Channel sounding is the process of actively probing a wireless channel by transmitting known reference signals and measuring the resulting Channel State Information (CSI) at the receiver, thereby characterizing how the channel attenuates, delays, and phase-shifts the signal across frequency subcarriers and time. It is fundamental to WiFi sensing research because it provides the fine-grained physical-layer measurements needed to infer environmental properties such as human presence, motion, and gesture without dedicated sensing hardware. Key variants include packet-based sounding, where CSI is extracted per received frame using commodity hardware tools such as the Linux 802.11n CSI Tool or the nexmon CSI Extractor, and purpose-built channel sounders that offer greater control over waveform and bandwidth but sacrifice the accessibility and ubiquity of commercial devices.
Source Papers
- An Overview on IEEE 802.11bf: WLAN Sensing ↗ — An Overview on IEEE 802.11bf: WLAN Sensing
- Enabling ISAC on Low-Cost Devices via Spatial-Channel Estimation With a Single-RF Chain ↗ — Enabling ISAC on Low-Cost Devices via Spatial-Channel Estima
- Free Your CSI ↗ — Free Your CSI
- Radio Radiance Field: The New Frontier of Spatial Wireless Channel Representation ↗ — Radio Radiance Field: The New Frontier of Spatial Wireless C
- Tool release ↗ — Tool release