Multi-Active/Passive-IRS Enabled Wireless Information and Power Transfer: Active IRS Deployment and Performance Analysis

TL;DR

This paper analyzes the deployment of active and passive IRSs in wireless networks to optimize signal quality and power transfer, deriving optimal placement strategies with demonstrated performance improvements.

Contribution

It provides the first closed-form solutions for optimal active IRS placement for both wireless information and power transfer, highlighting different deployment strategies for each.

Findings

Optimal active IRS deployment differs for WIT and WPT.

Proposed deployment strategies outperform baseline methods.

Analytical and numerical results confirm performance gains.

Abstract

Intelligent reflecting surfaces (IRSs), active and/or passive, can be densely deployed in complex environments to significantly enhance wireless network coverage for both wireless information transfer (WIT) and wireless power transfer (WPT). In this letter, we study the downlink WIT/WPT from a multi-antenna base station to a single-antenna user over a multi-active/passive IRS (AIRS/PIRS)-enabled wireless link. In particular, we aim to optimize the location of the AIRS with those of the other PIRSs being fixed to maximize the received signal-to-noise ratio (SNR) and signal power at the user in the cases of WIT and WPT, respectively. We derive the optimal solutions for these two cases in closed-form, which reveals that the optimal AIRS deployment is generally different for WIT versus WPT. Furthermore, both analytical and numerical results are provided to show the conditions under which the proposed AIRS deployment strategy yields superior performance to other baseline deployment strategies as well as the conventional all- PIRS enabled WIT/WPT.