Description
Passive WiFi Radar (PWR) is a hardware deployment pattern (not a chipset) where the existing Wi-Fi infrastructure transmits standard 802.11 frames and a separate passive receiver captures both the direct line-of-sight signal and reflections from moving targets — exactly the bistatic geometry of a passive radar, but using opportunistic Wi-Fi as the transmitter of opportunity. Listed as Hardware (rather than Method) because PWR papers are tightly bound to specific receiver platforms: SDRs (USRP B210, RTL-SDR), Atheros NICs in a separate physical location from the AP, or dual-Pi setups. The thesis cites PWR as the closest dedicated-hardware analogue to commodity-CSI sensing.
Specs / capabilities
- Bistatic (or multistatic): separate Tx and Rx geometry
- Reference channel (direct path) vs surveillance channel (reflected path)
- Cross-ambiguity function gives range × Doppler maps
- Uses standard 802.11n/ac frames as illuminator → no modification of the transmitter
Tooling
- USRP B210 + GNU Radio
- RTL-SDR (cheap entry; limited bandwidth)
- Custom dual-NIC Atheros setups
Used by (papers)
- Indoor passive radar / through-wall sensing papers
- Comparison hardware vs commodity-CSI sensing