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。     

物联网中大规模RFID标签盘存方法研究

面向物联网应用,对大规模RFID标签盘存方法进行分析研究。首先介绍RFID系统基本原理,特别是大规模RFID标签盘存方法,分析标签盘存中所包括的移动标签识别、丢失标签监测和未识别标签监测问题;其次,从现实信道环境角度考虑,分别着重综述标签盘存方法研究现状,包括对移动标签识别方法、丢失标签监测方法、未识别标签监测方法进行对比分析,并指出本领域存在主要问题及未来研究给出建议。     

无源反向散射RFID系统识别距离的影响因素分析

针对RFID技术应用的日益重要性,基于电磁场散射和微带天线理论,系统地研究了无源反向散射RFID系统识别距离的影响因数,并提出了无源反向散射RFID系统最大识别距离的计算方法。研究结果表明,天线参数直接影响系统的识别距离,其中,天线的增益、工作频率、雷达截面、品质因数、极化方式和应用环境等参数起决定性作用。研究结果对优化无源反向散射RFID系统的性能及天线设计有益。     

基于RFID传感标签的弯曲应变无线监测方法及实验

为解决结构应变有线监测方法存在的布线量大、安装维护费用高、可靠性差等问题,提出一种基于RFID传感标签技术的无线监测新方法。详细介绍了由应变信号调理电路、MSP430单片机和nRF905无线收发模块组成的标签硬件设计和软件实现。根据有限元分析的结果,在碳纤维增强复合材料层合板实验试件上布置了多个电阻应变片,利用设计的传感标签和读写器,在万能材料试验机上构建了结构应变无线监测的实验系统。弯曲实验结果表明分布的传感标签可有效获取结构应变信号并实现信号的无线传输与处理;多通道数据分析处理结果与实验现象一致,验证了该系统实现结构应变无线监测的有效性。     

RFID系统克隆标签检测方法综述

随着物联网的发展和无线射频识别技术(radio frequency identification, RFID)的广泛应用,RFID系统的安全问题越发突出。其中克隆标签的出现极大地阻碍了RFID系统的大规模发展,成为当前一个亟待解决的难题。通过总结分析目前RFID克隆标签检测领域的一些主流方法,旨在为后续研究更有效的RFID克隆标签检测策略奠定基础。针对目前已知的一些检测方法,该文将克隆标签检测方法归纳总结为射频指纹、同步秘密、轨迹分析和碰撞检测四大类,并较为系统地对这四大类方法所包含的具体策略进行了研究,同时对这些方法策略进行了横向与纵向的对比分析。目前这四类方法都存在一定的缺陷,导致其无法直接应用于现有RFID系统进行克隆标签检测或者应用条件较苛刻。针对目前这些方法存在的问题,认为匿名RFID系统克隆标签的分布式检测是未来的一个主要研究方向。     

标签运动状态下的RFID系统反碰撞算法

针对现实应用中标签经常处于运动状态的情况,对传送带模型下的无线射频识别(RFID)系统进行了分析,并使用Matlab做了相应的仿真实验。结果证明,当标签密度D与传送带速度V保持不变时,识别率P在帧长度N与作用范围内未识别标签数n相等时最高。当时隙持续时间一定时,识别率P只与V和D有关,而与作用区域内传送带长度L无关。同时针对该模型,对现有的标签估算方法进行了修正,在此基础上提出了一种新的估算方法,该方法的准确度在标签数目较大时有着明显的提高。     

RFID标签防碰撞研究

分别简要介绍了几种ALOHA算法与树形算法,并对ALOHA算法与树形算法作了简要的比较。同时详细介绍了具有一定自学习能力的"在时隙内利用贝叶斯更新的帧ALOHA"算法与"自适应二进制分裂(ABS)"算法。     

RFID标签抗克隆攻击研究现状

随着RFID技术的广泛应用,抗克隆攻击已成为亟待解决的问题。笔者首先在全面总结国内外抗克隆攻击研究成果的基础上,深入分析当前研究状况,然后结合实际应用情况,提出研究中存在的不足和未来进一步研究的建议。     

UHF RFID标签芯片整流电路设计

整流电路的设计是无源射频识别(RFID)标签关键技术之一.首先讨论了超高频无源电子标签整流电路的基本工作原理,然后分析了整流电路的等效电路模型.基于TSMC 0.18μm CMOS混合信号工艺设计了一种具有双输出的整流电路,并通过MPW项目流片验证.测试结果表明,该电路具有低输入电压,高整流效率的特点.     

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℃.     

Long read range and flexible UHF RFID tag antenna made of high conductivity graphene‐based film

An antenna made of a graphene‐based film with organic polyimide precursor of high conductivity 1.1 × 10⁶ S m^?1 and thickness 30 μm, operating in the ultrahigh frequency (UHF) band for radio frequency identification applications is presented in this article. The antenna is optimized to have a conjugate match to the impedance of the chip by tuning the design parameters. Tags are fabricated and tested using the designed antenna, which are shown to have realized gain above ?1.5 dBi and radiation efficiency beyond 90% in the whole UHF band from 860 to 960 MHz. The read range of proposed tag is greater than 12.3 m over the entire UHF band with a maximum value of 14 m at 920 MHz. In addition, the flexibility of the tags is demonstrated. After 2000 cycles of bending and stretching, the read range only decreases by 4.5 m comparing to the initial state at 915 MHz.     

