PRLS-INVES: A General Experimental Investigation Strategy for High Accuracy and Precision in Passive RFID Location Systems

Due to cost-effectiveness and easy-deployment, radio-frequency identification (RFID) location systems are widely utilized into many industrial fields, particularly in the emerging environment of the Internet of Things (IoT). High accuracy and precision are key demands for these location systems. Numerous studies have attempted to improve localization accuracy and precision using either dedicated RFID infrastructures or advanced localization algorithms. But these effects mostly consider utilization of novel RFID localization solutions rather than optimization of this utilization. Practical use of these solutions in industrial applications leads to increased cost and deployment difficulty of RFID system. This paper attempts to investigate how accuracy and precision in passive RFID location systems (PRLS) are impacted by infrastructures and localization algorithms. A general experimental-based investigation strategy, PRLS-INVES, is designed for analyzing and evaluating the factors that impact the performance of a passive RFID location system. Through a case study on passive high frequency (HF) RFID location systems with this strategy, it is discovered that: 1) the RFID infrastructure is the primary factor determining the localization capability of an RFID location system and 2) localization algorithm can improve accuracy and precision, but is limited by the primary factor. A discussion on how to efficiently improve localization accuracy and precision in passive HF RFID location systems is given

Adaptability evaluation of electronic vehicle identification in urban traffic: a case study of Beijing

Tehnologija elektroničke identifikacije vozila (EVI) često se uvodi kako bi se izvršila naplata cestarine u vrijeme zagušenja prometa. U radu je predstavljena metoda za procjenu prilagodljivosti EVI-a te razmatrana provedivost te tehnologije u nadzoru zagušenja na temelju procjene. Najprije je određena dinamika sustava u svrhu kvalitetne analize učinka EVI-a na sustav gradskog prometa s nizom povratnih informacija. Zatim je izgrađen model za procjenu prilagodljivosti EVI-a temeljen na analizi glavnih komponenti (principal component analysis - PCA) i analizi dobivenih podataka (data envelopment analysis – DEA). Zbog brojnih izlaznih varijabli sastavljen je PCA model kako bi se smanjile veličine varijabli. Nakon toga, predstavljena su dva scenarija primjene EVI-a za naplatu cestarine u vrijeme zagušenja prometa u Pekingu. Scenario 1 je obuhvatio 5 % ukupnog broja vozila, kao i naplatnu zonu unutar 2nd Ring Road. U međuvremenu, scenarijem 2 je obuhvaćeno 5 % više vozila i uključen je Zhongguancun West District baziran na scenariju 1. Prema dobivenim rezultatima procjene, scenarij 1 je označen kao u osnovi prilagodljiv, a scenarij 2 kao prilagodljiv, odnosno scenarij 2 je prepoznat kao prilagodljiviji i izvodljiviji nego scenarij 1. Osim toga, analizirali su se trendovi prilagodljivosti dvaju scenarija u periodu između 2003. i 2012. te se pokazalo da su bili u skladu s postojećom situacijom. Procjenjivanjem prilagodljivosti tih tehnologija prije njihove primjene u praksi, ti su rezultati značajno utjecali na određivanje područja od prioriteta u primjeni tehnologije interneta stvari (Internet of Things-IoT).Electronic vehicle identification (EVI) technology is often introduced to implement congestion-based toll. This paper presented an ex ante evaluation method for EVI adaptability and discussed the feasibility of this technology in congestion charge on the basis of assessment. First, system dynamics was introduced to qualitatively analyze the effect of EVI on urban traffic systems with feedback chains. An EVI adaptability evaluation model was then developed based on principal component analysis (PCA) and data envelopment analysis (DEA). Given numerous output variables, a PCA model was built to reduce variable dimensionalities. Subsequently, two scenarios of EVI application under a congestion-based toll in Beijing were presented and calculated according to field data. Scenario 1 covered 5 % of the total vehicles, as well as the toll zone within the 2nd Ring Road. Meanwhile, scenario 2 covered 5 % more vehicles and included Zhongguancun West District based on scenario 1. According to evaluation result, the adaptability classifications of scenarios 1 and 2 were identified as basic adaptive & adaptive respectively, and that scenario 2 was more adaptive and feasible than scenario 1. In addition, the adaptability trends of the two scenarios between 2003 and 2012 were analyzed and proved to be consistent with the practical situation. The findings had significant implications for policy makers who determined the priority domains of internet of things technology applications by assessing the adaptability of these technologies before deployment

