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关键词： RFID反向散射技术   并行解码   小波聚类   中间状态点  

摘要： 物联网以物理世界与信息网络的互联互通为目标,是互联网的延伸。在物联网应用方面,射频识别(Radio Frequency Identification,RFID)反向散射技术以其标签无源、免维护、成本低等优势,不仅在仓储、物流、图书管理等传统领域应用广泛,同时在呼吸感知、心率监测等新兴领域拥有广阔的前景。然而,随着反向散射标签的广泛部署,标签碰撞导致通信失败的概率大大增加,这将极大地限制反向散射系统的吞吐量和信道利用率。为此,本文通过对标签碰撞过程进行分析,从符号聚类、簇状态识别、码元解码三个阶段出发,设计了基于中间状态点和信号叠加特征的RFID反向散射系统并行解码方案。针对符号聚类过程中接收信号弱导致的同相正交(In-phase and Quadrature,IQ)域组合状态簇变化多、易重叠的问题,本文提出了基于中间状态点的小波聚类优化算法。本算法先对存在于状态转换之间的中间状态点进行处理。然后,通过中间状态点进行特征空间量化,对小波聚类算法进行优化,使其能够应对IQ域中在弱信号情况下受噪声影响出现的簇变化频繁、簇边缘重叠问题。最后,利用通用软件无线电外设(Universal Software Radio Peripheral,USRP)和无线认证感知平台(Wireless Identification and Sensing Platform,WISP)分别作为阅读器和标签,读取标签的碰撞数据,进行簇状态的识别分类,对聚类算法进行了评估。实验结果表明,改进的小波聚类算法能够对发生重叠的组合状态簇实现准确的符号聚类,同时组合状态之间有了更明显的区分,有利于准确的追踪数据点在状态之间的跳变,为后续的簇识别和解码奠定了良好的基础。针对并行解码过程中接收信号簇状态识别普适性差和码元周期不稳定的问题,本文提出了基于信号叠加特性的并行解码方案。首先,根据接收信号提取单个标签的幅度信息反推各组合状态的理论幅度水平,并将之与实际接收到幅度水平进行匹配,从而实现了组合状态的精确识别。然后,根据双相间空号(Bi-Phase Space,FM0)编码特征对不稳定的比特位的持续时间做统计,并基于概率模型提出了持续时间内包含的比特数计算方法,从而解码每个确定输出码元序列。最后,利用USRP和WISP分别作为阅读器和标签进行碰撞实验,通过改变碰撞标签的个数以及阅读器发射增益对并行解码方案进行了评估。实验结果表明,本文提出的方案能够使得整体误码率降低60%以上,吞吐量提高11%。

关键词： Path loss models   chipless RFID   RIS   experimental measurements  

摘要： In the realm of radio frequency identification (RFID) technology, the integration of reconfigurable intelligent surfaces (RISs) has opened up new possibilities for real-time remote data capturing and seamless connectivity. By manipulating the electromagnetic properties of the environment, RIS enables the control of electromagnetic wave propagation and allows for virtual line-of-sight (LOS) in cases where physical LOS is blocked. This has tremendous implications for the future of RFID applications, particularly with the emergence of chipless RFID technology. In this regard, this paper develops free-space path loss models for RIS-assisted RFID wireless communications. The proposed models in this study have taken into account several crucial physical factors, including tag radar cross-section (RCS), the physical properties of the RIS, and the radiative near-field/far-field effects of the RIS. To further validate the theoretical findings, we have conducted experimental measurements using a fabricated RIS. Numerical simulations were also utilized to validate the models and verify our findings. The channel measurements have demonstrated good agreement with the proposed path loss models, further bolstering the potential of RIS-assisted RFID wireless communications.

关键词： RFID技术   循环包装   循环包装管理系统  

摘要： 针对循环包装的日常流转管理，引入RFID无线识别技术代替现有目视化管理流程，结合循环包装管理系统，对涉及包装流转的仓储、运输、调拨等环节进行管理，精确管控循环包装，降低循环包装的丢失率，提高循环包装生命周期，从而降低包装使用成本，增加利润。

