• The KIPS Transactions:PartA
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• v.15A no.3
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• pp.155-160
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• 2008

RFID technology has been gradually expanding its application. One of the important performance issues in RFID systems is to resolve the collision among multi-tags identification on restricted area. We consider a new anti-collision scheme based on Class Identification algorithm using Depth-First scheme. We evaluate how much performance can be improved by Class identification algorithm in the cases of Query-tree more then 17% identification rate and 150% performance.

• International Journal of Contents
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• v.2 no.1
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• pp.34-38
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• 2006

In this paper, an overview of anti-collision algorithm for RFID system of a standard EPC Class1 protocol is presented, and the binslotted dynamic search algorithm (BDS) based upon the slotted ALOHA and binary tree procedure is proposed and analyzed. Also, the performance is evaluated as comparing the BDS algorithm with the standard bin-slotted algorithm (BSA) through the simulation program. The performance of the proposed BDS algorithm is improved by dynamically identifying the collided-bit position and the collided bins stored in the stack of the reader. As the results, the number of request command that a reader send to tags in the reader s interrogation zone and the total recognition time are decreased to 59% as compared with BSA algorithm. Therefore, the tag identification performance is fairly improved by resolving a collision problem using the proposed BDS algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1686-1697
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• 2011

This paper aims to build up a RFID-automated cargo movement system in an air-cargo warehouse. In our research, we do the spectrum measurements compliant with the RFID frequency bands to observe the interferences from legacy systems in the air-cargo warehouse. To overcome the dense-reader mode (DRM) problem, we apply three novel approaches, which are the periodic transmit of a reader, the Visible RFID reader & tag, and the sensor-based RFID system. Moreover, for the tag collision issue, we implement the Adaptive Adjustable Framed Q(AAFQ) algorithm, and the demonstration on RFID tag anti-collision algorithms show that the AAFQ algorithm has highly desirable tag anti-collision performance compared to any other commercially available solutions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.1
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• pp.98-104
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• 2012

In RFID Systems, collisions between multiple tags frequently arise due to simultaneous responses from multiple tags using the same communication channel. Most of anti-collision protocols such as QT regard these collisions as useless cycles, thereby wasting the channel bandwidth. In this paper, we propose a new anti-collision protocol, namely ASP (Adjustable splitting by patterns of collisions) protocol that utilizes the patterns collision for noticeable performance enhancements.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.747-754
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• 2013

This paper proposed a new transponder detection method to reduce tag recognition time and simplify anti-collision process in RFID systems. In conventional systems, a transponder in detectable area is passively recognized by responding to a reader command. In addition, if there are multiple tags in the area, a collision between tags occurs by responding at the same time to a command and anti-collision process begins. In the proposed method, tags are actively recognized without any command from a reader which results to reducing a tag recognition time and simplifying anti-collision process. To compare transponder recognition time, the process of transponder recognition in conventional systems is analysed. A circuit to detect transponder directly is developed and antenna voltage variation of a reader in the appearance of multiple transponders is analysed for the implementation of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1013-1022
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• 2012

Tag collection is one of the major concerns in radio frequency identification(RFID) system. All tags in RFID reader's transmission range send response message back to the reader in response to collection request message on the given rf channel. When multiple tags respond simultaneously, tag-collision may occur. Tag-collision problem is one of the most important issues in active RFID performance. To mitigate this problem, frame slotted ALOHA(FSA) anti-collision protocol is widely used in active RFID system. Several studies show that the maximum system efficiency of FSA anti-collision protocol is 36.8%. In this paper, we propose an efficient slotted CSMA/CA protocol to improve tag collection performance. We compare our protocol to the FSA anti-collision protocol. For the experiment, an 433MHz active RFID system is implemented, which is composed of an RFID reader and multiple tags. We evaluated the tag collection performance using one RFID reader and 40 tags in the real test bed. The experimental result shows that proposed protocol improves the tag collection time, round and collision probability by 18%, 37.4% and 77.8%, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.794-804
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• 2008

In this paper, we analyze the performance of probabilistic slotted anti-collision algorithm used in EPCglobal Class-1 Generation-2 (Gen2). To increase throughput and system efficiency, and to decrease tag identification time and collision ratio, we propose new tag anti-collision algorithms, which are FAFQ (fired adjustable flamed Q) algorithm and AAFQ (adaptive adjustable framed Q) algorithm, by using QueryAdjust command. We also propose grouping method based on Gen2 to improve the efficiency of tag identification. The simulation results show that all the proposed algorithms outperform Q algorithm, and AAFQ algorithm performs the best. That is, AAFQ has an increment of 5% of system efficiency and a decrement of 4.5% of collision ratio. For FAFQ and AAFQ algorithm, the performance of grouping method is similar to that of ungrouping method. However, for Q algorithm in Gen2, grouping method can increase throughput and system efficiency, and decrease tag identification time and collision ratio compared with ungrouping method.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.46-53
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• 2008

This paper presents a 13.56 MHz RFID reader that can be used as a door-lock system for smart home security. The RFID reader consists of a transmitter, a receiver, and a data processing block. To verify the operation of the developed RFID reader, we present both a PSPICE simulation for transmitter/receiver and a digital simulation for data processing block. In particular, a CRC block for error detection of received data and a Manchester decoding block for position detection of collided data are designed using VHDL. In addition, we applied a binary search algorithm for multi-tag anti-collision. The anti-collision procedure is carried out by PIC microcontroller on software. The experimental results show that the developed reader can provide the right multi-tag recognition.

• 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.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.85-94
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• 2008

When an RFID reader uses the same frequency or adjacent frequency with neighbor readers, the interference might occur. These interferences cause the RFID reader collision and errors during tag recognition. Therefore, the international standard for RFID and some papers proposed the methods to reduce the reader collision. The reader interference is closely related to the distance between the readers haying interference and used frequency band. In the previous RFID reader anti-collision algorithms, the location of readers inducing interference which is closely related to interference of readers is not considered. Only the reader collision is tried to reduce through frequency transfer after collisions occur or modification of frame size in relation to collision probability based a TDM(Time Division Multiplex). In this paper, the genetic algorithm using two-dimensional chromosome which reflect readers' location is proposed to prevent reader collision effectively. By executing evolutionary operation with two-dimensional chromosome, the location information having influence on reader interference can be used. The repair operation in the proposed algorithm makes all reader stably recognize their tags.