Hydrometeor scattering and stochastic modeling for free-space optical channel characterization

Free space communications, using optical carriers (Free Space Optics, FSO) technology, ensure high data rates, with relatively low error rates, low power consumption and inherent security. However, FSO links are quite sensitive to atmospheric conditions. Fog droplets, but also raindrops and snowflakes, may introduce severe path attenuation which drastically reduces the channel availability. A parametric model to simulate droplets scattering effects on FSO links (from visible to near infrared wavelengths) is proposed in terms of scattering coefficients, albedo factor and asymmetry coefficient as function of the particle water content. Both single and multiple scattering effects are shown and discussed. A prototype of a stochastic time series generator of FSO rain attenuation is also presented.