• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.41-42
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• 2008

무선방식으로 원격에서의 인식으로 정보교환을 가능하게 하는 RFID(Radio Frequency IDentification) 시스템은 태그 내의 배터리 유무에 따라 수동형과 능동형으로 구분된다. 수동형 태그는 판독기로부터 받은 RF 신호를 에너지로 이용하기 때문에 인식거리가 짧으며, 가격이 싸고 반영구적으로 사용할 수 있는 장점이 있다. 반면에, 능동형 태그는 금속재질에 취약한 수동형의 단점을 극복하는 동시에 인식거리가 길고, 인식률이 좋은 장점이 있다. 따라서 항만물류나 국방 분야에서 능동형 RFID 시스템에 대한 개발이 점차 확대되고 있다. 하지만 동일한 표준으로 개발된 제품의 서로 간에 인식이 불가능한 사례가 보고되고 있으며, 국제적으로 정확한 평가방법 및 장치가 정립되지 않아 개발된 제품들 간의 상호 운용성 및 표준 적합성 평가에 대한 어려움이 존재한다. 본 논문에서는 능동형 RFID 시스템의 적합성 평가를 위한 에뮬레이터의 하드웨어 및 소프트웨어를 설계하고 제작하였다. 설계된 장치는 Matlab의 Simulink를 통한 시뮬레이션으로 성능을 분석하였고, 실제 능동형 RFID 태그의 표준적합성 평가를 통해 에뮬레이터의 적용 가능성을 검증하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.422-429
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• 2007

Location awareness is one of the key functionalities to build an U-city. Recently, many of works of the location-aware systems are emerging to commercially apply to on-going large-scale apartment complex based on U-city. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers and receivers fixed along the street or in building use those information to calculate location of them. There are several issues to be considered for such an environment. The first is that the number of active tags operating in the same region are large as much as tens of thousands, and the second is that the active tags should be alive without change of batteries more than a year, hence low power consumption is very important. In this paper we propose i) a new architecture for location-aware system considering such issues, ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through the analysis we can show the theoretical boundary of the lowest packet loss rate and the maximum number of tags with acceptable performance for the systems based on active tags. The results can be applied to practical design of location-based systems of U-City projects.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1419-1435
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• 2015

In this study an active RFID system of low power consumption is proposed, for which we improved the tag collection algorithm of ISO/IEC 18000-7 standard and significantly reduced the tag collection time. We classified the type of power consumption according to the operating mode of active RFID and proposed the method which can accurately estimate battery life time. By calculating the power consumptions of proposed and current methods, we can compare the battery life times of both methods. Through this analysis we can demonstrate the superiority of the proposed method in battery life time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.3
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• pp.199-206
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• 2013

This paper proposes a modified tag collection algorithm that improves the drawback of the identified slot scan-based tag collection algorithm presented in a previous paper to improve the tag collection performance in active RFID systems. The previous identified slot scan-based tag collection algorithm is optimized in situations where all the tags store the fixed size of data, so it could not result in a good performance improvement with tags having the variable size of data. The improved tag collection algorithm proposed in this paper first collects the slot size information required for the data transmission from each tag via the identified slot scan phase, and then performs the tag collection phase using the information, which resolves the problem of the previous identified slot scan-based tag collection algorithm. The simulation results for performance evaluation showed that the proposed tag collection algorithm resulted in the almost same tag collection performance as the previous algorithm when all the tags have the same size of data and led a large improvement of the tag collection performance in ISO/IEC 18000-7 unlike the previous algorithm when each tag has a random size of data.

