• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.747-754
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• 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 the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.25-32
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• 2007

In this paper, we propose the Group Separation Algorithm for RFID Tag Anti-Collision. We study the RFID Tag anti-collision technique of ALOHA and the anti-collision algorithm of binary search. The existing technique is several problems; the transmitted data rate included of data, the recognition time and energy efficiency. For distinction of all tags, the Group Separation algorithm identify each Tag_ID bit#s sum of bit #1#. In other words, Group Separation algorithm had standard of selection by collision table, the algorithm can reduce unnecessary number of search even than the exisiting algorithm. The Group Separation algorithm had performance test that criterions were reader#s number of repetition and number of transmitted bits for understanding tag. We showed the good performance of Group Separation algorithm better than exisiting algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.29-37
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• 2004

In RFID system one of the problems that we must solve is to devise a good anti-collision algorithm to improve the efficiency of tag identification which is usually low because of tag collision. Among the existing RFID anti-collision algorithms, Framed Slotted ALOHA algorithm though simple, has a disadvantage that the number of slots used to identify the tags increases exponentially as the number of tags does. In the paper, we propose a new anti-collision algorithm called Partial-Response Framed Slotted ALOHA(PRFSA) which restricts the number of responding tags by dividing the tags into a number of groups when there are large number of tags and changes the frame size when there are small tags. Since the proposed algorithm keeps the frame size and the number of responding tags in such a way that can increase slot utilization, the algorithm shows superior performance to the existing ones. The simulation results showed that the proposed algorithm improves the slot efficiency by 85～100% compared to the existing algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.653-655
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• 2011

EPCglobal proposed a Q-algorithm, which is used for selecting a slot-count in the next query round. However, it is impossible to allocate an optimized slot-count because the original Q-algorithm did not define an optimized weight C value. In this paper, we propose an adaptive Q-algorithm, in which we differentiate the weight values with respect to collision and empty slots. The weight values are defined with the identification time as well as the collision probability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.942-949
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• 2004

This paper proposes and analyzes the anti-collision algorithm in Ubiquitous ID system. We mathematically compares the performance of the proposed algorithm with that of binary search algorithm, slotted binary tree algorithm using time slot, and bit-by-bit binary tree algorithm proposed by Auto-ID center. We also validated analytic results using OPNET simulation. Based on the analytic results, comparing the proposed algorithm with bit-by-bit algorithm which is the best of existing algorithms, the performance of proposed algorithm is about 5% higher when the number of tags is 20, and 100% higher when the number of tags is 200.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.85-94
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• 2008

When an RFID reader uses the same frequency or adjacent frequency with neighbor readers, the interference might occur. These interferences cause the RFID reader collision and errors during tag recognition. Therefore, the international standard for RFID and some papers proposed the methods to reduce the reader collision. The reader interference is closely related to the distance between the readers haying interference and used frequency band. In the previous RFID reader anti-collision algorithms, the location of readers inducing interference which is closely related to interference of readers is not considered. Only the reader collision is tried to reduce through frequency transfer after collisions occur or modification of frame size in relation to collision probability based a TDM(Time Division Multiplex). In this paper, the genetic algorithm using two-dimensional chromosome which reflect readers' location is proposed to prevent reader collision effectively. By executing evolutionary operation with two-dimensional chromosome, the location information having influence on reader interference can be used. The repair operation in the proposed algorithm makes all reader stably recognize their tags.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.330-336
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• 2020

An anti-collision system between equipment is essential on a drill floor where multiple moving machines are operated simultaneously. This is to prevent accidents by halting the machines when required, by inspecting possibility of a collision based on the relative position data sent by the equipment. In this paper, we propose a framework for an Anti-Collision System (ACS) by considering expandability of the number of machines and computational speed, to promote development of drilling machines and corresponding ACS software. Each drilling equipment is represented as an object in the software with its own message format, and the message is constructed with serialization/deserialization to manage any additional equipment or data. The data handling process receives the current status of machines from the drilling control network, and relays a collision related message (including bypass signal) back to the machines. A commercial visualization software shows the bounding boxes moving with the equipment and indicates probable collision. It has been determined that the proposed system maintains total execution time below 5ms to process data from the network and relay the information hence, the system has no effect on the machine control systems having 100ms control cycle.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.98-98
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• 2004

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.425-428
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• 2004

최근 각광을 받고 있는 RFID는 재고와 제조 유통분야를 중심으로 발전해 오던 바코드를 대체하여 물류유통의 혁명을 초래할 기술로 주목 받고 있다. 그러나 국내의 RFID에 대한 기술 및 자본의 투자는 해외에 비해 미흡한 실정이다. RFID 시스템에서 하나의 인터러게이터 영역에 다수의 트랜스 폰더가 동시에 데이터를 전송하게 되어 데이터 충돌이 발생하게 된다. 본 논문에서는 인터러게이터에서 각 트랜스폰더의 상호 충돌로부터 신뢰성 있게 데이터를 보호하고 해독이 가능하도록 하는 여러 충돌 방지 시스템에 대해서 알아본다.