基于无源超高频RFID温度标签的温度监测系统

设计一种基于无源超高频(UHF)射频识别(RFID)温度标签的温度监测系统.系统由课题组自主研发的无源超高频RFID温度标签、Speedway R220商用阅读器和上位机应用软件组成,实现了物品身份识别、温度实时测量和显示的功能.为提高温度标签的测温精度,提出了一种自适应功率匹配算法,使得天线扫描范围内的多个标签都能在最佳测温功率下测温.测试结果表明:当温度标签与阅读器天线的距离分别为0.5,1.0,1.5m时,测温误差小于±1℃.     

基于RCS的无源超高频RFID标签识别距离研究*

通过对无源超高频RFID系统中标签功率的获取、传递以及反射的研究,提出了一种基于雷达散射截面(RCS)对标签识别距离进行计算的新方法。采用高频电磁场仿真软件FEKO对不同标签天线进行建模与仿真,计算标签天线在不同负载下的RCS;再结合识别距离表达式计算该标签的最大识别距离,与标签已有的实测参数进行比较,计算结果与实际参数吻合。研究结果证实了该方法对研究标签识别性能具有很好的借鉴意义。     

应用于建筑设备物联网的超高频RFID读卡器设计

为在建筑设备物联网系统(BECPS)环境中实现人员信息的采集,设计了一个超高频RFID读卡器。首先简要描述了BECPS;其次给出了读卡器的硬件电路、器件选型、系统软件等的设计过程;最后在BECPS平台下对该RFID读卡器进行了实验测试,测试结果证实了该设计方案的有效性。与现有的超高频RFID读卡器相比,该读卡器不仅能够完成多标签识别,并且能够与BECPS完美结合,实现了人员信息的无线上传。     

超高频RFID读写器系统的设计与实现

采用ARM9微处理器为主控制器,射频处理采用奥地利微电子公司的AS3992芯片为核心,设计开发了超高频RFID读写器系统。系统设计了外置功率放大电路、功率探测电路和天线端阻抗匹配调谐电路,使发射机输出功率达到+33dBm,并有效地提高了接收机信噪比,实现了对符合ISO/IEC 18000-6C 900MHz RFID协议的多标签的稳定高速读写;同时在ARM9硬件平台上移植了嵌入式Linux系统,并设计了读写器Web固件控制系统,以实现多标签盘存和读写器的网络配置等操作,为读卡器之间数据通信和二次开发提供平台。该系统已搭建运行于某电厂运煤车辆出入RFID管理控制系统中,运行结果表明,系统最大稳定读取距离达到10m,满足了工程需求。     

无源UHF超高频标签天线设计与研究

无源UHF频段RFID技术信号传输速度快,覆盖距离远,通过与互联网、通讯等技术相结合,可实现全球范围内物品的跟踪与信息共享。该技术由射频模拟前端电路、控制逻辑电路等组成的无源UHF超高频射频识别标签系统,由外接天线与读写器完成通信,天线既要与识别标签相匹配,又要与读写器较好地通信,天线决定了标签是否能正常工作,同时也决定了信号传输的距离。为此,通过研究天线的匹配阻抗、形状尺寸与大小,以及频带的设计,探索出了低成本、高可靠的天线设计方案。     

大空间双模多频段射频识别复合定位

针对室内大范围射频识别定位,提出一种双模多频段射频识别复合定位方法。被定位对象同时携带有源和无源两种模式的标签,微波频段阅读器与被低频频段信号激活的有源标签通信,根据有源标签信号区域选通超高频频段读写器天线,以减轻读写器天线之间干扰;以固定时间读写器天线对无源标签的收包次数为定位参数,在被定位对象位置计算过程中分区筛选最大后验概率位置并利用欧式距离修正定位坐标,完成贝叶斯概率定位算法的改进。实验验证表明,本文提出的复合定位方法,不但可以改善大空间定位中读写器天线间的干扰,而且与LANDMARC算法相比较,定位误差降低59.86%。     

多径传播环境下的无源UHF RFID系统电波传播模型

针对自由空间模型在预测射频识别系统识别距离时存在的偏差,综合考虑射频识别系统应用的多径传播环境,建立一种无源超高频射频识别系统电波传播模型,并重点分析了前向链路路径损耗的主要影响因素及其计算方法。基于该电波传播模型,探索性地提出实际环境下的无源超高频射频识别应用模拟思路。仿真和测量结果表明,该模型在预测无源超高频射频识别系统识别距离时更为准确。     

一种用于食品链信息管理的RFID读写器的设计

介绍了一种符合ISO/IEC 15693协议的电子标签读写器系统,提出了一种适合于食品链信息管理的便携式RFID读卡器设计方案.该读卡器系统包括控制模块、射频识别通信模块、无线传感网数传模块、信息存储模块、电源管理模块、网络接口模块以及服务器数据备份等.本文主要介绍系统备模块的框架设计,并给出了信息的处理方法.     

