Description
Device-Free Localization estimates the position of one or more humans who carry no transmitter or tag, by observing perturbations they induce on RF links between fixed anchors. CSI-based DFL replaced earlier RSSI-only RTI (Radio Tomographic Imaging) systems by exploiting subcarrier-level multipath shifts. It sits at the intersection of wifi-csi-sensing and indoor-positioning and is a building block for occupancy and crowd-counting pipelines.
When it's used
- Single-target indoor tracking from passive Wi-Fi observations
- Region-level occupancy heatmaps from CSI link grids
- Anchor-based fingerprinting where targets cannot wear devices
- Privacy-preserving alternatives to camera tracking
Limitations
- Multi-target separation is underdetermined with few anchors
- Sensitive to anchor geometry and environment changes
- Re-calibration required when furniture moves