Made available in DSpace on 2014-12-17T14:55:42Z (GMT). No. of bitstreams: 1 patriciaAC_DISSERT.pdf: 1727038 bytes, checksum: 6d92b0a685d31e2550d0b963726e444f (MD5) Previous issue date: 2010-02-19 / This work deals with experimental studies about VoIP conections into WiFi 802.11b networks with handoff. Indoor and outdoor network experiments are realised to take measurements for the QoS parameters delay, throughput, jitter and packt loss. The performance parameters are obtained through the use of software tools Ekiga, Iperf and Wimanager that assure, respectvely, VoIP conection simulation, trafic network generator and metric parameters acquisition for, throughput, jitter and packt loss. The avarage delay is obtained from the measured throughput and the concept of packt virtual transmition time. The experimental data are validated based on de QoS level for each metric parameter accepted as adequated by the specialized literature / Este trabalho trata de estudos experimentais a respeito de conex?es VoIP em redes WiFi 802.11b com mobilidade de um dos usu?rios envolvidos na conex?o de voz e, por conseguinte, na presen?a de handoff. Os experimentos s?o realizados em ambientes indoor e outdoor com foco na medi??o dos ar?metros de desempenho usualmente tidos como indicadores da qualidade de servi?o - QoS em aplica??es VoIP: atraso, vaz?o, jitter, e perda de pacotes. Os par?metros de desempenho s?o obtidos com o aux?lio das ferramentas Ekiga, Iperf e Wimanager que possibilitam, respectivamente, simular uma conex?o VoIP, injetar tr?fego controlado em um ambiente de rede WiFi e medir a vaz?o, o jitter e a perda de pacotes. O atraso m?dio ? obtido analiticamente a partir da vaz?o medida e do uso do conceito de tempo de transmiss?o virtual m?dio de um pacote de voz. A aferi??o da aceita??o dos resultados ? feita com base nos n?veis de servi?os tidos como adequados na literatura para cada uma das m?tricas obtidas nos experimentos

Orientador: Prof. Dr. Carlos Alberto Kamienski / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia da Informação, Santo André, 2018. / A utilização das tecnologias de informação e comunicação (TICs) está cada dia mais presente na vida das pessoas, gerando mudanças em nosso comportamento, no modo como nos relacionamos, como nos comunicamos, ou ainda na forma como passamos a realizar certas ações. A cidade de São Paulo oferece desde 2014 acesso à Internet gratuitamente em 120 locais públicos através do Programa WiFiLivreSP. Embora estejam disponíveis dados de desempenho dessas praças, existe uma carência de informações sobre o perfil de utilização cotidiano destes locais e o impacto causado por ocorrência de eventos, elevando o número de usuários conectados. Este estudo modela estes perfis, analisando seu uso e procura realizar através da quantidade de usuários conectados a predição de situações atípicas (anomalias), caracterizando possíveis eventos e suas consequências. Para a modelagem e predição foram utilizadas as técnicas SARIMA e Suavização Exponencial Holt-Winters, onde a modelagem SARIMA demonstrou melhor desempenho e a detecção de possíveis anormalidades desenvolvida com a técnica de janelas deslizantes. Este estudo tem por finalidade desenvolver um conjunto de informações à tomada de decisões sobre as praças digitais já implantadas e parâmetros para análises em futuras implantações. / The use of information and communication technologies (ICTs) are increasingly present in people's lives, generating changes in our behavior, without terms how we relate, how we do not communicate, and how we do certain actions. Since 2014, the city of São Paulo has been offering free internet access on 120 public sites through WiFiLivreSP Project. Available performance data is available there is information about the daily usage profile of your sites and the impact caused by the occurrence of events, increasing the number of connected users. This study models these profiles, analyzing their use and seeks to perform through the number of users connected to a prediction of atypical situations (anomalies), characterizing events and their consequences. For a modeling and prediction with the SARIMA and Holt-Winters Exponential Smoothing techniques, where a SARIMA modeling demonstrated better performance and a detection of possible abnormalities developed with the sliding window technique. The purpose of this study is to develop a set of information to make decisions about how digital places already deployed and for analysis in future deployments.

