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关键词： Antennas   Planar waveguides   Switches   UHF antennas   Directive antennas   Electric fields   Receiving antennas   Planar waveguide antenna   reader antenna   UHF RFID   switching diversity  

摘要： UHF near-field RFID reader antenna based on leaky waveguide is proposed and the performance is evaluated using numerical simulation and experiment. In order to suppress the standing wave along transverse direction, a pair of notches is placed on the transverse edge of the mesh layer of the planar waveguide. Diversity operation by switching impedance of the end terminal of the planar waveguide antenna is also introduced to suppress the standing wave effect along longitudinal direction. Numerical simulation and experiment show that the near-field null lines parallel to the longitudinal direction is almost removed by the presence of the notches and the distribution of the field strength becomes almost uniform because of the utilization of the switching diversity. It is demonstrated that the reading performance of the commercial RFID tags is greatly improved by using the proposed RFID reader antenna with the diversity operation of termination impedance.

关键词： Microstrip antenna arrays   aperture coupled antennas   millimeter (mm)-wave measurements   radiofrequency identification   RFID tags   sensors  

摘要： An 8 x 8 linearly-polarized (LP) aperture-coupled microstrip patch antenna (ACMPA) array is presented for a long-range millimeter (mm)-wave chipless RFID tag-sensor reader. This antenna array is capable of reading the linearly-polarized (LP), orientation-insensitive (OI), and cross-polarized (CP) chipless RFID tags and sensors in the mm-wave frequency band from a long distance. A systematic approach is followed for developing the LP ACMPA array, which operates over the 22-27 GHz frequency band with 22 dBi gain. At first, a single antenna element is designed, which is followed by the design of a 1-64-way corporate feed network. Then, the 8 x 8 mm-wave LP ACMPA array is designed, optimized, fabricated, assembled, and tested. After that, the assembled antenna is used for measuring ten thermal printed mm-wave OI tags on paper from 30 cm and three CP tags on Taconic from 200 cm distance to validate its functionality in long-distance tag reading. Finally, the effects of different parameters on LP ACMPA are studied, which are used next for developing a novel step-by-step guideline for designing the LP ACMPAs with a new set of specifications. This high gain antenna array can be used commercially in a long-range mm-wave chipless RFID tag and sensor reader due to its low profile, low-cost, and lightweight structure.

关键词： RFID tags   Estimation   Kalman filters   Motion estimation   Antenna measurements   Reflection   COTS   Kalman filter   motion estimation   RFID   real-world application   sensor fusion  

摘要： Motion estimation of RFID tags has been shown to be possible using phase information, while position estimation is possible using received signal strength (RSS). This article combines phase and RSS information using a Kalman filter as sensor fusion technique. It compares the combined RSS and phase fusion Kalman filter technique for motion estimation with the phase only Kalman filter, exponential smoothing filter and raw phase motion estimation excluding a Kalman filter. The influence of frequency hopping broadcasting regulations on the performance of these techniques is investigated, an aspect that has not been properly addressed before. The primary factors found in real-world scenarios that have an effect on motion estimation techniques are identified as multipath reflections and the presence of multiple tags. The influence of such non-ideal environments are characterized and specific vulnerabilities of these techniques are investigated. Finally, the shortcoming of these techniques as well as advantages and possible environments where this technique can be successfully used are discussed.

关键词： Radiofrequency identification   Wireless sensor networks   Software radio   Communication system security   Location awareness   Internet of Things  

摘要： In recent years, RF identification (RFID) technology in the ultrahigh-frequency (UHF) range has become increasingly important in many applications, especially in the context of both the Internet of Things (IoT) and Industry 4.0. RFID is no longer simply a matter of identification; today, it is mainly concerned with recording data from the surrounding environment. As a result, researchers are working on the integration of sensors (or even small actuators) in passive RFID transponders (tags) for a variety of different applications and also on the localization and tracking of RFID tags attached to various objects and machinery. Another key aspect in UHF RFID technologies is security, as the data transmitted may be confidential and should not be shared with third parties. For the fast verification of novel algorithms in localization and novel protocols for security, wireless testbeds allow swift verification of these designs under real-world or real-time conditions [1]. Wireless testbeds are widely used in research and require scalability, modularity, and extendibility of the hardware and software. These needs can be achieved by using software-defined radios (SDRs). In the case of UHF RFID, SDR-based RFID readers have been developed and used as wireless testbeds for enhancements in UHF RFID systems.

关键词： Special issues and sections   Radiofrequency identification   Location awareness   Radio frequency   Digital signal processing   Backscatter  

摘要： The articles in this special section focus on the use of digital signal processing (DSP) techniques for radio frequency identification systems (RFID).

关键词： Healthcare   RFID   Privacy   Security   Authentication   Indistinguishability obfuscation  

摘要： RFID technology, which is concerned as one of the core technologies of Internet of Things, has been widely deployed in healthcare environment and brings a lot of convenience for people's daily life. However, the security and privacy challenges of RFID authentication protocols are receiving more and more attention. One of the problems is that the current RFID protocols usually use a backend server to store the detailed information of tagged objects, which may lead to the issue of information leakage if the server is hacked or attacked by the adversary. To address this challenge, in this paper, we propose a security enhanced RFID authentication protocol for healthcare environment using the technique of indistinguishability obfuscation, which prevents the leakage of sensitive data from the backend server. Meanwhile, we extend the protocol to fit for the scenario of cloud environment where the tags' information is stored in the cloud server. To our knowledge, our protocols are the first applications of indistinguishability obfuscation in the field of RFID authentication system. Moreover, our protocols are scalable and practical, and they are analyzed to achieve most of the security properties of the RFID system.

