Reconfigurable intelligent surfaces (RISs) are rapidly gaining prominence in the realm of 5G-advanced and predominantly 6G mobile networks, offering a revolutionary approach to optimizing wireless communications. This article delves into the intricate world of the RIS technology, exploring its diverse hardware architectures and the resulting versatile operating modes. These include RISs with signal reception and processing units, sensors, amplification units, transmissive capability, multiple stacked components, and dynamic metasurface antennas (DMAs). Furthermore, we shed light on emerging RIS applications, such as index and reflection modulation, noncoherent modulation, next-generation multiple access (NGMA), integrated sensing and communications (ISAC), energy harvesting (EH), as well as aerial and vehicular networks. These exciting applications are set to transform the way we will wirelessly connect in the upcoming era of 6G. Finally, we review recent experimental RIS setups and present various open problems of the overviewed RIS hardware architectures and their applications. From enhancing network coverage to enabling new communication paradigms, RIS-empowered connectivity is poised to play a pivotal role in shaping the future of wireless networking. This article unveils the underlying principles and potential impacts of RISs, focusing on cutting-edge developments of this physical-layer smart connectivity technology.

中文翻译：

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6G 可重构智能表面：新兴硬件架构、应用和开放挑战


可重构智能表面 (RIS) 在先进的 5G 和主要是 6G 移动网络领域迅速获得关注，为优化无线通信提供了革命性的方法。本文深入探讨 RIS 技术的复杂世界，探索其多样化的硬件架构以及由此产生的多功能操作模式。其中包括具有信号接收和处理单元、传感器、放大单元、传输能力、多个堆叠组件和动态超表面天线 (DMA) 的 RIS。此外，我们还介绍了新兴的 RIS 应用，例如索引和反射调制、非相干调制、下一代多址接入 (NGMA)、集成传感和通信 (ISAC)、能量收集 (EH) 以及空中和车载网络。这些令人兴奋的应用将改变我们在即将到来的 6G 时代的无线连接方式。最后，我们回顾了最近的实验性 RIS 设置，并提出了概述的 RIS 硬件架构及其应用的各种开放问题。从增强网络覆盖范围到实现新的通信范例，RIS 授权的连接将在塑造无线网络的未来方面发挥关键作用。本文揭示了 RIS 的基本原理和潜在影响，重点关注这种物理层智能连接技术的前沿发展。