R-LABS: An RFID-based indoor localisation system using antenna beam scanning

In this paper, we propose an indoor localisation system using radio frequency identification (RFID) technology. Locations of passive RFID tags are determined by scanning multiple RFID reader antennas' radiation beams. During each scan, the horizontal and elevation angles of the reader antenna are recorded when the transition of a tag entering or leaving the antenna beam's coverage area occurs, and this angle information is used in the developed algorithm to calculate the tag's location. The proposed system requires a minimum of two reader antennas, without the need for reference tags. In order to mitigate the multipath impact on the localisation accuracy and system coverage, an improved algorithm is also developed. Simulations are performed for a typical small indoor environment and validated by experiments using ultra-high frequency (UHF) RFID devices. The results demonstrate that for effective operations of the proposed system, directive antennas are necessary, and systems using antennas with narrower beam widths provide a higher localisation accuracy.