Secure Communications via Two-Phase Jamming Beamforming in UAV Relaying Networks

This paper investigates secure communications between a pair of ground transceivers with the aid of a relay unmanned aerial vehicle (UAV). Specifically, we consider a powerful eavesdropper who conducts eavesdropping attacks in two transmission phases. The multi-antenna transmitter communicates with the UAV through information beamforming in Phase I, and the UAV relays the secrecy data through a single antenna to the receiver in Phase II. We propose a secure transmission scheme where the transmitter utilizes artificial noise technique to interfere with the eavesdropper through jamming beamforming in two phases. In particular, we formulate an optimization problem, and employ the max-min optimization, block coordinate descent, semi-definite relaxation, and successive convex approximation methods to deal with it. Simulation results verify the effectiveness and superiority of the proposed secure transmission scheme.