Security Enhancement for NOMA-UAV Networks

Owing to its distinctive merits, non-orthogonal multiple access (NOMA) techniques have been utilized in unmanned aerial vehicle (UAV) enabled wireless base stations to provide effective coverage for terrestrial users. However, the security of NOMA-UAV systems remains a challenge due to the line-of-sight air-to-ground channels and higher transmission power of weaker users in NOMA. In this paper, we propose two schemes to guarantee the secure transmission in UAV-NOMA networks. When only one user requires secure transmission, we derive the hovering position for the UAV and the power allocation to meet the rate threshold of the secure user while maximizing the sum rate of remaining users, which effectively disrupts the eavesdropping towards the secure user. When multiple users require secure transmission, we further exploit the beamforming capability via multiple antennas at the UAV to guarantee their secure transmission. Due to the non-convexity of this problem, we convert it into a convex one for an iterative solution by using second order cone programming. Finally, simulation results are provided to verify the effectiveness of the proposed scheme in enhancing the security of NOMA-UAV networks.

IEEE Transactions on Vehicular Technology