Next-generation wireless networks are expected to utilize the limited radio frequency (RF) resources more efficiently with the aid of intelligent transceivers. To this end, we propose a promising transceiver architecture relying on stacked intelligent metasurfaces (SIM). An SIM is constructed by stacking an array of programmable metasurface layers, where each layer consists of a massive number of low-cost passive meta-atoms that individually manipulate the electromagnetic (EM) waves. By appropriately configuring the passive meta-atoms, an SIM is capable of accomplishing advanced computation and signal processing tasks, such as multiple-input multiple-output (MIMO) precoding/combining, multi-user interference mitigation, and radar sensing, as the EM wave propagates through the multiple layers of the metasurface, which effectively reduces both the RF-related energy consumption and processing delay. Inspired by this, we provide an overview of the SIM-aided MIMO transceiver design, which encompasses its hardware architecture and its potential benefits over state-of-the-art solutions. Furthermore, we discuss promising application scenarios and identify the open research challenges associated with the design of advanced SIM architectures for next-generation wireless networks. Finally, numerical results are provided for quantifying the benefits of wave-based signal processing in wireless systems.

翻译：下一代无线网络期望借助智能收发器更高效地利用有限的射频（RF）资源。为此，我们提出了一种基于堆叠智能超表面（SIM）的前瞻性收发器架构。SIM通过堆叠多组可编程超表面层构建，每层由大量低成本无源超原子构成，这些超原子可独立调控电磁波。通过适当配置无源超原子，当电磁波穿过超表面多层结构时，SIM能够完成先进计算与信号处理任务，例如多输入多输出（MIMO）预编码/合并、多用户干扰抑制及雷达感知，从而有效降低射频相关能耗与处理延迟。受此启发，本文综述了SIM辅助MIMO收发器设计，涵盖其硬件架构及相较于现有解决方案的潜在优势。此外，我们讨论了有前景的应用场景，并明确了面向下一代无线网络的高级SIM架构设计中存在的开放性研究挑战。最后，通过数值结果量化了基于波的信号处理在无线系统中的优势。