Passive Ultra-high Frequency Radio Frequency Identification Systems Research Articles

Efficient Modeling of On-Body Passive UHF RFID Systems in the Radiative Near-Field

A novel method is presented to accurately determine the operational range of an on-body, passive ultrahigh-frequency (UHF) radio frequency identification (RFID) system operating in the radiative near field, based on its far-field radiation patterns. To this end, an efficient algorithm based on 3-D multipole expansion of the electromagnetic fields is formulated. By combining the new operator with the simulated or measured stand-alone far-field radiation patterns of the on-body RFID system, a comprehensive and accurate range determination is obtained. Compared with commercial software tools and measurements, we prove the accuracy and improved speed of the novel technique.

Collision Detection and Signal Recovery for UHF RFID Systems

In this paper, we present a novel high-throughput anti-collision algorithm for passive ultrahigh-frequency (UHF) radio-frequency identification (RFID) systems. Our algorithm utilizes signal recovery techniques of collided tag signals to both recover tag communications and obtain an accurate count of all tags in the field. Passive UHF RFID systems are used for long-range passive communications for applications including supply chain management and electronic tolling. Anti-collision algorithms are used to ensure successful RFID tag communications due to the likelihood of multiple tags being in the field and attempting to communicate simultaneously. The limited on-tag functionality necessitates the use of simple anti-collision algorithms such as a dynamic frame slotted Aloha (DFSA) algorithm. With our novel collision detection and signal recovery anti-collision algorithm, the RFID reader can retrieve multiple valid communications from each collided slot in a DFSA-based anti-collision protocol, while our algorithm allocates an optimal number of slots resulting in more collided but recoverable slots and fewer empty slots. Our algorithm achieves a nearly 100% throughput improvement with an expected throughput of 0.85 compared with an expected throughput of 0.426 for a standard DFSA algorithm. The reader receiver with the proposed algorithm is implemented in a field-programmable gate array and the whole reader system is verified using the communication tests with commercial tags. According to the synthesized results in an SMIC 0.13- $\mu \text{m}$ CMOS technology, the collision detection and signal recovery module consumes about 135k GE. Note to Practitioners —Signal recovery methods are capable of extracting information from collided signals. In this paper, we introduce and analyze a signal recovery method based on the voltage histogram of the received signal. Both the original signals and the number of collided signals are recovered. The information of tags is used by our novel algorithm to increase the system throughput in DFSA-based anti-collision algorithms. The recovered signals allow our algorithm to directly obtain the tag identifier. By determining the number of collided signals, our algorithm is able to calculate an accurate estimate of the total number of tags in the reader’s field. With signal recovery and an accurate tag count, our algorithm is able to reduce the total number of slots needed to identify all tags, thereby increasing the throughput. We present a novel frame length optimization method that increases throughout by shrinking the number of slots, thereby intentionally causing collisions and reducing the total number of empty slots. In addition, we present a hardware implementation of our novel method that is suitable for integration into RFID readers. When the signal strengths of the tags in collision in the in-phase or quadrature path are not close to each other, the performance of our method is much better than that of the traditional method in which the collision signal is treated as ineffective and ignored.

An Energy-Efficient ECC Processor of UHF RFID Tag for Banknote Anti-Counterfeiting

In this paper, we present the design and analysis of an energy-efficient 163-b elliptic curve cryptographic (ECC) processor suitable for passive ultrahigh frequency (UHF) radio frequency identification (RFID) tags that are usable for banknote authentication and anti-counterfeiting. Even partial public key cryptographic functionality has long been thought to consume too much power and to be too slow to be usable in passive UHF RFID systems. Utilizing a low-power design strategy with optimized register file management and an architecture based on the Lopez-Dahab Algorithm, we designed a low-power ECC processor that is used with a modified ECC-DH authentication protocol. The ECC-DH authentication protocol is compatible with the ISO/IEC 18000-63 (“Gen2”) passive UHF RFID protocol. The ECC processor requires 12 145 gate equivalents. The ECC processor consumes 5.04 nJ/b at a frequency of 960 kHz when implemented in a 0.13- $\mu \text{m}$ standard CMOS process. The tag identity authentication function requires 30 600 cycles to complete all scalar multiplication operations. This size, speed, and power of the ECC processor makes it practical to use within a passive UHF RFID tag and achieve up to 1500 banknote authentications per minute, which is sufficient for use in the fastest banknote counting machines.

