Enhanced M-Ary Detecting Tree: A Novel Time-Efficient Protocol for Tag Identification in Active RFID Systems

In this paper, we present a novel time-efficient tag identification protocol for active radio frequency identification (RFID) systems. Our protocol design is based on a conventional M-ary Detecting Tree (MDT) that divides contention tags into M subgroups and performs the identification in two phases: scanning and collecting. While the MDT protocol effectively eliminates redundant empty slots (i.e., slots without any tag responses), it requires two success slots (i.e., slots with exactly one tag’s response) to identify one tag, raising concerns about potential identification delays. We introduce an innovative anti-collision protocol called Enhanced M-ary Detecting Tree (EMDT) to address this issue. The proposed EMDT switches from the scanning phase to the collecting phase when the estimated number of responding tags becomes smaller than a predefined threshold, which is found via theoretical analysis and has an optimal value of three. This adjustment allows the reader to typically require just one success slot for identifying each tag, thus significantly reducing the total time needed to identify all tags. The proposed phase-switching mechanism is backed by Zero-Estimation (ZE) for tag cardinality estimation and Manchester encoding for data transmission, both widely employed in RFID standards. Theoretical analysis and computer simulations are performed in different system settings, including ideal and non-ideal transmission channels, to validate the efficacy of the proposed protocol in comparison with conventional alternatives.