区域RFID信息公共服务系统的研究

射频识别RFID技术应用广泛,多种应用系统相对独立,因此建立区域RFID信息公共服务系统将成为新的发展热点。分析整合RFID信息资源、构建综合应用系统的必要性,介绍其中技术关键的设计,包括多种标签的信息采集和区域RFID信息服务平台,讨论兼容现有ISO标准的RFID复合读写器技术特点和标签的信息安全问题。     

RFID包装系统中防冲突算法研究

目的解决现阶段包装箱管理过程中RFID标签冲突的问题。方法在分析已有的解决标签冲突算法的基础上,采用多线程技术、后退式二进制防冲突算法和优化的数据结构等方法,设计并实现一种新的防冲突算法。RFID读写器发送一个三元组命令,RFID标签应答冲突位的信息,减少数据传输量;采用堆栈存储RFID读写器发送的命令,减少识别冲突的次数;利用多线程处理思想,对标签进行分类处理,缩短冲突处理的时间。结果经过仿真分析,这种并发执行的后退式二进制RFID防冲突算法效率可提高约51%。结论该算法解决了RFID标签冲突,提高了多标签情况下的读写效率,很好地解决了包装箱管理系统中RFID标签的功能和性能的问题。     

RFID读写器防冲突问题的混沌神经网络建模与求解

针对密集读写器环境下的RFID读写器冲突情况,提出了一种通过中央计算机集中控制读写器分时操作来避免读写器冲突的方法,并设计了基于退火策略的混沌神经网络算法进行读写器时隙分配的求解.首先,根据平面图着色问题与读写器防冲突问题的相似性,确定四时隙分时操作的防冲突原理;然后采用二维Hopfield神经网络建立四时隙分配问题模型,并构造了满足冲突约束条件的神经网络能量函数;最后,通过引入混沌机制和模拟退火策略进行问题求解以使得算法具有较好的搜索能力和收敛速度.与现有的分布式防冲突算法相比,该方法能够保证读写器具有更多的扫描标签时间和更高的标签扫描频度.仿真实验结果表明用该算法求解读写器防冲突问题是可靠的、高效的.     

RFID系统防冲突算法分析及其实现

在多标签对一个读写器的RFID系统中,标签有时会在同一个时间点一同向读写器传输数据,从而引起通信冲突,导致读写器读不到标签上的信息,主要论述通过时隙算法来解决这一问题的方法与仿真实现。     

基于改进ALOHA算法的RFID标签防碰撞研究

目的 为提高射频识别技术(Radio Frequency Identification,RFID)标签识别成功率,以及包装生产线自动分拣效率、智能化水平.方法 以包装生产线检测系统为研究对象,结合RFID技术设计一种自动包装、检测、配送系统.介绍RFID检测系统,主要包括标签、阅读器、天线和控制系统.针对RFID识别过程中标签碰撞问题,提出一种改进ALOHA算法,采用动态预测权值估计标签数目使标签数目与数据帧长度大致相等.通过实验验证ALOHA算法的有效性.结果 实验结果表明,碰撞比率平均值只有1.1％,整个系统的检测成功率可以达到99.6％;所述改进ALOHA算法可以有效避免标签碰撞.结论 该系统能够自动完成检验,并且用时较少,检验过程中正确率较高,具有较高的市场应用价值.     

Thinkify宣布推出新的台式RFID读写器

Dockon公司和嵌入式RFID应用创新领头羊Thinkify宣布,Thinkify推出了新的用于文件管理和标签编写用的TR-200台式RFID读写器,读写器采用Dockon的CPL天线设计。这种新读写器即可使用,比目前市场上同类产品更小、更便宜。     

标签防碰撞问题的研究

标签碰撞是射频识别(RFID)技术的常见问题,该问题影响了RFID系统数据通信过程中的数据传输的完整性.介绍了目前解决标签碰撞的两种主要算法:ALOHA算法和二进制搜索算法,对这两种算法做了详细的研究,并给出了它们的演进算法的分析,从而提高了RFID系统的通信性能.     

