Sensors and Systems for Indoor Positioning

This reprint is a reprint of the articles that appeared in Sensors' (MDPI) Special Issue on “Sensors and Systems for Indoor Positioning". The published original contributions focused on systems and technologies to enable indoor applications

パッシブRFIDシステムにおけるRFIDタグ位置推定に関する研究

関西大

Federated Sensor Network architectural design for the Internet of Things (IoT)

An information technology that can combine the physical world and virtual world is desired. The Internet of Things (IoT) is a concept system that uses Radio Frequency Identification (RFID), WSN and barcode scanners to sense and to detect physical objects and events. This information is shared with people on the Internet. With the announcement of the Smarter Planet concept by IBM, the problem of how to share this data was raised. However, the original design of WSN aims to provide environment monitoring and control within a small scale local network. It cannot meet the demands of the IoT because there is a lack of multi-connection functionality with other WSNs and upper level applications. As various standards of WSNs provide information for different purposes, a hybrid system that gives a complete answer by combining all of them could be promising for future IoT applications. This thesis is on the subject of `Federated Sensor Network' design and architectural development for the Internet of Things. A Federated Sensor Network (FSN) is a system that integrates WSNs and the Internet. Currently, methods of integrating WSNs and the Internet can follow one of three main directions: a Front-End Proxy solution, a Gateway solution or a TCP/IP Overlay solution. Architectures based on the ideas from all three directions are presented in this thesis; this forms a comprehensive body of research on possible Federated Sensor Network architecture designs. In addition, a fully compatible technology for the sensor network application, namely the Sensor Model Language (SensorML), has been reviewed and embedded into our FSN systems. The IoT as a new concept is also comprehensively described and the major technical issues discussed. Finally, a case study of the IoT in logistic management for emergency response is given. Proposed FSN architectures based on the Gateway solution are demonstrated through hardware implementation and lab tests. A demonstration of the 6LoWPAN enabled federated sensor network based on the TCP/IP Overlay solution presents a good result for the iNET localization and tracking project. All the tests of the designs have verified feasibility and achieve the target of the IoT concept

A two phase framework for visible light-based positioning in an indoor environment: performance, latency, and illumination

Recently with the advancement of solid state lighting and the application thereof to Visible Light Communications (VLC), the concept of Visible Light Positioning (VLP) has been targeted as a very attractive indoor positioning system (IPS) due to its ubiquity, directionality, spatial reuse, and relatively high modulation bandwidth. IPSs, in general, have 4 major components (1) a modulation, (2) a multiple access scheme, (3) a channel measurement, and (4) a positioning algorithm. A number of VLP approaches have been proposed in the literature and primarily focus on a fixed combination of these elements and moreover evaluate the quality of the contribution often by accuracy or precision alone. In this dissertation, we provide a novel two-phase indoor positioning algorithmic framework that is able to increase robustness when subject to insufficient anchor luminaries and also incorporate any combination of the four major IPS components. The first phase provides robust and timely albeit less accurate positioning proximity estimates without requiring more than a single luminary anchor using time division access to On Off Keying (OOK) modulated signals while the second phase provides a more accurate, conventional, positioning estimate approach using a novel geometric constrained triangulation algorithm based on angle of arrival (AoA) measurements. However, this approach is still an application of a specific combination of IPS components. To achieve a broader impact, the framework is employed on a collection of IPS component combinations ranging from (1) pulsed modulations to multicarrier modulations, (2) time, frequency, and code division multiple access, (3) received signal strength (RSS), time of flight (ToF), and AoA, as well as (4) trilateration and triangulation positioning algorithms. Results illustrate full room positioning coverage ranging with median accuracies ranging from 3.09 cm to 12.07 cm at 50% duty cycle illumination levels. The framework further allows for duty cycle variation to include dimming modulations and results range from 3.62 cm to 13.15 cm at 20% duty cycle while 2.06 cm to 8.44 cm at a 78% duty cycle. Testbed results reinforce this frameworks applicability. Lastly, a novel latency constrained optimization algorithm can be overlaid on the two phase framework to decide when to simply use the coarse estimate or when to expend more computational resources on a potentially more accurate fine estimate. The creation of the two phase framework enables robust, illumination, latency sensitive positioning with the ability to be applied within a vast array of system deployment constraints

