the atmospheric channelintroduces an effective method to improve the performance of wireless opticalcommunication system has certain guiding significance for the future development andresearch.