Leveraging Holographic Antennas and Reconfigurable Intelligent Surface for Integrated Sensing and Communication

Recently, reconfigurable intelligent surfaces (RIS) and metamaterial holographic antennas have attracted increasing interest for their potential to enhance performance and reduce hardware costs in integrated sensing and communication (ISAC) systems. This paper is the first to jointly exploit these two technologies within a unified ISAC framework. The objective is to maximize the achievable secrecy rate by jointly optimizing the RIS reflection coefficients, holographic beamforming, the transmit beamformer at the dual-functional base station (BS), and the radar receive beamformer. The design is constrained by the minimum signal-to-noise ratio (SNR) required for detecting a malicious unmanned aerial vehicle (UAV) and the total power budget. We tackle this non-convex problem via a low-complexity enhanced cross-entropy alternating optimization (ECE-AO) scheme with elite weighted updates and neighbor selection, and closed-form updates for the transmit and radar receive beamformers, yielding fast, monotone incumbent convergence. Simulations demonstrate that the proposed joint holographic–RIS ISAC system outperforms phased array structures with and without RIS, as well as strong discrete baselines.