Målet med detta arbete har varit att besvara frågan; ”Varför uppstår det så mycket problem med trådlösa nätverk?”. Detta har gjorts genom att studera relevant litteratur för att sedan kunna utföra två egna studier: en enkätundersökning och tre experiment. Teorin har framförallt hämtats ur kurser och material från Cisco. Undersökningen har hjälpt till att fastställa den generella datoranvändarens kunskaper om trådlösa nätverk. Respondenternas kunskapsnivå visade bland annat på skillnader i hur de använde sin utrustning; de med lägre kunskap om nätverk gick sällan eller aldrig in i sin routers webbgränssnitt. Det vanligaste problemet som uppgavs i undersökningen var en långsam trådlös hastighet; att uppleva svårigheter vid konfigurationen av en ny trådlös router visade sig däremot vara det mest ovanliga. Experimenten genomfördes med hjälp av två accesspunkter och två klientdatorer. De visade bland annat hur kanalöverlappning i trådlösa nätverk leder till minskad hastighet, och betonade även vikten av att välja rätt kanal. Avslutningsvis kunde vi konstatera att varken konsumenten eller teknikindustrin ensidigt kan beskyllas för problemen inom trådlösa nätverk. Båda två har enskilda saker att jobba på. Konsumenterna bör i allt högre grad ta reda på mer om den utrustning de använderför att undvika att ställa till problem, inte bara för sig själv men också för andra. Industrin skulle kunna underlätta genom att dra ner utvecklandet av nya standarder – och inte enbart fokusera på ökad genomströmningshastighet. / The goal with this research has been to answer the question; ”Why are there so many problems linked to wireless networks?”. This has been done by studying the relevant literature to then be able to conduct two self-written studies: one survey and three laboratory experiments. The theory has been taken primarily out of courses and material from Cisco. The survey has helped to determine the knowledge of the general computer-user in regards to wireless networks. The respondents level of knowledge showed, among other things, differences in the way they used their devices; those with less network-knowledge rarely, or never, accessed their routers web-interface. The most common problem that was selected in the survey was a slow wireless speed; experiencing difficulties when configuring a new wireless router proved to be the most unusual one. The experiments were completed through the use of two access points and two computer clients. They demonstrated, among other things, how channel overlap in wireless networks leads to a reduced data-rate, and also stressed the importance of choosing the right channel. Lastly, the work revealed that neither the consumer nor the industry can be solely blamed for the problems that appear in wireless networks. Both of them have separate things towork towards. The consumers should, to a higher extent, find out more about the equipment they use to avoid causing problems, not only for themselves but also for others. The industry could help by slowing down the development of new standards – and to not only focus on achieving higher throughput-rates.

This master’s thesis is focused on the properties and types of helical antennas. The helical antenna work in the different modes. These modes are described in this thesis. There are also discussed possibility for design a dual-band helical antennas. The main aim of this work is the selection of a suitable solution and design a dual-band helical antenna for the WiFi band working at resonance frequencies of 2,4 GHz and 5 GHz. The simulation of this antenna was performed in the program CST Microwave studio.

Denna rapport beskriver utvecklingen av en referensdesign för en WiFi-modul från före- taget H&D Wireless. Referensdesignen skulle vara en kamera som kan skicka videodata trådlöst via den nyss nämnda WiFi-modulen. Projektet genomfördes under våren 2015 på företaget som examensarbete för Högskoleingenjörsprogrammet i elektronik och da- torteknik på KTH. Projektet delades upp i tre olika faser: en förstudiefas, en genomförbarhetsfas och en avslutande fas. I förstudiefasen gjordes en litteraturstudie som behandlade vanliga funktioner hos ex- isterande nätverkskameror, videokodningstekniker samt en något djupare studie av olika typer av bildsensorer. Förstudiefasen fortsatte med en analys av olika hårdvarulösningar som skulle kunna användas i projektet. I slutet av fasen valdes den hårdvara som skulle användas i projek- tet. Genomförbarhetsfasen gick ut på att ta reda på om den valda lösningen gick att ge- nomföra. I denna fas skedde huvudsakligen mjukvaruutveckling, under vilken testdriven utveckling tillämpades. En videobuffert samt en HTTP-server för videoströmning togs fram i denna fas. I den avslutande fasen färdigställdes projektrapporten och mjukvaruutvecklingen av- slutades. Mjukvaruutvecklingen för den valda videokodaren sköts upp på grund av att den levererades sent i projektet. I projektet användes en Scruminspirerad projektmetod. Projektmetoden upplevdes fungera bra på grund av metodens flexibilitet och påtvingande av tydliga uppgifter. Vid projektets slut kunde inte den trådlösa kameran färdigställas på grund av problem i kommunikationen med videokodaren. Om videokodaren hade kommit tidigare hade detta problem troligtvis hunnit åtgärdas innan projektets slut, men det är osäkert om implementationen hade hunnit färdigställas ändå på grund av den korta tid som fanns tillgänglig. Trots att projektet inte hann färdigställas helt har det gett många nyttiga lärdomar för framtiden. / company H&D Wireless. The reference design would be a wireless camera that can send video data wirelessly using the aforementioned WiFi-module. The project was carried out at the company during spring 2015 as a thesis project for the Degree Program in Electronics and Computer Engineering at KTH. The project was divided into three stages: a pilot study stage, a feasibility stage and a concluding stage. A literature study was performed during the pilot study stage, which described common functions in existing network cameras, techniques for video encoding and a slightly deeper study of different types of image sensors. The pilot study stage continued with an analysis of different hardware solutions which could be used in the project. The hardware solution which would be used in the project was chosen at the end of the pilot study stage. The purpose of the feasibility stage was to find out whether the chosen hardware solution would be possible to implement. This stage consisted mainly of software de- velopment, during which test driven development was practiced. A video buffer and a HTTP-server for video streaming was developed in this stage of the project. The project report was finished and the software development was wrapped up during the concluding stage. The development of the software for the chosen video encoder was delayed until the concluding stage because of its late delivery. A Scrum inspired project method was used for this project. The project method was perceived to work well in the project because of its flexibility and demand of clear tasks. The wireless camera could was not finished at the end of the project, because of problems in the communication with the video encoder. The problem could probably have been resolved before the end of the project if the video encoder had arrived earlier. It is not sure if the implementation had been possible to complete anyways because of lack of time. Although the project was not completely finished a lot of valuable knowledge was obtained for future work.

