Read Accuracy Improvement by R/W Beam Scanning and Repeated Transmission for 920 MHz RFID

Radio Frequency Identification (RFID) has been expected as a promising solution that bring about revolution in the supply chain management. One of the important scenarios is that an RFID system is used for identifying goods in shops and warehouses. For achieving good read accuracy, however, it is necessary to understand indoor radio propagation environment with surrounding materials that reflect radio waves and generate standing waves. In this paper, we analyze RFID read success rate in metal shelf environment through FDTD simulation. In order to reduce the read error, we propose a reader/writer (R/W) beam scanning and repeated transmission scheme with a moving conductor. By displacing the conductor in the vicinity of R/W antennas, receiving power null position caused by the standing waves is moved. Then, read accuracy can be improved by repeated transmission and selection combining. It is confirmed from the simulations that the read rate is greatly improved by the proposed scheme.