A Multipath Mitigation Technique for UHF RFID Inlet/Outlet Management Systems

In this paper, a technique to mitigate the multipath fading is presented for a UHF RFID inlet/outlet management system. Two degrees of freedom can be used to minimize the multipath including the tilt angle of the illuminating RFID reader antenna and the reader's transmitted power. Two circularly polarized antennas are used to detect objects equipped with RFID tags in both incoming as well as outgoing directions. To detect the incoming and outgoing events, the tag's id, RSSI and the timestamp are recorded. By optimizing the antenna's tilt angle and the reader's transmitted power, direction of the tag's movement can clearly be detected. The proposed system can be applied for in- and outlet management of items in a warehouse.