• Journal of KIISE:Information Networking
• /
• v.34 no.6
• /
• pp.483-492
• /
• 2007

In this paper, we propose a new hybrid approach based on query tree protocol to arbitrate tag collisions in RFID systems. The hybrid query tree protocol that combines a tree based query protocol with a slotted backoff mechanism. The proposed protocol decreases the average identification delay by reducing collisions and idle time. To reduce collisions, we use a 4-ary query tree instead of a binary query tree. To reduce idle time, we introduce a slotted backoff mechanism to reduce the number of unnecessary Query commands. Simulation and numerical analysis reveal that the proposed protocol achieves lower identification delay than existing tag collision arbitration protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.4
• /
• pp.1460-1478
• /
• 2020

This paper proposes a novel anti-collision protocol for large-scale RFID tags identification, named Bi-response Collision Tree Protocol (BCT). In BCT, two group of tags answer the reader's same query in two response-cycles respectively and independently according to the bi-response pattern. BCT improves the RFID tag identification performance significantly by decreasing the query cycles and the bits transmitted by the reader and tags during the identification. Computation and simulation results indicate that BCT improves the RFID tag identification performance effectively, e.g. the tag identification speed is improved more than 13.0%, 16.9%, and 22.9% compared to that of Collision Tree Protocol (CT), M-ary Collision Tree Protocol (MCT), and Dual Prefix Probe Scheme (DPPS) respectively when tags IDs are distributed uniformly.

• Journal of Internet Computing and Services
• /
• v.10 no.2
• /
• pp.133-141
• /
• 2009

A tag collision problem occurs when many tags are placed in a interrogation zone in RFID system. A tag collision problem is one of core issues and various protocols have been proposed to solve the collision problems. Generally tree-based protocols generate unique prefixes and identify tags with them as quick as possible. In this paper, we propose the QT-BCS protocol which decreases the identification time by reducing the number of query-response. The QT-BCS protocol makes a prefixes using time slot and bit change sensing unit. This protocol compares the current bit of tags until the current bit is differ from the previous one. When this occurs, all of the bits scanned so far are transferred to slot-0 and slot-1 depending on the first bit value in Reader. Consequently, this method can reduce the number of queries by tracing prefixes easily. Simulation result shows QT-BCS is more efficient in identifying tags than Query Tree and 4-ary Query Tree protocol.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.6
• /
• pp.435-445
• /
• 2013

One of the most challenging issues in radio frequency identification (RFID) and near field communications (NFC) is to correctly and quickly recognize a number of tag IDs in the reader's field. Unlike the probabilistic anti-collision schemes, a query tree based protocol guarantees to identify all the tags, where the distribution of tag IDs is assumed to be uniform. However, in real implements, the prefix of tag ID is uniquely assigned by the EPCglobal and the remaining part is sequentially given by a company or manufacturer. In this paper, we propose an enhanced M-ary query tree protocol (EMQT), which effectively reduces unnecessary query-response cycles between similar tag IDs using m-bit arbitration and tag expectation. The theoretical analysis and simulation results show that the EMQT significantly outperforms other schemes in terms of identification time, identification efficiency and communications overhead.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.9B
• /
• pp.1092-1097
• /
• 2011

An anti-collision protocol which tries to minimize the collision probability and identification time is the most important factor in all identification technologies. This paper focuses on methods to improve the efficiency of tag's process in identification systems. Our scheme, Binary Slotted Query Tree (BSQT) algorithm, is a memoryless protocol that identifies an object's ID more efficiently by removing the unnecessary prefixes of the traditional Query Tree (QT) algorithm. With enhanced QT algorithm, the reader will broadcast 1 bit and wait the response from the tags but the difference in this scheme is the reader will listen in 2 slots (slot 1 is for 0 bit Tags and slot 2 is for 1 bit Tags). Base on the responses the reader will decide next broadcasted bit. This will help for the reader to remove some unnecessary broadcasted bits which no tags will response. Numerical and simulation results show that the proposed scheme decreases the tag identification time by reducing the overall number of request.

