As portable computers and wireless networks are becoming ubiquitous, it is natural to consider the user’s position as yet another aspect to take into account when providing services that are tailored to meet the needs of the consumers. Location aware systems could guide persons through buildings, to a particular bookshelf in a library or assist in a vast variety of other applications that can benefit from knowing the user’s position. In indoor positioning systems, the most commonly used method for determining the location is to collect samples of the strength of the received signal from each base station that is audible at the client’s position and then pass the signal strength data on to a positioning server that has been previously fed with example signal strength data from a set of reference points where the position is known. From this set of reference points, the positioning server can interpolate the client’s current location by comparing the signal strength data it has collected with the signal strength data associated with every reference point. Our work proposes the use of multiple successive received signal strength samples in order to capture periodic signal strength variations that are the result of effects such as multi-path propagation, reflections and other types of radio interference. We believe that, by capturing these variations, it is possible to more easily identify a particular point; this is due to the fact that the signal strength fluctuations should be rather constant at every position, since they are the result of for example reflections on the fixed surfaces of the building’s interior. For the purpose of investigating our assumptions, we conducted measurements at a site at Växjö university, where we collected signal strength samples at known points. With the data collected, we performed two different experiments: one with a neural network and one where the k-nearest-neighbor method was used for position approximation. For each of the methods, we performed the same set of tests with single signal strength samples and with multiple successive signal strength samples, to evaluate their respective performances. We concluded that the k-nearest-neighbor method does not seem to benefit from multiple successive signal strength samples, at least not in our setup, compared to when using single signal strength samples. However, the neural network performed about 17% better when multiple successive signal strength samples were used.

<p>As portable computers and wireless networks are becoming ubiquitous, it is natural to consider the user’s position as yet another aspect to take into account when providing services that are tailored to meet the needs of the consumers. Location aware systems could guide persons through buildings, to a particular bookshelf in a library or assist in a vast variety of other applications that can benefit from knowing the user’s position.</p><p>In indoor positioning systems, the most commonly used method for determining the location is to collect samples of the strength of the received signal from each base station that is audible at the client’s position and then pass the signal strength data on to a positioning server that has been previously fed with example signal strength data from a set of reference points where the position is known. From this set of reference points, the positioning server can interpolate the client’s current location by comparing the signal strength data it has collected with the signal strength data associated with every reference point.</p><p>Our work proposes the use of multiple successive received signal strength samples in order to capture periodic signal strength variations that are the result of effects such as multi-path propagation, reflections and other types of radio interference. We believe that, by capturing these variations, it is possible to more easily identify a particular point; this is due to the fact that the signal strength fluctuations should be rather constant at every position, since they are the result of for example reflections on the fixed surfaces of the building’s interior.</p><p>For the purpose of investigating our assumptions, we conducted measurements at a site at Växjö university, where we collected signal strength samples at known points. With the data collected, we performed two different experiments: one with a neural network and one where the k-nearest-neighbor method was used for position approximation. For each of the methods, we performed the same set of tests with single signal strength samples and with multiple successive signal strength samples, to evaluate their respective performances.</p><p>We concluded that the k-nearest-neighbor method does not seem to benefit from multiple successive signal strength samples, at least not in our setup, compared to when using single signal strength samples. However, the neural network performed about 17% better when multiple successive signal strength samples were used.</p>

To facilitate the learning of automatic navigation systems by engineering students an easy to obtain platform is useful. The topic of this thesis is the design and implementation of a basic self-guided vehicle that can be programmed and expanded by anyone possessing basic experience with the C programming language. The Self-Guided Micro Vehicle, (SGMV), uses off-the-shelf easy to obtain parts such as a toy R/C truck and the Handyboard to maximize availability of this technology to students.This thesis divides the SGMV design process by functionality. It starts by documenting the locomotion system, which was a modified R/C toy truck. Next, it describes the Microcontroller board and the Handyboard. Then it highlights the programming language, Interactive C, which makes multitasking systems easy for beginners. The sensor system was comprised of a GPS receiver, a solid state electronic compass and a wireless communications system.

