Doppler shift estimation is the problem of determining the frequency offset induced in a wireless signal when energy is reflected or scattered by a moving object, caused by the relative motion between the signal source, the moving scatterer, and the receiver. Accurate estimation of this shift is fundamental to WiFi/CSI sensing because it enables the inference of physical motion parameters such as velocity, direction, and activity type from channel measurements, making it central to applications like human activity recognition and gesture detection. Key variants of the problem include single-target versus multi-target estimation, narrowband versus wideband (per-subcarrier) Doppler analysis, and the challenge of separating micro-Doppler components from dominant static or slow-moving reflectors, with practical difficulty compounded in WiFi systems by hardware impairments, packet timing constraints, and PHY-layer features such as those introduced in IEEE 802.11ax that alter the structure of the received CSI.
Source Papers
- Doppler Effect: Analyses and Applications in Wireless Sensing and Communications ↗ — Doppler Effect: Analyses and Applications in Wireless Sensin
- Exposing the CSI: A Systematic Investigation of CSI-based Wi-Fi Sensing Capabilities and Limitations ↗ — Exposing the CSI: A Systematic Investigation of CSI-based Wi