On efficient UHF RFID coverage inside a room

This paper investigates the problem of improving the identification performance of a UHF RFID system inside a room. We assume static reader, passive tags and availability of commodity antennas. In sharp contrast to prior art that has focused on free space or simple two-ray model, a ray-tracing propagation model is developed that includes multipath in 3D space. It is found that careful selection of reader antenna placement and tilting must be performed to control destructive interference effects. Furthermore, 3D coverage performance gains on the order of 10% are observed by implementing tags´ diversity. Finally, a device that successfully manipulates destructive interference is introduced.