• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.469-472
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• 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 the Korea Society of Computer and Information
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• v.18 no.11
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• pp.87-97
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• 2013

In the RFID system, multiple tags respond in the process of identifying multiple tags in the reader's interrogation zone, resulting in collisions. Tag collision occurs when two or more tags respond to one reader, so that the reader cannot identify any tags. These collisions make it hard for the reader to identify all tags within the interrogation zone and delays the identifying time. In some cases, the reader cannot identify any tags. The reader needs the anti-collision algorithm which can quickly identify all the tags in the interrogation zone. The proposed algorithm efficiently divides tag groups through an efficient separation to respond, preventing collisions. Moreover, the proposed algorithm identifies tags without checking all the bits in the tags. The prediction with efficient separation reduces the number of the requests from the reader.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.6 s.312
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• pp.61-67
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• 2006

In this paper it was introduced that embedded RFID Reader /Writer system including PXA255 ARM chip which enables the Tag signal to be used by data and video processing via IEEE 802.11 communication protocol. Embedded RFID R/W middle ware was developed which transmit the searched result in the data base using the received Tag signal via IEEE 802.11 communication protocol. Developed embedded RFID R/W system was composed of three parts - PXA255 ARM chid (Core Part) 13.56 MHz RFID Reader /Writer, wireless LAN for data communication with server and TFT-LCD terminal. Once this system receives the Tag signal through the serial port, it transmits the data through the wireless LAN to the server and it displays the received image data which was processed by the server onto the TFT-LCD screen. Embedded RFID R/W Middle ware transmits the received Tag signal from RFID R/W to the embedded system, which activates the socket program to connect to the window server via IEEE 802.11 communication protocol and transmits the Tag signal. Window server program searches the Database using this Tag information and displays the result on to the TFT-LCD window in the embedded system via IEEE 802.11 protocol.

• Journal of Digital Convergence
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• v.7 no.4
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• pp.149-158
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• 2009

Although current RFID technologies can provide wide advantages in food industry area, most food companies do not consider willingly adopting this technology yet. This paper will present how the effective implementation of RFID systems in food industry could be realized. To Measure the importance of RFID systems, this study utilized the BMT(Bench Mark Test) methodology using RFID systems that were composed of tag and reader. After conducting this study, it suggests the effective tag attachment methods on the objects. The results are shown that the excellent tag product is a RFCamp and a fixed reader of Thingmagic Mercury 4 is the best product. Also, a portable reader of Motorola MC9090-RFID is recommend to the highest product. Therefore, this test is useful for selecting the best RFID systems to the food industry area. In addition, this study displays the effective tag attachment method to each bottle that was used to the experiments in food industry. Therefore, this study is contributed to the not only importance in the government IT areas as a growth engine but also the importance for consumer as a right for the knowledge about the food quality.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.579-582
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• 2008

Since there are a lot of researches regarding RFID nowadays, the idea of RFID Middleware has great popular appeal to improve the efficiency of most use the data from RFID Readers. Even though, there are many RFID Middleware products and solutions in the developing processing, there are unsatisfied researches to manage RFID equipments effectively. In this paper, highly recommends a solution to support various RFID Readers from ALE-complient RFID Middleware in an efficient path of constructing Middleware Connection Information and data protocol form various RFID Readers as an ontology metadata. Therefore, not only reuses of RFID Reader Ontology, but also, by adding the ontology regarding additional RFID Reader and protocol data as a Middleware in a near future, it is able to extend to be treated easily.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.4
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• pp.53-63
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• 2008

Reader collision may occur when neighboring RFID readers use the same channel at the same time. Especially when the readers are operated in dense mode, even though many channels are available, because of frequent reader collisions we can not guarantee the performance of RFID readers. Conventional solutions such as FH(Frequency Hopping) or LBT(Listen Before Talk) are not effective in this situation because they can not schedule RFID readers effectively when RFID readers are operated in multi-channel, dense reader mode, In this paper, we propose a new RFID reader anti-collision algorithm which employs LBT, random backoff before channel access, and probabilistic channel hopping at the same time. While LBT and Random backoff before channel access reduces collisions between competing readers, probabilistic channel hopping increases channel utilization by adaptively changing the hopping probability by reflecting the reader density and utilization. Simulation results shows that our algorithm outperforms conventional methods.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.231-234
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• 2005

In this paper, Dual-polarized Tx/Rx antenna for RFID reader is designed and fabricated to apply to RFID reader. Each feeding network of Tx/Rx is designed to improve the port-isolation and cross-polarization, and sequential rotation feeding scheme has been applied to increase of axial ratio bandwidth. Measured results show that 2.35dBi of antenna gain in 900MHz$\sim$928MHz, 150MHz of 3dB axial ratio bandwidth, -38dB$\sim$-40dB of port-isolation, and -30dB$\sim$-40dB of cross-polarization.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.25-33
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• 2005

We propose a method to protect the tag's information from illegal reader in RFID system. In this method, a special tag called ownership tag makes intentionally collisions during singulation. By the forced collision of an ownership tag a reader can obtain the information of ordinary tags. Whereas a reader can not find my information on tag's ID without the ownership tag.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3859-3865
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• 2010

Modeling a virtual reader and tags, the emulator system is realized by using a commercial signal generation device to make signal, a data collection equipment, and DSP board. By using a Virtual UHF RFID (860 ~ 960 [MHz]) reader/tags module, a developed RFID reader, protocol of tag, and properties of RF support to provide the way how to verify the suitability to international standards (ISO 18000-6 Type C, EPCglobal C1G2). In this paper, to implement a proposed model reader and tag model, Visual DSP is applied by using DSP board, composing the system's signal generators, signal analyzers and performance verification, the target readers or tags, RFID emulator control computesr and control programs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.752-760
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• 2010

This paper investigates the performance of EPCglobal Generation-2(Gen-2) radio frequency identification(RFID) protocol under reader-to-reader interfering environments. We establish a modified discrete-time Markov chain(DTMC) model for the Gen-2 and accordingly obtain quantitative results of query success rate(QSR) and tag identification speed (TIS). Extensive simulations validate our theoretical analysis and demonstrate that the number of tags over 100 has little impact on the performance. TIS linearly decreases by 10 tags/sec/reader as the number of interfering readers increases. Our model for Gen-2 protocol is also useful to study the performance of other RFID protocols.