Trajectory and Beamforming Vector Optimization for Multi-UAV Multicast Network

In this paper, we consider a multiple unmanned aerial vehicles (UAVs)-enabled multicast network, where each UAV is employed to send common messages to its corresponding group users via beamforming technology. Due to the simultaneous information transmission, the users may also receive the interference signals from other UAVs. The objective of this paper is to maximize the sum time-averaged multicast rate by jointly optimizing multiple UAV trajectories and beamforming vectors. The optimization problem is non-convex and too complicated to be solved directly. In light of this, an iteration algorithm is applied, which alternately optimizes variables to decompose the coupling problem. Finally, the optimized UAV trajectory compared with the pre-defined circular trajectory is presented. Numerical results imply that the proposed optimization algorithm gains larger sum-multicast rate than the circular trajectory scheme and static scheme.