Improving Physical Layer Security Using Multi-UAVs-Enabled Mobile Relaying

Unmanned aerial vehicles (UAVs) are expected to be widely deployed in practical scenarios, due to their advantages of high mobility and easy deployment. In this paper, we propose a secure UAV mobile relaying system where multiple relays collaboratively amplify and forward information from a source to a destination in the presence of multiple eavesdroppers. To enhance security, the problem is to simultaneously optimize the relay trajectory, the source’s and relay’s transmit power subject to quality of service (QoS), aiming to maximize the average secrecy rate. To this end, we design an iterative algorithm to solve the problem efficiently by applying the block coordinate descent and sequential convex programming, which is proven to converge to a Karush-Kuhn-Tucker (KKT) point of the original problem. The simulation results show that the proposed multiple mobile relaying scheme can attain significantly higher achievable secrecy rate than the single relaying scheme.