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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Simulátor pro pasivní multistatický radar s použitím WiFi/WiMAX / Simulator for Passive Multi-Static Radar using WiFi/WiMAX

Sládek, Ondřej January 2017 (has links)
This master’s thesis deals with the concept of passive multistatic radar. The radar system exploits WiFi or WiMAX transmitters as the source of radiolocation signal. The transmitters are considered non-cooperative. The master’s thesis evaluates limitations arising from utilization of WiFi or WiMAX signals. A Matlab simulator was created as a part of the thesis, which was used to verify the basic idea behind this concept. Based on the results of real-life simulations, conclusions are suggested towards a possible application of WiFi/WiMAX radar.
192

Pushing Traffic into the Digital Age : A Communication Technology Comparison and Security Assessment / Pushing Traffic into the Digital Age : A Communication Technology Comparison and Security Assessment

Krantz, Christoffer, Vukota, Gabriela January 2020 (has links)
With the rapid advances of technology, digitisation of many facets of our existence is taking place in an attempt to improve everyday life. The automotive industry is following suit, attempting to introduce connected traffic technology that is meant to improve traffic fluidity and safety. To facilitate this, connected vehicles aim to create solutions for the sharing of information between other vehicles, infrastructure - such as traffic light controllers, and pedestrians. In an attempt to further investigate the connected vehicle landscape of today, the thesis compared the two most prominent technologies, DSRC and cellular communication. An essential part of this comparison was highlighting the potential attacks that the two technologies could be exposed to. This was done in order to open up a discussion on what technology is the most suitable to focus on for the future both in terms of viability and security. DSRC has been considered the prominent communication technology for connected vehicles, but the development has stagnated. As such, the ever-evolving cellular technology is looking like the superior technology. This, however, is reliant on 5G delivering the speeds, stability and security promised. The state of constant vehicular connection is going to lead to many issues and concerns, both for the privacy of the individual but also the safety of the public. While connected traffic aims to solve a number of issues from traffic accidents to emissions - if the security of the communication is not constantly evolving to meet the rapid development of new technology, the consequences of connecting such a delicate system might nullify the potential benefits.
193

IS pro evidenci telefonních hovorů / IS for Phone Calls Accounting

Šitka, Petr January 2009 (has links)
This contribution refers to development of information system working with mobile communication devices. The information system is mainly for collecting and analyzing data made through the mobile devices. In the contribution there are described possibilities of connection between PC and mobile device, also there are described the most common information system for mobile devices, and tools for application development. Design and implementation of information system is based on this study.
194

Inomhuspositionering med bredbandig radio

Gustavsson, Oscar, Miksits, Adam January 2019 (has links)
In this report it is evaluated whether a higher dimensional fingerprint vector increases accuracy of an algorithm for indoor localisation. Many solutions use a Received Signal Strength Indicator (RSSI) to estimate a position. It was studied if the use of the Channel State Information (CSI), i.e. the channel’s frequency response, is beneficial for the accuracy.The localisation algorithm estimates the position of a new measurement by comparing it to previous measurements using k-Nearest Neighbour (k-NN) regression. The mean power was used as RSSI and 100 samples of the frequency response as CSI. Reduction of the dimension of the CSI vector with statistical moments and Principal Component Analysis (PCA) was tested. An improvement in accuracy could not be observed by using a higher dimensional fingerprint vector than RSSI. A standardised Euclidean or Mahalanobis distance measure in the k-NN algorithm seemed to perform better than Euclidean distance. Taking the logarithm of the frequency response samples before doing any calculation also seemed to improve accuracy. / I denna rapport utvärderas huruvida data av högre dimension ökar noggrannheten hos en algoritm för inomhuspositionering. Många lösningar använder en indikator för mottagen signalstyrka (RSSI) för att skatta en position. Det studerades studerade om användningen av kanalens fysikaliska tillstånd (CSI), det vill säga kanalens frekvenssvar, är fördelaktig för noggrannheten.Positioneringsalgoritmen skattar positionen för en ny mätning genom att jämföra den med tidigare mätningar med k-Nearest Neighbour (k-NN)-regression. Medeleffekten användes som RSSI och 100 sampel av frekvenssvaret som CSI. Reducering av CSI vektornsdimension med statistiska moment och Principalkomponentanalys(PCA) testades. En förbättring av noggrannheten kunde inte observeras genom att använda data med högre dimension än RSSI. Ett standardiserat Euklidiskt eller Mahalanobis avståndsåatt i k-NN-algoritmen verkade prestera bättre än Euklidiskt avstånd. Att ta logaritmen av frekvenssvarets sampel innan andra beräkningar gjordes verkade också förbättra noggrannheten.
195