超高频RFID读写器接收灵敏度测试方法研究

我国RFID产业不断壮大,RFID的应用领域不断扩展,超高频频段的RFID系统因其优点受到众多行业的青睐。RFID读写器作为RFID系统的重要组成部分,其接收灵敏度是一项关键的技术指标。本文通过对超高频RFID读写器接收灵敏度的测试环境、测试设备、测试布置图和测试步骤进行研究,从RFID读写器接收灵敏度优劣的角度为RFID实际应用中读写器的部署提供指导,从而推动RFID行业应用的基础工作的标准化进程。     

浅议智能手机平台与RFID中间件技术应用

<正>一、RFID技术分析1.1RFID技术基本原理20世纪80年代,由于大规模集成电路技术的成熟,RFID系统的体积大大缩小并进入实用化的阶段,成为一种成熟的自动识别技术。RFID技术利用射频方式进行非接触双向通信,以达到识别目的并交换数据。典型的RFID系统包括标签、读写器和天线三部分。     

Advanced ID公司开发新型UHF RFID标签

全球RF ID标签和读写器供应商Advanced ID公司宣布,与Solrayo公司和Enable IPC公司发展合作关系。合资企业将把超级电容器技术用于专门设计的UHF RFID际签上,以提高信号强度和读取距离。这种新标签将解决RFID行业的主要问题。普通的UHF RFID标签在现实世界条件下,读取距离约5米,限制了无源标签在许多方面的应用。该合资企业开发的用超     

Energy Scavenging for Inductively Coupled Passive RFID Systems

Deployment of passive radio-frequency identification (RFID) systems or RFID-enhanced sensor networks requires good understanding of the energy scavenging principles. This paper focuses on the energy scavenging design considerations of inductively coupled passive HF RFID systems. The theoretical estimation of the power by a loop antenna is derived, and the effect of the design parameters on the harvested power is investigated. It is shown that the power delivery performance is largely affected by the tag load at the reader. An adaptive matching circuit at the reader is proposed for achieving optimum power delivery performance when the reader has a variable load. Experimental studies confirm analytical derivations     

判断二进制树中标签识别完毕的方法

分析了射频识别(RFID)系统阅读器与标签通信的二进制树算法,指出在标签识别过程中,阅读器并不知道是否识别完标签,阅读器会以连续多次没有接收标签响应为依据结束对标签的查询,这样往往会造成标签漏读或浪费时间在已识别完的标签上。基于此分析,提出了判断二进制树中标签识别完毕的方法。该方法通过在阅读器中设置计数器,就可以很好地跟踪标签的识别情况,准确地判断出标签是否识别完毕。分析结果表明,该方法可以准确地判断标签是否识别完毕,增加系统识别效率和可靠性。     

Tag identification enhancement by using a distributed antenna structure for radio frequency identification systems

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. The distributed antennas are connected to a reader with a four-port power splitter/combiner which consists of Wilkinson power splitters (WPSs), band pass filters (BPFs) and power amplifiers (PAs). Due to the polarisation of the electromagnetic field, the antennas are positioned on opposite sides in both vertical and horizontal directions of the object. This positioning improves the performance of the system, and increases the sensitivity when identifying unclearly positioned tags. An experimental RFID system is also set up to demonstrate the proposed structure. Simulation and experimental results indicate that using four distributed patch antennae can improve tag identification in passive RFID systems.     

基于二进制树的RFID系统自适应多分支防碰撞算法

为提高射频识别(RFID)系统的识别效率,研究了系统的标签防碰撞问题。考虑到对标签进行多分支处理能够有效地提高RFID系统标签识别效率,而传统的多分支防碰撞算法都是在标签估计的基础上对标签进行最优分组,标签估计产生的时延和误差都会影响整体的识别效率,提出了一种基于二进制树的自适应多分支(AMB)防碰撞算法。该算法根据二进制树结构特点,利用识别的标签数目对树结构中右节点标签进行估计并进行分组识别,经过多次调整的自适应多分支防碰撞算法,可以规避一次标签估计所引入的估计误差,从而提高系统的识别效率。仿真结果表明自适应多分支算法可以大大提高标签识别效率,在标签数量较大时系统效率可达43%左右。同时该算法实现简单,只需在阅读器中增加若干计数器,不需要改变任何空中接口,很容易与现有协议兼容。     

