BER performance analysis of drone-assisted optical wireless systems with APD receiver

Abstract The integration of unmanned aerial vehicles (UAVs) and free space optical (FSO) systems has been recently proposed as a promising solution to establish flexible and high data rate backhaul/fronthaul links. However, due to the random fluctuations of hovering UAVs which cause optical beam fluctuations at the receiver, establishing UAV-assisted FSO links is technically challenging. In this paper, an avalanche photodiode (APD) at the optical receiver is utilized to successfully combat the effect of UAV’s fluctuations. To this aim, we first model the end-to-end signal-to-noise ratio (SNR) of an APD-based UAV-assisted FSO link. Then, given the analytical SNR model that we developed, closed-form expressions for the bit error rate (BER) of the considered system under different turbulence conditions are derived. The accuracy of the analytical expressions is verified by performing Monte Carlo simulations. Moreover, we study the effect of different link parameters, i.e., received optical beamwidth, the receiver field-of-view, optical transmit power, and different levels of UAV instability on the performance of the system. The results of this paper reveal insights into the importance of utilizing APD for UAV-based FSO system to mitigate the degradation effects of UAV’s fluctuations.