Integrated Sensing and Communication (ISAC) has emerged as a key paradigm in next-generation wireless networks. While the ubiquity and low cost of commodity Wi-Fi make it an ideal platform for wide-scale sensing, it is the continuous evolution of Wi-Fi standards-towards higher frequency bands, wider bandwidths, and larger antenna arrays-that fundamentally unlocks the physical resources required for high-performance ISAC. To structure this rapidly expanding field, numerous surveys have appeared. However, prevailing literature predominantly adopts a top-down perspective, emphasizing upper-layer applications or deep learning models while treating the physical layer as an opaque abstraction. Consequently, these works often fail to touch the bottom layer of signal formation and lack technical guidance on overcoming the physical barriers that constrain sensing performance. To bridge this gap, this tutorial takes a bottom-up approach, systematically analyzing the sensing gains brought by Wi-Fi advancements through the lens of physical-layer diversity. We organize the framework around four orthogonal dimensions: i) Temporal Diversity addresses synchronization gaps to enable absolute ranging; ii) Frequency Diversity expands the effective bandwidth to sharpen range resolution; iii) Link Diversity leverages distributed topologies and digital feedback to achieve ubiquitous observability; and iv) Spatial Diversity utilizes multi-antenna arrays to combine passive angular discrimination with active directional control. Collectively, these orthogonal dimensions resolve fundamental ambiguities in time, range, and space, bridging physical capabilities with challenging sensing diversities. By synthesizing these dimensions, this tutorial provides a comprehensive guide for "ISAC-izing" commodity Wi-Fi, paving the way for future standardization and robust deployment.

翻译：集成感知与通信（ISAC）已成为下一代无线网络的关键范式。商品Wi-Fi的普及性与低成本使其成为大规模感知的理想平台，而正是Wi-Fi标准向更高频段、更宽带宽和更大天线阵列的持续演进，从根本上释放了高性能ISAC所需的物理资源。为梳理这一快速发展的领域，已有大量综述文献涌现。然而，现有研究主要采用自上而下的视角，强调上层应用或深度学习模型，却将物理层视为不透明的抽象层。因此，这些工作往往未能触及信号形成的底层，也缺乏突破感知性能物理约束的技术指导。为弥补这一缺口，本教程采用自下而上的方法，通过物理层多样性的视角系统分析Wi-Fi技术进步带来的感知增益。我们围绕四个正交维度构建框架：i) 时间多样性通过解决同步间隙实现绝对测距；ii) 频率多样性通过扩展有效带宽提升距离分辨率；iii) 链路多样性利用分布式拓扑与数字反馈实现全域可观测性；iv) 空间多样性运用多天线阵列将被动角度分辨与主动波束控制相结合。这些正交维度共同解决了时间、距离与空间维度的基础模糊性问题，将物理能力与具有挑战性的感知多样性需求相衔接。通过综合这些维度，本教程为商品Wi-Fi的"ISAC化"提供了完整指南，为未来标准化与稳健部署铺平道路。