Fine-scale Through-Wall Positioning Using Tunneling RFID Tags

It has been shown that Tunneling Tags enable long-range communications and localization in line-of-sight (LoS) with an RFID reader operating in the 5.8 GHz band. This paper demonstrates how a received signal phase-based positioning method can be applied to localize tags in a non-line-of-sight (NLoS) scenario. In particular, a Tunneling Tag provides 20.0 dB more received signal strength than a Semi-passive one when they communicate through a plaster wall. Moreover, when calibration is applied, average distance estimation accuracies of 12.1 cm (percentage error: 2.1%) and 9.2 cm (percentage error: 1.4%) are achieved in LoS and NLoS, respectively. The low-power requirement of the Tunneling Tag and the low EIRP of the reader suggest that these tags can significantly contribute to developing new and low-powered indoor positioning applications.