  This letter investigates an uplink power control problem for unmanned aerial
vehicles (UAVs) assisted wireless communications. We jointly optimize the UAV's
flying altitude, antenna beamwidth, UAV's location and ground terminals'
allocated bandwidth and transmit power to minimize the sum uplink power subject
to the minimal rate demand. An iterative algorithm is proposed with low
complexity to obtain a suboptimal solution. Numerical results show that the
proposed algorithm can achieve good performance in terms of uplink sum power
saving.
