UHF射频读写器的设计

为满足市场需求,提高读写器的读写效率,提出了一种超高频读写器的设计方案,介绍了读写器的系统硬件结构,在此基础上阐述了RFID读写器的软件设计流程以及防冲撞算法的实现。相对于采用传统随机碰撞算法的读写器,此读写器适用于超高频段,能够在多标签环境下顺利读取标签,防冲撞算法性能具有一定的提高。     

An efficient resource allocation scheme in a dense RFID network based on cellular learning automata

Radio‐frequency identification (RFID) is a wireless communication technology. Radio frequencies can cause interference in a dense RFID system, thus decreasing efficiency. In recent years, many protocols have been proposed to reduce reader collisions based on multiple‐access techniques. The main weakness of Time Division Multiple Access (TDMA)‐based schemes is the random selection of resources. Additionally, they do not consider the distance between the interfering readers. Therefore, the likelihood of interference in an RFID system will be increased. To address this problem, we propose a new scheme for allocating resources to readers using a learning technique. The proposed scheme takes into account the distance between interfering readers, and these readers acquire the necessary knowledge to select new resources based on the results of the previous selection of neighboring readers using cellular learning automata. This approach leads to reduced interference in an RFID system. The proposed scheme is fully distributed and operates without hardware redundancy. In this scheme, the readers select new resources without exchanging information with each other. The simulation results show that the percentage of kicked readers decreased by more than 20%, and the proposed scheme also provides higher throughput than do state‐of‐the‐art schemes for dense reader environments and leads to further recognition of tags.     

UHF射频读写器的设计

为满足市场需求,提高读写器的读写效率,提出了一种超高频读写器的设计方案,介绍了读写器的系统硬件结构,在此基础上阐述了RFID读写器的软件设计流程以及防冲撞算法的实现。相对于采用传统随机碰撞算法的读写器,此读写器适用于超高频段,能够在多标签环境下顺利读取标签,防冲撞算法性能具有一定的提高。     

Energy-Aware Tag Anticollision Protocols for RFID Systems

Energy consumption of portable RFID readers is becoming an important issue as applications of RFID systems pervade many aspects of our lives. Surprisingly, however, these systems are not energy-aware with the focus till date being on reducing the time to read all tags by the reader. In this work, we consider the problem of tag arbitration in RFID systems with the aim of designing energy-aware anticollision protocols. We explore the effectiveness of using multiple time slots per node of a binary search tree through three anticollision protocols. We further develop an analytical framework to predict the performance of our protocols and enable protocol parameter selection. We demonstrate that all three protocols provide significant energy savings both at the reader and tags (if they are active tags) compared to the existing Query Tree protocol, while sharing the deterministic property of the latter. Further, we show that our protocols provide similar benefits even with correlated tag IDs.     

An efficient RFID anticollision algorithm using early adjustment of frame length

This paper proposes a radio frequency identification (RFID) anticollision algorithm to enhance the read performance of the EPCglobal UHF Class‐1 Generation‐2 standard. Our algorithm is based on the mechanism of early adjustment of frame length, as well as dynamic framed slotted ALOHA. To reduce computation complexity, the proposed algorithm adopts a simple rule for a reader to determine when and how the early adjustment starts. Furthermore, the proposed method resorts to at most three examinations of whether the early adjustment should start in each read round. As compared with the algorithms of examining at every time slot, the proposed method can significantly reduce the number of examinations. The normalized throughput of our method can reach a value of up to 34.6%. The advantage of low computation complexity comes at the expense of only 1.4% degradation of throughput. Therefore, it is suitable for most RFID readers built with a capability‐limited microprocessor. Copyright © 2015 John Wiley & Sons, Ltd.     

Objects tracking in a dense reader environment utilising grids of RFID antenna positioning

One of the fundamental constraints in radio frequency identification (RFID) large scale deployment, such as in warehouse RFID deployment, is the positioning of RFID reader antennas to efficiently locate all the tagged objects distributed in a dense RFID reader environment. For tracking the tagged objects in a dense RFID deployment, the required number of reader antennas must be optimised in order to reduce the overall cost. This study proposes highly accurate square and hexagonal grid-based positioning and tracking techniques mainly for use indoors and includes performance comparison of both of these grids. The study involves the design of the square and hexagonal grid reader antenna networks and position calculation using a diffusion algorithm. Both of these grids of RFID antenna positioning present a solution for the problem of the placement pattern of RFID reader antennas in a dense reader environment, hence an optimal number of required reader antennas and guaranteed coverage can be achieved. This study also presents a path loss model that can be applied to predict the radio signal strength information at a certain distance. The proposed diffusion algorithm estimates RFID tag position by using distance information between the reader and the tag. The obtained results show that a square grid can yield higher positioning accuracy compared to the hexagonal grid. The obtained results further show that the proposed tracking techniques can achieve an average positioning error below 1 m, which is 85% better in some cases than the results obtained by other known methods.     

