Secrecy sum rate maximization for UAV-aided NOMA communication systems

This article studies the secure communication of a non-orthogonal multiple access (NOMA) system with the help of an unmanned aerial vehicle (UAV). The UAV flies from an initial location to a final location and assists the NOMA communication between terrestrial nodes, including a source, a near user, and a far user, in the presence of an eavesdropper. Artificial noise (AN) is inserted into the transmitted signal of the UAV to enable secure communication for the users. To maximize the system secrecy sum-rate (SSSR), an algorithm is proposed to optimize key system parameters, such as the UAV’s trajectory, the power–allocation factors, and the transmit powers of the source and the UAV. Since the objective function of the SSSR maximization problem is non-convex, the successive convex optimization (SCO) and block coordinate descent (BCD) methods are applied to find efficient approximate solutions. The effectiveness of the proposed algorithms is confirmed by simulation results.