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.     

Autonomous Mobile Robot Navigation Using Passive RFID in Indoor Environment

This paper proposes an efficient method for localization and pose estimation for mobile robot navigation using passive radio-frequency identification (RFID). We assume that the robot is able to identify IC tags and measure the robot's pose based on the relation between the previous and current location according to the IC tags. However, there arises the problem of uncertainty of location due to the nature of the antenna and IC tags. In other words, an error is always present which is relative to the sensing area of the antenna. Many researches have used external sensors in order to reduce the location errors, with few researches presented involving purely RFID driven systems. Our proposed algorithm that uses only passive RFID is able to estimate the robot's location and orientation more precisely by using trigonometric functions and the IC tags' Cartesian coordinates in a regular gridlike pattern. The experimental results show that the proposed method effectively estimates both the location and the pose of a mobile robot during navigation.      

Evaluating the energy consumption of the RFID tag collision resolution protocols

RFID technology acts as a bridge to connect the physical world with the digital space, and RFID system is pervading our daily life in the last few years. The energy consumed by the reader and a tag in resolving the collisions caused by multiple tags is a key issue that affects life time of mobile reader and active tags, as well as the identification accuracy of passive tags. In this paper, the energy consumed by the reader and a tag in resolving the tag collision is examined for the commonly used RFID tag collision resolution protocols, including the frame slotted ALOHA based and the binary query tree based protocols. Numeric evaluation is also performed and the result verifies that regarding to energy consumption, the dynamic frame slotted ALOHA protocol for the Class-1 RFID system performs best among the frame slotted ALOHA protocols, and the modified binary query tree protocol also performs better than the standard binary query tree protocols.     

Position Tracking for Passive UHF RFID Tags with the Aid of a Scanned Array

Thanks to the proliferation of radio frequency identification systems (RFID), applications have emerged concerning positioning techniques for inexpensive passive RFID tags. The most accurate approaches for tracking the tag’s position, deliver precision in the order of 20 cm over a range of a few meters and require moving parts in a predefined pattern (mechanical antenna steering), which limits their application. Herein, we introduce an RFID tag positioning system that utilizes an active electronically-steered array, based on the principles of modern radar systems. We thoroughly examine and present the main attributes of the system with the aid of an finite element method simulation model and investigate the system performance with far-field tests. The demonstrated positioning precision of 1.5°, which translates to under 1 cm laterally for a range of a few meters can be helpful in applications like mobile robot localization and the automated handling of packaged goods.     

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.     

Reader Coverage Analysis for Multi-Carrier Passive UHF RFID Systems

Applications of passive radio frequency identification (RFID) systems have gained considerable attentions in recent years. Because a passive tag must obtain its operating power from a continuous wave transmitted from a reader in a conventional RFID system, reader coverage is limited. Thus, expanding reader coverage is a current goal in RFID research. In this work, passive tags are provided with additional operating power via continuous waves in multiple frequency bands. In an interrogation region, continuous wave emitters, which provide additional operating power to passive tags, are deployed according to the base station configuration in a cellular phone system. Because transmission power of continuous wave emitters must consider the reader command demodulation constraint and minimum operating power required by a tag, transmission power of continuous wave emitters must be chosen carefully. A method for analyzing reader coverage in multi-carrier passive UHF RFID systems is derived in this work. Assuming all tags are uniformly distributed in an interrogation region, the optimal continuous wave emitter transmission power that achieves the largest reader coverage can be analytically determined. Simulation results verify that continuous wave emitters with suitable transmission power expand reader coverage in a multi-carrier passive UHF RFID system. Additionally, adjusting reader power in the forward (reader-to-tag) link duration can loosen the reader command demodulation constraint and thereby further expand reader coverage.     

基于对数谱射频指纹识别的RFID系统信息监控方法

针对常规RFID系统对信息控制的不足,提出了一种基于辐射源识别的无源RFID系统的信息监控方法。采集无源RFID标签的辐射射频信号,变换为新的对数谱射频指纹,并进行特征提取与识别,获得标签身份真伪结果;把射频指纹等集成到读写器应用层协议,实现标签与读写器之间信息的控制。建模、仿真与实验表明,对数谱射频指纹仅由标签的频偏与冲击响应决定,具有稳健性等;给出了融合提出指纹的RFID系统挑战——应答认证协议实例。提出方法不仅能增强标签与读写器的认证安全强度,而且能实现通信中标签的身份监控,对于解决密钥泄漏检测公开问题也有一定贡献。     

An Efficient Anti-collision Protocol for Fast Identification of RFID Tags

Tag collision prevention/resolution for radio frequency identification (RFID) tags is one of the most significant issues for fast tag identification. This paper proposes a new anti-collision protocol that has objective of minimizing the tag identification delay. The proposed scheme reduces the tag collisions by allocating exclusive timeslot to each tag using identified timeslot information. Performance evaluation based on numerical and simulation results shows that the proposed anti-collision method improves RFID identification performance.     

