Intelligent reflecting surface (IRS) has emerged as a promising technology to reconfigure the radio propagation environment by dynamically controlling wireless signal’s amplitude and/or phase via a large number of reflecting elements. In contrast to the vast literature on studying IRS’s performance gains in wireless communications, we study in this paper a new application of IRS for sensing/localizing targets in wireless networks. Specifically, we propose a new self-sensing IRS architecture where the IRS controller is capable of transmitting probing signals that are not only directly reflected by the target (referred to as the direct echo link), but also consecutively reflected by the IRS and then the target (referred to as the IRS-reflected echo link). Moreover, dedicated sensors are installed at the IRS for receiving both the direct and IRS-reflected echo signals from the target, such that the IRS can sense the direction of its nearby target by applying a customized multiple signal classification (MUSIC) algorithm. However, since the angle estimation mean square error (MSE) by the MUSIC algorithm is intractable, we propose to optimize the IRS passive reflection for maximizing the average echo signals’ total power at the IRS sensors and derive the resultant Cramer-Rao bound (CRB) of the angle estimation MSE. Last, numerical results are presented to show the effectiveness of the proposed new IRS sensing architecture and algorithm, as compared to other benchmark sensing systems/algorithms.

中文翻译：

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具有智能反射表面的目标传感：架构和性能


智能反射表面（IRS）已成为一项有前景的技术，通过大量反射元件动态控制无线信号的幅度和/或相位，从而重新配置无线电传播环境。与研究 IRS 在无线通信中的性能增益的大量文献相比，我们在本文中研究了 IRS 在无线网络中感测/定位目标的新应用。具体来说，我们提出了一种新的自感知 IRS 架构，其中 IRS 控制器能够传输探测信号，这些信号不仅由目标直接反射（称为直接回波链路），而且还由 IRS 连续反射，然后目标（称为 IRS 反射回波链接）。此外，IRS上安装了专用传感器，用于接收来自目标的直接回波信号和IRS反射回波信号，以便IRS可以通过应用定制的多信号分类（MUSIC）算法来感测其附近目标的方向。然而，由于 MUSIC 算法的角度估计均方误差 (MSE) 很棘手，因此我们建议优化 IRS 无源反射，以最大化 IRS 传感器处的平均回波信号总功率，并导出所得的 Cramer-Rao 界 (CRB) ）的角度估计MSE。最后，数值结果显示了与其他基准传感系统/算法相比，所提出的新 IRS 传感架构和算法的有效性。