Mobile RFID Tag Detection Influence Factors and Prediction of Tag Detectability

Radio-frequency identification (RFID) readers are powered RF devices that communicate with tags (whether mobile or fixed) and read necessary information to be processed. A mobile RFID tag is detected by an RFID antenna. In a mobile RFID where the RFID tag is attached to a mobile object such as a vehicle, a human, or an animal, information is more difficult to detect than in the case where the tag is attached to a stationary object. Currently, deployment engineers and researchers use trial-and-error approaches to decide on the best conditions of the tag detection influence factors which affect tag detectability (detection rate). As expected, these approaches are time consuming. Even though mobile RFID systems have become widely used in industry and tag detection problems are crucial at deployment, very few researches on them have been conducted so far. Thus, a quick and simple method for finding tag detectability is needed to improve the traditional time consuming trial-and-error method. In this paper, we propose a unique approach ldquothe intelligent prediction method of tag detection rate using support vector machine (SVM).rdquo The intelligent method predicts the mobile RFID tag detectability instead of the trial-and-error experimental procedures. The simulation results of the proposed method are very comparable to the trial-and-error experimental approach. The proposed intelligent method gives a very high accuracy of mobile RFID tag detectability prediction and proves to be superior to the current method in time as well cost savings. The predicted tag detectability results can be used for analyzing mobile RFID tag detection influence factors and their conditions.     

A Dynamic Multi-ary Query Tree Protocol for Passive RFID Anti-collision

In this paper, a dynamic multi-ary query tree (DMQT) anti-collision protocol for Radio Frequency Identification (RFID) systems is proposed for large scale passive RFID tag identification. The proposed DMQT protocol is based on an iterative process between the reader and tags which identifies the position of collision bits through map commands and dynamically encodes them to optimize slots allocation through query commands. In this way, the DMQT completely eliminates empty slots and greatly reduces collision slots, which in turn reduces the identification time and energy costs. In addition and differently to other known protocols, the DMQT does not need to estimate the number of tags, reducing the protocol implementation complexity and eliminating the uncertainty caused by the estimation algorithm. A numerical analysis shows that DMQT has better performance than other algorithms for a number of tags larger than 300. Meanwhile, when the number of tags is 2000 and the tag identity (ID) length is 128 bits, the total identification time is 2.58 s and the average energy cost for a tag identification is 1.2 mJ, which are 16.9% and 10.4% less than those of state-of-the-art algorithms, respectively. In addition, a DMQT extension based on ACK command has also been presented to deal with capture effect and avoid missing identification.

     

A Novel Time-aware Frame Adjustment Strategy for RFID Anti-collision

Recently, object identification with radio frequency identification (RFID) technology is becoming increasingly popular. Identification time is a key performance metric to evaluate the RFID system. The present paper analyzes the deficiencies of the state-of-the-arts algorithms and proposes a novel sub-frame-based algorithm with adaptive frame breaking policy to lower the tag identification time for EPC global C1 Gen2 UHF RFID standard. Through the observation of slot statistics in a sub-frame, the reader estimates the tag quantity and efficiently calculates an optimal frame size to fit the unread tags. Only when the expected average identification time in the calculated frame size is less than that in the previous frame size, the reader starts the new frame. Moreover, the estimation of the proposed algorithm is implemented by the look-up tables, which allows dramatically reduction in the computational complexity. Simulation results show noticeable throughput and time efficiency improvements of the proposed solution over the existing approaches.     

Z-path SAW RFID tag

Surface acoustic wave (SAW) radio-frequency identification (RFID) tags are soon expected to be produced in very high volumes. The size and cost of a SAW RFID tag will be key parameters for many applications. Therefore, it is of primary importance to reduce the chip size. In this work, we describe the design principles of a 2.4-GHz SAW RFID tag that is significantly smaller than earlier reported tags. We also present simulated and experimental results. The coded signal should arrive at the reader with a certain delay (typically about 1 micros), i.e., after the reception of environmental echoes. If the tag uses a bidirectional interdigital transducer (IDT), space for the initial delay is needed on both sides of the IDT. In this work, we replace the bidirectional IDT by a unidirectional one. This halves the space required by the initial delay because all the code reflectors must now be placed on the same side of the IDT. We reduce tag size even further by using a Z-path geometry in which the same space in x-direction is used for both the initial delay and the code reflectors. Chip length is thus determined only by the space required by the code reflectors.     

基于RFID的工业炸药全流程智能监控系统研究与开发

针对工业炸药生产、仓储、销售和使用等全流程安全监管问题,提出用RFID(radio frequency identification)进行产品标识与产品信息获取,构建工业炸药全流程监控系统。为了解决工业炸药物理实体与监控系统信息的映射,提出可监控单元模型。该系统是多层分布式的体系结构,由数据采集层、数据处理层和数据服务层组成,并详细描述了各层的功能;该系统采用C#、ASP.Net和SQL Server 2005开发,运行在Windows平台。在企业生产线现场应用结果表明,当RFID读写器与贴有RFID标签产品距离保持在2~4 m之间时,标签读取准确率可以达到99.9%。