Two Couple-Resolution Blocking Protocols on Adaptive Query Splitting for RFID Tag Identification

How to accelerate tag identification is an important issue in Radio Frequency Identification (RFID) systems. In some cases, the RFID reader repeatedly identifies the same tags since these tags always stay in its communication range. An anticollision protocol, called the adaptive query splitting protocol (AQS), was proposed to handle these cases. This protocol reserves information obtained from the last process of tag identification so that the reader can quickly identify these staying tags again. This paper proposes two blocking protocols, a couple-resolution blocking protocol (CRB) and an enhanced couple-resolution blocking protocol (ECRB), based on AQS. CRB and ECRB not only have the above-mentioned capability as AQS but also use the blocking technique, which prohibits unrecognized tags from colliding with staying tags, to reduce the number of collisions. Moreover, CRB adopts a couple-resolution technique to couple staying tags by simultaneously transmitting two ID prefixes from the reader, while ECRB allows the reader to send only one ID prefix to interrogate a couple of staying tags. Thus, they only need half time to identify staying tags. We formally analyze the identification delay of CRB and ECRB in the worst and average cases. Our analytic and simulation results show that they obviously outperform AQS, and ECRB needs less transmitted bits than CRB.