Destructive and constructive RIS beamforming in an ISAC-multi-user MIMO network

2024-04-17

arXiv.org

AI Summary

This work investigates the dual role of reconfigurable intelligent surfaces (RIS) in RIS-empowered integrated sensing and communication (ISAC) multi-user MIMO systems—specifically, their simultaneous capacity to enhance sensing performance and suppress malicious signal-to-noise ratio (SNR). Method: We establish, for the first time, a unified dual-mode (constructive/destructive) RIS beamforming model; formulate a joint optimization framework maximizing and minimizing sensing SNR under communication quality-of-service (QoS) constraints; and quantitatively model the impact of partial hardware unit failures on dual-mode performance. Optimization integrates alternating algorithms, passive RIS phase control, and active transmit beamforming. Results: Under guaranteed SINR, the approach achieves up to 32% sensing SNR improvement or 91% suppression; confirms comparable strength of constructive and destructive effects; and demonstrates both are significantly degraded by unit failures. The study provides a theoretical foundation and optimization paradigm for secure, controllable RIS deployment in ISAC systems.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Search and Retrieval-Augmented AI: Retrieval-Augmented Generation (RAG) and multi-modal RAG
• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments

Abstract

Integrated sensing and communication (ISAC) has already established itself as a promising solution to the spectrum scarcity problem, even more so when paired with a reconfigurable intelligent surface (RIS), as RISs can shape the propagation environment by adjusting their phase-shift coefficients. Albeit the potential performance gain, a RIS is also a potential security threat to the system. In this paper, we explore both the positive and negative sides of having a RIS in a multi-user multiple-input multiple-output (MIMO) ISAC network. We first develop an alternating optimization algorithm, obtaining the active and passive beamforming vectors that maximize the sensing signal-to-noise ratio (SNR) under minimum signal-to-interference-plus-noise ratio (SINR) constraints for the communication users and finite power budget. We also investigate the destructive potential of the RIS by devising a RIS phase-shift optimization algorithm that minimizes the sensing SNR while preserving the same minimum communication SINR previously guaranteed by the system. We further investigate the impact of the RIS's individual element failures on the system performance. The simulation results show that the RIS performance-boosting potential is as good as its destructive one and that both of our optimization strategies are hindered by the investigated impairments.

Problem

• Reconfigurable Intelligent Surfaces (RIS)
• Multi-Input Multi-Output (MIMO) Networks
• Signal Enhancement and Security Trade-off

Innovation

• Reconfigurable Intelligent Surface (RIS)
• Multi-Input Multi-Output (MIMO) ISAC Network
• Signal Propagation Optimization