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

TL;DR

This paper introduces a novel RIS deployment strategy for mmWave D2D communication that leverages double reflections to improve connectivity and energy efficiency, outperforming existing methods.

Contribution

It proposes a set cover-based RIS deployment approach with double reflections and an energy-efficient group selection method, enhancing connectivity and resource utilization.

Findings

Double reflections can be more beneficial than single reflections.

The proposed approach reduces RIS density and improves connectivity.

Outperforms random and recent deployment strategies.

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.