Device-free Localization of Multiple Targets

In this paper, we consider the problem of multi-target device-free localization with special focus on modeling and inference. The motion of multiple targets inside the area covered by a wireless network leaves a characteristic footprint on the radio-frequency (RF) field, and in turn affects both the average attenuation and the fluctuation of the received signal strength (RSS). A diffraction-based model is developed to describe the impact of multiple targets on the RSS field, i.e. the multi-body-induced shadowing. As a relevant case study, the model is tailored to predict the effects of two co-located targets on the RF signals. Three novel algorithms are proposed for on-line localization, exploiting both the average and the deviation of the body-induced RSS perturbation. The proposed techniques are compared and some preliminary results, based on experimental data collected in a representative indoor environment, are presented.