Optimal Slot Assignment for Binary Tracking Tree Protocol in RFID Tag Identification

Abstract

Tag anti-collision has long been an important issue in RFID systems. To accelerate tag identification, some researchers have recently adopted bit tracking technology that allows the reader to detect the locations of collided bits in a collision slot. However, these methods still encounter the problem of too many collisions occurring at the beginning of identification. This paper proposes an optimal binary tracking tree protocol (OBTT) that tries to separate all of the tags into smaller sets to reduce collisions at the beginning of identification. Using bit tracking technology, OBTT mainly adopts three proposed approaches, bit estimation, optimal partition, and binary tracking tree. Bit estimation first estimates the number of tags based on the locations of collided bits. Optimal partition then determines the optimal number of the initial sets based on this estimation. Binary tracking tree lets the tag utilize one counter to achieve the split during the identification process. This paper formally analyzes the slot efficiency of OBTT, which represents how many tags can be identified in a slot. Results show that the slot efficiency is close to 0.614, the highest value published to date. Considering slot lengths, OBTT further determines the optimal number of the initial sets to minimize the identification delay. The analytical results show that the delay efficiency of OBTT achieves 0.750, where delay efficiency represents the number of tags that can be identified in a baseline slot, the length of which is the complete ID sent by the tag. The simulation results show that OBTT outperforms other existing algorithms. Index Terms-Anti-collision, bit tracking, Manchester code, RFID, tag identification.Yuan-Cheng Lai received the Ph.D. degree in computer and information science from National Chiao Tung University, Taiwan, in 1997.He joined the faculty of Information Management, National Taiwan University of Science and Technology, Taiwan, in 2001 and has been a Professor since 2008. Now, he is a Distinguished Professor at the university. He has published over 170 research papers and six Chinese books about computer networks. His research interests include performance analysis, protocol design, wireless networks, and network security.Ling-Yen Hsiao received the B.S.

A Comparison of RFID Anti-Collision Protocols for Tag Identification

“…• A modification of the OQTT is presented in [59] called Optimal Binary Tracking Tree (OBTT). This modification implements the estimator of the OQTT with a simple Binary Tree (BT) protocol [60].…”

A High Throughput Anticollision Protocol to Decrease the Energy Consumption in a Passive RFID System

“…A BT based protocol with a bit estimator and bit tracking technology, referred to as the Optimal Binary Tracking Tree (OBTT) protocol, is given in [8]. It first employs a bit estimation algorithm to estimate the existing number of tags.…”

“…Tree based protocols, on the other hand, are classified as deterministic since they are supposed to read all the tags in the interrogation zone [3]. These protocols usually split the set of tags upon collisions until achieving a successful response from all the tags; however, some recent solutions provide an estimation phase to define 2 Wireless Communications and Mobile Computing initial subsets which are easier to be identified by the reader [7,8].…”

“…All tags in the antenna range remain correctly energized during the interrogation cycle; all tags' responses are synchronized; and lastly, a collision occurs only when two different messages or bits are simultaneously transmitted since error transmissions are not considered. These assumptions are extensively made in other similar anticollision protocol works proposed [7,8,14,16]. The transmission model is explained below.…”

An Effective Frame Breaking Policy for Dynamic Framed Slotted Aloha in RFID

“…Therefore, an effective anti-collision algorithm is important in accelerating tag identification. To cope with the multiple tags identification, many anti-collision algorithms have been proposed, which can be classified into Aloha-based [2][3][4], query tree (QT)-based [5], and hybrid algorithms [6][7].…”