Intelligent reflecting surface (IRS) is an emerging technology that is able to significantly improve the performance of wireless communications, by smartly tuning signal reflections at a large number of passive reflecting elements. On the other hand, with ubiquitous wireless devices and ambient radio-frequency signals, wireless sensing has become a promising new application for the next-generation/6G wireless networks. By synergizing low-cost IRS and fertile wireless sensing applications, this article proposes a new IRS-aided sensing paradigm for enhancing the performance of wireless sensing cost-effectively. First, we provide an overview of wireless sensing applications and the new opportunities of utilizing IRS for overcoming their performance limitations in practical scenarios. Next, we discuss IRS-aided sensing schemes based on three approaches, namely, passive sensing, semi-passive sensing, and active sensing. We compare their pros and cons in terms of performance, hardware cost and implementation complexity, and outline their main design issues including IRS deployment, channel acquisition and reflection design, as well as sensing algorithms. Finally, numerical results are presented to demonstrate the great potential of IRS for improving wireless sensing accuracy and the superior performance of IRS active sensing compared to other schemes.

翻译：智能反射面（IRS）是一种新兴技术，能够通过智能调控大量无源反射元件的信号反射，显著提升无线通信性能。另一方面，随着无处不在的无线设备和环境射频信号，无线感知已成为下一代/6G无线网络中具有前景的新应用。通过将低成本IRS与丰富的无线感知应用相结合，本文提出了一种新的IRS辅助感知范式，以经济高效地提升无线感知性能。首先，我们概述了无线感知应用以及在实用场景中利用IRS克服其性能局限的新机遇。接着，我们基于三种方法讨论了IRS辅助感知方案，即无源感知、半无源感知和有源感知。我们从性能、硬件成本和实施复杂度方面比较了它们的优缺点，并概述了其主要设计问题，包括IRS部署、信道获取与反射设计，以及感知算法。最后，通过数值结果展示了IRS在提升无线感知精度方面的巨大潜力，以及IRS有源感知相比其他方案的优越性能。