• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.253-259
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• 2008

RFID is a generic term for technologies which use RF waves to identify, track, or categorize any object. A radio frequency identification (RFID) reader recognizes objects through wireless communications with RFID tags. Tag collision arbitration for passive tags is a significant issue for fast tag identification due to communication over a shared wireless channel. One of the research areas in RFID system is a tag anti-collision protocol. In this paper, various anti-collision protocols are discussed. The pros and cons of different anti-collision protocols are compared with each other and their performance is analyzed and the better performance anti-collision protocol is suggested.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.6
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• pp.299-311
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• 2008

The Radio Frequency IDentification (RFID) system is a contactless automatic identification system, which comprises readers and tags. In RFID systems, a reader collision occurs when there is interference in communication between one reader and the tags, due to the signals from other readers. The reader collision problem is considered as the fundamental problem affecting high density RFID reader installations. In this paper, we analyze the existing reader anti-collision algorithms. We also propose a pulse protocol-based reader anti-collision algorithm using slot occupied probability (SOP). The implementation of this improvement is simple, yet it effectively mitigates most reader collisions in dense reader mode, as shown in our simulation. That is, the proposed algorithm reduces the identification time, and increasesthe system throughput and system efficiency compared with the conventional reader anti-collision algorithms.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.24-28
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• 2008

In RFID System, when multiple tags respond simultaneously, a collision can occur. A method that solves this collision is referred to anti-collision algorithm. Among the existing anti-collision algorithms, static framed slot allocation algorithm is very simple. But when the number of tags is variable, its performance degrades because of the fixed frame size. This paper proposes an optimal frame size allocation scheme that determines the frame size. The proposed scheme is based on the number of collision slots at every frame. According to the simulation results, the tag identification time is faster that of SFSA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6B
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• pp.450-455
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• 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 KIISE:Information Networking
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• v.34 no.5
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• pp.316-327
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• 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.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.79-86
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• 2019

An anti-collision light of a rotary-wing aircraft is used for the purpose of preventing collision during the operation of an aircraft and is a key component to ensure flight safety. The anti-collision lights of the Korean Utility Helicopter (KUH) consist of upper and lower lights, and the power supply of anti-collision lights mounted on the aircraft. The anti-collision light is designed as a dual structure capable of brightness control and selective lighting. During the operation after delivery of the aircraft, abnormal lighting of anti-collision light occurred. In this paper, a comprehensive review of the aircraft system and component level was conducted to solve these phenomena at first. Then, the causes of anti-collision light anomalies were analyzed and the design changes are presented. The validity of design changes has been verified through the component and aircraft system ground/flight test.

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

• Journal of information and communication convergence engineering
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• v.9 no.3
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• pp.260-265
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• 2011

In RFID System, when multiple tags respond simultaneously, a collision can occur. A method that solves this collision is referred to anti-collision algorithm. In 13.56MHz RFID system, STAC protocol is defined as an anti-collision algorithm for multiple tag reading. In STAC protocol, there is no differentiation between the collided tags and others in the identification process. Therefore, tags may never be successfully identified because its responses may always collide with others. This situation may cause the tag starvation problem. This paper proposes a fair identification scheme for STAC protocol. In the proposed scheme, if the number of collided slots is large during a query round, the reader broadcasts a CollisionRound command to begin a collision round. During the collision round, the reader identifies only tags that are experienced collision during the previous query round.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.44-49
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• 2011

In RFID System, when multiple tags respond simultaneously, a collision can occur. A method that solves this collision is referred to anti-collision algorithm. In Gen-2 RFID system, if the slot-count size varies during a query round due to the collisions, a new query round begins with a QueryAdjust command. Anti-collision algorithm of Gen-2 RFID system is simple. But, it has the tag starvation problem that a tag may never be successfully identified because its responses always collide with others. Therefore, this paper proposes a scheme to guarantee the fair identification delay. In the proposed scheme, if the slot-count value changes due to the collisions, the reader broadcasts a CollisionRound command to begin a collision round. During the collision round, the reader identifies only tags that occurred collision during the previous query round.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1B
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• pp.17-26
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• 2005

RFID(Radio Frequency IDentification) is a technology that automatically identifies objects attached with electronic tags by using radio wave. For the implementation of an RFID system, an anti-collision algorithm is required to identify several tags within the RFID reader's range. Few researches report the performance trade-off among anti-collision algorithms in terms of the communications traffic between the reader and tags, the identification speed, and so on. In this paper, we analyze both tree based memoryless algorithms and slot aloha based algorithms that comprise of almost every class of existing anti-collision algorithms. To compare the performance, we evaluated each class of anti-collision algorithms with respect to low-cost RFID system with 96-bit EPC(Electronic Product Code). The results show that the collision tracking tree algorithm outperforms current tree based and aloha based algorithms by at least 2 times to 50 times.