Energy Efficient Optimal User Association and Node Placement Mechanism for Cooperative UAV Communications

To realize energy efficient communication coverage enhancement for cooperative unmanned aerial vehicles (UAVs) communications equipped with multi-beam array antennas, a nested multi-objective mixed integer non-convex model is established to determine the optimal association between user sets and UAV beams as well as the optimal position of UAVs, to minimize the number and total power consumption of UAVs while achieving load balance among UAVs. An alternate joint optimization algorithm that decouples the aforementioned optimization problem to inner and outer layer optimization is proposed. The inner layer alternately optimizes the user association, power consumption and node position of UAVs, while the outer layer optimizes the number of UAVs. Numerical results show that: cooperative UAV communications with multi-beam association and the proposed joint optimization algorithm can flexibly adapt to the demand distribution of complex traffic tasks, reduce total power consumption and achieve load balance among UAVs. These works provide good reference to enhance communication efficiency of cooperative UAV communications.