Passive RFID-Based Inventory of Traffic Signs on Roads and Urban Environments

This paper presents a system with location functionalities for the inventory of traffic signs based on passive RFID technology. The proposed system simplifies the current video-based techniques, whose requirements regarding visibility are difficult to meet in some scenarios, such as dense urban areas. In addition, the system can be easily extended to consider any other street facilities, such as dumpsters or traffic lights. Furthermore, the system can perform the inventory process at night and at a vehicle’s usual speed, thus avoiding interfering with the normal traffic flow of the road. Moreover, the proposed system exploits the benefits of the passive RFID technologies over active RFID, which are typically employed on inventory and vehicular routing applications. Since the performance of passive RFID is not obvious for the required distance ranges on these in-motion scenarios, this paper, as its main contribution, addresses the problem in two different ways, on the one hand theoretically, presenting a radio wave propagation model at theoretical and simulation level for these scenarios; and on the other hand experimentally, comparing passive and active RFID alternatives regarding costs, power consumption, distance ranges, collision problems, and ease of reconfiguration. Finally, the performance of the proposed on-board system is experimentally validated, testing its capabilities for inventory purposesMinisterio de Economía y Competitividad TEC2016-80396-C2-2-

RFID-based smart shelving storage systems

In recent years, RFID systems that are widely applied for the identification of objects and people in radio frequency, are also going to be applied used for localization purposes. In indoor applications (apartments, shopping malls, airports), conventional solutions can use a number of signal parameters: instant of arrival ( Time of Arrival , Time Difference of Arrival, TOA, TDOA), angle information (Angle of Arrival, AOA), phase information (Phase Difference of Arrival , PDOA ) or the amplitude of the received signal (Received Signal Strength Indicator, RSSI). There are also some scenarios with small dimensions where the location can be extremely useful. For example, in a hospital, a better service could be offered through RFID technology, as it can add more control to prevent human errors. Indeed, RFID technology can be useful for correct patient drug supply, dose recording, accurate dispensing, anti-counterfeiting as well as replenishment ordering; besides, it simplifies the information transfer between doctors and nurses (e.g. allergic reactions or drug treatment). In retail industry, real-time inventory based on RFID allows to monitor actual customer demand for products, to prevent an out-of-stock situation by timely replenishing orders, to increase sales through additional services (e.g. fitting rooms with smart mirrors providing suggestions to the customer). In food and restaurant industry, RFID technology allows for a better food control, as for example avoiding expired products sale. In this framework, RFID-based smart shelves, smart freezers, and proximity point readers have been developed in libraries, hospitals and retail industries. In Chapter I, a brief introduction on RFID systems will be presented, in particular describing the main components involved and the principle of operation. It will be described what is proposed in literature about RFID smart shelf and localization algorithms, with particular attention to the methods exploiting the RSSI information. In Chapter II, an exhaustive experimental study by using off-the-shelf reader, antennas and tags, will be presented with reference to a wooden drawer filled with drug boxes. The LDA algorithm (supervised classifier) will be compared with the K-Means clustering algorithm (unsupervised classifier), to validate the proposed method. The procedure to get several RSSI average samples during the drawer sliding actions is described, and classification performance is investigated. First of all, an RSSI analysis is described with reference to a static configuration of the drawer (not sliding). Then, two classification algorithms are compared by considering a different number of drawer sub-regions. In the second part, the algorithm exploiting the drawer sliding is described and system performance is illustrated to verify the classification capability in a two-region drawer. In Chapter III, a localization technique for smart bookshelves based on UHF-RFID systems is presented. Two off-the-shelf reader antennas attached to the bookshelf columns, one in front of the other, are used as an alternative to large-area thin planar antennas integrated onto the shelf top. Two scenarios were considered: the first one with a shelf that is D = 97 cm long, and the second one with D = 150 cm. Exploiting RSSI data acquired by the two antennas, a clustering algorithm is implemented to classify tagged books within one of the regions the shelf has been subdivided into. Preliminary results of the system performance analysis have been compared with simulations to demonstrate that is possible to create an interference region in different sectors on the shelf, through a proper phase shift between the feed currents of the two antennas. The system requires a power divider, a switch, variable phase shifters and finally a fixed or variable power attenuator based on the size of the shelf. In Chapter IV the algorithm implemented will be described and then the performance results (in terms of normalized confusion matrix) will be presented and discussed. Finally, a preliminary analysis has been presented considering different tags, even if it is still under developing