A Technology review of smart sensors with wireless networks for applications in hazardous work environments

Workers in hazardous environments such as mining are constantly exposed to the health and safety hazards of dynamic and unpredictable conditions. One approach to enable them to manage these hazards is to provide them with situational awareness: real-time data (environmental, physiological, and physical location data) obtained from wireless, wearable, smart sensor technologies deployed at the work area. The scope of this approach is limited to managing the hazards of the immediate work area for prevention purposes; it does not include technologies needed after a disaster. Three critical technologies emerge and converge to support this technical approach: smart-wearable sensors, wireless sensor networks, and low-power embedded computing. The major focus of this report is on smart sensors and wireless sensor networks. Wireless networks form the infrastructure to support the realization of situational awareness; therefore, there is a significant focus on wireless networks. Lastly, the "Future Research" section pulls together the three critical technologies by proposing applications that are relevant to mining. The applications are injured miner (person-down) detection; a wireless, wearable remote viewer; and an ultrawide band smart environment that enables localization and tracking of humans and resources. The smart environment could provide location data, physiological data, and communications (video, photos, graphical images, audio, and text messages)

Architecture for multi-technology real-time location systems

[Abstract] Indoor localization is a problem that has generated much interest in recent years. Proximity marketing, eHealth, smart-parking and smart-cities, security and emergency units, logistics management, or industrial control systems are some pf the sectors that have demanded new Location Based Services (LBSs). These services are usually implemented using Wireless Sensor Networks (WSNs), capable of transmitting and receiving Radio Frequency (RF) signals in order to locate mobile devices attached to vehicles, people, or animals. While systems based on satellite systems such as GPS work correctly in outdoor scenarios, indoor localization is still a challenging field of study. On one hand, signal propagation problems are common, not only due to reflections and scattering due to the building structures, but also because of signal attenuation and fading caused mainly by people in movement. To overcome these issues, most of the approaches use several WSNs with a combination of multiple wireless technologies, such asWiFi, ZigBee or Bluetooth, some of them also available in mobile devices such as smartphones and tablets. On the other hand, data received from multiple devices must be filtered and combined by means of location algorithms and techniques in order to obtain precise and robust Real-Time Location Systems (RTLSs). Therefore, it is common to implement hybrid location systems with support for several technologies at the same time. Nevertheless, the development of such systems entails a huge complexity. Thus, one of most widely accepted alternatives is the implementation of software architectures for localization, which provide several benefits. First, accessing to different kinds of hardware devices entails fewer platform and technology restrictions. Second, some common tasks are easier to perform, such as sensor data gathering and storage. Finally, architectures provide utilities for adding and retrieving localization data, user management, or the possibility of using several mapping and coordinate systems. In this work, we present several solutions for implementing software architectures for localization. First, we propose a mono-technology architecture using only Received Signal Strength (RSS) signal levels for ranging, which evolves into a much more complete multitechnology architecture in a second stage. The proposed approaches implement several functionalities that resolve most of the hybrid RTLS system requirements, such as: • Multi-technology. • Support for several coordinate systems and mapping applications. • Data fusion. • Protection and security for both data and user access. • Standardized API for remote access. • Support for off-line data queries, not only on-line data and in real-time. • Depending on different user roles, it eases