A Survey of Intelligent Reflecting Surfaces (IRSs): Towards 6G Wireless Communication Networks

TL;DR

This survey reviews recent advances in intelligent reflecting surfaces (IRSs) for 6G wireless networks, covering their applications, design, and future research directions, highlighting IRSs' potential to enhance spectrum and energy efficiency.

Contribution

It provides a comprehensive categorization and analysis of IRS research, including capacity, optimization, implementation, and novel applications, serving as a foundational overview for future 6G developments.

Findings

IRSs improve spectrum and energy efficiency in wireless networks

Deep learning enhances IRS design and deployment

IRSs are poised to play a key role in 6G networks

Abstract

Intelligent reflecting surfaces (IRSs) tune wireless environments to increase spectrum and energy efficiencies. In view of much recent attention to the IRS concept as a promising technology for 6G wireless communications, we present a survey of IRSs in this paper. Specifically, we categorize recent research studies of IRSs as follows. For IRS-aided communications, the summary includes capacity/data rate analyses, power/spectral optimizations, channel estimation, deep learning-based design, and reliability analysis. Then we review IRSs implementations as well as the use of IRSs in secure communications, terminal-positioning, and other novel applications. We further identify future research directions for IRSs, with an envision of the IRS technology playing a critical role in 6G communication networks similar to that of massive MIMO in 5G networks. As a timely summary of IRSs, our work will be of interest to both researchers and practitioners working on IRSs for 6G networks.