• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.7B
• /
• pp.1081-1090
• /
• 2010

$0.18{\mu}m$ CMOS UHF RFID tag frontend is presented in this paper. Several key components are highlighted: the voltage multiplier based on the threshold voltage terminated circuit, the demodulator using current mode, and the clock generator. For standard compliance, all designed components are under the EPC Global Class-1 Generation-2 UHF RFID protocol. Backscatter modulation uses the pulse width modulation scheme. Overall performance of the proposed tag chip was verified with the evaluation board. Prototype Tag Chip dimension is neary 0.77mm2 ; According to the simulation results, the reader can successfully interrogate the tag within 1.5m. where the tag consumes the power about $71{\mu}W$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.8
• /
• pp.954-963
• /
• 2007

As RFID systems are applied to various fields and applications such as supply chain management, asset management, location based applications etc. the requirements becomes diverse. For example, Much higher performance, TCP/IP protocol stack are required in some applications. However, low end processors based systems such as 8051 processor can not meet such requirements due to their low processing capacity and limited size of memory. In this paper a UHF band RFID system which meets the EPC Class-1 Generation-2 specification with ARM920T-based processor is implemented and tested.

• ETRI Journal
• /
• v.30 no.3
• /
• pp.486-488
• /
• 2008

In this paper, a scheme to increase the throughput of RFID systems is presented, which considers the capture effect in the context of framed ALOHA protocol. Under the capture model in which the probability of one tag is identified successfully depending on the number of tags involved in the collision, two probabilistic methods for estimating the unknown number of tags are proposed. The first method is the maximum likelihood estimation method, and the second method is an approximate algorithm for reducing the computational time. The optimal frame size condition to maximize the system throughput by considering the capture effect is also presented.

• Journal of information and communication convergence engineering
• /
• v.8 no.3
• /
• pp.307-311
• /
• 2010

EPCglobal Class-1 Gen-2 protocol has been proposed for UHF-band RFID systems. In Gen-2 standard, Q-algorithm was proposed to select a frame size for the next query round without estimating the number of tags. Therefore, the Q-algorithm has advantage that the reader's algorithm is simpler than other algorithms. However, it is impossible to allocate the optimized frame size. Also, the original Q-algorithm did not define an optimized parameter C for adjusting the frame size. In this paper, we propose an adaptive Q-algorithm with the different parameter $C_c$ and $C_i$ in accordance with the status of reply slot. Simulation results show that the proposed adaptive Q-algorithm outperforms the original Gen-2 Q-algorithm.

• Journal of information and communication convergence engineering
• /
• v.5 no.4
• /
• pp.311-315
• /
• 2007

This paper proposes a revised query tree algorithm in RFID systems. The proposed QT_ecfi algorithm revises the QT algorithm, which has a memory-less property. In the QT_ecfi algorithm, the tag will send the remaining bits of their identification codes when the query string matches the first bits of their identification codes. When the reader receives all the responses of the tags, it knows which bit is collided. If the collision occurs in the last bit, the reader can identify two tags simultaneously without further query. While the tags are sending their identification codes, if the reader detects a collision bit, it will send a signal to the tags to stop sending. According to the simulation results, the QT_ecfi algorithm outperforms the QT algorithm in terms of the number of queries and the number of response bits.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2008.02a
• /
• pp.129-132
• /
• 2008

일정한 라디오 주파수 대역을 이용해 무선 방식으로 사물을 식별하는 RFID 시스템의 보안 및 프라이버시 보호를 위한 많은 기법들이 제안되었다. 하지만 제안된 기법들의 대부분은 국제 표준인 Class-1 Generation-2 태그에는 적합하지 않으며 안전성에서도 취약성이 있다. 최근에 Chien과 Chen은 Class-1 Generation-2 태그에 적합하면서도 안전성이 보장되는 상호 인증 프로토콜을 제안하였는데, 이 또한 취약성이 존재하며 데이터베이스에서의 태그를 찾기 위해 전수조사를 해야 하기 때문에 효율성이 떨어지는 문제점이 있다. 본 논문에서는 Chien과 Chen이 제안한 기법을 분석하고 안전성과 효율성을 향상시킨 새로운 상호 인증 기법을 제안한다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.9
• /
• pp.915-919
• /
• 2007

