BFMSense: WiFi Sensing Using Beamforming Feedback Matrix
Talkat 21st USENIX Symposium on Networked Systems Design and Implementation (NSDI '24) · 2024-04-16..04-18·
summary
Paper shows that the beamforming feedback matrix (BFM) from new Wi‑Fi cards carries usable channel information and derives a mathematical relation to CSI, then builds a signal‑processing pipeline that forms a BFM ratio to cancel per‑antenna scaling and phase offsets. System runs on commodity gear (tested on six popular routers), includes an open‑source real‑time BFM capture tool, and achieves high accuracy for respiration and trajectory sensing with one AP and two single‑antenna nodes.
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chapters (8)
- 0:00BFMSense introduction
- 1:45Multi-user MIMO and beamforming
- 3:35Extracting BF matrix from Wi-Fi
- 4:36CSI to BFMSense theory
- 6:21BFMRatio for BFMSense
- 8:06Respiration monitoring with BFMRatio
- 9:52Human trajectory tracking
- 10:37Summary and release
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