小型RFID偶极子天线设计与优化

无源RFID标签的读写性能主要取决于其天线和芯片的性能,其中超高频RFID标签通常采用偶极子天线。从理论-仿真-实验的角度详细介绍了偶极子天线的设计和优化方法,并制作了4款小型超高频RFID标签样品。测试结果表明,4款样品标签的性能与仿真的优化结果高度一致,该设计和优化方法可行。     

一种基于物联网的多天线RFID纱锭定位系统

针对纺纱厂需要对大量纱锭筒管的位置信息采集的需求,在纱厂引入RFID技术。典型的RFID阅读器只有一根天线,一次只能读一个电子标签。为了实现一个RFID阅读器一个工作周期能够读取多个电子标签,设计了一种多天线RFID阅读器。描述了此种多天线RFID阅读器的硬件组成与软件构成,同时对多天线RFID阅读器的线圈数目、阅读距离与切换时间之间的关系进行了探索。为解决RFID系统对数据传输的需求,根据中间件思想构建了基于Web Services技术的接口,介绍了其具体实现的模型,为企业内部间、不同企业之间的信息提供了一个松耦合的系统集成方案。     

Design of a compact size tag antenna based on split ring resonator for UHF RFID application

In this article, a new design of miniaturized split‐ring resonator antenna using a meander line technique with a simple impedance matching method applicable to UHF‐RFID tags is presented. The new approach is based on the integration of a meander line into the radiating element of SRR to reduce the electrical tag size and a theoretical demonstration to calculate the conjugate impedance matching and directly attach the antenna with the chip. The new SRR antenna, which is printed on the flexible substrate Arlon CuClad 250LX, is designed using Alien Higgs 3 RFID ASIC whose input impedance is 25‐j190. The prototype antenna has a low‐cost compact size (18.28 mm × 18.28 mm) with a read range higher than 4 m within the RFID UHF band and with a roughly 4.2‐m peak range at 915 MHz. As a proof of behavior, a tag prototype is fabricated and measured to operate at a UHF RFID band. Based on some works' results, an optimized design is obtained with a 48% size reduction compared with the classic split ring resonator antenna and with a good impedance matching the antenna with RFID ASIC without the need for any external matching network.     

Optimization of tag reading performance in generation-2 RFID protocol

Radio frequency identification (RFID) provides a non-line-of-sight (NLOS) and contactless approach for object identification. But if there are multiple tags in the range of an RFID reader, tag collision can take place due to radio signal interference and therefore an anti-collision algorithm is required to resolve collisions. Recently, EPCglobal RFID generation-2 (Gen-2) protocol [EPCglobal Specification, EPCTM radio-frequency identity protocols class-1 generation-2 UHF RFID protocol for communications at 860 MHz–960 MHz, version 1.0.9, January 2005. Available from: <http://www.epcglobalinc.org>] is proposed for ultra-high frequency (UHF) passive tags and is being deployed. Gen-2 designs a slotted random anti-collision algorithm, especially, an adaptive slot-counter (Q) selection algorithm. The integer-valued parameter Q in Gen-2 plays a critical role in tag collision resolution. This adaptive algorithm dynamically adjusts the value of Q based on the type of replies from tags. In this paper, we propose an optimal Q algorithm that determines the optimal values of Q according to the number of remaining tags and in turn to optimize tag identification speed (TIS) and query success rate (QSR), respectively. It’s been demonstrated through extensive simulations that the proposed algorithm achieves higher TIS than Gen-2 adaptive Q algorithm.     

