Effect of Clouds and Rain Rate on the BER Performance of Ground-to-UAV Free Space Optical Communication System

In recent years, the combination of unmanned aerial vehicles (UAVs) and free-space optical (FSO) has gained researchers' attention as this combination is viewed as a potential candidate for future high capacity front-haul communication links. However, one of the main impairments affecting ground-to-UAV FSO links is signal outages or fading induced by clouds and rain. This manuscript focuses on the BER performance of ground-to-UAV-based FSO communication links using MODTRAN atmospheric data. The transmittance data gathered from the MODTRAN software for various cloud types, rain rates, and altitude was used to evaluate the BER performance of the FSO system under weak atmospheric turbulence. A comparative BER performance of a 2 Gpbs FSO link was analyzed for three different cloud models (Cumulus, Stratus, and Altostratus), four types of rain rate (no rain, drizzle, moderate and heavy rain) at multiple zenith angles (ranging from 0 to 60 degrees) and for a maximum FSO uplink range of 2 km. The wavelengths of interest used for this study were 850 nm, 1064 nm, and 1550 nm. It is concluded that the inclement weather conditions may severely degrade the FSO link at ranges less than 1 km. Also, the 1550 nm wavelength outperformed the other two wavelengths for every chosen model.