• Journal of Internet Computing and Services
• /
• v.14 no.5
• /
• pp.1-10
• /
• 2013

RFID(Radio Frequency Identification) system is non-contact identification technology. A basic RFID system consists of a reader, and a set of tags. RFID tags can be divided into active and passive tags. Active tags with power source allows their own operation execution and passive tags are small and low-cost. So passive tags are more suitable for distribution industry than active tags. A reader processes the information receiving from tags. RFID system achieves a fast identification of multiple tags using radio frequency. RFID systems has been applied into a variety of fields such as distribution, logistics, transportation, inventory management, access control, finance and etc. To encourage the introduction of RFID systems, several problems (price, size, power consumption, security) should be resolved. In this paper, we proposed an algorithm to significantly alleviate the collision problem caused by simultaneous responses of multiple tags. In the RFID systems, in anti-collision schemes, there are three methods: probabilistic, deterministic, and hybrid. In this paper, we introduce ALOHA-based protocol as a probabilistic method, and Tree-based protocol as a deterministic one. In Aloha-based protocols, time is divided into multiple slots. Tags randomly select their own IDs and transmit it. But Aloha-based protocol cannot guarantee that all tags are identified because they are probabilistic methods. In contrast, Tree-based protocols guarantee that a reader identifies all tags within the transmission range of the reader. In Tree-based protocols, a reader sends a query, and tags respond it with their own IDs. When a reader sends a query and two or more tags respond, a collision occurs. Then the reader makes and sends a new query. Frequent collisions make the identification performance degrade. Therefore, to identify tags quickly, it is necessary to reduce collisions efficiently. Each RFID tag has an ID of 96bit EPC(Electronic Product Code). The tags in a company or manufacturer have similar tag IDs with the same prefix. Unnecessary collisions occur while identifying multiple tags using Query Tree protocol. It results in growth of query-responses and idle time, which the identification time significantly increases. To solve this problem, Collision Tree protocol and M-ary Query Tree protocol have been proposed. However, in Collision Tree protocol and Query Tree protocol, only one bit is identified during one query-response. And, when similar tag IDs exist, M-ary Query Tree Protocol generates unnecessary query-responses. In this paper, we propose Adaptive M-ary Query Tree protocol that improves the identification performance using m-bit recognition, collision information of tag IDs, and prediction technique. We compare our proposed scheme with other Tree-based protocols under the same conditions. We show that our proposed scheme outperforms others in terms of identification time and identification efficiency.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.1
• /
• pp.98-104
• /
• 2012

In RFID Systems, collisions between multiple tags frequently arise due to simultaneous responses from multiple tags using the same communication channel. Most of anti-collision protocols such as QT regard these collisions as useless cycles, thereby wasting the channel bandwidth. In this paper, we propose a new anti-collision protocol, namely ASP (Adjustable splitting by patterns of collisions) protocol that utilizes the patterns collision for noticeable performance enhancements.

• Journal of information and communication convergence engineering
• /
• v.5 no.4
• /
• pp.311-315
• /
• 2007

This paper proposes a revised query tree algorithm in RFID systems. The proposed QT_ecfi algorithm revises the QT algorithm, which has a memory-less property. In the QT_ecfi algorithm, the tag will send the remaining bits of their identification codes when the query string matches the first bits of their identification codes. When the reader receives all the responses of the tags, it knows which bit is collided. If the collision occurs in the last bit, the reader can identify two tags simultaneously without further query. While the tags are sending their identification codes, if the reader detects a collision bit, it will send a signal to the tags to stop sending. According to the simulation results, the QT_ecfi algorithm outperforms the QT algorithm in terms of the number of queries and the number of response bits.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.2
• /
• pp.207-214
• /
• 2012

This paper is to improve an identification ratio of tags by analyzing Slotted ALOHA, Dynamic Slotted ALOHA, Binary-tree and Query-tree and shortening the tag identification time in mobile RFID. Also, it enables the stable information transmission of tags by saving backscattering power of tags through shortening of identification time. As a result, this increases the available time of the battery and accessibility to a RFID service. For this, we proposed the energy-efficient tag anti-collision protocol for mobile RFID. The proposed scheme shows advanced result in identification time and collision counts. This scheme may be the first attempt for the mobile anti-collision.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.4A
• /
• pp.358-364
• /
• 2007

RFID, Radio Frequency Identification, technology is a contactless automatic identification technology using radio frequency. For this RFID technology to be widely spread, the problem of multiple tag identification, which a reader identifies a multiple number of tags in a very short time, has to be solved. Up to the present, many anti-collision algorithms have been developed in order to solve this problem, and those can be largely divided into ALOHA based algorithm and tree based algorithm. In this paper, two new anti-collision algorithms combining the characteristics of these two categories are presented. And the performances of the two algorithms are compared and evaluated in comparison with those of typical anti-collision algorithms: 18000-6 Type A, Type B, Type C, and query tree algorithm.