Intelligent reflecting/refracting surface (IRS) is envisioned as a promising technology to reconfigure wireless propagation environment for enhancing the communication performance, by smartly controlling the signal reflection/refraction with a large number of tunable passive elements. In particular, the application of IRS in high-mobility scenarios can convert wireless channels from fast fading to slow fading, thus achieving more reliable communications. In this paper, we first provide an overview of the new applications and opportunities of IRS in high-mobility communications. Next, we present two practical strategies for deploying IRS to aid high-mobility communications, namely, roadside IRS versus vehicle-side IRS, and compare their different channel characteristics, handover requirements, and deployment costs. Then, the main issues in designing IRS-aided high-mobility communications, including node discovery, mode switching, beam alignment/tracking, handover, and multiuser scheduling are discussed for both IRS deployment strategies. Moreover, numerical results are presented to demonstrate the potential performance gains of IRSs in vehicular communications. Finally, new research directions are pointed out for future work.

翻译：智能反射/折射表面（IRS）被认为是一种有前景的技术，通过利用大量可调无源元件智能控制信号反射/折射，可重构无线传播环境以提升通信性能。特别是在高移动性场景中应用IRS，能够将无线信道从快衰落转换为慢衰落，从而实现更可靠的通信。本文首先概述了IRS在高移动性通信中的新应用与机遇。其次，提出了两种部署IRS以辅助高移动性通信的实用策略——路边IRS与车载IRS，并比较了二者不同的信道特性、切换需求及部署成本。随后，针对这两种IRS部署策略，讨论了设计IRS辅助高移动性通信面临的主要问题，包括节点发现、模式切换、波束对准/跟踪、切换以及多用户调度。此外，通过数值结果展示了IRS在车载通信中的潜在性能增益。最后，指出了未来工作的新研究方向。