Automated Residential Energy Audits and Savings Measurements Using A Smart WiFi Thermostat Enabled Data Mining Approach

Alanezi, Abdulrahman Mubarak Q 18 May 2021 (has links)
No description available.
196

Energy comparison of wireless data transfer in an energy critical driven system : Digitizing analog meters for the world of IoT - An energy study in a concrete environment

Kantis, Simon, Magnusson, Eric January 2022 (has links)
Digitizing analog meters into the IoT where meters can be read remotely is a solution which is both environmentally and economically beneficial. This study investigate show energy critical systems can gain a longer lifespan by optimizing their energy consumption. The purpose of this study is to evaluate the energy consumption of energy critical systems with different wireless data transfer protocols. This is conducted with experiments and observations.The data was collected by setting up two testbeds where the wireless transmission interfaces WiFi and BLE were used to send data between two microcomputers. These testbeds measured the energy consumption when altering with the variables of the two transmission protocols.The result shows that the internal protocols of WiFi were greatly affected by the changes made in the variables compared to BLE during the experiments. The results also show that when calibrating the different variables, the energy consumption is reduced by up around 52%. Furthermore, the result indicates that there is energy to saveif you optimize transmission power to a specific environment.In this study, BLE has little to no change to the energy consumption when changing the different variables. When investigating the internal protocols of WiFi, they are greatly affected by the different variables being changed. A lower transmission power can be more energy efficient but at the cost of shorter range and eventually a higher packet loss.
197

A study of limitations and performance in scalable hosting using mobile devices / En studie i begränsningar och prestanda för skalbar hosting med hjälp av mobila enheter

Rönnholm, Niklas January 2018 (has links)
At present day, distributed computing is a widely used technique, where volunteers support different computing power needs organizations might have. This thesis sought to benchmark distributed computing performance limited to mobile device support since this type of support is seldom done with mobile devices. This thesis proposes two approaches to harnessing computational power and infrastructure of a group of mobile devices. The problems used for benchmarking are small instances of deep learning training. One requirement posed by the mobile devices’ non-static nature was that this should be possible without any significant prior configuration. The protocol used for communication was HTTP. The reason deep-learning was chosen as the benchmarking problem is due to its versatility and variability. The results showed that this technique can be applied successfully to some types of problem instances, and that the two proposed approaches also favour different problem instances. The highest request rate found for the prototype with a 99% response rate was a 2100% increase in efficiency compared to a regular server. This was under the premise that it was provided just below 2000 mobile devices for only particular problem instances. / För närvarande är distribuerad databehandling en utbredd teknik, där frivilliga individer stödjer olika organisationers behov av datorkraft. Denna rapport försökte jämföra prestandan för distribuerad databehandling begränsad till enbart stöd av mobila enheter då denna typ av stöd sällan görs med mobila enheter. Rapporten föreslår två sätt att utnyttja beräkningskraft och infrastruktur för en grupp mobila enheter. De problem som används för benchmarking är små exempel på deep-learning. Ett krav som ställdes av mobilenheternas icke-statiska natur var att detta skulle vara möjligt utan några betydande konfigureringar. Protokollet som användes för kommunikation var HTTP. Anledningen till att deeplearning valdes som referensproblem beror på dess mångsidighet och variation. Resultaten visade att denna teknik kan tillämpas framgångsrikt på vissa typer av probleminstanser, och att de två föreslagna tillvägagångssätten också gynnar olika probleminstanser. Den högsta requesthastigheten hittad för prototypen med 99% svarsfrekvens var en 2100% ökning av effektiviteten jämfört med en vanlig server. Detta givet strax under 2000 mobila enheter för vissa speciella probleminstanser.
198

Heterogeneous Networking for Beyond 3G system in a High-Speed Train Environment. Investigation of handover procedures in a high-speed train environment and adoption of a pattern classification neural-networks approach for handover management

