  The demand for future wireless communication systems is being satisfied for
various circumstances through unmanned aerial vehicles (UAVs), which act as
flying base stations (BSs). In this letter, we propose an ellipse clustering
algorithm that maximizes the user coverage probability of UAV- BSs and avoids
inter-cell interference with minimal transmit power. We obtain the coverage of
each UAV by adjusting its antenna half-power beamwidth, orientation, and 3D
location by minimizing the path loss of the cell-edge user. Simulation results
confirm that the proposed algorithm achieves high system throughput and
coverage probability with lower transmit power compared to conventional
algorithms.