Integrating RFID and WLAN for indoor positioning and IP movement detection

Location awareness in an indoor environment and wireless access to Internet applications are major research areas towards the overwhelming success of wireless and mobile communications. However, the unpredictable indoor radio propagation and handover latency due to node mobility are the main challenging issues that need to be addressed. For tackling efficiently both problems of indoor localization and handover management, we propose combining key benefits of two outstanding wireless technologies, i.e. radio frequency identification (RFID) and a wireless local area network (WLAN) infrastructure. WLANs, such as IEEE 802.11 (WiFi), are now very common in many indoor environments for providing wireless communication among WiFi-enabled devices by accessing an Access Point (infrastructure mode) or through peer to peer connections (ad hoc mode). However, the small cell size of the Access Points (APs) in a WiFi-based network drives the need for frequent handovers leading to increased latency. RFID is an emerging technology consisting of two basic components, a tag and a reader, and its main purpose is the automatic identification of tagged objects by a reader. However, in the presence of multiple readers, RFID suffers from the so-called reader collision problem, mainly due to the inability for direct communication among them. In this paper, we propose a hybrid RFID and WLAN system; the RFID technology is employed for collecting information that is used for both localization and handover management within the WLAN, whereas the WLAN itself is utilized for controlling and coordinating the RFID reading process. In our system architecture, tag IDs of a RFID tag deployment are correlated with both location and topology information in order to determine the position and predict the next subnetwork of a Mobile Node (MN) with a reader attached to its mobile device. The role of the WLAN is to coordinate the readers when accessing the RFID channel for retrieving tags?? IDs, hence compensating the persisting RFID collision problem among multiple readers. Numerical results based on extensive simulations validate the efficiency of the proposed hybrid system in providing accurate and time efficient localization and reducing the IP handover latency.     

Heterogeneous Vehicle Navigation Platform Combined with Mobile RFID Using MIMO System

In a mobile Radio Frequency Identification (RFID) system, the RFID tag is attached to a mobile object such as a vehicle, a human etc. The information is more difficult to detect than in the case where the tag is attached to a stationary object. The RFID reader and back-end database both help to automatically record and store the vehicle driver information and real time status of a tracked geographic information system (GIS), and they cooperate to synchronize the information flow and monitor. In this paper, the Kalman filter (KF) has been implemented as the primary integration scheme of the global positioning system (GPS) and inertial navigation systems (INS) for many land vehicle navigation and positioning applications. It also includes estimating the state of dynamic systems, almost all systems have some dynamic component, and determine how to best use a given set of vehicle sensors for modeling a high performance analysis by using the KF algorithm.     

Tracking via Square Grid of RFID Reader Positioning and Diffusion Algorithm

The study and analysis of RFID (radio frequency identification) reader positioning is important for RFID large-scale deployment. Therefore, the purpose of this research is to investigate the art of RFID reader positioning in order to develop a highly accurate positioning and tracking system for usage inside a building and also to optimize the tracking performance that can be applied to different active and passive RFID standards. This study involves design of square grid RFID reader network and position calculation using diffusion algorithm. Square grid network presents the solution of placement pattern of RFID readers, hence optimal number of required readers and guaranteed coverage can be achieved. The proposed diffusion algorithm makes use of distance information between the reader and the tag to estimate the RFID tag position. This study has also introduced a probabilistic mathematical model to maintain coverage of the unit square region and to ensure connectivity of the proposed square grid network. The effectiveness of the diffusion algorithm is evaluated in this study and the obtained results show satisfactory performance. The obtained results show that the proposed positioning system can achieve average positioning error below 1 m with different RFID reading ranges and in some cases accuracy improvement of about 65% can be reached than the results obtained by known positioning system. It is also found that the proposed diffusion algorithm together with square grid can bring approximately 50–85% improvement on raw accuracy provided by only square grid method.     

基于动态共享密钥的移动RFID双向认证协议

针对移动无线射频识别认证协议面临的身份认证和隐私保护、动态密钥安全更新和去同步化攻击问题,提出一种可动态更新共享密钥的移动RFID双向认证协议.协议基于Hash密码机制,利用随机数同时进行密钥安全更新和身份认证,并采用对分表存储的当前和历史共享密钥进行动态添加和删除的方法,保留最后一次合法认证后的一致共享密钥.安全性能分析与效率分析表明,该协议能够实现动态密钥安全更新和身份认证、能够在遭受去同步化攻击后保证密钥同步,且具有较强的计算和存储性能.通过和同类RFID认证协议比较,协议弥补了同类RFID协议存在的不足,适用于被动式标签数量庞大的RFID系统.     

