RFEye in the Sky

TL;DR

RFEye is a UAV-based technique that localizes signals without waveform dependence by using asynchronous distributed beamforming and DoA estimation from uncoordinated positions, achieving meter-level accuracy in outdoor environments.

Contribution

The paper introduces RFEye, a novel UAV-based method for waveform-independent signal localization using a single antenna and distributed beamforming, with practical outdoor validation.

Findings

Median accuracy of 1.03m in 2D for Wi-Fi signals

Median accuracy of 2.5m in 3D for Wi-Fi signals

Robustness to wind and UAV position errors

Abstract

We introduce RFEye, a generalized technique to locate signals independent of the waveform, using a single Unmanned Aerial Vehicle (UAV) equipped with only one omnidirectional antenna. This is achieved by acquiring signals from uncoordinated positions within a sphere of 1-meter radius at two nearby locations and formulating an asynchronous, distributed receiver beamforming at the UAV to compute the Direction of Arrival (DoA) from the unknown transmitter. The proposed method includes four steps: 1) Blind detection and extraction of unique signature in the signal to be localized, 2) Asynchronous signal acquisition and conditioning, 3) DoA calculation by creating a virtual distributed antenna array at UAV and 4) Obtaining position fix of emitter using DoA from two locations. These steps are analyzed for various sources of error, computational complexity and compared with widely used signal subspace-based DoA estimation algorithms. RFEye is implemented using an Intel-Aero UAV, equipped with a USRP B205 software-defined radio to acquire signals from a ground emitter. Practical outdoor experiments show that RFEye achieves a median accuracy of 1.03m in 2D and 2.5m in 3D for Wi-Fi, and 1.15m in 2D and 2.7m in 3D for LoRa (Long Range) waveforms, and is robust to external factors like wind and UAV position errors.