Fast and reliable estimation schemes in RFID systems

Radio Frequency IDentification (RFID) technology successfully integrates radio transmitter and receiver, small size memory space and control circuitry to remotely store and retrieve data via wireless RF transceiver. As low-cost RFID tag can be massively manufactured by semiconductor industry, new applications associated with RFID technology have emerged rapidly such as inventory tracking, book storage and management, and airport baggage handling. Generally an RFID system is composed of many RFID tags (or tagged objects), at least one RFID reader, and one backend application system with database. An RFID tag gains its operation energy from query signals that are radio waves transmitted by RFID reader. Once a tag responds the query with its stored information to RFID reader, usually a unique identity number or string, the RFID system can recognize the tag carrier and perform required business logic operation. As RFID technique is widely used in supply chain management, the corresponding RFID application systems are expected to process and manage large amount of tagged objects at a predefined period of time regularly. Therefore, for large-scaled RFID applications, tag reading throughput is very critical since it will affect the total data processing time. To measure tag reading throughput of a RFID system, two performance criteria are usually adopted: tag reading delay and reader energy consumption [5]. As RFID reader and tag always communicate over a shared wireless channel, it is very easy to have signal collisions during a normal tag identification process when multiple tags exist in reader’s interrogation area. Signal collision results in query or data retransmission and eventually increases communication overhead and time delay of tag identification. Hence, an efficient tag collision arbitration mechanism is very important and critical for RFID systems to achieve effective performance. Existing RFID tag identification schemes can be classified into aloha-based solutions [3, 10, 12-13, 16, 21, 23-24] and tree-based solutions [1, 2, 4, 6-9, 14-15, 17-20, 22]. In aloha-based schemes, a reader estimates the number of tags in its interrogation area and broadcasts the total number of timeslots to each tag. Then each RFID tag randomly selects its own timeslot to transmit its ID without knowing which timeslots have been selected by other tags. By distributing tag responses to distinct timeslots instead of getting all tag responses at the same time, aloha-based schemes effectively reduce the probability of signal collision. However, aloha-based schemes have tag starvation problem in which certain tags may not

Radio Frequency IDentification (RFID) systems have rich applications in daily life. A crucial problem in RFID systems is to estimate the cardinality of RFID tags. Most exiting probabilistic RFID cardinality estimation algorithms utilize a certain pattern hidden in the response vector formed by the tag responses to make estimators. In this paper, we argue that finding the patterns is actually not necessary! In this paper, we present a novel approach to RFID cardinality estimation by making the full use of the whole response vector. We characterize the critical relationship between the number of RFID tags and the specific distribution of the bits in the response vector. In this paper, we consider two kinds of responses, i.e., empty / non-empty responses and empty / singleton / collision responses. To cater for RFID systems with a very large number of tags, we also generalize our estimation approach to handle geometrically distributed response vectors. Both rigid theoretical analysis and extensive simulations have been conducted and the conclusive results demonstrate that our approach is more accurate than existing state-of-the-art RFID estimation approaches.

In this paper, we focus on configuring a low cost RFID (Radio Frequency IDentification) system with less RFID readers and low density RFID tag textiles for stable and accurate self-localization for an omni-directional mobile robot. An RFID system using multiple RFID readers and high density RFID tags has already been applied to an indoor mobile robot self-localization. However, the system production cost is relatively high. To reduce the production cost of the system while maintaining the self-localization performance, we redesign two new RFID systems configured with 20 RFID readers and 5 RFID readers enlarging the size of an RFID reader antenna. Particularly, a new likelihood function of the tag detection with the redesigned large size RFID reader antenna is proposed for Monte Carlo Localization (MCL). Furthermore, we come up with a novel arrangement of RFID tags installed in a hexagon pattern. The new arrangement of ID tags enables both low cost ID tag installation and high performance of self-localization. We examine the performances of robot self-localization with less RFID readers and lower density RFID tags installed on the floor based on MCL(Monte Carlo localization). The simulation demonstrates the validity of our proposed configuration of the RFID based self-localization.

