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关键词： Magnetic fields   Antennas   UHF antennas   Radiofrequency identification   Noise measurement   Couplings   Antenna measurements   Artificial magnetic conductor (AMC)   multi segment loops coupled   near-field (NF) antenna   radio frequency identification (RFID)   ultrahigh-frequency (UHF)  

摘要： Two novel multisegment loops coupled ultrahigh-frequency (UHF) radio frequency identification near-field (NF) antenna with a uniform and strong magnetic field distribution over an electrically large interrogation zone are designed. Each proposed antenna is composed of eight loops, and the current distribution along the loop is kept in-phase using a segmented line. To further achieve a more uniform magnetic field, the last four loops of the two proposed antennas (ANT 1 and ANT 2) are loaded with parasitic structures. Here, a 100% detection rate is achieved by ANT 1 within an interrogation area of 370x560x105 mm(3) for the bidirectional operation setup. As for ANT2, it is backed by an artificial magnetic conductor to enhance the magnetic field strength and reduce the profile with respect to a configuration with a PEC reflector plane, and it has yielded a 100% detection rate within the interrogation area of 370x560x185 mm(3) for the unidirectional operation setup. The proposed ANT2 can cover the UHF band of China, the Federal Communications Commission band of North America, and European Telecommunication Standards Institute band of Europe.

关键词： RFID technology   RFID transponder   sewn tag   embroidered tag   textronics   dielectric properties of textiles   dielectric constant   dielectric loss  

摘要： Recent advances in the development of innovative textronic products are often related to the implementation of radio-frequency identification (RFID) technology. Such devices contain components of wireless telecommunications systems, in which radiofrequency circuits should be designed taking into account not only the frequency band or destined application, but also the dielectric properties of the materials. As is known from the theory of RFID systems, the dielectric permittivity and loss angle of the substrates significantly affect the performance of RFID transponders. Therefore, the knowledge on the variability of these parameters is highly important in the context of developing new solutions in textronic devices with the RFID interface. According to the plan of studies, at the beginning, the comprehensive characterization and determination of the dielectric parameters of various types of textile substrates were carried out. On this basis, the influence of fabrics on the performance of textronic RFID (RFIDtex) tags was characterized with numerical calculations. As the RFIDtex transponders proposed by the authors in the patent PL231291 have an outstanding design in which the antenna and the chip are located on physically separated substrates and are galvanically isolated, the special means had to be implemented when creating a numerical model. On the other hand, the great advantage of the developed construction was confirmed. Since the impedance at the chip's terminals is primarily determined by the coupling system, the selected fabrics have relatively low impact on the efficiency of the RFIDtex transponder. Such an effect is impossible to achieve with classical designs of passive or semi-passive transponders. The correctness of the simulations was verified on the exemplary demonstrators, in threshold and rotation measurements performed at the laboratory stand.

关键词： Vehicles   Receivers   Radiofrequency identification   Automobiles   Transponders   Costs   Frequency modulation   E-Toll collection   RFID   cross-technology communication   IoT  

摘要： This work enhances the machine-to-human communication between electronic toll collection (ETC) systems and drivers by providing an AM broadcast service to deployed ETC systems. This study is the first to show that ultra-high radio frequency identification signals can be received by an AM radio receiver due to the presence of the nonlinearity effect in the AM receiver. Such a phenomenon allows the development of a previously infeasible cross-technology and cross-frequency communication, called Tagcaster, which converts an ETC reader to an AM station for broadcasting short messages (e.g., charged-fees and traffic forecast) to drivers at tollbooths. The key innovation in this work is the engineering of Tagcaster over off-the-shelf ETC systems using shadow carrier and baseband whitening without the need for hardware nor firmware changes. This feature allows zero-cost rapid deployment in the existing ETC infrastructure. Two prototypes of Tagcaster are designed, implemented, and evaluated over four general and five vehicle-mounted AM receivers (e.g., Toyota, Audi, and Jetta). Experiments reveal that Tagcaster can provide good-quality (PESQ>2) and stable AM broadcasting service with a 30 m coverage range. Tagcaster remarkably improves user experience at ETC stations, and two-thirds of volunteer drivers rate it with a score of 4+ out of 5.

关键词： Queue   Delay   RFID sensors   Model-based estimation  

摘要： Queue and delay are the primary performance measures of an intersection. This study aims to determine queue and delay for an approach of a signalized intersection using data obtained from RFID sensors. Model-based estimation schemes were developed for queue estimation that utilized the conservation of vehicles equation as the state equation. Relationships were developed between the time of detection of RFID cars during the red and green phase of a signal cycle and corresponding queue to frame the measurement equation. Real-time estimation of queue was carried out using Kalman filter estimation scheme and delays were estimated from the queue polygons developed. The queue and delay values estimated were comparable with the actual values indicating that the developed method can be used for real-time estimation of queue and delay. The estimation scheme can be used for Advanced Traveller Information Systems (ATIS) for mixed traffic conditions.

