Towards Smart and Reconfigurable Environment: Intelligent Reflecting Surface Aided Wireless Network

Abstract

Intelligent reflecting surface (IRS) is a new and revolutionizing technology that is able to significantly improve the performance of wireless communication networks, by smartly reconfiguring the wireless propagation environment with the use of massive low-cost passive reflecting elements integrated on a planar surface. Specifically, different elements of an IRS can independently reflect the incident signal by controlling its amplitude and/or phase and thereby collaboratively achieve fine-grained three-dimensional (3D) passive beamforming for directional signal enhancement or nulling. In this article, we provide an overview of the IRS technology, including its main applications in wireless communication, competitive advantages over existing technologies, hardware architecture as well as the corresponding new signal model. We focus on the key challenges in designing and implementing the new IRS-aided hybrid (with both active and passive components) wireless network, as compared to the traditional network comprising active components only. Furthermore, numerical results are provided to show the great performance enhancement with the use of IRS in typical wireless networks.

Sum Rate Optimization for Two Way Communications With Intelligent Reflecting Surface

“…where [13] at the source S i (due to the non-ideal full-duplex signal processing), and z i is the additive white Gaussian noise with normalized covariance I N . Assume that the channel state information (CSI) of each link as well as Θ is perfectly known by each source, (CSI acquisition has been discussed in, e.g., [2]). Then the source S i can subtract the term G i ΘH i F i s i from its received signal (3) 1 .…”

“…Intelligent Reflecting Surface (IRS) has recently emerged as a promising technique to improve the performance of communication links [1], [2]. In particular, the IRS is composed of a large number of electromagnetically reconfigurable reflective elements, and can be made extremely low-cost and energy efficient [3].…”

Cooperative Double-IRS Aided Communication: Beamforming Design and Power Scaling

“…An IRS usually consists of a large number of passive reflecting elements, and by adaptively configuring the reflection amplitude and/or phase of each element, the IRS can modify the wireless propagation environment to fit specific needs [2]. Different from the traditional active relay, the IRS only leverages passive reflection, which does not require expensive hardware or high energy consumption [2]. Current research on IRS mainly focuses on passive or joint beamforming design [3]- [9], which only study the scenario with one IRS or multiple faraway IRSs each independently serving its associated users in the vicinity, thus no cooperation or joint passive beamforming among multiple IRSs is considered, to the authors' best knowledge.…”

Joint Power Control and Passive Beamforming in IRS-Assisted Spectrum Sharing

“…The quasi-static flat-fading model is assumed for all channels. Based on the various channel acquisition methods discussed in [1], we assume that the channel state information (CSI) of all channels involved is perfectly known at the ST/IRS for the joint power control and passive beamforming design. Though the assumption of perfect CSI knowledge is ideal, the result obtained in this letter provides useful insights and performance bounds for practical systems with partial/imperfect CSI, which need further investigation in future work.…”

“…However, to implement such technologies in practical systems, the increased network energy consumption and hardware cost become critical issues. Recently, intelligent reflecting surface (IRS) has emerged as a promising technology to achieve high spectrum and energy efficiency for wireless communication cost-effectively [1]- [5]. Specifically, IRS is a uniform planar array consisting of a large number of passive reflecting elements.…”