• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.736-752
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• 2010

We propose a novel collision-avoidance algorithm for the active type RFID regarding an indoor tracking system. Several well-known collision avoidance algorithms are analyzed considering the adequacy for the indoor tracking system. We prove the superiority of the slotted ALOHA in comparison with CSMA for short and fixed length packets like an ID message in RFID. Observed results show that they are not applicable for active type RFID in terms of energy efficiency. Putting these all together, we propose a dedicated collision avoidance algorithm considering the unique features of the indoor tracking system. The proposed method includes a scheduled tag access period (STAP) as well as a random tag access period (RTAP) to address both of the static and dynamic characteristics of the system. The system parameters are determined through a quantitative analysis of the throughput and energy efficiency. Especially, some mathematical techniques have been deployed to obtain the optimal slot count for RTAP. Finally, simulation results are provided to illustrate the performance of the proposed method with variations of the parameters.

• Journal of Internet Computing and Services
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• v.14 no.4
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• pp.25-33
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• 2013

The procedure of the arbitration which is the tag collision is essential because the multiple tags response simultaneously in the same frequency to the request of the Reader. This procedure is known as Anti-collision and it is a key technology in the RFID system. In this paper, we propose the 4-Bit Pattern Slot Allocation(4-BPSA) algorithm for the high-speed identification of the multiple tags. The proposed algorithm is based on the tree algorithm using the time slot and identify the tag quickly and efficiently through accurate prediction using the a slot as a 4-bit pattern according to the slot allocation scheme. Through mathematical performance analysis, We proved that the 4-BPSA is an O(n) algorithm by analyzing the worst-case time complexity and the performance of the 4-BPSA is improved compared to existing algorithms. In addition, we verified that the 4-BPSA is performed the average 0.7 times the query per the Tag through MATLAB simulation experiments with performance evaluation of the algorithm and the 4-BPSA ensure stable performance regardless of the number of the tags.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.35-46
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• 2006

When an RFID reader attempts to read the tags, interference might occur if the neighboring readers also attempt to communicate with the same tag at the same time or the neighboring readers use the same frequency simultaneously. These interferences cause the RFID reader collision. When the RFID reader collision occurs, either the command from the reader cannot be transmitted to the tags or the response of the tags cannot receive to the reader correctly, Therefore, the international standard for RFID and some papers proposed the methods to reduce the reader collision. Among those, Colorwave and Enhanced Colorwave is the reader anti-collision algorithm using the frame slotted ALOHA based a TDM(Time Division Multiplex) and are able to reduce the reader collision because theses change the frame size according to a collision probability. However, these can generate the reader collisions or interrupt the tag reading of other readers because the reader that collides with another reader randomly chooses a new slot in the frame. In this paper, we propose a new RFID reader anti-collision algorithm that each reader monitors the slots in the frame and chooses the slot having the minimum occupation probability when the reader collision occurs. Then we analyze the performance of the proposed algorithm using simulation tool.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.6
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• pp.435-445
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• 2013

One of the most challenging issues in radio frequency identification (RFID) and near field communications (NFC) is to correctly and quickly recognize a number of tag IDs in the reader's field. Unlike the probabilistic anti-collision schemes, a query tree based protocol guarantees to identify all the tags, where the distribution of tag IDs is assumed to be uniform. However, in real implements, the prefix of tag ID is uniquely assigned by the EPCglobal and the remaining part is sequentially given by a company or manufacturer. In this paper, we propose an enhanced M-ary query tree protocol (EMQT), which effectively reduces unnecessary query-response cycles between similar tag IDs using m-bit arbitration and tag expectation. The theoretical analysis and simulation results show that the EMQT significantly outperforms other schemes in terms of identification time, identification efficiency and communications overhead.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.483-492
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• 2007

In this paper, we propose a new hybrid approach based on query tree protocol to arbitrate tag collisions in RFID systems. The hybrid query tree protocol that combines a tree based query protocol with a slotted backoff mechanism. The proposed protocol decreases the average identification delay by reducing collisions and idle time. To reduce collisions, we use a 4-ary query tree instead of a binary query tree. To reduce idle time, we introduce a slotted backoff mechanism to reduce the number of unnecessary Query commands. Simulation and numerical analysis reveal that the proposed protocol achieves lower identification delay than existing tag collision arbitration protocols.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.6-12
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• 2004

Identification rate and time are very important in the identification of RFID tag, and the tag requires simple structure to use economically large quantity of tags. These factors make the MAC protocols of wired or wireless network environment result in different requirements. In the paper, we propose a method to apply spread spectrum scheme using orthogonal channel via Walsh function as the anti-collision communication system for the purpose of non-collision identification of multiple tags, and consider its property. The proposed system use two step identification. in the first step, collision is resolved via constructing to respond after specific delay time based on unique n, and conventional polling scheme follows in the second step.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1517-1530
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• 2017

Traditional anti-collision algorithms determine slot size of initial frame based on the information of number of collision slots, idle slots, and success slots. Since there is no information about collision at the beginning of tag information collection, traditional anti-collision algorithms can not determine the initial frame size. Considering that performance of anti-collision algorithm is very sensitive to initial slot size traditional anti-collision algorithms need some improvements. In this study two methods are proposed to determine slot size of initial frame efficiently, through which we can improve the performance of dynamic frame slotted aloha algorithm. To verify the performance of proposed algorithms, 2.4GHz RFID system is used. Throughput and delay time are derived through simulation, which is developed using JAVA. We have seen that proposed algorithm improves throughput by 9.6% and delay time by 9.8%.

• Journal of Multimedia Information System
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• v.7 no.2
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• pp.137-140
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• 2020

In this paper, we propose a simplified tag collection algorithm to improve the performance of ISO / IEC 18000-7, the standard of active RFID systems. In the proposed algorithm, the collection command is modified to include the result of the listening period response from the previous round. The tag, which has received the collection command, checks whether the slot to which it has responded is collided, transmits additional data to its data slot without a point-to-point read command and sleep command, and transitions to the sleep mode. The collection round in the standard consists of a series of collection commands, collection responses, read commands, read responses, and sleep commands. On the other hand, in the proposed tag collection algorithm, one collection round consists only of a collection command and a collection response. As a result of performance analysis, it can be seen that the proposed technique shows superior performance compared to the standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.360-367
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• 2006

In this paper, we designed a digital codec of an RFID tag for EPC global generation 2 class 1. There are a large number of studies on RRD standard and anti-collision algorithm but few studies on the design of digital parts of the RFID tag itself. For this reason, we studied and designed the digital codec hardware for EPC global generation 2 class 1 tag. The purpose of this paper is not to improve former studies but to present the hardware architecture, an estimation of hardware size and power consumption of digital part of the RFID tag. Results are synthesized using Synopsys with a 0.35um standard cell library. The hardware size is estimated to be 111640 equivalent inverters and dynamic power is estimated to be 10.4uW. It can be improved through full-custom design, but we designed using a standard cell library because it is faster and more efficient in the verification and the estimation of the design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.38-44
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• 2012

In this paper, we first formulate an optimal design problem for RFID tag identification processes and then propose a simplified estimation method for determining optimal frame sizes and termination time under an independence assumption. Through computer simulations we show that the proposed scheme outperforms Vogt's scheme in terms of identification delay.