This thesis is concerned with the usability of Raspberry Pi as the access point in the mobilebroadband network environment. The first part of the thesis is dedicated to Raspberry Pi itself;hardware required to set up WLAN and WAN; and to the analysis of suitable solutions forbandwidth aggregation, particularly the load balancing of mobile broadband connections andtheir aggregation into one logical link. The second part deals with the implementation of thesesolutions and subsequently with their testing and verification. The evaluation of results gives aninteresting outcome. Load balancing has proven to be resilient and feasible solution forbandwidth aggregation in the mobile broadband network environment where the speed, packetloss and jitter are of main concern. The second scenario, where the connections are bundled intoone logical link, has turned out to give variable results. Its performance is susceptible to thechanges in the mobile broadband network as the packets across the links in the bundle alternatein the round-robin fashion.

Avec l’apparition des nouvelles technologies de communication, le nombre des systèmes embarqués avionique et automobile est en constante augmentation. La gestion des communications entre ces systèmes devient alors de plus en plus complexe à mettre en oeuvre dans un contexte où les contraintes temporelles et environnementales sont très fortes et où le taux d’échanges de messages en augmentation continuelle. L’utilisation optimale des réseaux pour acheminer les données tout en respectant les contraintes temporelles imposées est essentielle du point de vue de la sûreté de fonctionnement. Historiquement, pour répondre aux problématiques d’efficacité et de sûreté, les industriels ont développé une palette de réseaux embarqués dédiés à leurs applications cibles (CAN, LIN, . . . ). Ces réseaux présentaient des débits relativement faibles à un moment où un besoin croissant en bande passante se faisait ressentir. le choix d’utiliser le concept de composants dit ‘sur étagères’ (off the shelf COTS) permettait alors de pallier à ce nouveau besoin. Dans un souci de conservation des capacités des réseaux à garantir les contraintes temporelles imposées par les systèmes embarqués temps réel, les industriels ont dû adapter ce concept de composants sur étagères aux systèmes embarqués. L’intérêt de l’utilisation de ces composants est un gain non négligeable en bande passante et en poids pour des coûts de développements relativement faibles. L’introduction de ces composants nouveaux s’est faite de telle sorte que leur impact sur les standards préexistants et les systèmes connectés soit minimal. C’est ainsi que les réseaux dit ‘hétérogènes’ ont vu leur apparition. Ces réseaux constituent une hybridation entre les technologies embarquées historiques et les composants sur étagère. Ils consistent en des réseaux d’extrémité utilisant des technologies éprouvées (telles que le CAN) interconnectés via des passerelles à un réseau fédérateur (backbone) utilisant des composants sur étagères. Dès lors, le défi majeur à relever lors de l’utilisation d’un réseau fédérateur est de respecter les contraintes temporelles des applications sollicitant les différents réseaux. L’objectif est mis à mal sur les points d’interconnexion des réseaux hétérogènes (Passerelles). Ainsi l’approche principale utilisée pour le passage d’un réseau à un autre est l’encapsulation de trames. Pour atteindre l’optimalité de performance de cette technique plusieurs paramètres sont à prendre en compte tels que le nombre de trames à encapsuler, les ordonnancements utilisés, le coût en bande passante ainsi que l’impact sur les distributions de délais (gigue). Dans l’optique de préservation des performances des réseaux, l’objet de nos travaux porte sur l’étude, la comparaison et la proposition de techniques permettant l’interconnexion de réseaux hétérogènes temps réels à la fois pour des applications à faibles et à fortes contraintes temporelles. Après un état de l’art sur les réseaux temps réel, nous spécifions différentes techniques d’interconnexion de réseaux hétérogènes, puis, nous présentons une étude de cas basée sur une architecture réseau interconnectant différents bus CAN via un réseau fédérateur sans fil Wi-Fi. L’étude que nous avons menée montre, par le biais de différentes simulations, que cette architecture réseau est une bonne candidate pour la transmission de flux à contraintes temporelles faibles. Une architecture réseau interconnectant différents bus CAN via un réseau fédérateur Ethernet commuté est ensuite considérée dans une seconde étude de cas ciblant les applications à fortes contraintes temporelles. Dans un premier temps, nous prenons en compte le cas d’un réseau fédérateur Ethernet-PQSE et, dans un second temps, le cas d’Ethernet-AVB. Cette étude nous permet de montrer l’impact des différentes techniques d’interconnexion sur les délais des flux du réseau.

