Indoor Positioning with GNSS-Like Local Signal Transmitters

Not all the techniques proposed have, of course, been based on radio techniques, but they are the most important ones for two main reasons: their level of development and maturity on the one hand and their ability to "cross" or to "get around" obstacles such as walls, furniture or people on the other hand. Optical based techniques, like laser based distance measurements or vision based (camera) scene analysis systems present some real advantages in terms of measurement accuracy (a few millimetres for the former) or orientation determination (very useful for any guidance system, available for the latter). Unfortunately, the foreseen use of positioning devices being mainly dedicated to pedestrians in urban environments, optical obstacles are numerous. These latter techniques are then considered as potential hybridisation candidates. Many types of sensors have also been studied for positioning, such as infrared or ultrasound. Once again, although accuracy can reach centimetre values, the environmental constraints are not compatible with the ubiquitous systems being sought. Another category is, of course, inertial systems which could be a valuable alternative to radio systems: time and distance associated position drifts are not yet sufficiently mastered and the given positioning is relative , which means the need for "something else" in order to provide the user with an absolute location. The object of this section is to focus on radio based approaches

Mass-Market Receiver for Static Positioning: Tests and Statistical Analyses

Nowadays, there are several low cost GPS receivers able to provide both pseudorange and carrier phase measurements in the L1band, that allow to have good realtime performances in outdoor condition. The present paper describes a set of dedicated tests in order to evaluate the positioning accuracy in static conditions. The quality of the pseudorange and the carrier phase measurements let hope for interesting results. The use of such kind of receiver could be extended to a large number of professional applications, like engineering fields: survey, georeferencing, monitoring, cadastral mapping and cadastral road. In this work, the receivers performance is verified considering a single frequency solution trying to fix the phase ambiguity, when possible. Different solutions are defined: code, float and fix solutions. In order to solve the phase ambiguities different methods are considered. Each test performed is statistically analyzed, highlighting the effects of different factors on precision and accurac

LOCAL POSITIONING SYSTEMS VERSUS STRUCTURAL MONITORING: A REVIEW

SUMMARY Structural monitoring and structural health monitoring could take advantage from different devices to record the static or dynamic response of a structure. A positioning system provides displacement information on the location of moving objects, which is assumed to be the basic support to calibrate any structural mechanics model. The global positioning system could provide satisfactory accuracy in absolute displacement measurements. But the requirements of an open area position for the antennas and a roofed room for its data storage and power supply limit its flexibility and its applications. Several efforts are done to extend its field of application. The alternative is local positioning system. Non-contact sensors can be easily installed on existing infrastructure in different locations without changing their properties: several technological approaches have been exploited: laser-based, radar-based, vision-based, etc. In this paper, a number of existing options, together with their performances, are reviewed. Copyright © 2014 John Wiley & Sons, Ltd

Low-Cost GNSS Simulators with Wireless Clock Synchronization for Indoor Positioning

In regions where global navigation satellite systems (GNSS) signals are unavailable, such as underground areas and tunnels, GNSS simulators can be deployed for transmitting simulated GNSS signals. Then, a GNSS receiver in the simulator coverage outputs the position based on the received GNSS signals (e.g., Global Positioning System (GPS) L1 signals in this study) transmitted by the corresponding simulator. This approach provides periodic position updates to GNSS users while deploying a small number of simulators without modifying the hardware and software of user receivers. However, the simulator clock should be synchronized to the GNSS satellite clock to generate almost identical signals to the live-sky GNSS signals, which is necessary for seamless indoor and outdoor positioning handover. The conventional clock synchronization method based on the wired connection between each simulator and an outdoor GNSS antenna causes practical difficulty and increases the cost of deploying the simulators. This study proposes a wireless clock synchronization method based on a private time server and time delay calibration. Additionally, we derived the constraints for determining the optimal simulator coverage and separation between adjacent simulators. The positioning performance of the proposed GPS simulator-based indoor positioning system was demonstrated in the underground testbed for a driving vehicle with a GPS receiver and a pedestrian with a smartphone. The average position errors were 3.7 m for the vehicle and 9.6 m for the pedestrian during the field tests with successful indoor and outdoor positioning handovers. Since those errors are within the coverage of each deployed simulator, it is confirmed that the proposed system with wireless clock synchronization can effectively provide periodic position updates to users where live-sky GNSS signals are unavailable.Comment: Submitted to IEEE Acces

Robustness, Security and Privacy in Location-Based Services for Future IoT : A Survey

