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

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.55-58
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• 2008

RFID(Radio frequency IDentification) leader is collision of data, when recognizing the multiple tag the inside area. This collision became the cause which delays the tag recognition time of the leader. The protocol which prevents the delay of tag recognition time of the leader the place where representative it uses QT(Query Tree) algorithms, it uses a collision bit position from this paper and are improved QT-MTC(Query Tree with Multi-Tag Cognition) algorithms which it proposes. This algorithm stored the bit position which bit possibility and the collision where the collision happens occurs in the stack and goes round a tree the number of time which, it reduced could be identified two tags simultaneously in order, it was planned. A result of performance analysis, It compared in QT protocols and the this algorithm against the tag bit which is continued a tush efficiency improvement effect was visible.

• Journal of KIISE:Software and Applications
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• v.36 no.7
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• pp.560-570
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• 2009

RFID, Radio Frequency Identification, is a technology of automated identification replacing bar-code. RFID technology has advantages that it recognizes fast and it is strong to contamination using wireless communication. However, there are difficult problems that should be solved for popularization of RFID. Among of these, tag anti-collision problem is dealed in this paper. It affected the performance of RFID system directly. This paper analyzes conventional algorithms and proposes new algorithms of tag anti-collision. The algorithm proposed was composed of appropriate properties to each phase of distribution and recognition as hybrid between ALOHA-based algorithm and QT-based algorithm. At phase of distribution, the number of tags recognizing at a frame was reduced using ALOHA-based algorithm. It addressed the delay problem because of deep depth of tree. At phase of recognition, it solved ALOHA-based chronic problem that couldn't recognize all the tags sometimes. Moreover, QTR algorithm that recognize by reversed tag IDs was adopted for the performance. The FQTR algorithm proposed in this paper showed brilliant performance as compared with convention algorithms by simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5C
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• pp.540-547
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• 2006

This paper proposes a novel anti-collision method for the ISO/IEC 18000-6 type B protocol which is the standard protocol of the 900 MHz RFID system. We improve the anti-collision performance by reducing the transmission number of commands and the length of bits required for multi-tag identification in the ISO/IEC 18000-6 type B protocol. Simulation results show that the proposed method improves the multi-tag identification time by 21.7% over the conventional method, irrespective of number of tags.

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

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.802-805
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• 2008

RFID 시스템에서 리더와 태그는 단일 무선 공유 채널을 갖기 때문에 RFID 수동형 태그를 위한 태그 충돌 중재가 태그 인식을 위한 중요한 이슈이다. 본 논문에서는 태그 충돌 방지를 위한 Improved Hybrid Query Tree algorithm 을 제안한다. 제안된 알고리즘은 쿼리 트리를 기반으로 태그가 리더에게 ID 를 전송하는 시점을 전송 ID 상위 3 비트 내의 '1' 값을 이용하여 결정한다. 또한 전송받은 Tag 의 상위 3 비트는 충돌이 발생하더라도 전송 슬롯에 따라 다르므로 제안한 알고리즘에서 예측이 가능하다. 시뮬레이션을 통한 성능 평가에서 다른 트리 기반 프로토콜에 비해 제안한 알고리즘이 쿼리 횟수에서 높은 성능을 갖는다는 것을 보여준다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.875-876
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• 2007

본 논문에서는 지능적으로 폴링과 랜덤접속모드를 사용하는 RFID 충돌방지 기법을 제안하고자 한다. 본 논문에서 제안하고자 하는 충돌방지 알고리즘은 태그의 교체율이 크지 않을 경우, 먼저 이전 인식과정에서 성공적으로 식별한 태그들에 대한 고유정보를 기억한 뒤 다음 인식 세션에서 그 고유 정보를 활용하여 출석을 부르는 것처럼 경쟁 없이 태그들을 호출하여 빠르게 식별한다. 이전 세션(session)에 비하여 많은 수의 태그가 교체되었으면 인식률이 저하될 수 있다. 이 경우에는 랜덤 접속모드로 전환하여 나머지 태그들을 읽어 낸다. 본 논문에서 제안하는 것처럼 인식이력을 활용한 모드와 랜덤 접속 모드를 적절히 조합하여 운용하면 태그 인식 시간을 단축할 수 있으며, 특히, 주기적으로 개체의 존재 유무를 확인하는 응용의 경우에 우수한 성능 향상을 얻을 수 있다.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.287-294
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• 2008

A tag collision arbitration algorithm for RFID passive tags is one of the important issues for fast tag identification, since reader and tag have a shared wireless channel in RFID system. This paper suggests Hyper-Hybrid Query Tree algorithm to prevent the tag-collisions. The suggested algorithms determine the specified point in time for tag to transfer ID to reader by using value 1 of the upper 3 bit based on Query Tree. Also, because the transferred upper 3 bits of tag is different depending on the time of transfer, it is possible to predict in the suggested Algorithm. In the performance evaluation through simulation, it shows the suggested algorithm has higher performance in the number of queries compared to other Tree-based protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.2
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• pp.202-207
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• 2013

RFID technology is applied to port logistics applications since it monitors objects wirelessly without line of sight and constructs ubiquitous system with low cost. Changes of stock status in the warehouse environment make the technology more important for managing such frequent storing and un-storing. Although the RFID has beneficial characteristics of low cost and low complexity, simultaneous responses of RFID tags cause tag identification collision due to absence of elaborate medium access control scheme. Several algorithms have been proposed to overcome the tag collision problem. However, it is difficult to adopt the methods to the logistics systems that has varying loads since there was no consideration on RFID tag's mobility. Therefore, we propose an efficient RFID tag anti-collision protocol, and simulation results demonstrate performance improvement by using the proposed scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.526-529
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• 2006

In this paper, a QT_ss protocol is proposed for identifying all the tags within the identification range. The proposed QT_ss protocol revises the QT protocol. which has a memoryless property. In the QT_ss protocol, the tag will send all the bits of their identification codes when the query string matches the first bits of their identification codes. 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_ss protocol outperforms the QT protocol in terns of the number of response bits.