Cloud Free Line of Sight Prediction Modeling for Optical Satellite Communication Networks

Analytical models for the prediction of cloud-free line-of-sight (CFLOS) probability for a single optical satellite link and for multiple spatially separated optical satellite links are presented. The presence of clouds along the slant paths causes their blockage. As a result, an ON/OFF channel with the presence of clouds is assumed. The proposed model for the calculation of CFLOS considers the elevation angle of the optical satellite links, the altitude of ground stations, and the spatial variability of clouds. The methodology is based on the assumption that integrated liquid water content (ILWC) follows lognormal distribution and a well-defined relationship between ILWC and liquid water density. Moreover, joint CFLOS statistics are evaluated and CFLOS probability for simultaneously available optical links for the application of spatial multiplexing transmission techniques is estimated. The models are validated through simulated results and finally, the numerical results are devoted to optical satellite network examples with a view to achieving specific availability percentage.