• Journal of Advanced Navigation Technology
• /
• v.27 no.6
• /
• pp.835-840
• /
• 2023

RFID(Radio Frequency Identification) systems are attracting attention as a key component of Internet of Things technology due to the cost and energy efficiency of application services. In order to use RFID technology in the IoT application service field, it is necessary to be able to store and manage various information for a long period of time as well as simple recognition between the reader and tag of the RFID system. And in order to read and write information to tags, a performance improvement technology that is strong and reliable in poor wireless channels is needed. In particular, in the UHF(Ultra High Frequency) RFID system, since multiple tags communicate passively in a crowded environment, it is essential to improve the recognition rate and transmission speed of individual tags. In this paper, Middleton's Class A impulsive noise model was selected to analyze the performance of the RFID system in an impulsive noise environment, and FM0 encoding and Miller encoding were applied to the tag to analyze the error rate performance of the RFID system. As a result of analyzing the performance of the RFID system in Middleton's Class A impulsive noise channel, it was found that the larger the Gaussian noise to impulsive noise power ratio and the impulsive noise index, the more similar the characteristics to the Gaussian noise channel.

• Journal of Internet Computing and Services
• /
• v.14 no.6
• /
• pp.9-18
• /
• 2013

In this paper, we design and implement an intelligent system for finding objects with RFID(Radio Frequency IDentification) tag in which an mobile robot can do. The system we developed is a learning system of artificial neural network that uses RSSI(Received Signal Strength Indicator) value as input and absolute coordination value as target. Although a passive RFID is used for location estimation, we consider an active RFID for expansion of recognition distance. We design the proposed system and construct the environment for indoor location estimation. The designed system is implemented with software and the result related learning is shown at test bed. We show various experiment results with similar environment of real one from earning data generation to real time location estimation. The accuracy of location estimation is verified by simulating the proposed method with allowable error. We prepare local test bed for indoor experiments and build a mobile robot that can find the objects user want.

• 한국정보통신설비학회:학술대회논문집
• /
• 2008.08a
• /
• pp.469-472
• /
• 2008

In this paper, we discuss the recent trends on the passive UHF RFID tag chip design techniques and several important system parameters. We also summarize link budget studies on both conventional and modem UHF RFID communications. The paper highlights the reverse link limited case, which has known to be the minor concern if reader continuous wave (CW) can reach the tag in sufficient level. This makes sense when the tag sensitivity is rather high (over 10-12${\mu}W$); however, since the tag chip fabrication technologies have been developed by time, the tag chip threshold levels are now less-dominant in determining link margin. If the tag limitation can be alleviated, the forward link limited case can be resolved; thus, we rather focus on the path-loss problem. Since the path-losses are still exist in both forward and reverse links, and it can be doubled while CW travels the reader-tag-reader path because forward link and reverse link are on the same distance. Consider if reader receiver sensitivity is very high in the worst case. In this case, weaken tag response (i.e., backscatters) cannot reach the level that reader receiver can process tag data; bit-error rate can be higher. Overall, backscatter levels should be high enough so that reader receiver can correctly function. After discussing link budget, we carried out practical measurements on fading effects between two circularly polarized UHF RFID antennas in a small scale area.

• Journal of Internet Computing and Services
• /
• v.10 no.2
• /
• pp.133-141
• /
• 2009

A tag collision problem occurs when many tags are placed in a interrogation zone in RFID system. A tag collision problem is one of core issues and various protocols have been proposed to solve the collision problems. Generally tree-based protocols generate unique prefixes and identify tags with them as quick as possible. In this paper, we propose the QT-BCS protocol which decreases the identification time by reducing the number of query-response. The QT-BCS protocol makes a prefixes using time slot and bit change sensing unit. This protocol compares the current bit of tags until the current bit is differ from the previous one. When this occurs, all of the bits scanned so far are transferred to slot-0 and slot-1 depending on the first bit value in Reader. Consequently, this method can reduce the number of queries by tracing prefixes easily. Simulation result shows QT-BCS is more efficient in identifying tags than Query Tree and 4-ary Query Tree protocol.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.16 no.2
• /
• pp.81-94
• /
• 2006