their tasks at different access levels: registration of WSNs, building blueprints, anchor and mobile node networks registration, generic sensor support, addition and retrieval of measurements and raw sensor data, multiple query support for filtered position estimations, etc. Moreover, we also contributed with different WSN physical layer implementations and experiments. And, due to collaborations with other research groups at different universities we have contributed with a customized hardware and software solution for localization based on RFID technology, as well as with the design of new antenna models based on linear-arrays of Electromagnetically Coupled Patchs (ECPs), valid for improving the WSN communication performance.[Resumo]O problema da localización no interior de edificios foi adquirindo cada vez máis importancia nos últimos anos debido á enorme demanda de novos servizos baseados en localización (LBSs). que apareeeron en todo tipo de sectores como eHealth. marketing por proximidade. smartparking e smart--cities. seguridade e emerxencias. loxística ou control industrial, entre outros. Estes sistemas habitualmente estan baseados na implementación de redes de sensores sen fíos (WSN) capaces de transmitir ou recibir sinais de radio (RF) para localizar dispositivos móbiles. xeralmente adheridos a vehículos. persoas ou animais. Menlres que en exteriores os sistemas de satélites baseados en tecnoloxías corno GPS funcionan correctamente na maioría de entornos. a localización en interiores non é unha tarefa sinxela de resolver e afnda inelúe múltiples retos. Principalmente aparecen problemas de propagación debido ás reflexións e rebotes dos sinais nas estruturas dos edificios. pero tarDén debido a atenuaci6ns e apantallamentos ocasionados xeralrnente por xente en movemento. Para resolver estes problemac;; é necesario implementar ac;; redes de sensores utilizando unha ou varias tecnoloxías sen fíos (como WiFi. ZigBee ou Bluetooth). a1gunhas delas disponibles en terminais sen fíos como smartphones ou tablets. Pero. por outra parte. tamén é necesario o uso de múltiples algoritmos e técnicas de localización para filtrar e posiblemente combinar os datos destas tecnoloxías. permitindo obter así sistemas de localización en tempo real (RTLS) robustos e coa maior precisión posible. Deste xeito. a aproximación máis usual na actualidade para resolver estos problemas é a implementación de sistemas de localización híbridos que soporten múltiples tecnoloxías simultaneamente. Nembargantes. O desenvolvemento destes sistemas leva implícito unha gran complexidade. Unha das alternativas comunmente aceptada é a implementación dunha arquitectura de software para localización, a cal ofrece varias vantaxes. En primeiro lugar, permite minimizar o número de restricci6ns multi-plataforma e multi-tecnoloxía á hora de acceder a distintos tipos de dispositivos hardware. En segundo lugar. facilítase a realización de tarefas comúns como a recolección e o almacenamento das medicións de sensores. Ademais, proporcinánse mecanismos para inserir e recuperar datos de localización ase como xestión de usuarios ou manipulación de múltiple" sistemas de mapas e coordenadas. Neste traballo presentamos varias solucións á hora de implementar arquitecturas de software para localización. comenzando por unha mono-tecnoloxía baseada unicarnente na recolección de niveis de sinal RSS, que evoluciona posteriormente a unha arquitectura multi-tecnoloxía. As solucións propostas ofrecen diferentes funcionalidades que resolven moitos dos problemas asociados aos sistemas híbridos RTLS, entre as que podemos destacar: • Multi-tecnoloxía. • Soporte de múltiples sistemas de coordenadas e de aplicacións de mapas. • Fusión de datos. • Protección e seguridad, tanto de datos como de acceso de usuarios. • API estandarizado para acceso remoto. • Soporte de consultas de datos off-line, non só on-line e en tempo real. • Facilidade de uso para os diferentes usuarios que utilicen a plataforma mediante chamadas a varios niveis: rexistro de WSNs, planos de edificios, rexistro de redes de áncoras e de nodos móviles, soporte de sensores xenéricos, inserción e consulta de medici6ns e de datos sensoriais en ero. inserción e consulta de posicións estimadas por algoritmos de localización, etc. Tamén contribuimos con múltiples implementacións da capa física de WSNs e experimentos. E grazas á colaboración con outros grupos de investigación de diferentes universidades puidemos, por unha parte, contribuir cunha solución de hardware e software para localización baseada en tecnoloxía RFID e, por outra parte, no deseño de novos modelos de antenas baseados en arrays lineais de ECPs, válidos para mellorar o rendemento das comunicacións en WSNs.