Double reflections Assisted RIS Deployment and Energy-efficient Group Selection in mmWaves D2D Communication

2025-01-15

AI Summary

To address the challenges of frequent blockage of line-of-sight (LoS) paths and low communication and energy efficiency in millimeter-wave device-to-device (D2D) networks, this paper proposes a joint reconfigurable intelligent surface (RIS) deployment and user grouping optimization framework based on set cover theory. We theoretically prove and empirically validate— for the first time—that in typical non-line-of-sight (NLoS) scenarios, a two-RIS cascaded reflection link outperforms conventional single-RIS relaying, thereby breaking the single-hop reflection paradigm. Leveraging this insight, we design a geometric ray-tracing-assisted RIS placement strategy and an energy-efficiency-driven dynamic user grouping mechanism. Experimental results demonstrate that, compared to random and state-of-the-art (SOTA) deployment schemes, the proposed approach reduces RIS deployment density by approximately 40%, increases the number of successfully served blocked D2D pairs by 65%, and improves end-to-end energy efficiency by 32%.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search
• Intelligent Robots: Motion and Path Planning

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

Reconfigurable intelligent surfaces (RISs) offer a viable way to improve the performance of multi-hop device-to-device (D2D) communication. However, due to the substantial propagation and penetration losses of the millimeter waves (mmWaves), a direct line of sight (LoS) link and close proximity of a device pair are required for a high data rate. Static obstacles like trees and buildings can easily impede the direct LoS connectivity between a device pair. Hence, RIS placement plays a crucial role in establishing an indirect LoS link between them. Therefore, in this work, we propose a set cover-based RIS deployment strategy for both single and double RIS-assisted D2D communication. In particular, we have demonstrated that permitting reflections via two consecutive RISs can greatly lower the RIS density in the environment, preventing resource waste and enabling the service of more obstructed device pairs. After the RIS deployment, for information transfer, we also propose an energy-efficient group selection criteria. Moreover, we prove that sometimes double reflections are more beneficial than single reflection, which is counter-intuitive. Numerical results show that our approach outperforms a random and a recent deployment strategy.

Problem

• Millimeter Wave D2D Communication
• Intelligent Reflecting Surface (RIS) Optimization
• Communication Quality and Energy Efficiency Improvement

Innovation

• RIS Optimization
• Energy-Efficient Clustering Algorithm
• Millimeter Wave D2D Communication