A Physical Layer Algorithm for Estimation of Number of Tags in UHF RFID Anti-Collision Design

A priori knowledge of the number of tags is crucial for anti-collision protocols in slotted UHF RFID systems.The number of tags is used to decide optimal frame length in dynamic frame slotted ALOHA(DFSA)and to adjust access probability in random access protocols.Conventional researches estimate the number of tags in MAC layer based on statistics of empty slots,collided slots and successful slots.Usually,a collision detection algorithm is employed to determine types of time slots.Only three types are distinguished because of lack of ability to detect the number of tags in single time slot.In this paper,a physical layer algorithm is proposed to detect the number of tags in a collided slot.Mean shift algorithm is utilized,and some properties of backscatter signals are investigated.Simulation results verify the effectiveness of the proposed solution in terms of low estimation error with a high SNR range,outperforming the existing MAC layer approaches.

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.

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.

木托盘RFID标签安装方式有限元分析及试验研究

目的采用仿真和试验手段并用的方法,研究RFID标签在木质平托盘上的适用安装方式及其对使用性能的影响。方法进行Ansys有限元仿真,分析木质平托盘承载和冲击试验中采用螺钉紧固及黏结剂粘贴方式安装的RFID标签所受应力。作为对比,在实验室进行实物试验,测量RFID标签表面应力,并测试标签读写性能。结果在托盘承载和冲击试验中,从RFID标签各构件及标签连接件的受力分析看,2种安装方式下的RFID标签均未出现脱落和物理性损坏。冲击试验后的RFID标签能够通过读写功能测试。有限元仿真与实物试验的应力分析结果相互吻合,验证了结果的正确性。结论RFID标签采用螺钉紧固和黏结剂粘贴的安装方式都能满足使用要求,且螺钉连接的耐用性更好。研究结果为RFID标签在木质平托盘的安装方式选择提供了理论依据。

基于RFID的医疗设备远程管理系统设计

为提高医院内设备定位精度,设计基于RFID的医疗设备远程管理系统。通过阅读器、电子标签和处理器组成RFID节点,引入AS3992芯片作为核心芯片,实现数据处理和编码,执行远程指令。采用自由空间传播模型计算路径损耗产生值,通过三角定位数学方法计算待定标签位置,采用RFID定位方法确定标签的最近邻居,实现医疗设备的远程定位。实验结果表明,在没有障碍物的情况下,所提系统设备定位误差少于1 m,在有障碍物的情况下,定位误差在2 m左右,证明所提出系统定位准确性较高,满足系统的设计需求。

RFID电缆中间接头无线无源湿度监测

针对电缆中间接头受潮导致的运行故障问题,提出一种基于13.56 MHz RFID技术的无源湿度监测方法。该文利用HFSS建立传感器模型,调整天线匝距使天线达到理想状态,并对天线进行谐振匹配;然后研究传感器天线在水中的传输效果及存在金属屏蔽层时金属对天线性能的影响;最后将所设计的传感器放置于中间接头内部进行性能测试。结果表明:天线匝距为0.6 mm时传感器性能最佳;在天线外部增加47μH电容可实现13.56 MHz谐振匹配;传感器天线在水中的传输效果良好;加装金属屏蔽层可解决路径上金属对传感器信号传输的抑制作用;实际测量距离可达到8.2 cm、相对湿度测量误差最大为0.48%,最大波动幅度仅为0.3%,传感器长期处于高湿度环境仍能准确测量。该方法可实现电缆中间接头内部湿度的直接、快速及无源测量,对防止电缆受潮具有一定的参考意义。

基于RFID和磁导航的AGV小车S7-1200PLC控制系统设计

该项目利用S7-1200PLC作为AGV主控制器,采取驱动轮差速进行转向控制,采用磁导航传感器和RFID标签传感器实现循迹和定位功能,实现AGV小车在立体仓库、VMC850数控加工中心、CK40S数控车床、RB20工业机器人、装配单元之间产品的搬运功能。

