In recent years, sensing technologies leveraging wireless signals, such as Wi-Fi, have attracted significant attention. Building on these advancements, this letter presents a novel approach for estimating water-surface variations using Wi-Fi channel state information (CSI). A theoretical model is derived to analyze the reflections of Wi-Fi signals from the water surface, showing that surface fluctuations induce periodic sinusoidal variations in the CSI amplitude. Furthermore, by applying the CSI quotient model, a relationship between the CSI phase and the surface velocity is established, forming the basis for estimating surface variation. Extensive experiments with commercial Wi-Fi devices verify the effectiveness and robustness of the proposed method.

DOI: 10.1109/LMWT.2026.3653012 IEEEXplore:https://ieeexplore.ieee.org/document/11371350