The most important research in the world in these days, research that looking at the internet of thing's (IoT) topics and their applications. Most of these applications depend on RFID system, which includes RFID readers and tags. The important issues in RFID system or network are how we can reduce anti-collision between readers to identify and read tags data. In these paper, we suggest an Improved anti-collision protocol, which can be used to connect RFID readers with RFID tags and reduce the number of RFID tag's collisions. The simulation shows that an Improved Class-1 Generation 2 algorithm is better than Slotted Aloha, Class-1 Generation-2 (Number of Tags Known), Class-1 Generation-2 (Number of Tags Unknown) algorithms.

In recent years, numerous authentication protocols for radio frequency identification (RFID) systems have been proposed to protect privacy. Due to the hardware resource limitation on RFID tags, the majority of these protocols are based on symmetric-key ciphers. However, most of them lack scalability at the reader side as they require a linear or logarithmic search proportional to the number of tags in the system in order to authenticate a tag. Recently proposed scalable protocols require a constant-time search and utilize hash look-up tables. However, the storage requirement of the hash-table in these protocols is very large, therefore not practical. Moreover, previous proposals do not support dynamic resizing where the number of tags changes during the life time of the RFID system. In this paper, a new Re-Hash technique is presented to reduce the hash-table storage in constant-time authentication protocols. To the best of our knowledge, it offers the smallest storage cost in comparison to previous proposals. The Re-Hash technique is also further adapted to support the dynamic scalability for RFID systems.

The RFID (Radio Frequency IDentification) system is paid attention to as a new identification source that achieves a ubiquitous environment. Each RFID tag has the unique ID, and is attached to some object. A user reads the unique ID of a RFID tag with RFID readers and obtains the information on the object. One of the most important technologies that use the RFID system is the position estimation of RFID tags. The position estimation means to estimates the location of the object with the RFID tag. It can be very useful to acquire the location information of RFID tag. If a user can understand the position of the RFID tag, the position estimation can be applied to a navigation system for walkers. In this paper, we propose a new method named as Swift Communication Range Recognition (S-CRR) method as an extended improvement of the previous CRR method on the estimation delay. In this method, the position of RFID tag is estimated by selecting the communication area model which corresponds to those boundary angles. We carry out the performance evaluation by the experiments of RFID system and show the effectiveness of S-CRR for position estimation.

This paper discusses the separation of signals in multiple-tag radio frequency identification (RFID) systems. First, a model for the RFID system in both single and multiple tag environments is presented. Then, an analytical constant modulus algorithm (ACMA) for the blind source separation problem is reviewed. An alternative approach to the traditional ACMA using joint diagonalization is considered. Finally, both the ACMAs are applied to the multiple-tag RFID environment and performance of the system is studied. Simulations are carried out for 4-QAM and 16-QAM modulations at tag and analyses of the simulation results reveal that the ACMA with joint diagonalization takes lesser CPU time to execute compared to the traditional ACMA, but with higher average modulus error (AME). The variation of system performance with the number of measurements, SNR (signal to noise ratio), number of tags and number of antennas at the reader is also studied. Based on these, some design guidelines are presented. Interestingly both the ACMA algorithms work for the 16-QAM case and yield trends similar to those of 8-PSK and 4-QAM.

This study presents a distributed antenna structure operating at a frequency of 915 MHz to increase the tag identification sensitivity for passive radio frequency identification (RFID) systems. An experimental RFID system is set up to demonstrate the proposed structure. Experimental results indicate that using four distributed patch antennae can improve tag identification in passive RFID systems.