This project aims to classify different units on a wireless network with the use of their frequency response. This is in purpose to increase security when communicating over WiFi. We use a convolution neural network for finding symmetries in the frequency responses recorded from two different units. We used two pre-recorded sets of data which contained the same units but from two different locations. The project achieve an accuracy of 99.987%, with a 5 hidden layers CNN, when training and testing on one dataset. When training the neural network on one set and testing it on a second set, we achieve results below 54.12% for identifying the units. At the end we conclude that the amount of data needed, for achieving high enough accuracy, is to large for this method to be a practical solution for non-stationary units.

Simple IoT devices such as WiFi adapters have the possibility of containing vulnerabilities because of the vast complexity of parsing and implementing the IEEE 802.11 standard correctly. Many of these adapters contain specific and obscure CPU archetypes, making it difficult to assess their security on the firmware from an ethical hacking standpoint. This thesis aims to identify and report possible vulnerabilities, bugs or exploits in the seemingly unexplored chipset called rtl8188eus from Realtek and its corresponding drivers and firmware within the given limitations. The methods used to assess the security of the adapter are based on the Pentesting standard, STRIDE model and corresponding OWASP lists. Several approaches were attempted to analyse the firmware for potential weaknesses, but all attempts were unsuccessful. Other approaches, such as dynamic testing, gave more promising results. One finding from the dynamic testing resulted in a Linux kernel crash through the WiFi adapter which was made possible with only two types of WiFi frames. / Enkla IoT produkter som WiFi adapters har möjligheten att innehålla sårbarheter på grund av det är svårt att implementera de komplexa IEEE 802.11 standarden korrekt. Många av dessa adapters innehåller simpla men okända processorarketyper, vilket gör det svårt att validera deras säkerhet på det firmware som används i ett etiskt hackning synpunkt. Detta examensarbete mål är att identifiera och rapportera möjliga sårbarheter eller buggar i den till synes outforskade chipsetet kallad rtl8188eus från Realtek, dess motsvarande drivrutiner och firmware inom de givna begränsningarna. Metoderna som används för att bedöma adapterns säkerhet är baserade på Pentesting-standarden, STRIDE-modellen och motsvarande OWASP-listor. Flera metoder försökte analysera firmwaret för potentiella svagheter, men alla försök misslyckades. Andra tillvägagångssätt, såsom dynamisk testning, gav mer lovande resultat. Ett fynd från det dynamiska testet resulterade i en Linux kernel krasch genom WiFi-adaptern som möjliggjordes med endast två typer av WiFi frames.

