Availability of a free-space optical communication link operating under various atmospheric conditions

Based on analysis of the meteorological visibility statistical data, the probability P of degradation (unavailability) of a free-space optical communication (FSOC)link caused by the light scattering in fog and precipitation versus distance of communication D has been investigated. It has been found that for a variety of geographical locations, P(D) dependence averaged over entire year is nearly proportional. Such linear dependence is valid for a wide range of communication distances, from tens of meters to kilometers. It can be shown that the averaged P(D) function is linear if the density of the light scattering partices number statistics is driven by Pareto distribution, and the distribution of particle sizes does not depend on the density of particles number. It is important that averaging of the unavailability data for any separate month of a year gives non-linear and significantly different for different months P(D)functions.