Electromagnetic Models for Device-Free Radio Localization with Antenna Arrays

Device-Free Localization (DFL) techniques are able to detect and localize people that do not need to wear any electronic devices. DFL systems, based on Radio Frequency (RF) nodes, employ a network of radio devices, typically equipped with a single antenna, that measure the attenuation introduced by the bodies located inside the monitored area to estimate their positions. To this aim, several physical, statistical and electromagnetic (EM) models have been introduced in the literature to relate the body positions to the RF signals received by the nodes. This paper develops an EM body model suitable for application to DFL systems relying on devices equipped with multiple antennas. In particular, the proposed EM body model describes the multi-link geometry found in array processing scenarios. The array-based body model, based on the scalar diffraction theory, is compared against the results obtained using an EM simulator to validate its prediction capabilities. The proposed model paves the way for a wider use of multi-antenna systems and novel beamforming algorithms for DFL array-based applications.