On Sum Rate Maximization Study for Cellular-Connected UAV Swarm Communications

The integration of cellular networks and unmanned aerial vehicle (UAV) swarm communications is expected to be a promising technology to provide ubiquitous network connectivity for various UAV assisted Internet of Things (IoT) applications. To support these IoT applications with stringent requirement of rate performance, this paper explores the maximum sum rate performance for the cellular-connected UAV swarm communications. The sum rate maximization can be formulated as a nonlinear and nonconvex optimization problem with the constraints of transmit power of UAVs, elevation angle, azimuth angle and height of antenna array equipped at base station (BS). According to the Karush–Kuhn–Tucker (KKT) optimality conditions and the standard interference function, we propose an iterative algorithm to solve the problem, wherein the problem is transformed into a concave optimization problem by utilizing the rate approximation and logarithmic transformations. The iterative algorithm is proved to converge to a global solution for the approximated concave optimization problem. Finally, simulation results are provided to indicate the effect of some important system parameters on the sum rate performance in the system.