Joint Beamforming and Trajectory Design for UAV-aided Integrated Sensing and Communication

Integrated sensing and communication (ISAC) is one of the key technologies for future wireless communication systems. Unmanned aerial vehicles (UAVs) have been widely adopted in ISAC systems. In this paper, we propose a UAV-assisted ISAC system, in which the UAV and the base station (BS) form a bistatic synthetic aperture radar (SAR). The UAV receives the reflected signal from the target area and sends the signal to the BS for sensing and imaging. The flight inclination angle is considered when designing the optimal receive and transmit beamforming schemes. We aim to minimize the flight and communication energy consumption of the UAV by optimizing its trajectory and transmit power while meeting the ISAC requirements. To this end, we convexify the non-convex problem and obtain a solution that satisfies the Karush-Kuhn-Tucker (KKT) condition using variable substitution and successive convex approximation. Simulation results show that the proposed scheme can save up to 48% energy while ensuring the ISAC and SAR imaging requirements, as compared to the baselines.