Integrated sensing and communications (ISAC) are envisioned to be an integral part of future wireless networks, especially when operating at the millimeter-wave (mm-wave) and terahertz (THz) frequency bands. However, establishing wireless connections at these high frequencies is quite challenging, mainly due to the penetrating path loss that prevents reliable communication and sensing. Another emerging technology for next-generation wireless systems is reconfigurable intelligent surface (RIS), which refers to hardware-efficient planar structures capable of modifying harsh propagation environments. In this article, we provide a tutorial-style overview of the applications and benefits of RISs for sensing functionalities in general, and for ISAC systems in particular. We highlight the potential advantages when fusing these two emerging technologies, and identify for the first time that 1) joint sensing and communications (S&C) designs are most beneficial when the channels referring to these operations are coupled, and that 2) RISs offer the means for controlling this beneficial coupling. The usefulness of RIS-aided ISAC goes beyond the obvious individual gains of each of these technologies in both performance and power efficiency. We also discuss the main signal processing challenges and future research directions that arise from the fusion of these two emerging technologies.

中文翻译：

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具有可重构智能表面的集成传感和通信：从信号建模到处理


集成传感和通信 (ISAC) 预计将成为未来无线网络不可或缺的一部分，特别是在毫米波 (mm-wave) 和太赫兹 (THz) 频段运行时。然而，在这些高频下建立无线连接非常具有挑战性，主要是由于穿透路径损耗阻碍了可靠的通信和传感。下一代无线系统的另一项新兴技术是可重构智能表面（RIS），它是指能够改变恶劣传播环境的硬件高效平面结构。在本文中，我们以教程形式概述了 RIS 在一般传感功能（特别是 ISAC 系统）中的应用和优势。我们强调了融合这两种新兴技术时的潜在优势，并首次确定 1) 联合传感和通信 (S&C) 设计在涉及这些操作的通道耦合时最有利，2) RIS 提供了方法用于控制这种有益的耦合。 RIS 辅助 ISAC 的实用性超出了这些技术在性能和功效方面的明显单独收益。我们还讨论了这两种新兴技术融合所带来的主要信号处理挑战和未来研究方向。