UAV-aided Secure NOMA Transmission via Trajectory and Resource Optimization

Abstract

The application of NOMA in UAV networks is an effective solution for communications. However, the security risk becomes more serious with the LoS channels and higher transmit power for weaker users in NOMA-UAV networks. In this paper, a UAV-assisted NOMA transmission scheme is proposed to achieve secure downlink transmission via artificial jamming, where a UAV flies straightly to serve multiple ground users in the presence of a passive eavesdropper. Only the closest users to the UAV can be connected in each time slot to achieve high LoS probability. To balance the security and transmission performance, the tradeoff between the jamming power and the sum rate is investigated by jointly optimizing the power allocation, the user scheduling and the UAV trajectory. To address the problem, we first decompose the problem into two subproblems of power allocation and trajectory optimization. Then, they are transformed into convex ones for an iterative algorithm via the first-order Taylor expansion. Finally, simulation results are presented to show the effectiveness of the proposed scheme.