Toward Smart Wireless Communications via Intelligent Reflecting Surfaces: A Contemporary Survey
Toward Smart Wireless Communications via Intelligent Reflecting Surfaces: A Contemporary Survey
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DOI：
10.1109/comst.2020.3004197
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发表时间：
2020-01-01
影响因子：
35.6
通讯作者：
Liang, Ying-Chang
中科院分区：
文献类型：
--
作者：
Gong, Shimin;Lu, Xiao;Liang, Ying-Chang
本文对智能反射面（IRS）在未来无线网络中的应用和设计进行了综述。传统上，网络优化被限制在两个端点处的传输控制，即，终端用户和网络控制器。无线信道的衰落是不可控的，并成为性能改善的主要限制因素之一。IRS由散射元件的大阵列组成，这些散射元件可以单独配置以产生对信号反射的附加相移。因此，它可以主动控制信号传播特性，以利于信号接收，从而实现智能无线电环境的概念。因此，与没有IRS的无线网络相比，IRS的相位控制与传统的传输控制相结合可以潜在地带来性能增益。本文首先介绍了IRS的基本概念及其可重构性的实现。然后，我们重点介绍了IRS在无线通信中的应用。我们概述了不同的性能指标和分析方法来表征IRS辅助无线网络的性能改善。为了利用性能增益，我们讨论了在不同的网络设计问题中IRS的相位控制和收发器的传输控制的联合优化，例如，速率最大化和功率最小化问题。此外，我们将IRS辅助无线网络的讨论扩展到一些新兴的用例。最后，我们强调了在超越5G通信中实现IRS辅助无线网络的重要实际挑战和未来研究方向。
This paper presents a literature review on recent applications and design aspects of the intelligent reflecting surface (IRS) in the future wireless networks. Conventionally, the network optimization has been limited to transmission control at two endpoints, i.e., end users and network controller. The fading wireless channel is uncontrollable and becomes one of the main limiting factors for performance improvement. The IRS is composed of a large array of scattering elements, which can be individually configured to generate additional phase shifts to the signal reflections. Hence, it can actively control the signal propagation properties in favor of signal reception, and thus realize the notion of a smart radio environment. As such, the IRS's phase control, combined with the conventional transmission control, can potentially bring performance gain compared to wireless networks without IRS. In this survey, we first introduce basic concepts of the IRS and the realizations of its reconfigurability. Then, we focus on applications of the IRS in wireless communications. We overview different performance metrics and analytical approaches to characterize the performance improvement of IRS-assisted wireless networks. To exploit the performance gain, we discuss the joint optimization of the IRS's phase control and the transceivers' transmission control in different network design problems, e.g., rate maximization and power minimization problems. Furthermore, we extend the discussion of IRS-assisted wireless networks to some emerging use cases. Finally, we highlight important practical challenges and future research directions for realizing IRS-assisted wireless networks in beyond 5G communications.