Description
Software-Defined Radio (SDR) is the umbrella class of radios where modulation, demodulation, and channel processing are done in software on top of a generic RF front-end. In the bibliography, SDR is cited as the methodology-validation tool: papers will cross-check commodity-NIC CSI against SDR-recorded I/Q to prove their measurements are well-calibrated, or use SDR to prototype non-standard waveforms before standardising on Wi-Fi. The most common SDRs in the literature are usrp (lab-grade), HackRF One (mid-range), and RTL-SDR (cheap entry).
Specs / capabilities
- Frequency coverage varies wildly: RTL-SDR (24 MHz - 1.7 GHz, 2-3 MHz BW), HackRF (1 MHz - 6 GHz, 20 MHz BW), USRP (DC-6 GHz, up to 200 MHz BW)
- 8-16 bit ADCs depending on tier
- USB or Gigabit Ethernet host interface
- GNU Radio is the canonical software stack; MATLAB / Simulink also common
Tooling
- GNU Radio: https://www.gnuradio.org/
- gr-ieee-802-11 (Bastian Bloessl) for software 802.11 PHY decoding + CSI
- SDR# / GQRX for spectrum exploration
Used by (papers)
- CSI calibration / validation papers
- Custom-waveform sensing experiments
- Passive WiFi radar receivers (see passive-wifi-radar)