I. Introduction
Using Unmanned Aerial Vehicles (UAVs) equipped with wireless transceivers acting as drone base-stations (BSs) is proposed to enhance the ground users’ connectivity in 4G & 5G systems, and beyond [1]–[3]. UAVs’ potential for enhancing capacity/coverage of LTE/LTE-A has also been demonstrated in cases of UAV-assisted communications and cellular-connected drones [4]–[6].