MAMPI – Multipath-assisted Device-free Localization with Magnitude and Phase Information

Narrowband radio-frequency (RF)-based device-free localization (DFL) systems suffer from multipath propagation. Therefore, we propose multipath-assisted device-free localization with magnitude and phase information (MAMPI), a DFL system that employs ultra-wideband (UWB) channel impulse response (CIR) measurements between a transmitter and receiver and thereby benefits from multipath propagation. We implement a model that includes raytracing, diffraction, and inaccuracies of measurements in a validated error model. The multipath-assisted DFL system creates feature vectors at any position based on magnitude and phase measurements of each multipath component (MPC) of the CIR. We evaluate our new approach with a position error probability based on the propagation model including errors, as well as a distance metric of the feature vector of the positions. We compare the performance of the system with a line-of-sight solution with four instead of two nodes and variants of magnitude-only and phase-only approaches. By combining the magnitude and phase measurements of a multipath-assisted DFL system, we achieve a position error probability that is similar to the conventional DFL system.