Channel and Time Slot Allocation for Dense RFID Networks

This paper presents a constraint satisfaction approach to the reader collision problem in dense mode environments for static RFID networks. Our method assigns available channels and time slots to the RFID readers to increase the read rate while satisfying all the interference constraints. We model the problem with a hybrid frequency and time division multiplexing constraint satisfaction for reader anti-collision and assign workable channels and time slots to each reader using backtracking search algorithms. A depth-first-search based on backtracking was performed to find solutions to constraint satisfaction problems. Instead of performing an exhaustive search for the optimal result, we adopted good variable ordering heuristics as branching strategies where the search can be completed quickly. Thus, the search space is greatly reduced, and approximate solutions are found instantly. To find appropriate heuristics, we applied a problem classifying rule to determine the quality of the variable ordering heuristics. Computer simulations of the comparable performance of some variable ordering algorithms in the channel and time slot allocation for dense RFID networks are presented.     

A practical quadratic residues based scheme for authentication and privacy in mobile RFID systems

In this paper we propose a novel approach to authentication and privacy in mobile RFID systems based on quadratic residues and in conformance to EPC Class-1 Gen-2 specifications. Recently, Chen et al. (2008) [10] and Yeh et al. (2011) [11] have both proposed authentication schemes for RFID systems based on quadratic residues. However, these schemes are not suitable for implementation on low-cost passive RFID tags as they require the implementation of hash functions on the tags. Consequently, both of these current methods do not conform to the EPC Class-1 Gen-2 standard for passive RFID tags which from a security perspective requires tags to only implement cyclic redundancy checks (CRC) and pseudo-random number generators (PRNG) leaving about 2.5k–5k gates available for any other security operations. Further, due to secure channel assumptions both schemes are not suited for mobile/wireless reader applications. We present the collaborative authentication scheme suitable for mobile/wireless reader RFID systems where the security of the server–reader channel cannot be guaranteed. Our schemes achieves authentication of the tag, reader and back-end server in the RFID system and protects the privacy of the communication without the need for tags to implement expensive hash functions. Our scheme is the first quadratic residues based scheme to achieve compliance to EPC Class-1 Gen-2 specifications. Through detailed security analysis we show that the collaborative authentication scheme achieves the required security properties of tag anonymity, reader anonymity, reader privacy, tag untraceability and forward secrecy. In addition, it is resistant to replay, impersonation and desynchronisation attacks. We also show through strand space analysis that the proposed approach achieves the required properties of agreement, originality and secrecy between the tag and the server.     

Low Access Delay Anti-Collision Algorithm for Readers in Passive RFID Systems

Even though radio frequency identification (RFID) systems are spreading more and more as a medium for identification, location and tracking purposes, some reliability issues of these systems still need to be solved. In fact, RFID readers and tags experience collisions when sharing the wireless transmission channel over the same area. In this work, we propose a centralized scheduling-based algorithm as possible candidate solution for the reader collision problem in passive RFID systems. This algorithm has been designed taking into account the circuitry limitations of the tags, which do not allow the usage of frequency or code division multiple access schemes in passive RFID systems. The solution herewith proposed, which is suitable for those scenarios involving static or low mobility readers, aims at preventing reader collisions and provides at the same time low channel access delay to the readers. The performance of this algorithm has been tested via computer simulations. The results show that the proposed solution strongly reduces collision occurrences and, especially in static scenarios, provides low access delay to the readers during the channel contention phase.     

一种基于中间件的RFID系统阅读器去冗余算法

 冗余阅读器判别是大规模RFID系统性能优化的重要问题之一.本文基于EPC网络架构提出一种阅读器去冗余算法MRRE.该算法利用RFID中间件的标签信息判别冗余阅读器,不需阅读器对标签写入信息.仿真结果表明,MRRE算法比LEO+RRE算法在冗余阅读器检测率上提高了6.27%～20.80%,在系统处理的标签信息量上降低了4.50%～35.73%,而且在系统部署合理性方面更具优势.     

一种基于散列函数的RFID安全认证方法

RFID系统中有限的标签芯片资源,导致数据与信息的安全成为RFID系统的重要问题之一,散列函数的单向性为RFID的识别和认证提供了一种既可靠又有效的途径.在分析了现有几种典型散列认证协议的基础上,提出了一种新的基于散列函数的安全认证协议.本协议旨在解决手持式、无线连接的RFID阅读器与标签、服务器间的识别,利用散列函数实现服务器、阅读器以及电子标签三者之间的相互认证.经过安全性与性能的分析,新协议在采用较小的存储空间和较低的运算开销的情况下,可抵抗已知的大多数攻击,有效地保证了RFID系统中数据和隐私的安全,实现了终端与服务器间的双向认证和匿名认证,非常适合于在大型分布式系统中使用.     