• 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 Korean Society for Geospatial Information Science
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• v.16 no.3
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• pp.43-49
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• 2008

The Real Time Location System (RTLS) is very important in the ubiquitous society for real time tracking of men, high price assets, and logistics products. In this work, we developed an active RF system for RTLS and tested its performance. The RTLS system developed in this work was constructed of three active readers and one active tag. The small size tag developed in this work operated with a coin type battery. To make the tag smaller, we used an internal PCB antenna and a chip antenna. We tested the performance of the tag. To reduce the manufacturing cost of our RF system, we used low price RF transceiver CC2510 chip-set. The CC2510 chip-set provided RSSI(Received Signal Strength Indicator) signal which could be used to determine the distances between an active tag and three active readers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.518-527
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• 2008

Tag collection is one of the major functions in Radio Frequency Identification (RFID) systems. IS0/IEC 18000-7 defines the tag collection algorithm using the anti-collision algorithm, based on the framed slotted ALOHA for active RFID systems. However, it has inefficiency problems that reduce tag collection performance by deciding non-optimum slot size or using point-to-point commands to put collected tags to sleep. In this paper, we propose two mechanisms to overcome the inefficiency problems and improve tag collection performance: 1) a new slot size decision mechanism to allow the reader to choose the optimum slot size flexibly and 2) a broadcast-based sleep mechanism to put collected tags to sleep effectively. We also implemented an active RFID system, composed of an active RFID reader and multiple tags, and the reader is designed to maximize tag collection performance when the proposed mechanisms are applied. In experiments, we evaluated the tag collection performance using one reader and 50 tags in the real-world environment. The experimental results show that when two mechanisms are applied and the initial number of slots is chosen appropriately, the performance of the proposed tag collection algorithm is greatly enhanced, compared with that of the standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.753-761
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• 2010

In this paper, we propose a novel tag collection algorithm to improve tag collection performance in active RFID systems. In the proposed algorithm, the reader detects the occurrence of empty slots and collided slots through the identified slot scan process and reduces the time wasted by empty slots and collided slots, resulting in improvement of tag collection performance. To evaluate the performance improvement by the proposed tag collection algorithm via the experiments in a real-world environment, we implemented an active RFID reader and tags. The experimental results with the reader and 60 tags showed that the proposed algorithm could reduce the average tag collection time by 21.7% and improve the average identification throughput by 28.3%, compared with the standard tag collection algorithm in ISO/IEC 18000-7. In addition, the proposed algorithm reduced the average battery consumption on tags by 22.7% in the battery consumption experiment with 20 tags.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.3 s.55
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• pp.26-32
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• 2005

RFID 기술은 사물에 전자 태그를 부착하여 무선으로 사물의 ID를 인식하여 정보를 수집하고 주변상황 정 보를 감지하고 수집 된 정보를 저 장, 가공, 추적함으로써 사물에 대한 측위, 원격처리, 관리 및 사물간 정보 교환 등의 서비스를 제공하는 기술이다. 특히,.미 관세청에서 2005년 미국에 수출되는 컨테이너에 RFID 태그를 부착하는 정책을 발표하여 2006년부터는 능동형 RFID 태그를 이용한 컨테이너 통관을 시행할 예정이며, 현재 태그 부착은 의무 사항은 아니지만 선별적으로 컨테이너 전수 검사를 실시한다는 방침이어서 반강제적인 성격을 지닌 것으로 판단할 수 있다. 또한, 물류 산업의 변화의 대세에 따라 제조업체의 생산품이 유통 과정을 거쳐 항만에서 처리되는 과정을 실시간으로 추적이 가능함은 물론이고 나아가서 외국 항만과의 연계를 통하여 수출입 전 과정의 추적성을 파악하고 거기에 다른 시스템의 효율적인 통합을 이루어 언제 어디서나 화물의 추적과 관리가 가능한 유비쿼터스 환경의 선진화된 항만 시스템을 구축할 수 있다. 본고에서는 항만 물류용 능동형 RFID 기술과 관련하여 시스템 구성 요소 및 관련 기술 동향, 항만 물류 시스템의 응용에 대해 알아본다.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.581-590
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• 2016

This paper proposes an efficient collision avoidance algorithm that a group of RFID readers manage each of their affiliated active RFID tags in a space by establishing wireless network and avoids communication collision between RFID reader to reader and RFID tag to tag, and reader to tag. RF readers operate as wireless network nodes, create synchronous links each other, and can exchange messages. Active tags also are operated communicating each reader devices synchronously, and competing slot position between tags algorithm using unique tag identification number is implemented. Each reader node operates their own reader function different time slot network communication period to prevent collision between readers communication.