Wind Influence on Rate-Adaptive Transmission Techniques in Free Space Optical Communications

Free-space optical communication systems represent one of the most promising approaches for addressing the emerging broadband access market and its "last mile" bottleneck. However, atmospheric turbulence may cause fluctuation in both intensity and phase of the received light signal, impairing the link performance. In this paper, a novel model for the atmosphere as an optical communication channel is presented, considering not only the turbulence effects due to the refractive index variation but also the negative effect of the wind velocity. Additionally, the very good performance of a simple rate-adaptive transmission scheme based on the use of variable silence periods and OOK formats with memory, previously proposed in indoor unguided optical links by the authors, is also corroborated in free-space optical links, showing a greater robustness to adverse conditions of turbulence and wind velocity.