RIS-Assisted Coordinated Multi-Point ISAC for Low-Altitude Sensing Coverage
Ying Zhang, Zeqi Hao, Tingting Zhang
TL;DR
This work tackles secure, continuous sensing of unauthorized low-altitude targets by integrating ISAC with a RIS-enhanced CoMP architecture. It proposes a joint BS beamforming and RIS phase-shift design, solved via alternating optimization and SDR to minimize total transmit power while meeting SE and sensing SNR requirements. Numerical results show substantial power savings and full sensing coverage when using RIS, with fast convergence and robustness to initial phase settings. The approach offers a practical framework for energy-efficient, wide-area low-altitude sensing in urban environments.
Abstract
The low-altitude economy (LAE) has emerged and developed in various fields, which has gained considerable interest. To ensure the security of LAE, it is essential to establish a proper sensing coverage scheme for monitoring the unauthorized targets. Introducing integrated sensing and communication (ISAC) into cellular networks is a promising solution that enables coordinated multiple base stations (BSs) to significantly enhance sensing performance and extend coverage. Meanwhile, deploying a reconfigurable intelligent surface (RIS) can mitigate signal blockages between BSs and low-altitude targets in urban areas. Therefore, this paper focuses on the low-altitude sensing coverage problem in RIS-assisted coordinated multi-point ISAC networks, where a RIS is employed to enable multiple BSs to sense a prescribed region while serving multiple communication users. A joint beamforming and phase shifts design is proposed to minimize the total transmit power while guaranteeing sensing signal-to-noise ratio and communication spectral efficiency. To tackle this non-convex optimization problem, an efficient algorithm is proposed by using the alternating optimization and semi-definite relaxation techniques. Numerical results demonstrate the superiority of our proposed scheme over the baseline schemes.