• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.4A
• /
• pp.431-439
• /
• 2006

RFID Anti-Collision technique is needed to avoid collision problem caused by Radio interference between tags in the same RFID Reader area. It affects the performance and reliability of the RFID System. This paper propose the QT-CBP(Query Tree with Collision-Bit Positioning) Algorithm based on the QT(Query Tree) algorithm. QT-CBP Algorithm use precise collision bit position to improve the performance. We demonstrated the proposed algorithm by simulation. Our algorithm outperformed when each tag bit streams are the more duplicate and the number of tags is increased, compared with QT.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.6B
• /
• pp.450-455
• /
• 2008

We analyze the tag identification procedure of conventional EPC Class 1 RFID system and propose the fast anti-collision algorithm for the performance improvement of the system. In the proposed algorithm, the reader uses information of tag collisions and reduces unnecessary procedures of the conventional algorithm. We evaluate the performance of the proposed anti-collision algorithm and the conventional algorithm using mathematical analysis and simulation. According to the results, the fast anti-collision algorithm shows greatly better performance than conventional algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.3
• /
• pp.747-754
• /
• 2013

This paper proposed a new transponder detection method to reduce tag recognition time and simplify anti-collision process in RFID systems. In conventional systems, a transponder in detectable area is passively recognized by responding to a reader command. In addition, if there are multiple tags in the area, a collision between tags occurs by responding at the same time to a command and anti-collision process begins. In the proposed method, tags are actively recognized without any command from a reader which results to reducing a tag recognition time and simplifying anti-collision process. To compare transponder recognition time, the process of transponder recognition in conventional systems is analysed. A circuit to detect transponder directly is developed and antenna voltage variation of a reader in the appearance of multiple transponders is analysed for the implementation of the proposed method.

• Journal of Korea Society of Industrial Information Systems
• /
• v.15 no.3
• /
• pp.1-9
• /
• 2010

In recent year, the cores of ubiquitous environment are sensor networks and RFID systems. RFID system transmits the electronic information of the tag to the reader by using RF signal. Collision happens in RFID system when there are many matched tags, and it degrades the tag identification performance. Such a system needs algorithm which is able to arbitrate tag collision. This paper suggests a hybrid method which reduces collision between the tags, and can quickly identify the tag. The proposed method operates based on certainty, which takes an advantage of tree based algorithm, and to reduce collision it selects transmission time slot by using tag ID. The simulation results show the suggested method has higher performance in the number of queries and collision compared to other tree based and hybrid algorithms.

• Journal of KIISE:Information Networking
• /
• v.34 no.5
• /
• pp.316-327
• /
• 2007

RFID (Radio Frequency Identification) is one of the most promising air interface technologies in the future for object identification using radio wave. If there are multiple tags within the range of the RFID tag reader, all tags send their tag identifications to the reader at the same time in response to the reader's query. This causes collisions on the reader and no tag is identified. A multi-tag identification problem is a core issue in the RFID. It can be solved by anti-collision algorithm such as slot based ALHOA algorithms and tree based algorithms. This paper, proposes a collision tree based anti-collision algorithm using collision tree in RFID system. It is a memory-less algorithm and is an efficient RFID anti-collision mechanism. The collision tree is a mechanism that can solve multi-tag identification problem. It is created in the process of querying and responding between the reader and tags. If the reader broadcasts K bits of prefix to multiple tags, all tags with the identifications matching the prefix transmit the reader the identifications consisted of k+1 bit to last. According to the simulation result, a proposed collision tree based anti-collision algorithm shows a better performance compared to tree working algorithm and query tree algorithm.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.7 no.2
• /
• pp.235-242
• /
• 2012

In RFID System, one of the problem that we must slove is to devise a good anti-collision algorithms to improve the efficiency of tag identification which is usually low because of tag collision. Among of the existing RFID anti-collision algorithm, BS (Binary Search) algorithm, though simple, has a disadvantage that the stage of times used to identify the tags increase exponentially as the number of tags does. In this paper, I propose a new anti-collision algorithm called Multi-collision reflected frame which restricts the number of stages and decided bit. Since the proposal algorithm keep the length size of UID and density of total tag when have 100%. The simulation results showed that the proposed algorithm improves the efficiency by 30~50% compared to the existing algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37A no.12
• /
• pp.1013-1022
• /
• 2012

Tag collection is one of the major concerns in radio frequency identification(RFID) system. All tags in RFID reader's transmission range send response message back to the reader in response to collection request message on the given rf channel. When multiple tags respond simultaneously, tag-collision may occur. Tag-collision problem is one of the most important issues in active RFID performance. To mitigate this problem, frame slotted ALOHA(FSA) anti-collision protocol is widely used in active RFID system. Several studies show that the maximum system efficiency of FSA anti-collision protocol is 36.8%. In this paper, we propose an efficient slotted CSMA/CA protocol to improve tag collection performance. We compare our protocol to the FSA anti-collision protocol. For the experiment, an 433MHz active RFID system is implemented, which is composed of an RFID reader and multiple tags. We evaluated the tag collection performance using one RFID reader and 40 tags in the real test bed. The experimental result shows that proposed protocol improves the tag collection time, round and collision probability by 18%, 37.4% and 77.8%, respectively.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.3
• /
• pp.373-378
• /
• 2006

One of the biggest problems that should be solved in present RFID systems is a reduction of identification efficiency by the collision of singals between different tags. As the number of tags, which should be identified, increases over the size of allocated round, more slots experiences the collision between them. It can causes generation of tag collision assigning the fixed round size and so, allocated round size should be regulated properly. This paper proposes the algorithm which can reduce collision between tags, and allocate specific round size dynamically for efficient tag identification. After each round is finished, the reader allocates the round size dynamically using the collision information of the slot. All collision informations of the slot consists of the number of slots which came into conflict, tags which were realized properly without any conflictions and empty slots. We used slotted aloha algorithm as the collision detection algorithm and finally, checked that this could be used very usefully when this algorithm which was proposed effectively could not know how many number of tags were exisisted through the simulation in advance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.05a
• /
• pp.616-619
• /
• 2012

When multiple Tags transmit their IDs to the Reader, tag identification time is delayed due to collisions. Therefore, to reduce the reader's identification time, an efficient anti-collision technology is needed. In this paper, a new anti-collision method is proposed. The method estimates the number of tags and allocates proper number of slots based on the DFSA. The performance of proposed method is compared with existing methods through extensive simulations.