UAV Placement and Power Allocation in Uplink and Downlink Operations of Cellular Network

The wireless communication field is approaching the realization of the integrated unmanned aerial vehicle (UAV) and cellular network for further improved communication performance. In this paper, we consider a cellular network with a UAV-mounted aerial base station (ABS) coexisting with multiple terrestrial base stations (TBSs), where each base station (BS) is serving multiple users. Under the probabilistic channel based environment, we design the three-dimensional (3D) positioning for the ABS and the transmit power allocation for all the nodes in the uplink (UL), downlink (DL), and combined UL and DL operations. Considering the ABS user (AU) and the TBS user (TU) as contending parties, our objective is to maximize the weighted sum of the minimum data rate of the AUs and the minimum data rate of the TUs. The whole optimization problem is non-convex and difficult to be directly solved, for which we employ the block coordinate descent (BCD), the successive convex approximation (SCA), the particle swarm optimization (PSO), and the discrete search algorithm (DSA) methods. Numerical results shed some light on interesting observations regarding the comparison between our solution and benchmark schemes, as well as the optimal 3D position of the ABS in UL, DL, and combined UL and DL operations.