[Resumen] El problema de la localización en el interior de edificios ha ido adquiriendo cada vez más importancia en los últimos años debido a la enorme demanda de nuevos servicios basados en localización (LBSs), que han ido apareciendo en la industria en sectores de todo tipo como eHeallb, marketing por proximidad, smart-parking y smart-cities, seguridad y emergeocias, logística o control industrial, entre otros. Estos sistemas habitualmeote se basan en la implementación de redes de sensores inalámbricos (WSN) capaces de transmitir o recibir señales de radio (RF) para localizar dispositivos móviles, generalmente adheridos a vehículos, personas o artimales. Mientras que en exteriores los sistemas satelitales basados en tecnologías como GPS funcionan correctamente en la mayoría de entornos, la localización en inleriores todavía plantea múltiples retos y no es una tarea sencilla de resolver. Principalmente aparecen problemas de propagación debido a los reflejos y rebotes de las sefiales en las estructuras de los edificios, pero también debido a atenuaciones y apantallamientos ocasionados generalmente por gente en movimiento. Para resolver estos problemas es necesario implementar Jas redes de sensores utilizando una o varias tecnologías inalámbricas (como pueden ser WiFí, ZigBee o Bluetooth), algunas de ellas disportibles en terminales inalámbricos como smartphones o tablets. Pero, por otra parte, también es necesario el uso de múltiples algoritmos y técnicas de localización, para filtrar y posiblemente combinar los datos de estas tecnologías, permitiendo obtener así sistemas de localización en tiempo real (RTLS) robustos y con la mayor precisión posible. De este modo, la aproximación más usual en la actualidad para resolver estos problemas es la implementación de sistemas de localización híbridos que soporten múltiples tecnologías simultáneamente. No obstante, el desarrollo de estos sistemas lleva implícito una gran complejidad. Una de las alternativas comúnmente aceptada es la implementación de una arquitectura de software para localización, que ofrece varias ventajas. En primer lugar, permite minimizar el número de restricciones multi-plataforma y multi-tecnología a la hora de acceder a distintos tipos de dispositivos hardware. En segundo lugar, se facilitan tareas comunes como la recolección y almacenamiento de las mediciones de los sensores. Además. se proveen mecanismos para insertar y recuperar datos de localización así como gestión de usuarios o manejo de múltiples sistemas de mapas y coordenadas. En este trabajo presentamos varias soluciones a la hora de implementar arquitecturas de software para localización, empezando por una mono-tecnología basada únicamente en la recoleccion de niveles de señal RSS, que se evoluciona posteriormente a una arquitectura mllltitecnología. Las soluciones propuestas ofrecen diferentes funcionalidades que resuelven muchos de los problemas asociados a los sistemas híbridos RTLS, entre las que podemos destacar: Multi-tecnología. Soporte de múltiples sistemas de coordenadas y de aplicaciones de mapas. • Fusión de datos. • Protección y seguridad, tanto de datos como de acceso de usuarios. • API estandarizado para acceso remoto. • Soporte de consultas de datos off-line, no solo on-line y en tiempo real. • Facilidad de uso para los diferentes usuarios que utilicen la plataforma, mediante llamadas a varios rtiveles: registro de WSNs, planos de edificios, registro de redes de anchors y de nodos móviles, soporte de sensores genéricos, inserción y consulta de mediciones y de datos sensoriales en crudo, inserción y consulta de posiciones estimadas por algoritmos de localización, etc. También contribuimos con múltiples implementaciones de la capa física de WSNs y experimentos. y gracias a la colaboración Con otros grupos de investigación de diferentes universidades hemos podido, por una parte, contribuir con una soluciÓn de hardware y software para localización basada en tecnología RFID y, por otra parte, en el diseño de nuevos modelos de antenas basados en arrays lineales de ECPs, válidos para mejorar el rendimiento de las comunicaciones en WSNs