具有感应反馈环的超高频RFID标签天线设计

针对标签天线在RFID系统中的重要性,基于微带天线设计和电磁场散射理论,设计和分析了一种具有感应反馈环的超高频段RFID标签天线。天线的谐振频率为915 MHz,尺寸为78 mm×23 mm,天线显示近线性相位特性,在电压驻波比小于2的条件下,天线的阻抗带宽为100 MHz。可以通过调整感应反馈环的长度来调整天线的谐振频率,天线的增益为2.5 dBi左右。通过仿真和测量可知,这种天线能较好地满足RFID超高频段标签的要求。     

Efficient detection of counterfeit products in large-scale RFID systems using batch authentication protocols

RFID technology facilitates processing of product information, making it a promising technology for anti-counterfeiting. However, in large-scale RFID applications, such as supply chain, retail industry, pharmaceutical industry, total tag estimation and tag authentication are two major research issues. Though there are per-tag authentication protocols and probabilistic approaches for total tag estimation in RFID systems, the RFID authentication protocols are mainly per-tag-based where the reader authenticates one tag at each time. For a batch of tags, current RFID systems have to identify them and then authenticate each tag sequentially, one at a time. This increases the protocol execution time due to the large volume of authentication data. In this paper, we propose to detect counterfeit tags in large-scale system using efficient batch authentication protocol. We propose FSA-based protocol, FTest, to meet the requirements of prompt and reliable batch authentication in large-scale RFID applications. FTest can determine the validity of a batch of tags with minimal execution time which is a major goal of large-scale RFID systems. FTest can reduce protocol execution time by ensuring that the percentage of potential counterfeit products is under the user-defined threshold. The experimental result demonstrates that FTest performs significantly better than the existing counterfeit detection approaches, for example, existing authentication techniques.     

标签可重用的仓储管理系统UHF RFID阅读器设计

UHF RFID标签具有非光学可视阅读、感应距离远和读取速度快的特点.针对中小型仓储应用提出了UHF RFID标签可重用和UHF RFID阅读器软硬件定制的设计方案.UHF RFID阅读器硬件采用了Cortex- M3内核处理器LPC1768、UHF RFID模块读取标签、SPI Flash扩展存储和TFT LCD显示...     

Recovery of Collided RFID Tags With Frequency Drift on Physical Layer

In a passive ultra-high frequency (UHF) radio frequency identification (RFID) system, the recovery of collided tag signals on a physical layer can enhance identification efficiency. However, frequency drift is very common in UHF RFID systems, and will have an influence on the recovery on the physical layer. To address the problem of recovery with the frequency drift, this paper adopts a radial basis function (RBF) network to separate the collision signals, and decode the signals via FM0 to recovery collided RFID tags. Numerical results show that the method in this paper has better performance of symbol error rate (SER) and separation efficiency compared to conventional methods when frequency drift occurs.      

超高频无源RFID系统中Capture效应建模与分析

针对超高频无源射频识别(RFID)系统中 Capture效应的分析问题,提出一种新颖的Capture模型-RFIDCap,并通过Monte-Carlo仿真分析了各系统参数对Capture效应的影响,同时比较了RFIDCap及其他传统模型与测试结果的符合程度.RFIDCap综合考虑了读写器抗干扰能力、无线信道损耗及衰落、...     

Security analysis of two recently proposed RFID authentication protocols

Radio frequency identification (RFID) systems suffer many security risks because they use an insecure wireless communication channel between tag and reader. In this paper, we analyze two recently proposed RFID authentication protocols. Both protocols are vulnerable to tag information leakage and untraceability attacks. For the attack on the first protocol, the adversary only needs to eavesdrop on the messages between reader and tag, and then perform an XOR operation. To attack the second protocol successfully, the adversary may execute a series of carefully designed challenges to determine the tag’s identification.     

一种UHF无源RFID标签芯片阻抗测试方法研究

提出一种用于UHF无源RFID标签芯片阻抗测试的新方法.利用ADS仿真软件对测试原理进行了仿真并实际制作了测试板.利用设计的测试板对NXP_XM芯片和Impinj_Monza4芯片进行了测试,分析了误差产生的原因,最终测试结果符合预期效果.     

多天线空分定位RFID阅读器的设计

RFID是近年来发展迅速的非接触式自动识别技术,为使基于RFID技术的智能管理系统具有定位识别的功能,本文提出了多天线空分定位RFID阅读器的设计方案,即采用阅读器与多个检测天线的分离式装置,使每个天线仅识别自己工作区域内的标签,天线的地址码与标签的数据共同构成传送的信息,从而使阅读器具有定位识别标签的功能。基于本文提出的RFID阅读器的智能战备药箱管理系统可以为战备药品提供安全、准确、实时的信息收集、处理和查询,该管理系统不仅可以提供定位识别,还可以节约系统的成本,具有广阔的应用前景。