Le développement des systèmes de communication et de localisation et les progrès des dispositifs mobiles rendent possible la mise en œuvre de nouvelles applications et services, permettant l'accès à des informations temps réel et l'amélioration de l'intégration des personnes aveugles. Dans ce contexte, la thèse a contribué au développement d'un système d'information et de guidage destiné aux personnes aveugles dans les transports en commun. La thèse a porté sur deux aspects critiques de ce type de systèmes: la fiabilité de la transmission de données et la capacité à localiser et à guider l'utilisateur de manière robuste. Elle a d'autre part développé un environnement de simulation pour le prototypage et l'analyse du fonctionnement de l'application nomade ainsi que l'étude des aspects réseaux de communication mobile. Les travaux se sont appuyés sur les acquis des projets RAMPE et INFOMOVILLE / The development of communication and locating systems and the progress of mobile devices have made possible new applications and services, allowing access to real-time information and improving the integration of blind people. ln this context, the thesis has contributed to the development of an information and guidance system to be used by blind travellers in public transports. The work has focused on two critical aspects for this kind of systems: the reliability of data transmission and the ability of localizing and guiding the user in an efficient way. A simulation environment has also been developed that can be used for the prototyping and the analysis of the mobile application as well as for the study of communication over the wireless network. The thesis is based on the results of the RAMPE and INFOMOVILLE projects

This diploma thesis describes the work performed in the optimization of the corporate network in the company Alps Electric Czech to expand the amount of information obtained about the state of the network and thus improve the response of the IT department to potencial errors. During the optimization, a monitoring system was also deployed and its connection to the helpdesk and a tailor-made website running on the Flask microframework. With the gradual deployment, adjustments were made based on feedback from the IT department staff. Overall, the network has become more clarified, increasing the efficiency of maintenance and service.

Préfigurant la prochaine grande étape dans le domaine de la navigation, la géolocalisation intra-muros est un domaine de recherche très actif depuis quelques années. Alors que la géolocalisation est entrée dans le quotidien de nombreux professionnels et particuliers avec, notamment, le guidage routier assisté, les besoins d'étendre les applications à l'intérieur se font de plus en plus pressants. Cependant, les systèmes existants se heurtent à des contraintes techniques bien supérieures à celles rencontrées à l'extérieur, la faute, notamment, à la propagation chaotique des ondes électromagnétiques dans les environnements confinés et inhomogènes. Nous proposons dans ce manuscrit une approche statistique du problème de géolocalisation d'un mobile à l'intérieur d'un bâtiment utilisant les ondes WiFi environnantes. Ce manuscrit s'articule autour de deux questions centrales : celle de la détermination des cartes de propagation des ondes WiFi dans un bâtiment donné et celle de la construction d'estimateurs des positions du mobile à l'aide de ces cartes de propagation. Le cadre statistique utilisé dans cette thèse afin de répondre à ces questions est celui des modèles de Markov cachés. Nous proposons notamment, dans un cadre paramétrique, une méthode d'inférence permettant l'estimation en ligne des cartes de propagation, sur la base des informations relevées par le mobile. Dans un cadre non-paramétrique, nous avons étudié la possibilité d'estimer les cartes de propagation considérées comme simple fonction régulière sur l'environnement à géolocaliser. Nos résultats sur l'estimation non paramétrique dans les modèles de Markov cachés permettent d'exhiber un estimateur des fonctions de propagation dont la consistance est établie dans un cadre général. La dernière partie du manuscrit porte sur l'estimation de l'arbre de contextes dans les modèles de Markov cachés à longueur variable. / Foreshadowing the next big step in the field of navigation, indoor geolocation has been a very active field of research in the last few years. While geolocation entered the life of many individuals and professionals, particularly through assisted navigation systems on roads, needs to extend the applications inside the buildings are more and more present. However, existing systems face many more technical constraints than those encountered outside, including the chaotic propagation of electromagnetic waves in confined and inhomogeneous environments. In this manuscript, we propose a statistical approach to the problem of geolocation of a mobile device inside a building, using the WiFi surrounding waves. This manuscript focuses on two central issues: the determination of WiFi wave propagation maps inside a building and the construction of estimators of the mobile's positions using these propagation maps. The statistical framework used in this thesis to answer these questions is that of hidden Markov models. We propose, in a parametric framework, an inference method for the online estimation of the propagation maps, on the basis of the informations reported by the mobile. In a nonparametric framework, we investigated the possibility of estimating the propagation maps considered as a single regular function on the environment that we wish to geolocate. Our results on the nonparametric estimation in hidden Markov models make it possible to produce estimators of the propagation functions whose consistency is established in a general framework. The last part of the manuscript deals with the estimation of the context tree in variable length hidden Markov models.