• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.9
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• pp.598-605
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• 2014

In this paper, we suggest a modified slotted ALOHA algorithm for fast tag collection in active RFID system and implement the reader and tag operation using CC2530 chip of Texas Instruments Co. to prove the performance of the proposed algorithm. In the present international standard related with active RFID including ISO/IEC 18000-7 the reader sends sleep command to each tag after successful obtaining tag's information. Meanwhile, in this paper, the tags decide to sleep after checking the second command from the reader resulting in enormously decreased tag collection time. We tested the proposed algorithm with 30 tags over the range of 0-3m and the results showed that the tag collection process was completed in 400msec at average. And 30 tags are collected in one second with 99.7% and the collection rate is 100% in 2m distance between reader and tag. The collection rates are 99.94% and 99.7% for distance 2.5m and 3m, respectively. The average collection rate is 99.91% over all range and it is concluded that the proposed algorithm is enough to apply to real fields.

• Journal of KIISE:Information Networking
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• v.36 no.2
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• pp.118-129
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• 2009

The ISO 18000-7 Active RFID standard, a single channel system operating in the 433Mhz, faces technical difficulties in supporting some recently introduced application demands because of its low transmission rates and radio interference between readers. We propose a new multi-channel active RFID system operating in the 2.4Ghz. The special feature of the proposed system is that a reader makes use of multiple interfaces to improve its performance like a multi-core processor. However if only a small part of interfaces are actually used, the performance improvement would not meet the expectation. To overcome this problem, a new multi-channel multi-interface active RFID protocol, which balances communication loads among all available interfaces, is necessary. 3 protocols, named as "Aggregated", "LP-Combined", "AP-Balanced", are proposed. Through simulation, we compare them for various conditions by changing number of tags, number of interfaces, tag data size. AP-Balanced shows the best performance and its performance increases almost linearly as the number of interface increases, which meets our expectation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.669-681
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• 2010

In this paper, we analyze the active RFID system ISO/IEC 18000-7. In order to apply to USN, which consists active RFID tags and sensor nodes, we propose UWB-based Class 4 active RFID protocol using active RFID relay tag as relay AP. To compare the performance between the existing ISO/IEC 18000-7 system and the proposed system, we introduce sensitivity-based measurement of achieved coverage and system efficiency. Also, we analyze the performance of the proposed system and compare it with that of the existing system through MCL analysis and SLS analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.95-98
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• 2009

RFID(Radio Frequency IDentification) technology is an automatic identification method using radio frequencies between RFID reader which collects the informatin and tag which transmits the information. RFID technology develops passive RFID which transmit the only ID to active RFID which transmit the additional information such as sensing information. there is ISO/IEC 18000-7 as typical standard of active RFID. it is single channel system of 433.92MHz and has limitation of collection of a number of tags. to overcome limitation of collection of many tags, we propose the new 2.4GHz active RFID technology which can use the multi-channel. if reader has multi-interface and uses another channel in each, reader could fast collect the tags. but, if a reader which has many interfaces collects tags through the specific interface, the performance may not improve any more comparing with a reader using single interface. in this paper, we show the fast collection through design and implementation of protocol for load balancing between interfaces in multi-interface RFID reader.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.453-456
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• 2006

본 논문은 유비쿼터스 컴퓨팅 시대를 열어가는 유비쿼터스의 핵심 기술인 RFID 시스템의 구성요소 중 하나인 Type B RFID 태그를 설계하였다. RFID 태그는 전원공급 여부에 따라 능동형과 수동형으로 구분한다. 본 논문에서는 현재의 IT분야에서의 RFID 시장과 연구동향에 맞춰 수동형 Type B RFID 태그의 Digital 파트를 설계하고, 성능을 검증하였으며, 향후 RFID 시스템의 연구방향에 대해서도 제시하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.1
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• pp.1-11
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• 2013

