教学课程资源库 更多>>

关键词： eigenvalue   eigenvector   RFID security   authentication protocol   privacy  

摘要： Radio frequency identification technology has been rapidly embraced throughout different wireless communication domains as one of the primary identification solutions for the internet of things. Most present RFID authentication techniques are susceptible to a wide range of malicious attacks. A typical security feature in RFID authentication protocols is key updating, which leads to desynchronisation attacks. We propose a shared key update approach to overcome this issue by the hash function, properties of eigenvectors of a matrix, and addition and concatenation operations. Formal and informal security analyses of the proposed protocol reveal that it is durable to numerous assaults. To simulate the protocol, we apply the Scyther tool, and the findings suggest that the proposed protocol may endure severe assaults. The performance analysis also shows that it has less computation costs on the tag side, making it suitable for use in real-time control systems.

关键词： 室内定位   Wi-Fi指纹   RFID   RSS   RPCA  

摘要： 近年来,随着物联网(Internet of Things,Io T)技术的迅猛发展以及室内场景的增加,室内定位技术成为了研究和应用的热点。室内定位技术主要面临全球定位系统(Global Positioning System,GPS)无法在复杂室内环境中有效工作的挑战,原因不限于室内环境的复杂性、信号散射以及多径效应等。本文聚焦于利用智能小车进行目标的三维定位,针对传统定位方法在现有应用场景中遇到的噪声干扰、参考点稀疏及三维空间定位精度不足等问题,分别提出对应的解决策略,研究重点与创新之处如下: (1)针对传统室内Wi-Fi指纹定位算法在采集指纹过程中遇到的问题,特别是室内环境中存在离群噪声、参考点过于稀疏以及参考点间隔较远等问题,本研究提出一种基于虚拟RP指纹技术的智能小车自定位算法。首先,在离线阶段,通过采集接收信号强度(Received Signal Strength,RSS)数据,其次,对这些RSS数据执行预处理。这一过程中,利用基于鲁棒性主成分分析(Robust Principal Components Analysis,RPCA)的双度量提纯算法对原始数据进行降噪,从而生成更纯净的离线指纹。然后引入了虚拟参考点(Reference Point,RP)技术,并生成虚拟指纹,进而构建离线指纹库。在线阶段,智能小车接收到多个接入点(Access Point,AP)发出的Wi-Fi信号,并利用RPCA双度量提纯算法进行处理,生成在线指纹。通过分析离线阶段与在线阶段信号的质量赋予对应的置信度权重。最后,采用自适应K值的加权K近邻(Weight K Nearest Neighbors,WKNN)方法,实现了对货架目标邻域内的智能小车的二维定位。 (2)针对传统货架定位算法中设备部署成本高和目标三维定位精度不足的问题,本研究提出了一种基于移动射频识别(Radio Frequency Identification,RFID)阅读器和双标签的三维目标定位算法。首先,智能小车根据上一阶段的定位结果,前往对应货架目标邻域的参考标签处,执行第二阶段定位,并沿着货架方向采集来自粘贴在货架目标上RFID无源标签的后向散射信号。其次,通过RSS峰值信息与双标签相位模型实现了对货架上的待测目标初步估计。然后,以这个初步估计的值作为初值,采用基于泰勒级数展开的校准算法进行多次迭代。最终,通过综合两次估计的结果,该算法实现了对货架目标的三维高精度定位。

关键词： Resonators   Electromagnetics   Strips   Encoding   Harmonic analysis   Codes   Reflection coefficient   Chipless-RFID   electromagnetic encoder   microstrip technology   motion control   phase/frequency modulation   position sensor  

