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Atmospheric Effects on Downlink Channel of Satellite to Ground Free Space Optical Communications

The free space optical (FSO) communication system promises to be one of the most key technologies for dealing with high bandwidth requirements which have prompted the use of optical links between space and ground stations. In this paper, we investigate the atmospheric effect on downlink satellite-to-ground FSO communication. To consider various atmospheric conditions, we present FSO channel factors such as fog attenuation coefficient, refractive index parameter, coherence length, turbulence models and angle of arrival fluctuations. From the simulation result, we examined the influence of optical channel conditions such as atmospheric attenuation and intensity fluctuation on channel performance of a satellite to ground FSO downlink. Based on this, we proved that the use of longer wavelengths is preferable to minimize the effect of turbulence whilst using larger receiver apertures reduce angle of arrival variations. Moreover, the location of the optical receiver has a significant impact on atmospheric turbulence. The obtained mathematical results can be utilized to discover the optimal channel parameters for the design of a satellite to ground the FSO link.