• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.21-28
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• 2011

We consider an RFID network configured as a star in which tags stationarily move into and out of the vicinity of the reader. To cognize the neighboring tags in the RFID network, we propose a scheme based on dynamic framed and slotted ALOHA which determines the number of slots belonging to a frame in a dynamic fashion. The tag cognizance scheme distinctively employs a rule for estimating the expected number of neighboring tags, identified as R-retrospective maximum likelihood rule, where the observations attained in the R previous frames are used in maximizing the likelihood of expected number of tags. Simulation result shows that a slight increase in depth of retrospect is able to significantly improve the cognizance performance.

• 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.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.10
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• pp.1-5
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• 2011

A magnetic resonant coil system for enhancement of wireless power transfer efficiency of NFC devices was proposed. The NFC system consists of resonant coils arrange between source coil and device coil. The effects of resonant coil was measured using a 13.56MHz RFID reader and tag system and simulated by 3D RF simulator. The measurement results from RFID reader and tag show that the maximum distance of signal transmission is increased by 96.72% and received voltage of RFID tag is grew by 17.95% thanks to the magnetic resonant coils.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4A
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• pp.358-364
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• 2007

RFID, Radio Frequency Identification, technology is a contactless automatic identification technology using radio frequency. For this RFID technology to be widely spread, the problem of multiple tag identification, which a reader identifies a multiple number of tags in a very short time, has to be solved. Up to the present, many anti-collision algorithms have been developed in order to solve this problem, and those can be largely divided into ALOHA based algorithm and tree based algorithm. In this paper, two new anti-collision algorithms combining the characteristics of these two categories are presented. And the performances of the two algorithms are compared and evaluated in comparison with those of typical anti-collision algorithms: 18000-6 Type A, Type B, Type C, and query tree algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2C
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• pp.168-172
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• 2012

An UHF RFID tag is designed and fabricated using the national code in a bar-code with conductive ink. The bar-code sample was taken from a general bar-code from a general box. The conductivity of the conductive ink was measured, and the measured conductivity was used for the simulation tool to design the printed bar-code shape tag antenna. The tag antenna was fabricated using T-matching to reduce the size of the tag, and the bar-code tag antenna is recognized by both a general bar-code reader and an UHF RFID reader. The input reflection coefficient characteristic, the reading range pattern and the reading rate of the tag antenna are measured.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.616-619
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• 2012

When multiple Tags transmit their IDs to the Reader, tag identification time is delayed due to collisions. Therefore, to reduce the reader's identification time, an efficient anti-collision technology is needed. In this paper, a new anti-collision method is proposed. The method estimates the number of tags and allocates proper number of slots based on the DFSA. The performance of proposed method is compared with existing methods through extensive simulations.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.4
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• pp.31-39
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• 2008

RFID diffusion and origin technique being developed gradually, according to the various branch application solutions are coming out plentifully. Developed distance variable style 2.45 Ghz Active Tag from the present paper and according to century of corresponding frequency the distance of the leader and the tag between should have been falling as will freeze, will be able to grasp in order. The experimental result plan develops the data which measures from field test and the electromagnetic waves laboratory with base.

• Journal of information and communication convergence engineering
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• v.9 no.3
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• pp.260-265
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• 2011

In RFID System, when multiple tags respond simultaneously, a collision can occur. A method that solves this collision is referred to anti-collision algorithm. In 13.56MHz RFID system, STAC protocol is defined as an anti-collision algorithm for multiple tag reading. In STAC protocol, there is no differentiation between the collided tags and others in the identification process. Therefore, tags may never be successfully identified because its responses may always collide with others. This situation may cause the tag starvation problem. This paper proposes a fair identification scheme for STAC protocol. In the proposed scheme, if the number of collided slots is large during a query round, the reader broadcasts a CollisionRound command to begin a collision round. During the collision round, the reader identifies only tags that are experienced collision during the previous query round.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.147-150
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• 2007

This paper presents an advanced RFID reader system implementing multi-protocols and multi-standards at 900MHz. In accordance with the strict regulations specified by ISO 18000-6 B-Type and EPC Global Gen 2, we have designed corresponding systemic factors which meet the domestic radio frequency utilizing bands of 910-914MHz. In addition, we develop numerous crucial factors of system compatibility options including SSB (Single-Side Band) and DSB (Double-Side Band) specifications, also OOK (On-Off Keying), ASK (Amplitude Shift Keying) and PR-ASK (Phase Reversed-Amplitude Shift Keying) modulation formula. Remarkable technical features of system in this paper can be the direct conversion routines using I/Q Modulation/Demodulation respectively, and Full-Duplex formulation operating at identical frequency bands.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.761-767
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• 2007

In this paper, we deal wih a concurrent dual band low noise amplifier for a Radio Frequency Identification(RFID) reader operating at 912MHz and 2.45GHz. The design of the low noise amplifier is based on the TSMC $0.18{\mu}m$ CMOS technology. The chip size is $1.8mm\times1.8mm$. To improve the noise figure of the circuit, SMD components and a bonding wire inductor are applied to input matching. Simulation results show that the 521 parameter is 11.41dB and 9.98dB at 912MHz and 2.45GHz, respectively The noise figure is also determined to 1.25dB and 3.08dB at the same frequencies with a power consumption of 8.95mW.