Intelligent reflecting surface (IRS) has emerged as a promising technique to control wireless propagation environment for enhancing the communication performance cost-effectively. However, the rapidly time-varying channel in high-mobility communication scenarios such as vehicular communication renders it challenging to obtain the instantaneous channel state information (CSI) efficiently for IRS with a large number of reflecting elements. In this paper, we propose a new roadside IRS-aided vehicular communication system to tackle this challenge. Specifically, by exploiting the symmetrical deployment of IRSs with inter-laced equal intervals on both sides of the road and the cooperation among nearby IRS controllers, we propose a new two-stage channel estimation scheme with off-line and online training, respectively, to obtain the static/time-varying CSI required by the proposed low-complexity passive beamforming scheme efficiently. The proposed IRS beamforming and online channel estimation designs leverage the existing uplink pilots in wireless networks and do not require any change of the existing transmission protocol. Moreover, they can be implemented by each of IRS controllers independently, without the need of any real-time feedback from the user's serving BS. Simulation results show that the proposed designs can efficiently achieve the high IRS passive beamforming gain and thus significantly enhance the achievable communication throughput for high-speed vehicular communications.
翻译:智能反射表面(IRS)已成为一种大有希望的技术,可以控制无线传播环境,提高通信性能,具有成本效益;然而,在诸如车辆通信等高流动性通信情景中,快速时间变化的频道,使得为IRS高效获得具有大量反映要素的即时频道状态信息(CSI)变得很困难;在本文件中,我们提议建立一个新的路边IRS辅助车辆通信系统,以应对这一挑战;具体地说,通过利用公路两侧间间隔间隙的对称部署IRS系统以及附近的IRS控制器之间的合作,我们提出一个新的两阶段频道估计计划,分别进行离线和在线培训,以获得拟议的低兼容性被动波束组合计划所要求的静态/时间变化的CSI系统;拟议的IRS成型和在线频道估计设计,利用无线网络中的现有通信连接试点,而不需要对现有传输协议作任何改动;此外,可以由IRS控制器的每个控制器独立实施新的两阶段频道估计计划,分别进行离线和在线培训,以便获得拟议的低兼容性被动波段式被动图像的高版本,从而从任何可高效的用户的图像中获取任何可实现的图像。