In this bachelor thesis, low latency wireless sensor and actuator networks are studied.In particular IEEE 802.15.4e/LLDN and IEEE 802.11g/RT-WiFi protocols. It is in-vestigated if the protocols are suitable for being used in typical industrial automationenvironments with high update frequencies of around 100 Hz. The protocols are exam-ined on a low level to shed lights on the sources of latency and followed by an analysis ofa specific configuration. It is found that LLDN is limited by low transmission rate andRT-WiFi is limited by interference with itself and other appliances. They both work wellfor update frequencies around 100 Hz.

A partir del surgimiento de la computación móvil, la necesidad de conocer la ubicación de recursos y/o personas ha sido imperante en el desarrollo de nuevas tecnologías que persiguen estos objetivos. En particular, los sistemas de localización en tiempo real cobran cada día más importancia. Típicamente, este tipo de sistemas persigue fines de seguridad, optimización y administración. Rubros de todas las áreas aprovechan cada vez más las ventajas de estas tecnologías y las incorporan en su plan de negocios. Aplicaciones conocidas de este tipo de soluciones van desde el seguimiento de activos dentro de un recinto cerrado, hasta el control de flota en empresas de transporte. En el presente trabajo se diseñó e implementó una aplicación de software que funciona en un dispositivo móvil. La aplicación estima la posición del usuario de dicho dispositivo, dentro de un recinto cerrado, con un margen de error que ayude a tomar decisiones a un ser humano. Un escenario de ejemplo donde esta solución podría utilizarse es un hospital. Allí, el personal podría usar la aplicación más el apoyo visual, para conocer la ubicación y disponibilidad de recursos móviles (por ejemplo, personas y equipos). La información necesaria para realizar la estimación se obtiene del contraste entre un modelo del espacio cargado en memoria y las señales inalámbricas observadas. Además, se requiere que el entorno en el cual se desea implantar posea distintos puntos de accesos WiFi para usar como referencia. La aplicación desarrollada permite construir, de manera expedita y con la mínima información, un modelo del decaimiento de las señales WiFi para toda la zona objetivo. Esta solución se adapta fácilmente ante cambios en las referencias del recinto, y permite que un mismo modelo funcione en distintos dispositivos con un leve cambio en la configuración. La calidad del modelo es proporcional a la densidad de señales WiFi del ambiente. En su estado actual, en un ambiente de densidad moderada, se puede obtener márgenes de error aceptables para que un humano pueda encontrar, a través de la inspección visual, a otra persona cuya posición ha sido estimada por la aplicación.

This diploma thesis focuses on the issue of evaluation VoIP services (from the perspective of QoE) and their quality in university network. It includes theoretical basics of VoIP testing, principals of QoS, and also overview of QoE/MOS measurement methods. Next part describes the test bed and methodology used for measurements and evaluating of results. Site survey results and VoIP quality measurement are evaluated at the end, followed by recommendations that can lead to better VoIP quality in MENDELU wireless network.

This thesis deals with mapping and reengineering of existing wifi network. The goal is an analysis of the measured characteristics with the program Ekahau Site Survey. On its basis is designed new solution. Own work is also an financial assessment of the solution.

In the modern society, almost everyone has a smartphone. These devices tend to almost always use WiFi-networking. For the device to identify nearby WiFi access points it has to send out WiFi probing broadcasts. Nearby access points respond to these broadcasts in order to let the device know that they are within reach. This technique is called active scanning. This paper aims to answer if it is possible to use the signal strength of these broadcasts to localize the device transmitting them. We are interested in the possibility of creating this kind of system and the accuracy that it would be able to provide. This is a quantitative study where we produce our results based on experiments, measurements and observations. The experiments are set in a large square shaped area. A sensor was placed at each corner of the area that the smartphone will be tracked within. The smartphone will be sending WiFi probing broadcasts that will be monitored and measured by the sensors. The strength of the broadcast signal will be converted into the relative distance between the devices position and the sensors. These four distances, collected from each of the sensors, will further be converted into a position within the area by using trilateration. To measure the accuracy of the system, the true position of the device will be compared against the calculated position from the system using only the signal strength. Further, a deviation in the distance between the two locations will be calculated. The experiments resulted in a positioning system that was able to estimate positions within an 80 x 80m area. Fourteen location positions were taken which resulted in a mean deviation of 16.6 meters from the true location and a root mean squared error of 19.5 meters. We concluded that more readings within the same position gave a significant increase in accuracy, to the expense of time. Using single measurements would be more practical, but would not produce reliable positions. Keywords: WiFi, Probe Broadcast, Local Positioning System, Trilateration, RSSI.