Robust Cooperative Secure Beamforming Based on Multi-UAV Localization

Abstract

Low-altitude communication networks provide essential infrastructure for the rapidly developing low-altitude economy. However, the propagation environment poses significant challenges to transmission security. In this paper, a robust cooperative secure beamforming scheme is proposed for networks comprising multiple uncrewed aerial vehicles (UAVs), where a swarm of UAVs cooperatively transmits confidential information to a ground base station in the presence of a passive eaves-dropper (Eve). To address the difficulty in obtaining the Eve channel, we propose a localization method based on angle of arrival (AoA) estimation, and the corresponding Cramér-Rao lower bound (CRLB) of the localization error is derived for the multi-UAV cooperative localization system. Then, the localization uncertainty is modeled as an ellipsoidal region, and a robust beamforming optimization problem is formulated to maximize the average secrecy rate within the uncertainty region. Simulation results demonstrate that the proposed robust cooperative secure beamforming scheme achieves significant secrecy rate gains compared to conventional approaches under various system parameters.