The field-based model: a new perspective on RF-based material sensing

This study introduces the design and implementation of WiField, a commercial off-the-shelf (COTS)-device-deployed WiFi-based sensing system that can simultaneously identify multiple wavelength-level targets placed flexibly.Dissimilar to traditional radio frequency (RF)-based sensing schemes that focus on specific targets and RF links, WiField focuses on all media in the sensing area of the entire electric field.Consequently, WiField provides a unified framework for accurately characterizing diffraction, scattering, and other effects of targets across various positions, materials, and shapes.Notably, this combination of targets for different positions, numbers, and sizes only represents a special case.Furthermore, WiField provides a scheme that utilizes phaseless data to complete inverse mapping from an electric field to material distribution, thereby ensuring the simultaneous identification of multiple wavelength-level targets at any position and having the potential for deployment on a wide range of low-cost COTS devices.Our evaluation results reveal that WiField achieves an average identification accuracy of over 97% for 1–3 targets (size: 5 cm $\times$ 10 cm) with different materials randomly placed within an area of 1.05 m $\times$ 1.05 m.And the identification accuracy is about 83% for eight liquids placed in a 700 mL container.