摘要： Hybrid time/phase/frequency domain linear electromagnetic encoders are presented in this paper for the first time. The encoders consist of a linear chain of electric-LC (ELC) resonators etched in a dielectric substrate. Encoding is achieved by phase and frequency modulation simultaneously, namely, by considering different transverse positions and dimensions of the ELC resonators in the chain. The reader is a simple matched microstrip transmission line terminated with a matched load, and encoder reading proceeds by displacing the encoder over the reader line, at short distance, in the direction orthogonal to the line axis. When an ELC resonator lies on top of the line, the phase of the reflection coefficient at resonance depends on the distance to the input port and hence on the transverse position of the resonator in the chain (phase modulation). Moreover, the size of the resonator determines its resonance frequency (frequency modulation). This means that the reader line should be fed by as many harmonic signals as ELC resonator sizes considered, to identify the phase and the resonance frequency of the inclusion (ELC) on top of the line. In this paper, we consider 16 different transverse positions and 4 different sizes of the ELC resonators, which are read sequentially, in a time-division multiplexing scheme. Thus, 6 bits per encoder position (or row) in the chain are achieved. These encoders, with a per-unit-length density of bits of DPL = 6 bit/cm, can be applied to the implementation of synchronous near-field chipless-RFID systems with high data capacity, as well as long-range displacement sensors. In the latter case, the number of bits per encoder row can be doubled (i.e., 12 bits) by considering two chains and two readers, allowing for the discrimination of 2(12) (= 4096) absolute positions.

关键词： Slot antennas  

摘要： This research work investigates the performance of a novel low profile 20-bit frequency coded L-shape slot loaded resonator for chipless RFID applications. The proposed chipless RFID comprises a CPW-fed UWB radiator and an L-shaped multi-slot resonator to achieve 20-bit data capacity. CPW technique is implemented to enhance antenna bandwidth and radiation characteristics. The designed UWB radiator covers the entire band from 3 to 12 GHz with better return loss. Also, the peak gain is measured as 6 dBi in the respective frequency spectrum. The proposed L-shaped frequency-coded multi-slot resonator is developed with a compact size of 23.6 × 14.1 × 1.6 mm3. Moreover, the frequency coding technique allows for a wide range of frequency combinations for data representation, as well as contributes to reducing the RFID tag size. The research holds significance in propelling RFID technology forward and ushering in a new era of small, efficient, and flexible data encoding solutions. © 2024, Electromagnetics Academy. All rights reserved.

关键词： Aerosol jet printing   anti-tamper   authentication   passive RFID   security  

摘要： The development of innovative, miniaturized, and low-cost Radio Frequency Identification (RFID) tags for application in asset monitoring, counterfeit prevention, or personnel tracking requires advancements in materials, fabrication processes, and packaging. Typical RFID tags can be circumvented by tampering, cloning, or spoofing;however, by adding security features to the tag, nefarious actions such as these can be mitigated. Toward this objective, this paper presents the design and fabrication of an Ultra High Frequency (UHF) RFID tag through flexible hybrid electronics (FHE) materials and processes for authentication and anti-tamper /anti-counterfeit applications. The presented UHF RFID tag consists of a passive RF chip and dipole antenna with embedded hardware and software security features. The tag was fabricated using a hybrid of manufacturing techniques including, conventional photolithography and additive aerosol jet printing. The design, materials selection, processing, and tailored FHE fabrication processes, led to achieving a system-level functional RFID tag with a read distance of up to 15 in (0.381 m). The dependency of the read distance on the host surface was studied by attaching tags to different materials including surfaces with various dielectric constants and thicknesses. The performance of the tags was evaluated under realistic use conditions by performing thermal cycling, bending, and wearability tests. The RFID tag's resistance to different tamper attack vectors (vulnerability assessment) is demonstrated. Overall, the demonstrated UHF RFID tag opens new opportunities for the development of flexible, lightweight, and low-cost RFID tags that leverage FHE fabrication techniques and materials for authentication and anti-tamper applications.

关键词： Dual-band   dual polarization   metasurface   patch antenna   RF identification (RFID)   backed-cavity   hybrid coupler   multiple-input multiple-output  

摘要： This paper proposes dual-band dual linearly-polarized (LP)/circularly-polarized (CP) antennas using combined metasurface and patch for ultra high frequency (UHF) and 2.45-GHz RF identification (RFID) readers. A metasurface and two stacked patches are employed for the lower and upper bands, respectively. The metasurface and patches are incorporated with a common feeding structure which is composed of two orthogonal microstrip lines and a crossed slot to produce the dual-wideband dual-LP radiation. To reduce the back radiation and improve the gain, the antenna is backed by a metallic cavity. Taking advantage of its low-profile structure, the dual-LP antenna is further integrated with a dual-band branch-line coupler to realize dual-CP radiation. Both proposed antennas yield stable radiation performances across dual operating bands which completely cover the assigned RFID spectrum at the UHF (860 - 960 MHz) and 2.45-GHz (2400 - 2500 MHz) bands.