Anti-collision protocols for radio frequency identification (RFID) tag reading processes are designed to reduce the frequency of collisions and to quickly identify all RFID tags during a tag reading collision process. In this paper, we propose a tree-based anti-collision algorithm using a bit change sensing unit (TABCS) based on the bi-slotted collision tracking tree algorithm (BSCTTA) algorithm. The proposed algorithm can identify bits returned from tags using a bit change sensing unit, even in the event of multiple collisions. The algorithm rapidly generates a unique prefix that identifies each tag and reduces the total number of bits. Simulation results show that the proposed algorithm reduces the cost of tag identification compared with legacy algorithms, such as the query tree algorithm with a bit change sensing unit (QT-BCS) or BSCTTA. When the number of tags is 10000, the average number of tags identified per second in TABCS is improved by 4%, and TABCS requires 28% fewer steps to successfully identify one tag compared to BSCTTA.

Dynamic time slot frame ALOHA algorithm is currently the most widely used anti-collision technology in radio frequency identification (RFID) system. Based on the traditional ALOHA algorithm analysis, we propose an improved algorithm. The algorithm is based on a packet adaptive ALOHA anti-collision algorithm (PA-ALOHA). First, the reader scans and counts the time slots which are randomly selected by tags, and sends it to each tag. The tags, then, adjust accordingly the time slot that enable the reader to skip idle slots and collision slots, adaptively allocate effective slots, and then identify tags rapidly. The algorithm employs packet and dynamically adjusts the frame size and other strategies, in order to reduce the time of processing slots. Simulation results show that PA-ALOHA algorithm improves the efficiency and stability of the system and reduce the transmission overhead. Especially, when the number of tags is over 1000, the algorithm throughput is still above 70% that has been greatly improved system efficiency than conventional ALOHA algorithm.

최근 RFID (Radio Frequency Identification) 기술이 다양한 분야에서 관심을 받고 사용됨으로써 RFID 리더 제조회사들은 다양한 종류의 리더를 생산하고 있다. 현재 RFID 기술에서 RFID 태그 데이터 전송 형태는 EPCglobal에서 제공하는 표준 규약을 따르고 있지만 각 리더 별 리더 연결 및 통신 방법은 회사별로 다른 실정이다. RFID 리더를 사용하던 중 타 회사나 리더 인터페이스가 다른 RFID 리더로 변경하거나 새롭게 추가해야 하는 경우에는 사용자가 직접 RFID 미들웨어 개발단계로 돌아가 미들웨어의 내부 요소를 변경해야 하는 상황이 발생한다. 본 논문에서는 RFID 기술을 사용 시, 특히 여러 회사 또는 표준화되지 않은 인터페이스를 제공하는 RFID 리더를 사용하는 경우에 RFID 애플리케이션과 독립적으로 리더를 관리할 수 있는 리더 프레임워크를 개발하고자 한다. 본 리더 프레임워크는 RFID 애플리케이션과 RFID 리더 사이에 존재하여 RFID 리더 투명성을 제공한다. 본 리더 프레임워크는 현재 작동되고 있는 리더를 모니터링 할 수 있고, 리더의 속성을 확인할 수 있으며 RFID 태그 이벤트 정보, 시스템 로그 정보를 확인할 수 있다. 본 리더 프레임워크를 통해 수십 대의 이기종의 RFID 리더 상태를 용이하게 관리할 수 있게되며 애플리케이션 상의 코드 수정 없이 리더의 추가, 삭제가 가능하게 된다. More recently, variety RFID (Radio Frequency Identification) readers are produced by RFID equipment manufactures. Although a transmission standard instituted by EPCglobal is proposed for data transmission between the RFID readers and tags, other RFID reader protocols and the communication connection methods are be in use in other RFID companies. To replace or add the RFID readers of an RFID system, the developers should make changes to the core of the application and/or middleware. In this paper, we propose an RFID reader framework which can manage RFID readers without having to make changes the code of the application in environment with the growing number of heterogeneous RFID readers.This framework that sits on the layer between the RFID readers and the applications provides transparency to the RFID readers. Additionally, it can be used for monitoring the state and the property of all connected RFID, and for recording the RFID tag event logs and system logs. By using this framework, heterogeneous readers can be replaced and added without writing additional code in the applications. Consequently the readers can be easily managed and controlled by the RFID system administrator.

