NOMA-Based UAV Communications for Maritime Coverage Enhancement

The lack of communication infrastructure in the ocean inevitably leads to coverage blind zones.In addition to high-throughput marine satellites, unmanned aerial vehicles(UAVs) can be used to provide coverage for these blind zones along with onshore base stations. In this paper, we consider the use of UAV for maritime coverage enhancement. Particularly, to serve more ships on the vast oceanic area with limited spectrum resources, we employ non-orthogonal multiple access(NOMA). A joint power and transmission duration allocation problem is formulated to maximize the minimum ship throughput, with the constraints on onboard communication energy. Different from previous works, we only assume the slowly time-varying large-scale channel state information(CSI) to reduce the system cost, as the large-scale CSI is locationdependent and can be obtained according to a priori radio map. To solve the non-convex problem, we decompose it into two subproblems and solve them in an iterative way. Simulation results show the effectiveness of the proposed solution.