基于单天线视轴信号传播模型的RFID定位方法

为了解决现有单天线超高频RFID技术在室内静态目标定位中精度不高的问题,本文提出了一种基于天线视轴信号传播模型的RFID定位新方法。该方法首先通过天线纵向扫描确定目标的高度位置;其次,调整天线高度与目标高度一致,然后步进旋转扫描以识别目标的方向角;进一步的,利用麻雀搜索算法优化的反向传播神经网络建立路径损耗模型并用于测距;最后,综合高度、方向角和距离数据完成目标的定位。实验结果表明,在室内环境测试中,所提出的方法平均定位误差为7.2 cm,能够满足一般室内场景下物品的定位需求。

基于RFID系统的智能图书馆图书盘点探究

智能图书馆时代图书盘点工作依然是图书馆一项重要的基础性工作。文章对基于RFID系统的智能图书馆图书盘点问题进行探究,并分析问题产生的原因,提出了相应的解决对策,以提高图书盘点工作质量和读者自助借还满意度。

基于RFID的智能分类编目系统设计与实现

阐述基于RFID技术的智能分类编目系统设计,它可有效提升图书馆对图书进行分类编目的效率、降低管理成本。RFID技术的应用,有效避免人为原因造成的分类错误。

基于UWB和RFID的装配式建筑堆场管理系统研究

针对装配式混凝土建筑构件种类繁杂、尺寸较大的特点,在大规模堆场中采用人工或二维码难以有效识别和定位构件,文章基于UWB(超宽带)和RFID(射频识别)技术构建了分为四个层级的堆场管理系统,进而将功能模块划分为识别模块、定位模块、监控模块、数据模块和应用模块,实现对堆场构件的快速识别、精准定位和实时监测,可有效提高堆场利用率、管理效率和质量安全保障程度,促进智能建造技术在装配式建筑实施过程中的应用。

基于RFID技术的风险规避型双渠道供应链投资决策研究

本文在单一零售商和制造商构成的双渠道供应链中仅零售渠道发生库存损耗,研究实施RFID技术消除库存损耗对定价及收益的影响,同时引入均值–方差理论研究零售商的风险厌恶偏好对实施RFID技术的决策影响。研究发现:1) 不采用RFID技术时零售商的库存损耗率、采用RFID技术后的单位标签成本均会影响零售价和批发价,且不影响直销价,进而影响各成员的期望收益;2) 不论是否采用RFID技术,零售商的风险厌恶程度均会影响零售价和批发价,且应用RFID技术后,零售价低于不采用时的零售价,批发价高于不采用时的批发价;3) 当零售商的风险厌恶程度给定时,当且仅当单位标签成本低于某一阈值,零售商和制造商均可从RFID技术中获益,且这个阈值与产品生产成本、零售商的库存损耗率有关。

基于RFID技术的高校管制化学品管理

高校作为教育实践和科学研究的重要场所,通常需要使用到种类繁多、性质复杂、易燃易挥发的管制类药品。管制类药品的有效管理是高校实验室安全稳定的重要因素之一。基于RFID技术在高校管制化学品管理上的应用,实行“一瓶一码”,对每瓶化学品进行了精准管理,精确掌握管制化学品从“申购”到“消瓶”的完整流向,实现了全流程闭环管理,极大提升管制化学品的管理效率。

集成双频无源RFID传感器标签设计

针对超高频和高频RFID传感器由于各自测量距离和使用便捷性而导致应用场合的局限,提出一种集成超高频和高频的双频无源RFID传感器标签设计方法。首先,集成超高频和高频射频供电和数据收发模块,达到超高频和高频双频读写目的;其次,为提高双频RFID传感器标签在超高频模式下的读取距离,采用电荷泵对射频收发芯片输出电压进行升压管理以延长放电时间;然后,为增强传感器标签的通用性,将测量数据集成到高频NDEF消息和超高频用户数据段中。根据以上方法,设计了双频无源RFID温湿度传感器标签。同时搭建了实验平台对电荷泵提升读取距离的可行性和传感器标签功能进行了实验验证。实验结果表明:该传感器标签可以同时支持超高频和高频2种读取模式;使用电荷泵升压能量管理有效提升了读取距离;可通过支持EPCC1G2协议的通用超高频读写器和NFC手机方便地获取传感器测量数据。