关键词： 人体动作识别   无线感知   射频识别   深度学习  

摘要： 在当今智能化时代的背景下,人体动作识别技术在物联网的框架中发挥着至关重要的作用。通过与智能设备和传感器的无缝集成,人体动作识别技术能够让计算设备捕捉到人体动作信息并据此执行相应操作,如今广泛应用于医疗康复、体育训练、虚拟现实等多个领域。手势识别和步态识别作为人体识别技术的两个关键分支,分别在人机交互和安全认证领域展现出其重要价值。传统动作识别主要依赖于视觉方式和穿戴式式传感器,面临成本、便携性及隐私保护等限制。相比之下,基于射频识别(Radio Frequency Identification,RFID)的人体动作识别技术因其无需物理接触、不受光线条件限制以及不侵犯个人隐私的优点而受到人们的重视。本文针对基于RFID技术的手势及步态识别方向存在的识别率不高及数据预处理不充足等问题,提出了基于RFID与深度学习的手势识别和步态识别方案。本文的主要研究内容包括: (1)本文首先提出了基于RFID和双输入卷积神经网络(Dual-Input Convolutional Neural Network,DICNN)的手势识别方案。通过将预处理后的信号数据的相位和接收信号强度(Received Signal Strength Indicator,RSSI)作为卷积神经网络的双输入,从而使网络学习两者的特征并进行手势识别。实验结果表明,本文提出的方法对18种动态手势的识别达到了97.81%的识别率,证明了本文方法的有效性。 (2)本文随后提出了一种基于RFID和跳跃连接长短期记忆网络(Skip Connection Long Short-Term Memory,SCLSTM)的步态身份识别方案。该方案首先设计了新的预处理流程对原始相位数据进行处理,然后设计了多种数据增强方式模拟步态的变化。实验结果表明,本文提出的步态识别方法对参与者的身份达到了97.57%的识别准确率,超过了用于比较的其他基准方法。

关键词： 室内定位   射频识别   合成孔径   农业物联网  

摘要： 农业智能仓库作为现代化农业的高级产物,能够有效解决传统仓储管理依赖人工操作导致管理效率差、误差率高等问题。对货物的精准识别定位是农业智能仓库应用实现的基础,其中射频识别定位技术是实现精准定位的关键技术,射频识别定位的精度直接影响着农业智能仓库的管理效率。现有的射频定位方法针对复杂的农产品仓库定位环境存在着定位精度的不足,通过研究现有定位方法在农产品仓库中误差原因并改进可以有效的提升农产品仓库的管理效率。本研究面向农业智能仓库应用的需求,选取基于相位的合成孔径定位方法在农产品仓库环境下进行定位测试分析,并提出改进方案,具体研究内容如下: (1)采用基于相位的合成孔径雷达(SAR)定位算法针对农产品包装定位的应用进行了深入研究。首先,通过仿真分析,评估了算法的定位精度与抗干扰性能。接着构建了专门的射频测试环境于农产品仓库内,以实际验证农产品包装及标签在仓库环境下的定位性能。实验结果显示,在无干扰环境中,该算法实现的定位精度误差为10厘米,但在干扰环境中信噪比(SNR)取20dB时,算法的定位误差控制在40厘米以内,实际农产品仓库环境中进行的测试表明,标签定位的误差为20厘米,而农产品包装定位的误差则为30厘米。实验结果表明了该定位方案在应用于农产品仓库时,尤其是在纵向定位精度及抗干扰能力方面存在一定的局限性。 (2)为解决定位算法应用于农产品仓库定位的误差问题,设计实施了四个参数的研究,研究在农产品包装射频定位中可能存在的标签方向、天线方向、农产品包装材料、多径传播、标签破损等影响。实验结果表明RSSI值与阅读器天线的旋转角度存在联系,而相位值具有较好的抗干扰性,基于该发现提出基于RSSI的纵向定位算法及双天线的干扰抑制策略,通过与基于相位的合成孔径定位算法相结合,提出了RSSI与相位融合的农产品包装射频定位方法,最后在农产品仓库环境中对该融合定位方法进行了实验验证,实验结果证明,相比于原始算法,该融合定位方法在纵向定位精度上有显著提升,同时增强了系统的抗干扰能力,成功满足了农产品仓储定位的精度要求。

