Joint Optimization of Altitude and Transmission Direction in UAV-Based Two-Way Communication

Unmanned aerial vehicles (UAVs) can be used as flying base stations. When one-way communication is considered, either uplink or downlink, the system performance is limited by the strong co-channel interference that takes place over the UAV-ground channel. This letter considers two-way communication and takes advantage of the fact that the interference over ground-ground channel is likely lower than the one over the UAV-ground channel. This sets the stage for joint optimization of the user association, UAV altitude, and transmission direction, which is shown to lead to improved system throughput for a given known placement of the ground devices.