The Practicality of Multi-Tag RFID Systems

Radio Frequency Identification (RFID) is an increasingly popular technology that uses radio signals for object identification. Successful object identification is the primary objective of RFID technology (after all, the last two letters of the acronym “RFID” stand for “identification”). Yet, a recent major study by Wal-Mart has shown that object detection probability can be as low as 66%. In this paper we address the fundamental issue of improving object detection by tagging objects with multiple tags. This confirms for the first time the practicality and efficacy of previous works on multi-tag RFID systems. Using different configurations of commercial RFID equipment, we show significant improvements in object detection probability as the number of tags per object increases. We compare various combinations of multi-tags, readers, and antennas, and demonstrate that adding multi-tags to a system can improve object detection probabilities more dramatically than adding more readers. We also address issues such as tag orientation and variability, effects of multi-tags on anti-collision algorithms and on object detection in presence of metals and liquids, as well as the economics of multi-tags.