Distributed load-balancing algorithm for fast tag reading

The radio frequency identification (RFID) technology has gained a lot of recent interests because it has been widely recognised as a foundation technology for the ‘Internet of things’. In current multi-reader RFID systems, readers work with fairly less cooperation and are responsible to retrieve data from different number of tags individually, which results in large reading time of obtaining all tag data. In this paper, a fast tag reading problem in multi-reader RFID systems with the goal of obtaining all tag data by using minimum reading time is studied. A distributed load-balancing algorithm based on diffusion method is proposed to solve the problem by migrating tags from highly loaded reader to lightly loaded reader. The simulation results demonstrate the effectiveness and efficiency of proposed algorithm.     

基于RFID的虚拟标签算法研究与改进

针对室内定位算法VIRE的定位精度,特别是邻近边界目标的定位精度较低的问题,以RFID标签定位为研究基础,从改变VIRE算法中虚拟标签的插值方式和在边界上加入虚拟标签两个方面进行研究和改进。使用拉格朗日插值代替VIRE算法中的线性插值方式,使虚拟标签的数据更加接近实际环境值;在边界上加入虚拟参考标签能增加已知标签数,防止在计算待定位标签坐标时引入误差标签。实验结果表明,标签定位精度有了明显提高,整体能提高了35%,邻近边界标签定位精度提高较大,可达到50%以上。     

Elliptical slot based polarization insensitive compact and flexible chipless RFID tag

A miniaturized, polarization insensitive, and fully passive chipless radio frequency identification tag is proposed in this research article. The realized tag is based on slotted elliptical structures in a nested loop fashion with identical lengths and widths of slot resonators. Alteration of data sequence is accomplished by addition and elimination of nested resonators in the geometric structure. The tag is capable to encode 10 bits of data and covers spectral range from 3.6 to 15.6 GHz. The formulated structure demonstrates polarization insensitive characteristic. The data encoding structure is analyzed and optimized for different substrates that are, Rogers RT/duroid/5880, Rogers RT/duroid/5870, and Taconic TLX‐0 over the miniaturized footprint of 22.8 × 16 mm². The presented tag is robust, novel, compact, and flexible exhibiting a stable response to impinging electromagnetic waves at various angles of incidence.     

Compact size flexible UHF RFID tag antenna for racing pigeon ring applications

A very small size radio frequency identification (RFID) tag antenna specifically designed for racing pigeon ring applications is proposed. The structure of this UHF tag is a closed‐loop type printed on a 30 × 8 mm² polyimide film of thickness 0.063 mm. Thus, it can be wrapped into a double layer plastic cylindrical ring of size similar to those used for racing pigeon. By simply tuning the inner width of the loop, good conjugate matching between the tag chip input impedance and the tag antenna can be achieved. When mounted onto a real preserved dried pigeon feet specimen, the measured impedance bandwidth of the tag antenna was 901‐929 MHz. Further experimental results have also shown that the proposed antenna has a maximum reading range of up to 50 cm.     

Compact meandered RFID tag antenna with high read range for UHF band applications

In this work, a compact, long read range, and an efficient spiral loop structure coupled tag antenna is proposed for UHF‐RFID applications. Meandered line element is inductively coupled to spiral loop for matching its input impedance to Higgs‐4 chip. Equivalent circuit of antenna is extracted to analyze its working mechanism in the operating band. Experimental characterization validates the performance of proposed tag antenna in free space and on cardboard sheet in terms of read range, tag sensitivity, and differential radar cross section with an EIRP of 3.28 W. The measured radiation pattern of the tag is found to be omnidirectional in H plane and figure of eight in E plane. The tag's read range is measured on objects like fiber, wood, plastic, and glass in outdoor scenario to study its environment tolerance. The tag antenna has volumetric size of 1736 mm³ and read range of 13.6 m in US RFID band.     

浅谈RFID电子标签及卷到卷电子标签生产线

在RFID系统中,电子标签用量十分巨大。根据电子标签的不同用途,其材料组成和封装工艺也不同,电子标签一般分为硬体标签和柔体标签(又称柔性标签)。文章结合柔性电子标签封装工艺专门研制的卷到卷电子标签生产线,说明其前道倒封装(Flip Chip)电子标签生产线和后道层合模切电子标签生产线等两部分卷到卷电子标签生产线具有生产效率高、稳定性好等特点。     

新的基于分组处理的射频识别标签防碰撞算法

针对现有几种基于二叉树的防碰撞算法识别时延较长、数据传输量大的情况,提出一种新颖的防碰撞算法。算法采用分组策略,读写器按顺序依次识别每个分组,减少了每次应答标签的数量和碰撞发生的概率;此外,把标签ID分为两段识别,第一段为前7位,剩余部分为第二段,标签ID分段处理能减少冗余数据的传输。仿真结果表明,该算法相比其他几种算法,查询次数少,数据传输量仅为动态二叉树搜索(DBS)算法的1/6,识别效率有较大幅度提高。