Joint Rate and Coverage Design for UAV-Enabled Wireless Networks with Underlaid D2D Communications

Unmanned aerial vehicle (UAV) can be utilized as aerial base station to provide emergency coverage in disasters, due to its flexible deployment, potential mobility and low cost. However, the wireless coverage of a UAV is limited because of the constrained transmit power. Therefore, device-to-device (D2D) transmission can be exploited to extend wireless coverage of UAV. In this paper, we aim to jointly maximize the weighted sum rate of the UAV-served users and the total number of users with wireless service for UAV-enabled wireless networks with underlaid D2D communications. The optimal set of UAV-served users are determined, while satisfying the information causality constraint. The formulated problem involving binary variables is non-deterministic polynomial (NP)-hard and extremely difficult to solve. Accordingly, we propose the algorithm to transform the problem into solving linear programming problem with low-complexity, and obtain a suboptimal solution. Simulation results demonstrate that the proposed joint rate and coverage design achieves better system performance.