ASAF ALOHA Protocol for Dense RFID Systems

RFID tags are used for varied applications in large numbers. Human Tracking is one such important application wherein the RFID system detects the presence of a tag in a dense tag environment. Quick estimation of the number of tags in the field at a desired level of accuracy is one of the most common requirements in the present scenario. Identification of tags has become a critical area which need more time and unsuitable in many situations; especially where tag set is dense. We introduce a novel medium access control (MAC) protocol for Radio Frequency IDentification (RFID) systems which exploits the statistical information collected at the reader. The protocol, termed Adaptive Slot Adaptive Frame (ASAF) ALOHA protocol, is motivated to significantly improve the total read time performance of the currently suggested MAC protocols for RFID systems by minimizing the collisions of the tags. In order to perform this task, ASAF estimates the dynamic tag population and adapts the frame size and number of slots simultaneously in the subsequent round via a simple policy that maximizes an appropriately defined function. We demonstrated that ASAF is better than the current RFID MAC protocols. We also considered the case where suddenly if the number of tags increases, the running frame with adapted slots gets flushed away and new frame with increased number of slots gets adapted automatically by the system showing the robustness in this case as well.     

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.     

Simulations and experiments for optimal deployment of an RFID‐based location‐aware system

The proliferation of communication and mobile computing devices and local‐area wireless networks has cultivated a growing interest in location‐aware systems and services. An essential problem in location‐aware computing is the determination of physical locations. RFID technologies are gaining much attention, as they are attractive solutions to indoor localization in many healthcare applications. In this paper, we propose a new indoor localization methodology that aims to deploying RFID technologies in achieving accurate location‐aware undertakings with real‐time computation. The proposed algorithm introduces means to improve the accuracy of the received RF signals. Optimal settings for the parameters in terms of reader and reference tag properties were investigated through simulations and experiments. The experimental results indicate that our indoor localization methodology is promising in applications that require fast installation, low cost and high accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

Adaptive Binary Splitting: A RFID Tag Collision Arbitration Protocol for Tag Identification

In the RFID system, a reader recognizes tags through communications over a shared wireless channel. When multiple tags transmit their IDs at the same time, the tag-to-reader signals lead to collision. Tag collision arbitration for passive RFID tags is significant for fast identification since collisions disturb the reader's identification process. This paper presents an Adaptive Binary Splitting (ABS) protocol which is an improvement on the binary tree protocol. To reduce collisions and identify tags efficiently, ABS uses information which is obtained from the last processes of tag identification. Our performance evaluation shows that ABS outperforms other tree based tag anti-collision protocols. This work was supported by Korea Research Foundation Grant (KRF-2005-041-D00680).     

Design of a RFID System for Real-Time Tracking of Laboratory Animals

In this paper, a real-time RFID system capable of tracking laboratory animals is designed and implemented. Four passive RFID tags based on low frequency are designed and implemented. The tags can be read by any RFID reader that operates on the low frequency range 125–134 kHz. The tags are designed through the investigation of various antenna, encoding, modulation, and energy harvesting techniques. The tag receives the electromagnetic signal via the antenna, and converts it to a DC signal that the microcontroller can use to manipulate the electromagnetic signal with the data such that the reader can decode the unique tag identifier. RFID sensors are designed and implemented to collect data from various monitored areas of a semi natural environment. The data is sent to a central data coordinator for pre-processing and middleware for data error checking, display and storage. The RFID system can successfully detect and store movement data in real time. A read range of 14.5 cm is achieved.     

Adaptive binary splitting for efficient RFID tag anti-collision

Tag collision arbitration for passive RFID tags is a significant issue for fast tag identification. This letter presents a novel tag anti-collision scheme called adaptive binary splitting (ABS). For reducing collisions, ABS assigns distinct timeslots to tags by using information obtained from the last identification process. Our performance evaluation shows that ABS outperforms other tree based tag anti-collision protocols.     

Accurate tag estimation for dynamic framed-slotted ALOHA in RFID systems

Dynamic Framed-Slotted ALOHA (DFSA) is one of the most popular algorithms to resolve tag collision in RFID systems. In DFSA, it is widely known that the optimal performance is achieved when the frame size is equal to the number of tags. So, a reader dynamically adjusts the next frame size according to the current number of tags. Thus it is important to estimate the number of tags accurately. In this paper, we propose a novel tag estimation method for DFSA. We compare the performance of the proposed method with those of other existing methods. And, simulation results show that our scheme improves the accuracy of tag estimation and the speed of tag identification.     

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.     

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.     

RFID系统中面向服务的动态资源配置优化机制

针对物联网中RFID(radio frequency identification)系统的tag和reader的速率不匹配及其资源受限问题,从理论上对tag和reader之间的协作通信上下文进行分析,提出一种面向服务的RFID系统资源配置优化机制,该机制利用tag与reader的组件QoS(quality of service)信息建立闭环控制框架,使用3种控制策略根据其资源状态和类型调节QoS参数。通过实验对机制进行了性能分析和验证,结果表明,该优化机制有效地提高RFID系统的吞吐量,高效地使用系统资源,减少了能量消耗和reader-to-reader干扰。     

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.     

ASK调制度对无源RFID系统能量和数据传输的影响

研究了无源射频识别（RFID）系统中幅移键控（ASK）调制度对读写器与标签之间能量传输及数据传输的影响,推导出了能量传输效率和数据传输可靠性随调制度变化的计算公式,并给出了相应的性能曲线。这些公式和曲线有助于RFID系统ASK调制度的选取和读写器的功率设计,可用于指导实际无源RFID系统的应用设计与开发。