A Physical Layer Security Method Based on Multi-AAV Collaborative Beamforming

With the development of the low-altitude economy, a large number of autonomous aerial vehicles (AAVs) will be deployed in low-altitude environments, capable of effectively performing data collection and relay tasks. Unlike non-line-of-sight transmission environments on the ground, the line-of-sight transmission of AAVs offers greater channel gain while facing a higher risk of data interception. Although the traditional encryption method can decrease the risk of data being cracked, it cannot diminish the probability of data being intercepted by eavesdroppers. In this paper, we propose a physical layer security method based on the distributed collaborative beamforming for the multi-AAV networks, in which both scenarios of known and unknown eavesdropper locations are considered. Then, two beamforming algorithms are designed for these scenarios. Besides, the theoretical performance is derived for the case where the location of the eavesdropper is known, while for the unknown-location case, a beamforming scheme based on the generalized Rayleigh quotient is introduced to substantially improve the secure transmission performance. Simulation results demonstrate that the proposed approach achieves a substantial improvement in average secrecy rate without increasing the payload of AAVs compared with the conventional methods.