A knowledge-based Query Tree with Shortcutting and Couple-Resolution for RFID tag identification

Abstract

In Radio Frequency Identification (RFID) systems, the reader identifies tags through communications over a shared wireless channel. However, when multiple tags transmit their IDs simultaneously, their signals collide, thereby prolonging the identification delay. However, in some applications, the RFID system has the availability of a database containing the IDs of all the tags that may possibly appear. The present study proposes a novel knowledge-based Query Tree with Shortcutting and Couple Resolution (QTSC) protocol for reducing the identification delay in RFID systems with such a database. In the proposed protocol, a knowledge-based query tree is first constructed to store the queries required to identify all the possible tags in the database. Then, at identifying appearing tags, the tags actually appear among possible tags, shortcutting and couple-resolution techniques are employed to skip redundant queries in the query tree and transmit two ID prefixes simultaneously within the same slot, respectively. The simulation results show that compared to the existing knowledge-based protocols, Knowledge Query Tree (KQT) and Heuristic Query Tree (HQT) protocols, QTSC reduces the identification delay by 60.5% and 39.0%, respectively.