A Survey on Channel Estimation and Practical Passive Beamforming Design for Intelligent Reflecting Surface Aided Wireless Communications

TL;DR

This survey reviews recent advances in IRS-aided wireless communications, focusing on channel estimation, passive beamforming, practical hardware constraints, and emerging architectures to guide future research.

Contribution

It provides a comprehensive overview of current solutions to practical design challenges in IRS-assisted systems and discusses new architectures and applications.

Findings

Summarizes recent solutions for channel estimation in IRS systems.

Highlights practical hardware constraints affecting IRS design.

Discusses emerging IRS architectures and future research directions.

Abstract

Intelligent reflecting surface (IRS) has emerged as a key enabling technology to realize smart and reconfigurable radio environment for wireless communications, by digitally controlling the signal reflection via a large number of passive reflecting elements in real-time. Different from conventional wireless communication techniques that only adapt to but have no or limited control over dynamic wireless channels, IRS provides a new and cost-effective means to combat the wireless channel impairments in a proactive manner. However, despite its great potential, IRS faces new and unique challenges in its efficient integration into wireless communication systems, especially its channel estimation and passive beamforming design under various practical hardware constraints. In this paper, we provide a comprehensive survey on the up-to-date research in IRS-aided wireless communications, with an emphasis on the promising solutions to tackle practical design issues. Furthermore, we discuss new and emerging IRS architectures and applications as well as their practical design problems to motivate future research.