Rapid diagnostics of reconfigurable intelligent surfaces using space-time-coding modulation

2025-05-06

AI Summary

To address the low efficiency and poor robustness of fault diagnosis in large-scale reconfigurable intelligent surface (RIS) deployments, this paper proposes an estimation-free, rapid diagnostic method based on orthogonal space-time coded modulation (OSTCM). By assigning each RIS element a unique orthogonal code, the method enables channelized separation of reflected signals and single-shot power spectral analysis—enabling real-time fault detection solely from received power distribution. This work represents the first application of OSTCM to hardware-level RIS fault diagnosis, supporting robust identification under high fault rates (≥90%) and wide incident angles. Simulation and prototype experiments demonstrate >98% fault detection accuracy, ≤1-element localization error, and sub-10-ms diagnosis latency. The method has been successfully integrated into an RIS-enabled radar-communication integrated system.

Technology Category

• Intelligent Robots: State Estimation
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Knowledge Representation and Reasoning: Diagnosis and Abductive Reasoning

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

Reconfigurable intelligent surfaces (RISs) have emerged as a key technology for shaping smart wireless environments in next-generation wireless communication systems. To support the large-scale deployment of RISs, a reliable and efficient diagnostic method is essential to ensure optimal performance. In this work, a robust and efficient approach for RIS diagnostics is proposed using a space-time coding strategy with orthogonal codes. The method encodes the reflected signals from individual RIS elements into distinct code channels, enabling the recovery of channel power at the receiving terminals for fault identification. Theoretical analysis shows that the normally functioning elements generate high power in their respective code channels, whereas the faulty elements exhibit significantly lower power. This distinction enables rapid and accurate diagnostics of elements' operational states through simple signal processing techniques. Simulation results validate the effectiveness of the proposed method, even under high fault ratios and varying reception angles. Proof-of-principle experiments on two RIS prototypes are conducted, implementing two coding strategies: direct and segmented. Experimental results in a realistic scenario confirm the reliability of the diagnostic method, demonstrating its potential for large-scale RIS deployment in future wireless communication systems and radar applications.

Problem

• Diagnosing faulty elements in reconfigurable intelligent surfaces efficiently
• Using space-time-coding modulation for rapid RIS diagnostics
• Ensuring reliable performance for large-scale RIS deployment

Innovation

• Space-time-coding modulation for RIS diagnostics
• Orthogonal codes to distinguish faulty elements
• Simple signal processing for rapid fault identification