Recent Advances in Indoor Localization Systems and Technologies

Despite the enormous technical progress seen in the past few years, the maturity of indoor localization technologies has not yet reached the level of GNSS solutions. The 23 selected papers in this book present the recent advances and new developments in indoor localization systems and technologies, propose novel or improved methods with increased performance, provide insight into various aspects of quality control, and also introduce some unorthodox positioning methods

Minimal Infrastructure Radio Frequency Home Localisation Systems

The ability to track the location of a subject in their home allows the provision of a number of location based services, such as remote activity monitoring, context sensitive prompts and detection of safety critical situations such as falls. Such pervasive monitoring functionality offers the potential for elders to live at home for longer periods of their lives with minimal human supervision. The focus of this thesis is on the investigation and development of a home roomlevel localisation technique which can be readily deployed in a realistic home environment with minimal hardware requirements. A conveniently deployed Bluetooth ® localisation platform is designed and experimentally validated throughout the thesis. The platform adopts the convenience of a mobile phone and the processing power of a remote location calculation computer. The use of Bluetooth ® also ensures the extensibility of the platform to other home health supervision scenarios such as wireless body sensor monitoring. Central contributions of this work include the comparison of probabilistic and nonprobabilistic classifiers for location prediction accuracy and the extension of probabilistic classifiers to a Hidden Markov Model Bayesian filtering framework. New location prediction performance metrics are developed and signicant performance improvements are demonstrated with the novel extension of Hidden Markov Models to higher-order Markov movement models. With the simple probabilistic classifiers, location is correctly predicted 80% of the time. This increases to 86% with the application of the Hidden Markov Models and 88% when high-order Hidden Markov Models are employed. Further novelty is exhibited in the derivation of a real-time Hidden Markov Model Viterbi decoding algorithm which presents all the advantages of the original algorithm, while producing location estimates in real-time. Significant contributions are also made to the field of human gait-recognition by applying Bayesian filtering to the task of motion detection from accelerometers which are already present in many mobile phones. Bayesian filtering is demonstrated to enable a 35% improvement in motion recognition rate and even enables a floor recognition rate of 68% using only accelerometers. The unique application of time-varying Hidden Markov Models demonstrates the effect of integrating these freely available motion predictions on long-term location predictions

Angle of Arrival Estimation Utilising Frequency Diverse Radio Antenna Arrays

The purpose of this research is to investigate a novel way of combining carrier signals that are transmitted successively over Multiple Frequencies (MF) and traditional metrics to improve AoA estimation. Every signal contains three metrics, amplitude, phase, and frequency. To achieve localisation, current systems utilise the metrics of amplitude (also known as Received Signal Strength (RSS)) and phase that resolves the AoA. However, the metric of frequency is mostly used with Orthogonal Frequency-Division Multiplexing (OFDM) to increase the number of RSS and AoA metrics, which is not optimal. This research answers two questions. Can the use of MF improve AoA estimation? Also, how can MF and traditional metrics be combined for AoA estimation? The aim is to prove that the metric of frequency can be utilised more optimally. Therefore, measurements of RSS and AoA are performed in different environments for MF. To perform these measurements, ten frequency diverse Software Defined Radios (SDRs) are employed. A novel technique to time/frequency synchronise the SDRs is developed and presented. Moreover, a ten element Uniform Linear Array (ULA) is designed, simulated and manufactured. The outcomes of this research are two novel algorithms for the MF AoA estimation of a carrier transmitter. Findings of the first algorithm show that the use of MF with the RSS metric performs equally with current systems that have a higher cost and complexity. The second algorithm that utilises MF with the AoA metric demonstrates a significant reduction in the AoA estimation error, compared to current systems. Specifically, for 50\% of the measured cases the AoA estimation error is reduced by 3.7 degrees, while for 95\% of the measured cases the AoA estimation error is reduced by 27 degrees. Hence, this research proves that MF with traditional metrics can reduce system complexity and greatly improve AoA estimation