Reducing the energy that consumed by tag is a key requirement for the wider acceptance of the active RFID systems that use battery constrained tags. When the reader is not interrogating, the active RFID standard protocols try to reduce energy consumption of tags by using sleep mode. On sleep mode tags is active by receiving a specific signals from reader, until tag receive a sleep mode command from the reader, a tag waste energy for remaining in RX mode. Overhearing is a state of a tag in which it wastes energy for maintaining active RX state while there is no frame destined to it. According to our analysis, the amount of energy consumed by a tag due to overhearing is several time larger than that consumed by the effective communication. We propose RANO(Reservation Aloha for No Overhearing) that is designed to inform a tag of its effective communication intervals to eliminate overhearing problem in active RFID communication. The performance of the proposed protocol was evaluated through the real world by changing the number of tags and size of data. The result of an experiment, the proposed protocol performed saving about 22 times less than the standard protocol did.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.372-380
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• 2009

In this paper, we analyze the active RFID systems ISO/IEC 18000-7 and ISO/IEC 18000-4. In order to improve the coverage in sensor networks, which consist active RFID tag, we propose RFID multi-hop relay system using active RFID relay tag. To compare the performance between the existing ISO/IEC 18000-7 system and the proposed RFID multi-hop relay system, we introduce new system efficiency measure and sensitivity-based measure of achieved coverage. Also, we analyze the performance of the proposed system and compare it with that of the existing system through MCL (Minimum Coupling Loss) analysis and SLS (System Level Simulation) analysis.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.46-51
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• 2013

In this paper, a dual-band antenna is proposed for the RF power harvester system as well as RFID tag. The proposed antenna operates as the passive and active RFID tag antenna in the UHF and microwave band, respectively. In addition, to charge the battery of an active RFID tag in the microwave band, it harvest the RF signal for tagging from the passive RFID tag antenna in the UHF band. The proposed antenna operates in the UHF band (917~923.5 MHz) and microwave band (2.4~2.45 GHz). In order to obtain the dual-band operation, the dipole structure and meander parasitic elements are proposed as the ${\lambda}/2$ and $1{\lambda}$ dipole antenna, respectively. The radiating dipole structure in the microwave band acts as the coupled feed for the meander parasitic elements in the UHF band. The impedance bandwidth (VSWR < 2) of the proposed antenna covers 917~923.5 MHz (UHF band) and 2.4~2.45 GHz (Microwave band). Measured total efficiencies are over 45 % in the UHF band and over 70 % in the microwave band. Peak gains are over 0.18 dBi and 2.8 dBi in the UHF and microwave band with an omni-directional radiation pattern, respectively.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.365-368
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• 2004

유비쿼터스에 대한 인프라의 증가로 수많은 터미널들이 연동되어 우리 생활 주변에 자리 잡아 가고 있으며 정부와 개인, 사업장, 일상생활에 많은 영향을 미치는 차세대의 컴퓨팅 패러다임으로 다가오고 있다. 다양한 센서 기술들 중에 능동형 RFID를 사용하면 실세계에서 사용자들의 위치정보를 신속하고, 정확하게 파악하여 사용자의 위치에 따른 정보 제공을 지능적이고 효율적으로 할 수 있다. 본 논문에서는 병원에서 능동형 RFIB 시스템을 이용한 정보의 획득과 활용에 관한 API의 설계와 구현을 위한 기본적인 방법을 제안한다.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.113-120
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• 2009

Through the automatic sensing of the environment, USN technology can give the best services. In this work, we have developed an active RFID system and examined its performance. By implementing it into water quality sensors, we constructed a system that can detect diverse indoor/outdoor environment and provide information about the pollution level obtained from the temperature and PH sensors. Our RF system had an internal Print-on-PCB antenna for the miniaturization of the tag. We used a RF transceiver CC2510 chipset of TI company to realize the active RFID function. By using RSSI constants obtained, we performed the evaluation of real time location accuracy with a software written in Labview. Among 10 arbitrary locations, we obtained average measurement errors of 1.69 m in x axis and 1.66 m in y axis. This technology can be applied to logistics, environmental monitoring, prevention of missing children and various applications.