关键词： 电子货架   RFID   CT改进分组算法   近场天线  

摘要： 公安机关在警用仓库中,长期使用传统货架管理警用装备,这种方式存在许多短板,包括装备管理效率低下、信息追溯困难等,这些问题严重影响警用装备的管理水平。因此,研发一款用于警用装备管理的电子货架系统,对传统货架进行信息化升级,已成为公安机关急需解决的重要事项。 本文研究了一种基于RFID标签防碰撞算法的警用电子货架系统。该系统通过RFID模块,能够自动读取货架内的装备信息;通过红外装置,能够自动检测货架库位状态;通过温湿度传感器,能够自动感知货架所处环境的温湿度状况。同时,该系统还可以通过通信总线上传上述数据,从而实现对警用装备的有效管理。 为了提升电子货架系统对警用装备的识别效率,对传统的标签防碰撞算法进行了性能分析和对比研究,并选择CT算法作为装备标签识别算法的基础。通过分析电子标签编码和CT算法存在的不足,提出了一种基于CT算法的改进分组算法。算法性能测试结果表明,CT改进分组算法相较于CT算法平均性能提升了28.4%,能够满足系统对警用装备的识别要求,并提高了电子货架系统读取装备标签的效率。 在工程实践中,使用常规天线识别标签时,容易引发天线“串读”标签问题。为了解决这一问题,进行了近场天线的仿真与优化。根据天线尺寸,进行了多次实物打样与改进,设计了一种应用于UHF频段的近场天线。经过近场天线性能测试,该近场天线能够解决天线“串读”标签问题。 根据电子货架系统的架构设计,完成了电子货架系统的硬件电路设计,同时完成了相应的软件程序开发。通过搭建系统测试平台,对系统进行了测试。结果表明,本文研究的电子货架系统可以简化警用装备存取的流程,提高警用装备管理的效率。

关键词： Kalman filters   Robot kinematics   Filtering algorithms   Mathematical models   RFID tags   Kinematics   Autoregressive processes   Finite impulse response filters   TWOR modeling   self-localization   colored noise   extended unbiased FIR filter   extended Kalman filter  

摘要： This paper discusses the three-wheeled omnidirectional robot (TWOR) self-localization in radio frequency identification (RFID) tag environments. The nonlinear TWOR model is significantly improved by using geometric interpretation and incremental time representation in discrete time. The TWOR position and heading are self-estimated using distance measurements to RFID tags and a digital gyroscope in the presence of typical colored measurement noise (CMN). The extended unbiased finite impulse response (EFIR) is developed along with the extended Kalman filter (EKF) and their versions, cEKF and cEFIR, modified for Gauss-Markov CMN. A particle filter is used as a benchmark. It is shown that the cEFIR filter is more robust than the cEKF and almost as robust as the particle filter, although the latter is less accurate in real time.

关键词： Meta-heuristics   redundant antenna elimination   optimisation   artificial neural networks   RFID network planning  

摘要： Radio frequency identification (RFID) is a wireless technology that uses radio waves to automatically identify and track objects within a certain range. Due to the benefits of the technology, RFID technology has been adopted as a reliable and efficient solution and is an important technology used in various IoT applications. The deployment of the RFID system has caused an RFID network planning (RNP) problem. However, the RNP problem can be defined as an NP-hard combinatorial optimisation problem that requires the examination of a large number of combinations to obtain the best solution. The goal of this research is to introduce and describe a new hybrid approach to solve the problem of RNP optimisation that is based on artificial intelligence algorithms that require a minimum number of initial parameters. Based on widely used benchmarks, our approach is compared against a hybrid approach based on the genetic algorithm, and the results are efficient, cost-effective and assure a good deployment of the RFID system.

关键词： Developing countries  

摘要： Effective management of public shared spaces such as car parking space, is one challenging transformational aspect for many cities, especially in the developing World. By leveraging sensing technologies, cloud computing, and Artificial Intelligence, Cities are increasingly being managed smartly. Smart Cities not only bring convenience to City dwellers, but also improve their quality of life as advocated for by United Nations in the 2030 Sustainable Development Goal on Sustainable Cities and Communities. Through integration of Internet of Things and Cloud Computing, this paper presents a successful proof-of-concept implementation of a framework for managing public car parking spaces. Reservation of parking slots is done through a cloud-hosted application, while access to and out of the parking slot is enabled through Radio Frequency Identification (RFID) technology which in real-time, accordingly triggers update of the parking slot availability in the cloud-hosted database. This framework could bring considerable convenience to City dwellers since motorists only have to drive to a parking space when sure of a vacant parking slot, an important stride towards realization of sustainable smart cities and communities. © 2022, CC BY-NC-SA.

关键词： Wearable technology  

摘要： Recent studies have focused on facilitating perception and outdoor navigation for people with blindness or some form of vision loss. However, a significant portion of these studies is centered around treatment and vision rehabilitation, leaving some immediate needs, such as interaction with the sur- rounding objects or recognizing colors and fine patterns without tactile feedback. This study targets such needs and delivers a straightforward communication method using a wearable, unobtrusive device with the environment. We initially discuss the advantages and limitations of related works to draw out the best-fitting design concepts. Then, we introduce the potential for emerging technologies such as radio-frequency identification. We present the design details and the experimental results of an assistive glove to allow people with vision disabilities to interact with the environment more efficiently. Based on the collected data from 17 blind-folded healthy participants, the implemented system's success rate in identifying objects was about 96.32%. Overall, 70% of the users found the device very satisfactory. © 2022, CC BY-NC-ND.