Ong, Felicia Li Chin January 2016 (has links)
Based on the targets outlined by the EU Horizon 2020 (H2020) framework, it is expected that heterogeneous networking will play a crucial role in delivering seamless end-to-end ubiquitous Internet access for users. In due course, the current GSM-Railway (GSM-R) will be deemed unsustainable, as the demand for packet-oriented services continues to increase. Therefore, the opportunity to identify a plausible replacement system conducted in this research study is timely and appropriate. In this research study, a hybrid satellite and terrestrial network for enabling ubiquitous Internet access in a high-speed train environment is investigated. The study focuses on the mobility management aspect of the system, primarily related to the handover management. A proposed handover strategy, employing the RACE II MONET and ITU-T Q.65 design methodology, will be addressed. This includes identifying the functional model (FM) which is then mapped to the functional architecture (FUA), based on the Q.1711 IMT-2000 FM. In addition, the signalling protocols, information flows and message format based on the adopted design methodology will also be specified. The approach is then simulated in OPNET and the findings are then presented and discussed. The opportunity of exploring the prospect of employing neural networks (NN) for handover is also undertaken. This study focuses specifically on the use of pattern classification neural networks to aid in the handover process, which is then simulated in MATLAB. The simulation outcomes demonstrated the effectiveness and appropriateness of the NN algorithm and the competence of the algorithm in facilitating the handover process.
199

Control system and simplified timesynchronization for heterogenous IoT systems with medium time requirements / Styrsystem och förenklad tidssynkronisering för heterogena IoT-nätverk med måttliga tidskrav

Touma, Jemma, Hejdenberg, Simon January 2024 (has links)
The company QTPIE conducts research on drivers and their unconscious reactions when driving. To help, they use smart devices that today must be individually handled at the start and end of a run, and have individually set timestamps, which can lead to differences between the units when data is entered and collation of the units' data after a run.   The purpose of this study is an integrated control system in the form of an Android mobile application that partly facilitates the start and end of a run, and partly synchronizes time stamps between all devices. The intention is to build a heterogeneous mobile network with a central control unit and implement time synchronization and investigate whether the heterogeneity affects the implementation of the network.   The result was an Android mobile application that controlled selected external smart devices, synchronized these, and had time synchronization built in at the start of each run. / Företaget QTPIE gör undersökningar på förare och deras omedvetna reaktioner vid körning. Till hjälp använder de smarta enheter som idag måste hanteras individuellt vid start och slut av en körning, samt har individuellt satta tidsstämplar, vilket kan leda till differenser mellan enheterna vid datainmatning och sammanstrålning av enheternas data efter en körning.  Avsikten med den här studien är ett integrerat styrsystem i form av en Android mobilapplikation som dels underlättar vid start och slut av en körning, dels synkroniserar tidsstämplar mellan alla enheter. Avsikten är att bygga upp ett heterogent mobilt nätverk med en central kontrollenhet samt implementera tidssynkronisering och undersöka om heterogeniteten påverkar implementeringen av nätverket.   Resultatet blev en Android mobilapplikation som styrde valda externa smarta enheter, synkroniserade dessa samt hade tidssynkronisering inbyggt vid start av varje körning.
200

Simulation de la propagation des ondes radio en environnement multi-trajets pour l'étude des réseaux sans fil.

De La Roche, Guillaume 12 December 2007 (has links) (PDF)
Le but de cette thèse est d'implémenter une méthode déterministe pour modéliser le canal radio des réseaux wifi. Pour cela la méthode MR-FDPF (Multi Resolution Frequency Domain ParFlow) a été adaptée, Le paramétrage et la calibration du modèle sont présentés, donnant une erreur inférieure a 4dB. Nous montrons comment prendre en compte les autres étages d'un bâtiment en développant la méthode 2.5D. De plus pour bien prendre en compte les diagrammes d'antennes des points d'accès un nouveau procédé est présenté. Enfin l'implémentation de la méthode MR-FDPF en 3D est développée ainsi que les optimisations nécessaires Enfin trois extensions sont proposées: la première concerne une extension de la méthode en milieu urbain, la deuxième présente une méthode de prédiction des évanouissements, et la troisième explique comment le modèle a été intégré dans un logiciel de planification de réseau WiFi.

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