The sixth-generation (6G) wireless networks are expected to deliver ubiquitous connectivity, resilient coverage, and intelligence-driven services in highly dynamic environments. To achieve these goals, distributed wireless architectures such as cell-free massive multiple-input multiple-output (MIMO) have attracted significant attention due to their scalability and fairness. Recently, stacked intelligent metasurfaces (SIMs) have emerged as a promising evolution of reconfigurable intelligent surfaces, offering multi-layer electromagnetic domain processing with enhanced controllability and spatial degrees of freedom. By integrating SIMs into distributed wireless networks, advanced wave-domain operations can be realized, enabling efficient interference management, improved energy and spectral efficiency, and robust physical-layer security. This article provides a comprehensive overview of SIM-aided distributed wireless networks, including their application scenarios, classification, and system architectures. Key signal processing challenges, such as hierarchical frameworks, user association, and joint precoding, are discussed, followed by case studies demonstrating significant performance gains. Finally, future research directions in hardware design, energy consumption modeling, algorithm development, and artificial intelligence integration are highlighted, aiming to pave the way for scalable and intelligent 6G distributed wireless networks.

翻译：第六代（6G）无线网络有望在高度动态的环境中提供泛在连接、弹性覆盖和智能驱动的服务。为实现这些目标，分布式无线架构（如无蜂窝大规模多输入多输出（MIMO））因其可扩展性和公平性而受到广泛关注。近年来，堆叠式智能超表面（SIMs）作为可重构智能表面的一种有前景的演进技术而兴起，它通过多层电磁域处理提供了更强的可控性和空间自由度。将SIMs集成到分布式无线网络中，可以实现先进的波域操作，从而实现高效的干扰管理、提升能量与频谱效率，并增强物理层安全性。本文全面综述了SIM辅助的分布式无线网络，包括其应用场景、分类和系统架构。文中讨论了关键信号处理挑战，例如分层框架、用户关联和联合预编码，并通过案例研究展示了显著的性能增益。最后，本文重点展望了硬件设计、能耗建模、算法开发以及人工智能集成等未来研究方向，旨在为可扩展且智能的6G分布式无线网络铺平道路。