关键词： Probability distributions  

摘要： The aim of this study is to solve the problem of RFID reader antenna deployment when an obstacle in the environment or the material itself is an obstacle. The article establishes a new reader antenna constraint model based on the rectangular obstacle RFID antenna deployment optimization environment model and the reader antenna sensing model containing Gaussian distribution noise probability and applies the improved firefly algorithm to find the optimum with coverage rate, interference degree, and load balance function as multiobjective functions. First, to obtain a uniform traversal of the target space, and a cube mapping is applied for chaos initialization. Second, a weighting model is proposed to control the speed of firefly variation and combine the variable step strategy of elite individuals to expand the movement step of elite individuals and reduce the movement step of nonelite individuals to improve population diversity. Finally, to improve the algorithm's continuous optimality-seeking ability, a Gaussian variation operation strategy based on elite fireflies is introduced to ensure the algorithm's optimality-seeking throughout the process.

摘要： In order to solve the problem that the traditional e-commerce logistic distribution path optimization algorithm takes a long time to find the optimal path, this paper presents the best ways for exporting based on RFID and sensor technology. First, the integration algorithm is used to divide the logistic area;then, the purpose of various goals to improve the performance of the export consists of five things: measuring weight, measuring time, measuring the importance of customers, window measuring time, and general measurement method. Finally, determine the weight distribution target and find ways to better the target according to the differences in e-commerce logistics to improve the efficiency of e-commerce logistic distribution methods. Experimental results show that the optimal time to find the optimal method is less than 2 minutes, while the custom algorithm takes 3 minutes to find the optimal method. Conclusion. The logistic distribution optimization algorithm based on RFID and sensor technology takes less time to find a better way than the traditional process and can meet the needs of e-commerce logistic distribution layer standard optimization.

关键词： Radio frequency identification (RFID)  

摘要： This article presents a cost-efficient flexible chipless radio frequency identification (RFID) tag with wireless humidity sensing, which is fabricated by in situ metallization and inkjet printing techniques. The inkjet printing technique is applied to print the mask for RFID antenna, which is designed with frequency-encoding simulation by a high-frequency structure simulator (HFSS). A high-quality patterned Ag antenna is realized by the in situ metallization of a polyimide (PI) film, leading to strong adhesion between the Ag antenna and PI substrate. The patterned Ag antenna of the chipless RFID tag consists three parallel dipole resonators, one of which is sensitive to humidity, while the other two are utilized to encode and store data. As a result, a 2-bit chipless RFID with high humidity sensitivity based on a Ag/PI film is developed, which displays excellent flexibility and good mechanical stability. The performance of the fabricated tag shows good agreement with the simulation results. Moreover, the tag is applied to detect the water source, where the resonance frequency shows good linearity versus the distance to the water source. These results demonstrate that the proposed chipless RFID tag with humidity sensing has a 2-bit storage capacity, high humidity sensitivity, excellent mechanical properties, and long-term stability, confirming a cost-efficient preparation process for flexible electronics.

关键词： Chipless radio-frequency identification (RFID) sensing   cold chain monitoring   food quality monitoring   oil phase changes for sensing   time-temperature (TT) sensing  

摘要： This article presents a low-cost, food-safe chipless radio-frequency identification (RFID) time-temperature (TT) sensor that operates in the 3-5 GHz [ultra wide band (UWB)] band. The sensor is capable of detecting three types of TT exposure events typically found in cold chain operations. We achieve this by interfacing a chipless RFID tag with three cooking oils having melting points of 142 degrees C, 17.3 degrees C, and 23.6 degrees C, respectively. The three TT events induce unique changes in the oil phase (solid to liquid) for all three oil types and this manifests as distinct signal responses from the chipless RFID tag. We discuss how logistic providers can infer TT exposure data at key steps in the cold chain via quantitative data obtained from these responses. Planned sensor improvements and future research directions are also discussed.

关键词： Difference co-array   direction of arrival (DOA)   indoor localization   radio-frequency identification (RFID)   sparse array  

摘要： With the rapid growth of the Internet of Things (IoT), the radio-frequency identification (RFID) technology has been recognized as an effective and low-cost solution for many IoT applications. In this article, we study the problem of utilizing a sparse RFID tag array for backscatter indoor localization. We first theoretically and experimentally validate the feasibility of using sparse tag arrays for the direction of arrival (DOA) estimation. We then present the SparseTag system, which leverages a novel sparse tag array for high-precision backscatter indoor localization. The SparseTag system includes sparse array processing, difference co-array design, DOA estimation using a spatial smoothing-based method, and a localization method. A robust channel selection method based on the RFID tag array is adopted for mitigating the multipath effect. The SparseTag system is implemented with commodity RFID devices. Its superior performance is validated in two different environments with extensive experiments and comparison to baseline schemes.

关键词： Internet of things  

摘要： With the increasing development of information science and technology and the vigorous use and promotion of new technologies, profound changes have taken place in all aspects of our daily life. With this huge change, the IoT industry was born. And it analyzes and processes the large amount of data generated between them, and finally, it helps the development of the economy. The RFID system studied in this paper is the radio frequency identification system, which is an automatic signal identification system. The relationship between the RFID system and the Internet of Things is that the former will obtain a large amount of Internet of Things information data by identifying the Internet of Things. However, it is difficult to guarantee the analysis and processing of data and the security of data in the RFID system. This paper aims to study the effective processing and security guarantee of a large amount of data obtained by the RFID system after processing the identification of the Internet of Things. It is expected to overcome the problems of conventional related art. This paper proposes the encryption technology for the Internet of Things RFID system, as well as the corresponding algorithm, and establishes a processing system for information data. The experimental results of this paper show that the cryptographic mechanism run by the algorithm PECC has better security performance compared with other cryptographic mechanisms, and its computational complexity can be reduced by 28.35%.