• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.473-476
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• 2007

RFID(Radio Frequency IDentification) 기술은 RF 신호를 사용하여 물품에 부착된 전자 태그(tag)를 인식하는 자동인식 기술이다. 이런 RFID 기술의 확산을 위해서는 다수의 태그를 빠르게 읽는 다중접속 방식에서 태그 간 충돌 문제를 해결 하는 충돌방지(anti-collision) 알고리즘이 필수적으로 요구된다. 본 논문에서는 이 문제를 해결하기 위해 충돌 방지 알고리즘 중에서 트리 기반 메모리래스(tree based memoryless) 충돌방지 알고리즘 기반인 충돌 추적(collision tracking) 알고리즘을 개선한 RCT(Revised Collision Tracking) 방식을 제안한다. 그리고 기존의 충돌 추적 알고리즘과의 성능 비교를 통해 제안하는 방식의 성능을 증명한다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.16-18
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• 2006

RFID는 RF신호를 이용하여 물체에 부착된 태그(tag)를 읽어 물체를 식별하는 비 접촉 인식 기술이다. RFID 리더의 식별영역에 여러 개의 태그가 있는 경우 이들 사이의 충돌(collision)이 발생되기 때문에 이들을 식별할 수 있는 메커니즘이 있어야 한다. 본 논문에서는 먼저 기존에 제안된 트리 기반 메모래스 충돌방지 알고리즘들을 살펴보고, 본 논문에서 제안하는 향상된 쿼리 기반 충돌 알고리즘(AQT : Advanced Query Tree based Collision Algorithm)을 소개한다.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.18-22
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• 2016

In this paper, we proposed a scheme for signal detection based on average of detected energy of frequencies for backscatter communications. We applied this scheme on the bistatic backscatter radio architecture for RF energy harvesting. Tags reflected entire RF signals on a same bandwidth when transmitted energy signals. Receivers can optimal switching antenna by this scheme. Simulation results show that the proposed scheme can precisely detect signals from tag with properly calculated parameters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1013-1022
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• 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 Internet Computing and Services
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• v.9 no.1
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• pp.43-54
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• 2008

In this paper, we implement an automatic entity information management system for smart refrigerator using RFID technology in which objects containing electronic tags are automatically identified using radio wave. Unlike current "smart" refrigerators, the system presented in this paper implements smart tag information acquisition mechanism and real-time information management system to provide various information on entities in refrigerators to local and remote users. As the first step, this paper analyzes the requirements for smart refrigerator system based on the RFID and suggests design considerations. Based on the analysis, we propose and implement an efficient tag location tracking method based on antenna transfer method and an intelligent tag information management system based on embedded database and web server. We also provide a wide range of experimental results on the number of tags identified at a time and the tag recognition ratio according to the RFID antenna transfer speed and the angle between tag reader and tags.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.99-108
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• 2010

RFID(Radio Frequency IDentification) is a technology that automatically identifies objects containing the electronic tags by using radio wave. When there are some tags in the domain of the RFID reader, the mechanism that can solve a collision between the tags occurs is necessary. The multi tag identification problem is the core issue in the RFID and could be resolved by the anti-collision algorithm. However, RFID system has another problem. The problem id user information security. Tag response easily by query of reader, so the system happened user privacy violent problem by tag information exposure. In the case, RFID system id weak from sniffing by outside. In this paper, We study of security robustness for tree-walking algorithm, query tree algorithm and advanced query tree algorithm of tree based memoryless algorithm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2007.02a
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• pp.97-100
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• 2007

본 논문은 유비쿼터스 센서 네트워크와 텔레매틱스 서비스에 사용되는 무선 환경 프로토콜 표준 중 UHF 대역 프로토콜인 EPCglobal의 Class 1 Gen 1, Class 1 Gen 2의 에어인터페이스를 분석하고 각 프로토콜에서 규정된 충돌방지 알고리즘을 구현하였다. 그리고 각 프로토콜에서 규정하는 충돌방지 알고리즘의 성능을 개선한 알고리즘을 제안하고 성능을 비교하였다. 개선된 알고리즘과 표준 알고리즘의 성능 시뮬레이션 결과 개선된 Class 1 Gen 1 알고리즘은 태그 수 100개 일 때 54.5%, 태그 수 1000개 일 때 63.4% 감소하였다. 개선된 Class 1 Gen 2 알고리즘은 태그 수 100개 일 때 7.9%, 태그 수 1000개 일 때 11.7% 감소하였다. 개선된 충돌방지 알고리즘은 표준 알고리즘보다 태그 인식 성능이 상당히 개선됨을 알 수 있다. 따라서 개선된 충돌방지 알고리즘은 유비쿼터스 센서 네트워크와 텔레매틱스 서비스 등에 사용되는 무선인식 시스템의 성능 개선방안으로 적용될 수 있다.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.46-53
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• 2008

This paper presents a 13.56 MHz RFID reader that can be used as a door-lock system for smart home security. The RFID reader consists of a transmitter, a receiver, and a data processing block. To verify the operation of the developed RFID reader, we present both a PSPICE simulation for transmitter/receiver and a digital simulation for data processing block. In particular, a CRC block for error detection of received data and a Manchester decoding block for position detection of collided data are designed using VHDL. In addition, we applied a binary search algorithm for multi-tag anti-collision. The anti-collision procedure is carried out by PIC microcontroller on software. The experimental results show that the developed reader can provide the right multi-tag recognition.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.3
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• pp.34-41
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• 2009

This paper investigates the issue of efficient reading for sensor data of semi-passive sensor tag. The Cold Chain management system requires complete sensor data without data loss and the short processing time of reading sensor tag data. However, reading the sensed data could be interfered by RF environment such as a jamming, obstacle and so on. This study found that it could lead to loss of the sensed data and takes much time to read it when data loss is occurred. To solve this problem, we propose the transaction processing mechanism that guarantees efficient reading of the sensed data. To do this, we present the technique of dynamic packet size and technique of data recovery to execute read transaction. These techniques improve the reliability of reading operation as well as speed up of read process for the large capacity data. This paper contributes to the improvement of efficient reading of sensed data without any loss of data and large time required.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.516-521
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• 2022

In this paper, a compact 4-bit chipless RFID(radio frequency identification) tag using a modified ELC(electric field-coupled inductive-capacitive) resonator and multiple slot resonators is proposed. The modified ELC resonator uses an interdigital-capacitor structure in the conventional ELC resonator to lower the resonance peak frequency of the RCS. The multiple slot resonators are designed by etching three slots with different lengths into an inverted U-shaped conductor. The resonant peak frequency of the RCS for the modified ELC resonator is 3.216 GHz, whereas those of the multiple slot resonators are set at 4.122 GHz, 4.64 GHz, and 5.304 GHz, respectively. The proposed compact four-bit tag is fabricated on an RF-301 substrate with dimensions of 50 mm×20 mm and a thickness of 0.8 mm. Experiment results show that the resonant peak frequencies of the fabricated four-bit chipless RFID tag are 3.285 GHz, 4.09 GHz, 4.63 GHz, and 5.31 GHz, respectively, which is similar to the simulation results with errors in the range between 0.78% and 2.16%.