This paper proposed a transponder detection method to reduce recognition time in RFID system. It's also shown that conventional procedure of communication in the system could cause a waste of time when a reader recognizes a transponder. The reduction of recognition time can be obtained by developing a circuit to detect a transponder actively. Detecting a transponder is achieved by using the voltage variation of reader antenna voltage that happens when a transponder approaches to the vicinity of magnetic field formed by the reader. By adding a comparator to the antenna receiver of a reader, the reader can perceive approach or existence of a transponder. A reader for experiment is made using the MFRC500 by Phillips that supports ISO/IEC 14443 protocol. Comparing the proposed method with the conventional methods by experiment, there are 47.5ms reduction of recognition time maximally and 12ms in average.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.32 no.1
• /
• pp.1-10
• /
• 2009

Inventory Management has become a very important issue in supply chain management, because inventories may be used as a means to accomplish the certain strategic goals in company decisions. RFID(radio frequency identification) technology is used to help manage inventories. It is known that the ideal control of inventories is to replenish item by item. This paper points out several misinterpretations from the Wal-mart report presented in '07 Seoul Forum and suggests the new direction of RFID application. In this paper we consider RFID as not 'identification technology' but 'information technology.' The 'RF-Kanban' suggested here is adopted from the'Kanban'concept of TPS(Toyota Production System). The RF-Kanban system shows the easier control for replenishing various items in boxes. Lots of inventories can be reduced through RF-Kanban System. This work develops the protocol of RF-Kanban and introduces the case study for easier understanding.

• Journal of Industrial Technology
• /
• v.26 no.A
• /
• pp.147-152
• /
• 2006

Wireless Sensor Networks provide a new paradigm for sensing and disseminating information from various environments, with the potential to serve many and diverse applications. Recent advancement in wireless communications and electronics has enabled the development of low-cost sensor networks. The sensor networks can be used for various application areas. For different application areas, there are different technical issues that researchers are currently resolving. The current state of the art of sensor networks is captured in this article, where solutions are discussed under their related protocol stack layer sections. This article also points out the open research issues and intends to spark new interests and developments in this field. In order to evaluate the application of field monitoring system, lab tests, field test and FEM analysis are conducted. Therefore the accuracy of RFID wireless sensor data is verified.

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06d
• /
• pp.16-20
• /
• 2010

최근 급격히 발전하는 RFID(Radio Frequency Identification)나 USN(Ubiquitous Sensor Network)과 같은 무선환경은 태그(tag)와 리더(reader)간에 라디오 주파수를 이용하여 통신한다. 이러한 통신은 그 특성상 주파수 범위내의 다른 태그나 리더들 또한 이들의 통신내용을 들을 수 있다. 따라서 이렇게 도청된 정보는 악의적인 사용자에 의해 여러 가지 보안 공격을 야기할 수 있다. 반면 이러한 형태의 공격에 대해 대부분의 보안프로토콜은 외부의 공격에 주목하는 반면, 같은 알고리즘으로 통신하는 내부자의 공격, 특히 참여(entry)객체의 프라이버시정보는 이러한 프로토콜에서 보호되기 어렵다. 따라서 본 논문에서는 무선환경에서 최근 이슈가 되고 있는 불룸필터(bloom filter)를 이용하여 개인의 프라이버시 정보를 효과적으로 보호할 수 있는 기법을 제안하고 불룸필터를 확장 적용해서 그 성능을 개선하여 좀 더 효율적인 프라이버시 보호 기법을 설계하고자한다.