Application of Ultra-Wideband Technology to RFID and Wireless Sensors

Aquesta Tesi Doctoral estudia l'ús de tecnologia de ràdio banda ultraampla (UWB) per sistemes de identificació per radiofreqüència (RFID) i sensors sense fils. Les xarxes de sensors sense fils (WSNs), ciutats i llars intel•ligents, i, en general, l'Internet de les coses (IoT) requereixen interfícies de ràdio simples i de baix consum i cost per un número molt ampli de sensors disseminats. UWB en el domini temporal es proposa aquí com una tecnologia de radio habilitant per aquestes aplicacions. Un model circuital s'estudia per RFID d'UWB codificat en el temps. Es proposen lectors basats en ràdars polsats comercials amb tècniques de processat de senyal. Tags RFID sense xip (chipless) codificats en el temps son dissenyats i caracterizats en termes de número d'identificacions possible, distància màxima de lectura, polarització, influència de materials adherits, comportament angular i corbatura del tag. Es proposen sensors chipless de temperatura i composició de ciment (mitjançant detecció de permitivitat). Dos plataformes semipassives codificades en temps (amb un enllaç paral•lel de banda estreta per despertar el sensor i estalviar energia) es proposen com solucions més complexes i robustes, amb una distància de lectura major. Es dissenya un sensor de temperatura (alimentat per energia solar) i un sensor de diòxid de nitrogen (mitjançant nanotubs de carboni i alimentat per una petita bateria), ambdòs semipassius amb circuiteria analògica. Es dissenya un multi-sensor semipassiu capaç de mesurar temperatura, humitat, pressió i acceleració, fent servir un microcontrolador de baix consum digital. Combinant els tags RFID UWB codificats en temps amb tecnologia de ràdar de penetració del terra (GPR), es deriva una aplicació per localització en interiors amb terra intel•ligent. Finalment, dos sistemes actius RFID UWB codificats en el temps s'estudien per aplicacions de localització de molt llarg abast.Esta Tesis Doctoral estudia el uso de tecnología de radio de banda ultraancha (UWB) para sistemas de identificación por radiofrecuencia (RFID) y sensores inalámbricos. Las redes de sensores inalámbricas (WSNs), ciudades y casas inteligentes, y, en general, el Internet de las cosas (IoT) requieren de interfaces de radio simples y de bajo consumo y coste para un número muy amplio de sensores diseminados. UWB en el dominio temporal se propone aquí como una tecnología de radio habilitante para dichas aplicaciones. Un modelo circuital se estudia para RFID de UWB codificado en tiempo. Configuraciones de lector, basadas en rádar pulsados comerciales, son propuestas, además de técnicas de procesado de señal. Tags RFID sin chip (chipless) codificados en tiempo son diseñados y caracterizados en términos de número de identificaciones posible, distancia máxima de lectura, polarización, influencia de materiales adheridos, comportamiento angular y curvatura del tag. Se proponen sensores chipless de temperatura y composición de cemento (mediante detección de permitividad). Dos plataformas semipasivas codificadas en tiempo (con un enlace paralelo de banda estrecha para despertar el sensor y ahorrar energía) se proponen como soluciones más complejas y robustas, con una distancia de lectura mayor. Se diseña un sensor de temperatura (alimentado por energía solar) y un sensor de dióxido de nitrógeno (mediante nanotubos de carbono y alimentado por una batería pequeña), ambos semipasivos con circuitería analógica. Se diseña un multi-sensor semipasivo capaz de medir temperatura, humedad, presión y aceleración, usando un microcontrolador digital de bajo consumo. Combinando los tags RFID UWB codificados en tiempo y tecnología de radar de penetración de suelo (GPR), se deriva una aplicación para localización en interiores con suelo inteligente. Finalmente, dos sistemas activos RFID UWB codificados en tiempo se estudian para aplicaciones de localización de muy largo alcance.This Doctoral Thesis studies the use of ultra-wideband (UWB) radio technology for radio-frequency identification (RFID) and wireless sensors. Wireless sensor networks (WSNs) for smart cities, smart homes and, in general, Internet of Things (IoT) applications require low-power, low-cost and simple radio interfaces for an expected very large number of scattered sensors. UWB in time domain is proposed here as an enabling radio technology. A circuit model is studied for time-coded UWB RFID. Reader setups based on commercial impulse radars are proposed, in addition to signal processing techniques. Chipless time-coded RFID tags are designed and characterized in terms of number of possible IDs, maximum reading distance, polarization, influence of attached materials, angular behaviour and bending. Chipless wireless temperature sensors and chipless concrete composition sensors (enabled by permittivity sensing) are proposed. Two semi-passive time-coded RFID sensing platforms are proposed as more complex, more robust, and longer read-range solutions. A wake-up link is used to save energy when the sensor is not being read. A semi-passive wireless temperature sensor (powered by solar energy) and a wireless nitrogen dioxide sensor (enabled with carbon nanotubes and powered by a small battery) are developed, using analog circuitry. A semi-passive multi-sensor tag capable of measuring temperature, humidity, pressure and acceleration is proposed, using a digital low-power microcontroller. Combining time-coded UWB RFID tags and ground penetrating radar, a smart floor application for indoor localization is derived. Finally, as another approach, two active time-coded RFID systems are developed for very long-range applications