Private companies and government have decided to provide Radio Frequency Identification (RFID) systems in places of free access to the population. However, as a result of such exposition, these systems become vulnerable to Denial of Service (DoS) attacks that can cause unavailability in the services. Furthermore, another complicating factor in that context regards the equipment or devices used on RFID systems, since they operate in frequency bands reserved for secondary communication systems, and consequently they have too few computational resources to deal with malicious electromagnetic interferences. Therefore, in this paper an Intrusion Detection System (IDS) is proposed to identify the occurrence of the malicious behavior and to notify the system operator about one specific type of electromagnetic interference in RFID systems - the Jamming attack. The obtained results of the system show the jamming attacks are detected prior of having a significant impact on the communication between the RFID reader and the tag - i.e., the jamming attack was detected even with insufficient power to impact on communication.

Every year researchers and engineers are finding new and useful applications for Radio Frequency Identification (RFID) systems (Finkenzeller, 2003). Because of the growing use of RFID systems, many different areas of research have also been developed to improve the performance of such systems. A few of these areas of research include novel antenna designs (Rao et at., 2005; Calabrese & Marrocco, 2008; Amin et al. 2009), analysis on the backscatter properties of RFID tags (Yen et al., 2007; Feng et al., 2006), mutual coupling between RFID tags (Li et al., 2008; Owen et al., 2009) and the deployment of RFID systems to complex and extreme environments (Qing & Chen, 2007; Sanford, 2008). There are many aspects to each area of research in RFID. A major topic in many of these areas involves research on the antenna design for RFID tags. This chapter will focus on the design of efficient space-filling antennas for passive UHF RFID tags. First, an introduction to RFID systems is presented. This is done by describing the major components in a RFID system and how they communicate. Then, the particular backscattering properties of a passive tag are described from a unique electric field integral equation standpoint and from an overall systems perspective (i.e., using the Friis transmission equation). This discussion will then be followed by a section describing a practical design process of various space-filling antennas for passive tags. Finally, a summary of future work and a conclusion about the chapter is presented.

In Radio Frequency Identification (RFID) systems, the reader identifies tags through communication over a shared wireless channel. When multiple tags transmit their IDs simultaneously, their signals collide, prolonging the identification delay. Currently, there are many anti-collision protocols and one important approach of them is Query Tree (QT) protocol. In general applications, an RFID system has a database, which owns all tag IDs that possibly appear. Thus, considering the case that the RFID system has this knowledge, we propose a Query Tree with Knowledge-based Splitting (QTKS) protocol. From the known database, QTKS constructs a knowledge-based query tree, which stores queries that can more quickly identify appearing tags, which belong to possible tags in the database. The simulation results show that QTKS significantly outperforms related previous work. Compared to QT, QTKS can reduce its identification delay by 52%.

Radio Frequency Identification (RFID) technology has been used in numerous applications, e.g., supply chain management and inventory control. This paper focuses on the practically important problem of the rapid estimation of the number of tags in large‐scale RFID systems with multiple readers and multicategory RFID tags. RFID readers are often static and have to be deployed strategically after careful planning to cover the entire monitoring area, but reader‐to‐reader collision (R2Rc) remains a problem. R2Rc decreases the reliability of the estimation of the tag population size, because it results in the failure of communication between the reader and tags. In this paper, we propose a coloring graph‐based estimation scheme (CGE), which is the first estimation framework designed for multireader and multicategory RFID systems to determine the distribution of tags in different categories. CGE allows for the use of any estimation protocol to determine the number of tags, prevents R2Rc, and results in higher time efficiency and less power‐consumption than the classic scheduling method DCS.