An RFID-based indoor localization system using antenna beam scanning

In this paper, we propose an indoor localization 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. Experimental results obtained from a controlled environment demonstrate that the average localization error distance of the proposed beam scanning method is less than 20 cm.