Internet of Things (IoT) connects sensing devices to the Internet for the purpose of exchanging information. Location information is one of the most crucial pieces of information required to achieve intelligent and context-aware IoT systems. Recently, positioning and localization functions have been realized in a large amount of IoT systems. However, security and privacy threats related to positioning in IoT have not been sufficiently addressed so far. In this paper, we survey solutions for improving the robustness, security, and privacy of location-based services in IoT systems. First, we provide an in-depth evaluation of the threats and solutions related to both global navigation satellite system (GNSS) and non-GNSS-based solutions. Second, we describe certain cryptographic solutions for security and privacy of positioning and location-based services in IoT. Finally, we discuss the state-of-the-art of policy regulations regarding security of positioning solutions and legal instruments to location data privacy in detail. This survey paper addresses a broad range of security and privacy aspects in IoT-based positioning and localization from both technical and legal points of view and aims to give insight and recommendations for future IoT systems providing more robust, secure, and privacy-preserving location-based services.Peer reviewe

Techniques to Leverage RF Signals for Context Sensing

RF signals and devices have been used for wireless communication to improve the mobility and ubiquity of mobile devices. In this dissertation, we show that these RF signals can also be used for context sensing applications. Specifically, we present cyber-physical systems and algorithms to sense human vital signals, object vibrations and movements, and object’s location to deliver new sensing capabilities for a variety of new applications including health-care monitoring, privacy protection, and indoor localization. We deliver three fundamental contributions. First, we develop an RF-based system to “sense” human breathing volume continuously in fine-grained from afar. Second, we develop a technique to “sense” the wireless signals emitted from drones/fly-cams to detect them and alert users for privacy protection. Last, we present our preliminary study on building a system to enable the mobile device to “sense” their global locations at the indoor environment. To deliver these contributions, we exploit the properties of physical characteristics of RF signals, analyze and understand targeted subjects behaviors (i.e., human, drones), work across different limitations and hardware-software barriers, and introduce novel systems and new algorithms to overcome the challenges. We implement and evaluate the system on real users/patients, test the systems across different environments, and demonstrate how they can enable many other real-world applications

Impact of Used Communication Technology on the Navigation System for Hybrid Environment

This paper deals with navigation of mobile device in outdoor and indoor environment by only navigation system or application. In the paper, the navigation system is proposed in the light of seamless navigation service. Main parts of the system from positioning point of view are based on GPS and WifiLOC system. WifiLOC is an indoor positioning system based on Wi-Fi technology. The proposal of the system will be described in detail. The system is implemented at the University of Zilina as a pilot, noncommercial project; therefore it is called University Mobile Navigation System (UMNS). The navigation system can be characterized as realtime system, that is, the system operations cannot be significantly delayed. Since delay of the system depends significantly on communication platform used for map information downloading or communication with the localization server. We decided to investigate an impact of the used communication platform on the time needs for some of the functions implemented in navigation system. Measurements were performed in the real-world application. Next experiment is focused on testing of the accuracy of used indoor positioning system. Outdoor positioning accuracy is not tested because GPS is utilized in outdoor, and this system was already exhaustively investigated

Optimisation de l'infrastructure d'un système de positionnement indoor à base de transmetteurs GNSS