关键词： Alcohol   HM2   Radiofrequency identification   RFID   Oxytocin   Two-bottle choice   Socially housed   Sex differences   Ethanol preference   Drink size  

摘要： Rationale The majority of preclinical studies assessing treatments for alcohol use disorder use singly housed animals. Because social factors affect ethanol intake, studies investigating such treatments in group-housed animals are needed. Objectives We investigated the effects of repeated oxytocin treatment on ethanol intake in socially housed male and female C57BL/6J mice. Methods We used the novel "Herdsman" system implementing radiotracking technology to measure individual ethanol intake in group-housed animals. Mice were housed in same-sex groups of 4 per cage and exposed to 3 and 6% ethanol solutions. After baseline drinking was established, half of the animals in each cage received repeated intraperitoneal injections of 3 mg/kg oxytocin. Results During baseline, females consumed more ethanol than males partly due to greater number of ethanol drinks taken by females. We also observed a gradual development of two peaks of ethanol consumption during the dark phase of the circadian cycle. The effects of oxytocin treatment were short-acting and varied across treatment days. Oxytocin significantly decreased ethanol intake on three out the four treatment days. On the fourth treatment day, oxytocin decreased ethanol intake and water intake. Conclusion The greater intake of ethanol in female mice is associated with the number of drinks taken. Oxytocin treatments not only cause an acute decrease in ethanol consumption, but can also change in efficacy over time. While the oxytocin system remains a promising therapeutic target for alcoholism, studies investigating longer periods of repeated oxytocin treatment and those using additional oxytocin receptor agonists are warranted.

关键词： Impedance   Backscatter   RFID tags   Integrated circuit modeling   Transistors   Modulation   Resistance   Radio frequency identification   RFID   backscatter radio   propagation characterization   link budget  

摘要： This article presents a circuit impedance model and results of propagation characterization at 26.5 GHz and 300 GHz for a new type of RFID tag that is based on digital electronics. This RFID tag leverages the backscatter radio generated from switching of transistors inside digital circuits, which does not need antennas or RF front-end circuits thereby further reducing the device's form factor. Moreover, the proposed RFID tag is compatible with a wide range of interrogating frequencies and can be implemented on existing electronics without additional cost. The proposed circuit impedance model explains the modulation mechanism of this new backscatter radio and provides an estimation of digital circuits' impedance using SPICE model parameters. Based on the proposed circuit impedance model, we develop a modified modulation loss factor to estimate the modulation loss resulting from the switching activity of the digital electronics. Furthermore, propagation characterization is conducted at 26.5 GHz and 300 GHz, where the shadowing gain for the carrier power and the backscattered power is characterized as 3.93 dB and 0.96 dB at 26.5 GHz, and 1.01 dB and 0.52 dB at 300 GHz, respectively, showing that the backscatter channel can provide a more reliable link that is resistant to the constructive and destructive interference from the multipaths as compared to the carrier channel.

关键词： Antennas   Folded dipole   loop antenna   near-field radio frequency identification (RFID)   RFID technology   textile antenna   wearable antennas   Yagi-Uda antenna  

摘要： A novel combination of loop and dipole antennas into a Yagi-like structure is here investigated to implement a wearable antenna. The textile antenna is designed for being integrated into a smart glove together with a compact UHF-radio frequency identification (RFID) reader. A number of compact Yagi-like textile structures have been analyzed and compared, which consist of a rhombus-shaped folded dipole and parasitic elements acting as either a reflector or directors. The latter are needed to focus the field out of the operator hand, so limiting the radiation toward undesired directions. Four compact Yagi-like layouts (with one or two directors, with one director and one reflector, and with one reflector and two directors) are developed on a stretchable fabric and their performance is measured in terms of reflection coefficient and near-field distribution. Read range performance is measured by using COTS RFID reader and tags.

关键词： Software defined networking   Transmitting antennas   Receiving antennas   UHF measurements   UHF antennas   Hardware   Radiofrequency identification  

摘要： In this article, we discuss how one can make, with modern and low-cost tools, a software-defined ultra high-frequency (UHF) RF identification (RFID) reader. Since we have chosen to leave the discussion of the top-level reader implementation until the very end, an introductory outline is warranted to help guide our audience. We first provide the uninitiated with some background context by answering four questions: What is UHF RFID? How does it work? What happened with UHF RFID? And, finally, what's next? That is, how do we envision the technology evolving in the future with the support of a broad community? Second, we describe the fundamental metrics and performance budgeting of RFID readers. Following this, we provide an overview on how to design, make, and automatically tune two critical components of UHF RFID readers: the antenna and transmit leakage canceller. Third, we delve even further into details of the transmit leakage canceller. Finally, we describe the complete high-level architecture of a proposed low-cost reader.