Sensing-enabled Secure Rotatable Array System Enhanced by Multi-Layer Transmitting RIS

TL;DR

This paper introduces a secure rotatable array system enhanced by multi-layer transmitting RIS, utilizing sensing and optimization algorithms to improve secrecy rate in communication systems with array pose adjustments.

Contribution

It proposes a novel joint optimization framework for array pose, antenna distribution, RIS phase matrices, and beamforming, with algorithms validated through simulations.

Findings

Achieves approximately 22% improvement in secrecy rate.

Array rotation outperforms position changes in performance gains.

Validates effectiveness of proposed algorithms through simulations.

Abstract

Programmable metasurfaces and adjustable antennas are promising technologies. The security of a rotatable array system is investigated in this paper. A dual-base-station (BS) architecture is adopted, in which the BSs collaboratively perform integrated sensing of the eavesdropper (the target) and communication tasks. To address the security challenge when the sensing target is located on the main communication link, the problem of maximizing the secrecy rate (SR) under sensing signal-to-interference-plus-noise ratio requirements and discrete constraints is formulated. This problem involves the joint optimization of the array pose, the antenna distribution on the array surface, the multi-layer transmitting RIS phase matrices, and the beamforming matrices, which is non-convex. To solve this challenge, an two-stage online algorithm based on the generalized Rayleigh quotient and an offline algorithm based on the Multi-Agent Deep Deterministic Policy Gradient are proposed. Simulation results validate the effectiveness of the proposed algorithms. Compared to conventional schemes without array pose adjustment, the proposed approach achieves approximately 22\% improvement in SR. Furthermore, array rotation provides higher performance gains than position changes.