Minimum Secrecy Rate Maximization for UAV-Mounted Movable Antenna Empowered Wireless Networks

In response to the problems in unmanned aerial vehicle (UAV) communications such as limited antenna number, exposure of the line-of-sight (LoS) for eavesdroppers, and limited onboard energy, this paper proposes a secure UAV communication scheme based on movable antennas (MAs). This scheme jointly designs the user scheduling factors, the UAV beamforming, the small-scale adjustment of MA positions, and the large-scale planning of UAV trajectories to maximize the system’s minimum secrecy rate under uncertain eavesdropper regions. To solve the non-convex optimization problem, a block coordinate descent (BCD) algorithm is used to decompose the original problem into four subproblems for iterative solving, followed by an analysis of the algorithm’s convergence and computational complexity. Simulation results reveal that the UAV follows the strategy of “maximum-speed-flight-and-then-low-speed-hovering” to serve each user in sequence. In this way, it can quickly pass through the uncertain region of the eavesdroppers and minimize the distance to the served user during the flight period. The proposed scheme leverages millimeter-level MA position reconstruction and wide-range UAV trajectory design. When the system’s minimum secrecy rate is maintained at 3.5 bps/Hz, the proposed scheme can securely support approximately 20% more users than the fixed-position antenna (FPA) scheme, while achieving more than 40% reductions in both transmit power and antenna count.