Problem of dynamic change of tags location in anticollision RFID systems

Presently the necessity of building anticollision RFID systems with dynamic location change of tags appear more often. Such solutions are used in identification of moving cars, trains (automatic identification of vehicles – AVI processes) as well as moving parts and elements in industry, commerce, science and medicine (internet of things). In the paper there were presented operation stages in the RFID anticollision system necessary to communicate with groups of tags entering and leaving read/write device interrogation zone and communication phases in conditions of dynamic location change of tags. The mentioned aspects influence RFID system reliability, which is characterized by the efficiency coefficient and the identification probability of objects in specific interrogation zone. The communication conditions of correct operation of multiple RFID system are crucial for efficient exchange of data with all tags during their dynamic location changes. Presented problem will be the base to specify new application tag parameters (such as maximum speed of tag motion) and synthesis of interrogation zone required for concrete anticollision RFID applications with dynamic location change of tags.     

Model of dynamic clustering-based energy-efficient data filtering for mobile RFID networks

Data filtering is an essential task for improving the energy efficiency of radio-frequency identification (RFID) networks. Among various energy-efficient approaches, clustering-based data filtering is considered to be the most effective solution because data from cluster members can be filtered at cluster heads before being sent to base stations. However, this approach quickly depletes the energy of cluster heads. Furthermore, most previous studies have assumed that readers are fixed and interrogate mobile tags in a workspace. However, there are several applications in which readers are mobile and interrogate fixed tags in a specific area. This article proposes a model for dynamic clustering-based data filtering (DCDF) in mobile RFID networks, where mobile readers are re-clustered periodically and the cluster head role is rotated among the members of each cluster. Simulation results show that DCDF is effective in terms of balancing energy consumption among readers and prolonging the lifetime of the mobile RFID networks.     

基于相互认证的移动RFID安全协议

移动RFID系统是指利用植入RFID读写芯片的智能移动终端,获取标签中的信息,并通过移动网络,访问后台数据库,获取相关信息。然而,由于移动RFID系统的无线通信环境和无可视性读写,带来了很多安全隐患,已经成为制约移动RFID发展的重要因素,针对此问题,在分析了移动RFID网络构成及其安全隐患后,提出了一种基于相互认证的安全协议,该协议引入了一个第3方服务器来为移动读写器和后台数据库提供签名密钥,并且利用椭圆曲线加密体制(ECC)对信息进行签名验证,最后分析表明该协议可以为移动读写器与后台数据库提供安全的通信环境,以应对各种攻击。     

Keyless Security in Wireless Networks

Security and privacy issues in RFID technology gain tremendous popularity recently. However, existing work on RFID authentication problems always make assumptions such as (1) hash function can be fully employed in designing RFID protocols; (2) channels between readers and server are always secure. The first assumption is not suitable for EPC Class-1 Gen-2 tags, which has been challenged in many research work, while the second one cannot be directly adopted in mobile RFID applications where wireless channels between readers and server are always insecure. To solve these problems, in this paper, we propose a novel ultralightweight and privacy-preserving authentication protocol for mobile RFID systems. We only use bitwise XOR, and several special constructed pseudo-random number generators to achieve our aims in the insecure mobile RFID environment. We use GNY logic to prove the security correctness of our proposed protocol. The security and privacy analysis show that our protocol can provide several privacy properties and avoid suffering from a number of attacks, including tag anonymity, tag location privacy, reader privacy, forward secrecy, and mutual authentication, replay attack, desynchronization attack etc. We implement our protocol and compare several parameters with existing work, the evaluation results indicate us that our protocol significantly improves the system performance.     

Multiple RFID Tags Access Algorithm

One of the main problems that affect the data integrity of passive RFID systems is the collision between the tags. A popular anticollision algorithm which dominates the standards in HF and UHF passive RFID systems is Framed Slotted Aloha (FSA) and some variations of FSA. Throughput and average time delay of the RFID system which determines the performance/efficiency of the system are reduced rapidly when the number of tags inside the interrogation zone is increased. Using larger frame sizes is not always the solution. This paper discusses and compares the existing protocols, and proposes a variation of FSA, called Progressing Scanning (PS) algorithm. The PS algorithm divides the tags in the interrogation zone into smaller groups and gives the reader the ability to communicate with each of them. For performance analysis, the PS algorithm was evaluated with the parameters of a typical passive RFID system at 2.5 GHz. The results showed that the PS algorithm can improve the efficiency of the RFID system and provide a reliable solution for cases with a high density of tags in the area (over 800 tags).