An Adaptive Tag Anti-Collision Protocol in RFID Wireless Systems

A novel anti-collision algorithm in RFID wireless network is proposed.As it is put forward on the basis of collision tree(CT)and improved collision tree(lCT) anti-collision protocols,we call it adaptive collision tree protocol(ACT).The main novelty of this paper is that the AD strategy is introduced and used in ACT to decrease collisions and improve the tag system throughput.AD strategy means that query strings will divide into two or four branches adaptively according to the label quantity.This scheme can decrease both depth of query and collision timeslots,and avoid producing too much idle timeslots at the same time.Both theoretical analysis and simulation results indicate that the novel proposed anticollision protocol ACT outperforms the previous CT and ICT protocols in term of time complexity,system throughput,and communication complexity.

Performance Analysis of RFID Framed Slotted Aloha Anti-Collision Protocol

In this paper, we develop a novel mathematical model to estimate the probability distribution function of the number of tags discovered after a certain number of interrogation rounds. In addition, the pdfs of the number of rounds needed to discover all the tags are also calculated. The estimation of such pdfs will be helpful in estimating the number of interrogation rounds and the optimal parameter configuration of the RFID system which in turn will be helpful in estimating the time needed to discover all tags. Our results show that the proposed model accurately predicts the tags detection probability. We then use the proposed model to optimally configure the reader parameters (i.e. the frame size and the number of interrogation rounds).

高性能微型RFID阅读器天线的设计与优化

为提高射频识别系统的应用范围和传输性能,设计了工作频率在13.56 MHz微型标签天线,该天线采用电感耦合方式进行信息传输,利用三维高频电磁仿真软件(High Frequency Structure Simulator,HFSS)设计出了微型射频识别天线的模型并进行了优化仿真,通过参数化扫描方式对天线的结构、介质板厚度、线间距以及线圈的匝数进行了可视化分析和比较,在模型的基础上完成了天线阻抗匹配。仿真结果表明,设计的微型天线在工作频率13.56 MHz时具有良好的辐射性能,其回波损耗值(S11)达到-58.18 dB,且天线的耦合性能优异,理论传输距离可达30 cm以上。对微型RFID阅读器天线的测试结果表明,该天线工作在13 MHz~15 MHz频段上时明显优于同环境、同类型的其他设计方案,实测回波损耗最小值达到-37 dB。其中在工作频率13.56 MHz时的回波损耗约为-27 dB。设计的微型标签天线在物流运输、图书管理以及可穿戴设备等方面具有广阔的应用前景。

A Frame Breaking Based Hybrid Algorithm for UHF RFIDAnti-Collision

Multi-tag collision imposes a vital detrimental effect on reading performanceof an RFID system. In order to ameliorate such collision problem and to improve thereading performance, this paper proposes an efficient tag identification algorithm termedas the Enhanced Adaptive Tree Slotted Aloha (EATSA). The key novelty of EATSA is toidentify the tags using grouping strategy. Specifically, the whole tag set is divided intogroups by a frame of size F. In cases multiple tags fall into a group, the tags of the groupare recognized by the improved binary splitting (IBS) method whereas the rest tags arewaiting in the pipeline. In addition, an early observation mechanism is introduced toupdate the frame size to an optimum value fitting the number of tags. Theoretical analysisand simulation results show that the system throughput of our proposed algorithm canreach as much as 0.46, outperforming the prior Aloha-based protocols.

An Improved Binary Search Anti-Collision Protocol for RFID Tag Identification

Radio frequency identification(RFID)has been widespread used in massive items tagged domains.However,tag collision increases both time and energy consumption of RFID network.Tag collision can seriously affect the success of tag identification.An efficient anti-collision protocol is very crucially in RFID system.In this paper,an improved binary search anti-collision protocol namely BRTP is proposed to cope with the tag collision concern,which introduces a Bi-response mechanism.In Bi-response mechanism,two groups of tags allowed to reply to the reader in the same slot.According to Bi-response mechanism,the BRTP strengthens the tag identification of RFID network by reducing the total number of queries and exchanged messages between the reader and tags.Both theoretical analysis and numerical results verify the effectiveness of the proposed BRTP in various performance metrics including the number of total slots,system efficiency,communication complexity and total identification time.The BRTP is suitable to be applied in passive RFID systems.