Dans le but de fournir un service GNSS (Global Navigation Satellite System) de localisation continu et disponible partout, les systèmes utilisant des pseudolites et des répéteurs semblent être des solutions pertinentes pour la localisation en indoor. Le système à répélites, inspiré de ces deux méthodes (répéteurs et pseudolites), est aussi proposé pour résoudre cette problématique. Les répélites sont des transmetteurs locaux qui, installés en intérieur, formeront une constellation locale. Ils émettent tous un signal GNSS unique mais déphasé par un délai spécifique à chacun d eux. Ces délais sont nécessaires pour distinguer les différents signaux reçus au niveau du récepteur. Les travaux de cette thèses sont réalisés dans le cadre du système à répélites et dans l objectif d améliorer son architecture et de réduire ses interférences inter-système. En effet, l architecture du système (un peu encombrante) et les interférences éventuelles avec les signaux satellitaires reçus par un récepteur placé à l extérieur font partie des inconvénients de ce système. On cherche donc à traiter ces deux difficultés de façon à minimiser leurs effets. Dans une première partie, on étudie les différents codes GNSS existants dans la littérature ainsi que les techniques de modulation employées. Ceci nous mène à proposer des codes ayant un niveau d interférence équivalent à la référence GPS (obtenue entre deux codes GPS) pour les bandes L1 de GPS et G1 de Glonass. Dans une seconde étape, on développe la modulation IMBOC (Indoor Modified Binary Offset Carrier) pour générer de nouveaux codes caractérisés par des niveaux d interférence réduits (comparés à la référence GPS). Parmi ces codes il y a deux catégories : ceux qui sont adaptés aux systèmes à répélites (émettant un code unique) et ceux qui sont adaptés aux systèmes pseudolites. Une étude théorique et des simulations des niveaux d interférences pour les codes émis dans la bande GPS et Glonass sont réalisées pour déterminer les gains en termes de niveaux de bruit. Ce gain (par rapport à la référence GPS) en puissance d interférence s élève à 16 dB pour Glonass et 20 dB pour GPS. Pour valider les performances de ces codes, on génère les signaux IMBOC et on observe les interférences réelles qu ils induisent sur un récepteur GPS recevant un signal satellitaire. Dans la deuxième partie, on utilise la fibre optique pour transmettre le signal du générateur jusqu aux répélites et pour créer les délais initiaux par propagation du signal dans des bobines de fibre. Ainsi on remplace les câbles coaxiaux et les montages électroniques (de déphasage) par des bobines de fibres plus légères, facile à installer et à faible perte de puissance. Il reste cependant à évaluer avec une précision centimétrique les délais réels induits sur chaque signal dans le but de garantir une précision de localisation inférieure au mètre. Cette précision semble en effet représenter un bon compromis entre complexité globale du système de localisation et réponse à un ensemble suffisant de besoins des utilisateurs potentiels. On développe alors une technique d estimation des délais basée sur la mesure de déphasage (entre deux signaux sinusoïdaux) et une analyse statistique des séries de mesures. Pour finir, on présente quelques résultats de localisation obtenus avec notre système à répélites déployé dans un environnement indoor typiqueIn order to make the GNSS positioning service continuous and available when going from an outdoor to an indoor environment, pseudolite and repeater based systems have been developed. A new system called repealite is a combination of both pseudolites and repeaters. It is based on transmitting a single signal through a set of transmitters (thus creating the local constellation). In order to avoid interference between the repealite signals and to distinguish between them at the receiver s end, each signal is shifted with a specific delay. The research carried out in this PhD aims at optimizing two aspects of the repealite based system. Firstly, we need to mitigate the effect of the interference caused on the satellite signals received outdoors. So we decided to design new codes characterized by low interference levels with outdoor signals. Secondly, we worked on the infrastructure part in order to simplify it and to make it easier to install: this is mainly achieved through the use of optical fibers. In the first part, we study the codes and the modulation techniques currently used in the GNSS systems. Then, we propose a few codes having an interference level equivalent to that of the GPS (obtained when computing two GPS codes). These new codes are compatible with the GPS L1 or the Glonass G1 bands. In a second step, we focus on the modulation techniques and create the so-called IMBOC (Indoor Modified Binary Offset Carrier) that aims at minimizing the interference levels with outdoor signals. With this modulation, we propose new IMBOC codes capable of much lower interference levels than the GPS reference. In order to evaluate the performance of the proposed codes, we carried out a theoretical study, simulations and experimental tests. The interference gain reached about 20 dB on the GPS band and 16 dB on the Glonass one. The proposed codes are divided into two categories: those reserved to the repealite system (using a single code) and families of codes suited to pseudolite based systems. Finally, we generated the IMBOC signals modulated by the new codes and tested the real interference induced on an outdoor receiver tracking the satellite signals. In the second part, we use optical fibers in order to replace the coaxial cables used to transmit signals from the GNSS-like signal generator to the repealites. In addition, the initial delay needed for each repealite is added by propagating the signals through rolls of fibers. Indeed, optical fiber offers advantages such as lightness, flexibility and low power loss that make it suitable to simplify the infrastructure of the system. In order to evaluate the real delays of these various fibers, we develop an estimating method based on phase shift measurements (between two sinusoidal signals) and statistical analysis of the series of measurements. This method should have uncertainties lower than one centimeter in order to insure a sub-meter precision (in absolute positioning with the repealite positioning system). In order to validate this method, we compare it to a GNSS based calibration approach. Finally, we carry out a few positioning tests with the repealite positioning system deployed in a typical indoor environment. These tests deal with absolute and relative positioning and give an idea about the system s performanceEVRY-INT (912282302) / SudocSudocFranceF