• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.561-571
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• 2006

RFID technology, as one contact-less identification technology with using electronic tag, is the field where its multiple researches have been studied. Especially, in the field of supply chain management, when it is necessary to identify a lot of objects by real-time, performance of anti-collision algorithm for multiple tag identification has an effect on performance of entire system. GEN2 is global, open, interoperability protocol for UHF RFID system, the active researches and developments are processed about it. In this paper, we introduce an anti-collision algorithm based on Slotted-ALOHA for GEN2 protocol, focus on estimating number of tags and setting number of slots and review the previous works. We propose new scheme that can estimate number of tags efficiently, and define system efficiency newly when it's used in setting number of slots. We also present result of compare and analysis with previous scheme through simulation. The proposed scheme of estimating number of tags is easy to implement, number of tags which is less than 4 times of number of slots can estimate tags efficiently, we also proved that identification efficiency based on weighted-slot distinguished with definition of previous slot efficiency can improve system efficiency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.247-252
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• 2013

In this paper, a microwave tag system of a frequency-scanning type is proposed with multi-resonators using defected ground structures. While a conventional chip-based RFID stores time-sequential codes, the proposed type achieves pure passive tags by using multi-resonant bits over a frequency range. Moreover, the resonators of the spiral defected ground structures implemented on the back side of transmission lines have advantages of the excellent bandstop characteristics as well as the bit-error avoidance by the re-radiation on normal resonators. The proposed microwave tag is designed with UWB antennas at 3~7 GHz. From the experimental results in an anechoic chamber, it has been verified of the excellent recognitions for various 5-bits identification codes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1569-1580
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• 2016

For the 2.4 GHz active RFID to be successful in the market, one of the requirements is the increased battery life. However, currently we do not have any accurate power consumption estimation method. In this study we develop a simulation model, which can be used to estimate power consumption of tag accurately. Six different simulation models are proposed depending on collision algorithm and query command method. To improve estimation accuracy, we classify tag operating modes as the wake-up receive, UHF receive, sleep timer, tag response, and sleep modes. Power consumption and operating time are identified according to the tag operating mode. Query command for simplifying collection and ack command procedure and newly developed collision control algorithm are used in the simulation. Other performance measures such as throughput, recognition time for multi-tags, tag recognition rate including power consumption are compared with those from the current standard ISO/IEC 18000-7.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1887-1894
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• 2016

In the RFID system, the reader transmits a query message to tags in order to identify a unique ID of tags within its detection range. The procedures for arbitrating a collision is essential because the multiple tags can response simultaneously in the same to the query of the Reader. This procedure is known as conflict resolution algorithm and it is a key technology in the RFID system. In this paper, we proposed a variable bits M-ary QT algorithm based on Manchester coding techniques. The proposed algorithm use the location information of the collision bits in the reader and tags. The proposed algorithm can reduce the number of the query-response cycle because it is capable of recognizing discontinuous bits and a variable number of bits. From computer simulation, the proposed method give better performance than the conventional M-ary QT techniques in terms of response, recognition efficiency, communication overhead.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.111-121
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• 2014

In this paper, we propose tree-based hybrid query tree architecture utilizing time slot. 4-Bit Pattern Slot Allocation(4-SL) has a 8-ary tree structure and when tag ID responses according to query of the reader, it applies a digital coding method, the Manchester code, in order to extract the location and the number of collided bits. Also, this algorithm can recognize multiple Tags by single query using 4 fixed time slots. The architecture allows the reader to identify 8 tags at the same time by responding 4 time slots utilizing the first bit($[prefix+1]^{th}$, F ${\in}$ {'0' or '1'}) and bit pattern from second ~ third bits($[prefix+2]^{th}{\sim}[prefix+3]^{th}$, $B_2{\in}$ {"00" or "11"}, $B_1{\in}$ {"01" or "10"}) in tag ID. we analyze worst case of the number of query nodes(prefix) in algorithm to extract delay time for recognizing multiple tags. The identification delay time of the proposed algorithm was based on the number of query-responses and query bits, and was calculated by each algorithm.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.259-260
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.261-262
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• 2008

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.46-55
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• 2009

In RFID field, when the neighboring readers try to occupy the same or adjacent channel simultaneously, there exists reader-to-reader interference; it calls reader collision. From the reader collision, the tags cannot response correctly query from the reader. Reader anti-collision schemes have been developed, and particularly, the Listen-Before-Talk(LBT) scheme is proposed to avoid reader collision in ETSI in multi channel environment. However, in ETSI, there is a drawback that the reader collision does not decreases effectively because the reader selects randomly a channel without considering the channel environment and readers try to occupy the channel concurrently. In this paper, we propose a algorithm based on LBT scheme considering multi channel environment as well as made up for the drawbacks of LBT The proposed algorithm applies random backoff, the collision avoidance mechanism. And it can reduce delay because of our proposed estimation mechanism Simulation using OPNET shows that the proposed algorithm achieves higher superiority than that of the simple algorithms in sparse and dense reader mode.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1438-1446
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• 2010

In this paper, we compared and analyzed the antenna characteristics such as bandwidth, efficiency, and readable range in terms of the size and the number of turns of the multiple meander RFID tag antenna in the UHF band. The sizes of the each antenna are $20.0{\times}19.7$, $25.0{\times}24.8$ and $30.0{\times}29.7\;mm^2$. The bandwidths of the antennas for VSWR<5.8 are 857~963 MHz, 844~965 MHz, and 844~968 MHz which cover the worldwide UHF RFID bandwidth. The readable range of the antenna was greatly affected by the efficiency and gain of the antenna which depends on the size and the number of turns of the meander antenna.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.313-319
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• 2009

Recently the RFID system, which can recognize multiple tags simultaneously through wireless communication, is emerging as a new technology that can replace the barcode system. Furthermore, related industries are carrying out active research on tags and authentication protocols with guaranteed security that are widely applicable to logistics, distribution, etc. The present study proposes a protocol with enhanced security by introducing the concept of RBAC to the authentication protocol, and a method with lower security for effective mass authentication. The proposed method is advantageous in that it guarantees security against spoofing attack, traffic analysis, replay attack, etc. based on hash function.