关键词： 射频识别技术   非线性传输线   分布式小型化节点   室内三维定位算法   射频标签定位系统  

摘要： 射频识别(Radio Frequency Identification,RFID)是一种接收特定目标的反射信号并获取其ID和空间位置的非接触式技术,当下已经成为库存管理、资产追踪和供应链优化等领域的热门解决方案。但由于室内环境的复杂性和系统内的同频自干扰的问题,RFID的定位精度和范围受到限制。针对以上挑战,本文以提高定位精度和范围为目标,从宽带非线性标签设计、分布式小型化节点设计以及系统构建,对分布式谐波RFID定位系统进行了系统性探索。 首先,为消除发送端至接收端的同频干扰并高效地产生谐波信号,本文设计并制作了基于非线性传输线的被动谐波标签。其利用非线性器件实现了上行和下行链路的分离,提高了回波信号的信噪比,并获取下行链路中的射频能量为片上芯片供电,以此实现多标签识别的功能。该功能基于射频开关调控阻抗变换对谐波信号进行了不同频率的调制,利用调制频率与ID的映射关系,来识别多个标签。 其次,针对大规模分布式系统的需求,本文设计并制作了低成本、小型化的分布式节点。其采用一种零中频的通信架构,并具备宽带工作的特性,能够通过上位机远程调控各节点的系统参数。为全面展示该技术路线的优势与特点,本文介绍了其相关原理、系统构成及射频性能参数,并计算了其硬件成本;为进一步验证分布式小型化节点的可靠性,对其进行了发射及回环测试,实验证明发射与接收链路均能正常工作。 结合上述研究,本文提出了基于载波相位的分布式谐波定位系统。通过采用收发机分离模型实现非同频的全双工系统且避免了使用环行器。理论分析表明,该模型利用空间差分解决了收发机分离产生的非相干问题,且不依赖于发射机的先验位置信息。为充分利用收发分离带来的优势以及接收机较高的灵敏度,采用分布式放置发射机的方式以扩大系统的定位范围。针对相位具有周期性的问题,本文采用启发式多频连续波测距算法对相位周期整数进行求解获得距离信息,进而获得目标的三维坐标。该算法能容错较大的相位误差,并选择最佳多频点组合,以此提高系统的鲁棒性。为验证所提出方案的可靠性和准确性,本文通过1D相位稳定性实验、3D定位实验、分布式系统的仿真与实验以及抗多径测试对此方案进行了全方位验证。

关键词： Radio frequency identification technology (RFID)   blockchain   smart factory   authentication  

摘要： With the deepening exploration of Industry 4.0, smart factories are gradually replacing traditional factories with rapid momentum. In smart factories, a large number of digitally networked devices are deployed in a less-populated or even unmanned environment. Data security and fast access have become particularly important due to the automation and intelligence of production. As the environment of smart factories becomes increasingly complex, meeting the requirements for rapid authentication has become increasingly difficult for traditional authentication systems. In this study, a lightweight blockchain-based radio-frequency identification (RFID) identity authentication mechanism is proposed for smart factories represented by the medical device manufacturing industry by integrating blockchain and RFID technologies. Through bitwise operations, cyclic shift operation, and hash arithmetic, the proposed mechanism cannot only guarantee security between the RFID reader and the electronic tag but also requires less communication and storage to complete authentication. Thus, this mechanism is suitable for the environment of medical device manufacturing factories with a high-load operation of equipment. It helps further research on the data security of smart factories.