Dual port temperature sensor tag for passive UHF RFID systems

Purpose – The purpose of this paper is to develop a novel totally passive, wireless temperature sensor tag based on ultra high-frequency (UHF) radio frequency identification (RFID) technology. The temperature-sensing functionality is enabled by using distilled water embedded in the tag antenna substrate. The novel sensor tag is designed to provide wireless temperature readings comparable to a commercial thermocouple thermometer even in environments with high levels of interference, such as reflections. The structure of the novel sensor tag is aimed to increase its usability by minimizing user-created errors and to simplify the measurement procedure. Design/methodology/approach – The sensor tag is based on a dual port sensing concept in which two ports are used to obtain sensor readings. By utilizing two ports instead of one, the effects of environmental interference, tag-reader antenna orientation and distance can be effectively minimized. Two alternative methods of acquiring the sensor reading from the operating characteristics of the two ports are presented and discussed. Findings – Temperature measurements in practical scenarios show that by utilizing the dual port sensing concept, the developed tag produces temperature readings wirelessly which are comparable to readings from a commercial thermocouple thermometer. Research limitations/implications – The concept of dual port sensing was shown and two alternative methods on extracting sensor readings from the differences in the port operating characteristics were introduced and discussed. In this paper, the dual port sensing concept is utilized in creating a temperature sensor tag; however, the same concept can be utilized in a variety of passive wireless sensors based on UHF RFID technology. This enables a new approach in designing accurate, easy to use and easily integrable passive sensors. The dual port sensing concept is in its early stages of development; its accuracy could be improved by developing more advanced data post-processing techniques. Practical implications – The accuracy of a passive dual port UHF RFID-enabled temperature sensor tag is proven to be sufficient in many applications. This indicates that other sensor types utilizing the dual port sensing concept can reach high levels of accuracy as well. Furthermore, the passive RFID-enabled sensors based on the dual port sensing concept are superior in usability versus sensor tags equipped only with a single port. Therefore, dual port sensing concept in passive UHF RFID-enabled sensor tags could make such sensors more attractive commercially and lead to truly widespread ubiquitous sensing and computing. Originality/value – This paper presents a novel passive, wireless temperature sensor tag for UHF RFID systems. The sensor tag utilizes a new structure which allows tight integration of two ports and two tag antennas. The accuracy of the developed tag is confirmed throughout measurements and it is found comparable to the accuracy of commercial thermometers in practical measurement scenarios. Moreover, the paper presents a dual port sensing concept and two readout methods based on the concept which are aimed to increase the accuracy and usability of all kinds of UHF RFID-enabled sensor tags.

Long Range Passive UHF RFID System Using HVAC Ducts

In this paper, the use of hollow metal heating, ventilating, and air-conditioning (HVAC) ducts as a potential communication channel between passive ultrahigh-frequency (UHF) radio-frequency identification (RFID) readers and tags is studied. HVAC ducts behave as electromagnetic waveguides with much lower signal attenuation compared to free-space propagation. This low-loss electromagnetic environment allows one to greatly increase the communication range of passive UHF RFID systems and build, for example, a long range passive sensor network spanning an entire infrastructure such as a large building. In this work, it is shown both theoretically and experimentally that the read range of passive UHF RFID systems can be increased by multiple times compared to operation in a free-space environment.

Passive UHF RFID in Paper Industry: Challenges, Benefits and the Application Environment

Radio frequency identification (RFID) systems for the paper industry is an emerging research topic due to the need for an automated identification system for the paper industry which would carry on the identification codes of paper and board reels throughout their life cycle. This paper discusses the application of passive ultra-high frequency (UHF) RFID systems to the paper industry. Challenges, benefits, and the application environment of using passive UHF RFID systems in the paper industry are presented and discussed. The major challenges are development of globally operable tag antenna designs and integration of reader units and reader antennas to paper handling machinery. To confront and solve these challenges, this paper presents novel tag antenna designs for paper and board reel identification and proposes solutions for reader and reader antenna integration to paper handling machinery. In addition, the identification locations within the paper reel supply chain and the effects of RFID systems to supply chain visibility are presented and discussed. In addition, test results of using passive UHF RFID systems in the paper industry environment are presented.