A phase-based technique for discriminating tagged items moving through a UHF-RFID gate

A phase-based technique is presented for discriminating tagged items moving on a conveyor belt from other tagged items that are present in the scenario, when a UHF RFID gate is installed at a conveyor section. Indeed, tagged items (either static or randomly moving in the scenario) that are close to the reader antenna could be detected even if they are not on the conveyor (false positive readings). The classification procedure here proposed is based on some features that are extracted from a phase-based technique used to localize tags on a conveyor belt, which takes advantage of the fact that the tagged items move along a conveyor whose speed and path are both known a priori. Differently from other techniques that are used to solve the above misclassification issue, the proposed approach does not require multiple antennas.