• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.17-20
• /
• 2012

In the RFID system, A collision occurs when the multiple tags transmit at the concurrent in slot. Reduce conflicts, in order to maximize the efficiency of the system, the number of tags with the same number of slots are allocated. the number of slots to the next frame determined by the number of contention tags. In this paper, it estimate the number of tags based on the DFSA. Analyzed the performance of the system by the initial set number of tags through simulation.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10c
• /
• pp.712-714
• /
• 2004

최근 유비쿼터스 주요 이슈로 부각되는 Atuo ID나 유비쿼터스 ID(Ubiquitous ID)은 RFID(Radio Frefuency Identification) 태그(Tag)를 사용한 차세대 ID 체계이다. 이들 식별 체계는 해당 물품에 부착된 태그 정보를 RFID 리더(Reader)가 판독하여 이를 바탕으로 식별 작업을 수행함으로써 짧은 시간에 많은 물류 식별 처리가 가능할 수 있는 메커니즘을 가지고 있다. 하지만 리더가 수많은 태그 정보를 한꺼번에 모두 받아드림으로써 발생하는 여러 가지 오류가 발생할 수 있는데, 이를 충돌 문제(collision problem)이라 한다 본 논문은 충돌 문제들의 형태를 분석하고, 이를 개선할 수 있는 방안에 대해 모색, 제안하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.4
• /
• pp.638-644
• /
• 2006

In this paper, a QT_ss protocol is proposed for identifying all the tags within the identification range. The proposed QT_ss protocol revises the QT protocol, which has a memoryless property. In the QT_ss protocol, the tag will send all the bits of their identification codes when the query string matches the first bits of their identification codes. 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_ss protocol outperforms the QT protocol in terms of the number of response bits.

• ETRI Journal
• /
• v.37 no.5
• /
• pp.929-939
• /
• 2015

Ultra-high-frequency radio-frequency identification (UHF RFID) is widely applied in different industries. The Frame Slotted ALOHA in EPC C1G2 suffers severe collisions that limit the efficiency of tag recognition. An efficient full-duplex anti-collision scheme is proposed to reduce the rate of collision by coordinating the transmitting process of CDMA UWB uplink and UHF downlink. The relevant mathematical models are built to analyze the performance of the proposed scheme. Through simulation, some important findings are gained. The maximum number of identified tags in one slot is g/e (g is the number of PN codes and e is Euler's constant) when the number of tags is equal to mg (m is the number of slots). Unlike the Frame Slotted ALOHA, even if the frame size is small and the number of tags is large, there aren't too many collisions if the number of PN codes is large enough. Our approach with 7-bit Gold codes, 15-bit Gold codes, or 31-bit Gold codes operates 1.4 times, 1.7 times, or 3 times faster than the CDMA Slotted ALOHA, respectively, and 14.5 times, 16.2 times, or 18.5 times faster than the EPC C1 G2 system, respectively. More than 2,000 tags can be processed within 300 ms in our approach.

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06a
• /
• pp.185-186
• /
• 2008

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.11A
• /
• pp.1130-1137
• /
• 2006

One of the important performance issues in large-scale RFID systems is to resolve collisions among responses from RFID tags. Considering two do facto anti-collision solutions, namely the binary-tree splitting algorithm and the Slotted-Aloha algorithm, we propose to use multi-packet reception (MPR) capability to enhance the RFID tag reading rate (i.e., throughput). MPR allows an RFID reader to receive multiple reponses transmitted by tags at the same time. We analyze the effect of MPR capability in the above anti-collision algorithms, which is also validated by simulation. The analysis and simulation results show that RFID reader antenna design and signal separation techniques play an important role in improving RFID system performance with MPR capability.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.6B
• /
• pp.561-571
• /
• 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 the Korea Contents Association
• /
• v.7 no.4
• /
• pp.10-19
• /
• 2007

In this paper, Class-1 Air-interface protocols of EPCglobal applied to RFID system in UHF band are analyzed, and the standard anticollision algorithms are realized. Also, the improved anticollision algorithms of the Class-1 Generation-1 and Generation-2 protocol are proposed and the performances of anticollision algorithms are compared. As the results, reduction ratio of total tag recognition time of the improved Generation-1 algorithm is 54.5% for 100 tags and 63.4% for 1000 tags with respect to standard algorithm, respectively. And the reduction ratio of the improved Generation-2 algorithm is 7.9% for 100 tags and 11.7% for 1000 tags. Total recognition times of the improved algorithms are shorter than those of standard algorithms according to increasing the number of tag. Therefore, the improved anticollision algorithm proposed in this paper is the advanced method improving the performance of tag recognition in the RFID system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.6B
• /
• pp.585-594
• /
• 2009

Efficient filtering is an important factor in RFID system performance. Because of huge volume of tag data in future ubiquitous environment, if RFID readers transmit tag data without filtering to upper-layer applications, which results in a significant system performance degradation. In this paper, we provide an efficient filtering technique which operates on RFID air protocol. RFID air protocol filtering between tags and a reader has some advantages over filtering in readers and middleware, because air protocol filtering reduces the volume of filtering work before readers and middleware start filtering. Exploiting the air protocol filtering advantage, we introduce a geometrical algorithm for generating air protocol filters and verify their performance through simulation with analytical time models. Results of dense RFID reader environment show that air protocol filtering algorithms reduce almost a half of the total filtering time when compared to the results of linear search.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.4
• /
• pp.1005-1014
• /
• 2010

When reader collect tags, we found that they tend to get together to specific interface in Multi-Interface Multi-Channel 2.4GHz Active RFID system. To solve this problem, we designed the LP-Combind and AP-Balanced protocol for load distribution between interfaces, then verified its superiority of the performance through the simulation. There are three problems to implement designed protocols in hardware of firmware-level. first, tag selects randomly the channel of reader and reader need the method which can change the channel of tags. second, reader has the synchronization problem between reader and tag. third, reader has problem that MCU of reader have to operate simultaneously dual interface. To slove this problems, we designed the message and implemented method for tag channel change and the protocol in order to adjust synchronization between reader and tag, Therefore, we compared and analyzed the performance of protocols by experiment. If LP windows size is same, the performance of LP-Combined protocol and AP-Balanced protocol which lower collision probability by its load distribution is more outstanding than single interface protocol performance.