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关键词： Axial Ratio (AR)   Coplanar Waveguide (CPW)   Circularly Polarized (CP)   Global Positioning System (GPS)   RFID reader   Ultrahigh Frequency (UHF)  

摘要： A novel compact printed broadband circularly polarized slot antenna is proposed in this paper. The antenna consists of an inverted L-shaped coplanar waveguide feed structure and a square ground plate loaded with three rectangular slots. The antenna achieves good impedance matching and circular polarization characteristics by adjusting the size of the L-shaped band and the rectangular slot. The simulation results show that the antenna has a 10-dB impedance bandwidth of 1360 MHz (690-2050 MHz) and a 3 dB axial ratio (AR) bandwidth of 490 MHz (770-1260 MHz). Additionally, the maximum gain reached 4.02 dBi. The antenna proposed in this paper can be applied to UHF RFID and GPS frequency bands.

关键词： indoor localization   radio frequency identification (RFID)   Kalman filter (KF)   semi-definite programming (SDP)  

摘要： State-of-the-art radio frequency identification (RFID)-based indoor autonomous vehicles localization methods are mostly based on received signal strength indicator (RSSI) measurements. However, the accuracy of these methods is not high enough for real-world scenarios. To overcome this problem, a novel dual-frequency phase difference of arrival (PDOA) ranging-based indoor autonomous vehicle localization and tracking scheme was developed. Firstly, the method gets the distance between the RFID reader and the tag by dual-frequency PDOA ranging. Then, a maximum likelihood estimation and semi-definite programming (SDP)-based localization algorithm is utilized to calculate the position of the autonomous vehicles, which can mitigate the multipath ranging error and obtain a more accurate positioning result. Finally, vehicle traveling information and the position achieved by RFID localization are fused with a Kalman filter (KF). The proposed method can work in a low-density tag deployment environment. Simulation experiment results showed that the proposed vehicle localization and tracking method achieves centimeter-level mean tracking accuracy.

关键词： Radio frequency identification (RFID)  

摘要： A nested octagon passive chipless radio frequency identification (RFID) tag with an encoding capacity of 12 bits has polarization diversity and 1:1 slot-to-bit correspondence. Its compact 23 x 23 mm footprint yields a bit density of 2.26 bits/cm(2). The tag is fabricated on a flexible Rogers RT/duroid 5880 laminate.

关键词： Machinery  

摘要： RFID technology can help manufacturers control access to critical hardware and software. What’s the best way to ensure product quality and production uptime in industrial automation? Make sure that only trained and authorized people can access the programmable controllers. A typical assembly plant is equipped with an assortment of machinery and robots to fabricate and assemble various products.

关键词： RFID   excess inventory   revenue‐   cost‐   sharing contract   retail supply chain   bargaining game   wholesale‐   price contract  

摘要： This paper considers a supply chain consisting of one supplier and one retailer who jointly invest in item-level radio frequency identification (RFID) by considering their demands and inventories. Since the supplier can be negative to adopt RFID, the main objective of this study is to design an effective mechanism that maximizes the profits of both players and the whole supply chain by implementing item-level RFID. For this objective, we propose a novel revenue-cost-sharing (RCS) contract based on the bargaining game as the incentive to encourage the implementation, and numerical results show that the RCS contract is considerably more effective than the wholesale-price contract for supply chain coordination. Moreover, we show that the retail supply chain can be coordinated perfectly under the RCS contract when the thresholds of the revenue/cost sharing rates are set appropriately. This study provides significant managerial insight into the incentive and coordination strategy to implement item-level RFID in the retail supply chain.

关键词： Wireless communication   Wireless sensor networks   Plants (biology)   Soil   Agriculture   Sensors   Intelligent sensors  

摘要： With the advent of emerging technologies, traditional agriculture practices are now shifting towards the “smart” approach. Smart agriculture aims to automate most aspects of the plant growing process to save the labor and improve the efficiency, the yield and quality of the crops/harvest. In recent years, Radio Frequency Identification (RFID) sensing technology has emerged and unleashed a new series of applications in the field of agriculture. This paper first introduces RFID sensing technology, then surveys its applications to the four areas of agriculture: plant growing environment, soil conditions, plant growth, and the quality of the harvests. The paper aims to identify the uniqueness of RFID sensing technology in solving agriculture issues and its limitations.

关键词： chipless-RFID   motion control   electromagnetic encoders   3D-printing   dielectric permittivity   microstrip technology  

摘要： This paper presents electromagnetic encoders useful for chipless-RFID and motion control applications. The encoders consist in a pair of linear chains of rectangular apertures implemented by means of 3D printing. One of these chains is periodic and acts as a clock, whereas the other chain contains an identification (ID) code. With these two aperture chains, the ID code can be synchronously read, so that the relative velocity between the tag and the reader is irrelevant. Additionally, it is shown in the paper that by properly designing the reader, it is possible to determine the motion direction. The sensitive part of the reader is a microstrip line loaded with three complementary split ring resonators (CSRRs) etched in the ground plane and fed by three harmonic signals. By encoder motion, the characteristics of the local medium surrounding the CSRRs are modified, and the harmonic signals are amplitude modulated (AM) at the output port of the line, thereby providing the clock signal (which gives the encoder velocity), the ID code (providing also the quasi-absolute position) and the direction of motion. A fabricated prototype encoder is characterized by reading it with a dedicated reader.

关键词： RFID   NoSQL   Cassandra   Indian Public Distribution System (PDS)   Supply chain traceability  

摘要： Purpose The purpose of this paper is to design a supply chain database schema for Cassandra to store real-time data generated by Radio Frequency IDentification technology in a traceability system. Design/methodology/approach The real-time data generated in such traceability systems are of high frequency and volume, making it difficult to handle by traditional relational database technologies. To overcome this difficulty, a NoSQL database repository based on Casandra is proposed. The efficacy of the proposed schema is compared with two such databases, document-based MongoDB and column family-based Cassandra, which are suitable for storing traceability data. Findings The proposed Cassandra-based data repository outperforms the traditional Structured Query Language-based and MongoDB system from the literature in terms of concurrent reading, and works at par with respect to writing and updating of tracing queries. Originality/value The proposed schema is able to store the real-time data generated in a supply chain with low latency. To test the performance of the Cassandra-based data repository, a test-bed is designed in the lab and supply chain operations of Indian Public Distribution System are simulated to generate data.

关键词： Bit error rate  

摘要： In an ultrahigh frequency (UHF) radio frequency identification (RFID) system, the throughput can be greatly improved by collision resolution on a physical layer when tags collide, and high-performance coding technology can improve the bit error rate (BER) performance of the physical-layer separation. Most of the traditional physical collision resolutions focus on the code with a single subcarrier. This paper pays more attention to Miller code with multiple subcarriers and proposes a novel physical-layer separation method based on the Miller code. In this method, the separated collision signals are multiplied by clock signals with the same frequency as the subcarrier to complete the frequency shift. And then, a coherent demodulation and a low-pass filter are used to remove high-frequency separation noise. In the simulation, the Miller code with more subcarriers has lower BER than FM0 code with a single carrier. Especially when Miller 8 is selected, the separation efficiency and BER performance of the proposed method are 4 dB higher than those of the traditional XOR method at lower SNR.