This study, in particular, aims to regulate the core techniques of ubiquitous computing, such as the use of an ad hoc network and the smart-tag technique, and to look more closely into RFID Tag's smart-tag-related security service. The study aims to do so because several important technical factors and structures must be taken into account for RFID Tag to be applied in the ubiquitous-computing-related infrastructure, and the security of the tag is considered one of the core technologies. To realize secure ubiquitous computing in the case of the Passive-tag-Performing RF communication, a less costly security service, the technical items needed to carry this out, a security service to be applied to passive tags, and network management techniques are required. Therefore, the passive-tag-based networks as the authentication level is established based on the secure authentication of each tag and the service that the tag delivers in the passive-tag-based networks and as the same service and authentication levels are applied, and the active-tag-based network system proposed herein is not merely a security service against illegal RFID tags by performing a current-location and service registration process after the secure authentication process of the active RFID tag, but is also a secure protocol for single and group services, is proposed in this study.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.19 no.5
• /
• pp.59-69
• /
• 2009

RFID tag search system which is used to find a specific tag has an application such as asset management, supply chain, and this search scheme has been given much attention so far. In RFID tag search system, especially, mobility of the reader is important in order to search tags. Therefore, even though the handheld reader cannot connect with the central database because of unreliable wireless connection or remote location, handheld reader should search the specific tag without help of the central database. In addition, in RFID tag search system, users hold not the tag but the reader, the privacy of users should be considered. Since the signal strength of the reader is stronger than that of the tag, the privacy of the reader holder is very important. Recently, in order to solve these problems, a number of RFID tag search schemes have been proposed. However, since these schemes did not consider the privacy of reader holders, there are serious privacy breaches of reader holders. In this paper, we propose efficient RFID tag search protocol for passive tags. Our proposed scheme preserves the privacy of reader holders.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.20 no.1
• /
• pp.63-72
• /
• 2010

RFID is one of useful identification technology in ubiquitous environments which can be a replacement of bar code. RFID is basically consisted of tag, reader, which is for perception of the tag, and back-end-database for saving the information of tags. Although the usage of mobile readers in cellular phone or PDA increases, related studies are not enough to be secure for practical environments. There are many factors for using mobile leaders, instead of static leaders. In mobile reader environments, before constructing the secure protocol, we must consider these problems: 1) easy to lose the mobile reader 2) hard to keep the connection with back-end-database because of communication obstacle, the limitation of communication range, and so on. To find the solution against those problems, Han et al. suggest RFID mutual authentication protocol without back-end-database environment. However Han et al.'s protocol is able to be traced tag location by using eavesdropping, spoofing, and replay attack. Passive tag based on low cost is required lots of communication unsuitably. Hence, we analyze some vulnerabilities of Han et al.'s protocol and suggest RFID mutual authentication protocol without online back-end-database in aspect of efficiency and security.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.9
• /
• pp.978-984
• /
• 2008

In this paper, we propose a RFID metal tag antenna with a minimum by size of a metal surface to attach. This proposed tag antenna is a patch antenna which is able to stick on metal surface and designed for very slim structure ($119{\times}30{\times}1.6$ mm) antenna that is matched to a chip impedance. This has a loop coupling feeding and consists of a inner radiator and a outer radiator. The outer radiator activates the current to concentrate on the inner radiator regardless of metal size to attach. Also the tag antenna is designed by CST microwave tool and the performance is measured in the anechoic chamber. The optimum antenna has 3.77 % of the matching bandwidth($S_{11}<-10$ dB). The readable range of the tag antenna is about 2.9 m on metal(max. size $700{\times}700$ mm) and 5.5 m in free space according to the measurement results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.12A
• /
• pp.1311-1319
• /
• 2007

This paper presents the VHDL implementation procedure of the passive RFID tag operating in Ultra High Frequency. The operation of the tag compatible with the EPCglobal Class1 Generation2(GEN2) protocol is verified by timing simulation after synthesis and implementation. Due to the reading range with relatively large distance, a passive tag needs digital processor which facilitates faster decoding, encoding and state transition for enhancement of an interrogation rate. In order to satisfy linking time, the pipe-line structure is used, which can minimize latency to serial input data stream. We also propose the sampling strategy to decode the Preamble, the Frame-sync and PIE symbols in reader commands. The simulation results with the fastest data rate and multi tags environment scenario show that the VHDL implemented tag performs faster operation than GEN2 proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.671-674
• /
• 2009

We design a low-power and low-area asynchronous EEPROM of 256 bits used in a passive UHF RFID tag chip. For a low-power solution, we use a supply voltage of 1.8V and design a Dickson charge pump using N-type Schottky diodes with a low-voltage characteristic. And we use an asynchronous interface and a separate I/O method for a low-area solution of the peripheral circuit of the designed EEPROM. And we design a Dickson charge pump using N-type Schottky diodes to reduce an area of DC-DC converter. The layout area of the designed EEPROM of 256 bits with an array of 16 rows and 16 columns using $0.18{\mu}m$ EEPROM process is $311.66{\times}490.59{\mu}m^2$.