This diploma thesis focuses upon mobility which structures time and space of Prague's hinterland. The time-space regions are conceptualised and serve to explore the structure of suburban space. The positioning data from mobile phones are used to investigate tangential mobility throughout suburban municipalities. It happened in two time-sections which distinguish the working and the service commute. The method of the time-space regionalisation was introduced for this purpose. In total, 45 local centres were found. Moreover, their regions were delimited and two regions without cores were delimited as well. The resulting time-space regions are distinguished into three types: small inner regions, large outer regions and river regions. The case study in Dolní Břežany municipality seeks causes and consequences of centrality in local scale. The significance of the thesis lies in partial, but highly interconnected contributions in all three dimensions: theory, methodology and empirics. Key words: mobility, suburbanisation, structuration, regionalisation, mobile data, Prague, Dolní Břežany

In this paper, we present a novel approach to mine moving object group patterns from object movement database. At first, our approaches summarize the raw data in the source object movement database into trajectories, and then discover valid 2-groups mainly from the trajectory-based object movement database. We propose two trajectory conversion methods, namely linear regression and vector conversion. We further propose a trajectory based mobile group mining algorithm that is intended to reduce the overhead of mining 2-Group Patterns. The use of trajectories allows valid 2-groups to be mined using smaller number of summarized records (in trajectory model) and examining smaller number of candidate 2-groups. Finally, we conduct series of comprehensive experiments to evaluate and compare the performances of the proposed methods with existing approaches that use source object movement database or other summarization techniques. The experimental results demonstrate the superior performance of our proposed approach.

Device-to-device communication has been suggested as a complement to traditional cellular networks as a means of offloading cellular traffic. In this thesis we explore a solution for device-to-device communication based on opportunistic content distribution in a content-centric network. Communication opportunities arise as mobile nodes roam around in an area and occasionally enter in direct communication range with one another. We consider a node to be a pedestrian equipped with a mobile device and explore the properties of opportunistic communication in the context of content dissemination in urban areas. The contributions of this thesis lie in three areas. We first study human mobility as one of the main enablers of opportunistic communication. We introduce traces collected from a realistic pedestrian mobility simulator and demonstrate that the performance of opportunistic networks is not very sensitive to the accurate estimation of the probability distributions of mobility parameters. However, capturing the space in which mobility occurs may be of high importance. Secondly, we design and implement a middleware for opportunistic content-centric networking, and we evaluate it via a small-scale testbed, as well as through extensive simulations. We conclude that energy-saving mechanisms should be part of the middleware design, while caching should be considered only as an add-on feature. Thirdly, we present and evaluate three different energy-saving mechanisms in the context of opportunistic networking: a dual-radio architecture, an asynchronous duty-cycling scheme, and an energy-aware algorithm which takes into account node selfishness. We evaluate our proposals analytically and via simulations. We demonstrate that when a critical mass of participants is available, the performance of the opportunistic network is comparable to downloading contents directly via the cellular network in terms of energy consumption while offloading large traffic volumes from the operator. / <p>QC 20151120</p>

La popularité des plateformes mobiles telles que smartphones et tablettes génère un volume croissant de données à transférer. La principale raison de cette croissance est l'accès simplifié aux contenus vidéo sur ces plateformes. La future génération (5G) de téléphonie mobile est en cours de développement et a pour objectif d'offrir une bande passante suffisante pour de tels volumes de données. Néanmoins, un déploiement en masse de la 5G n'est pas envisagé avant 2020. De plus, la croissance est telle qu'il sera forcément intéressant de développer des solutions alternatives et complémentaires capables de délester le réseau cellulaire. L'exemple actuel le plus représentatif est le délestage de données cellulaires vers des réseaux d'accès WiFi par les principaux opérateurs mobiles. Dans ce contexte, nous proposons de déployer un nouveau réseau de contenus qui s'appuie sur les réseaux de transports publics urbains. Cette solution déploie des bornes sans-fil dans les bus et sur certaines stations de bus pour offrir du contenu aux passagers des bus. Les bus enregistrent et transportent les données, et se comportent donc comme des mules qui peuvent s'échanger des données dans certaines stations de bus. L'ensemble des bus créé un réseau de transport de données tolérantes au délai telles que de la vidéo à la demande. La création d'un tel réseau soulève de nombreuses questions. Les questions traitées dans les trois parties de cette thèse sont les suivantes: (i) le choix des stations de bus sur lesquelles une borne sans-fil doit être déployée, (ii) le choix du protocole de routage des données, (iii) la gestion efficace de la contention dans les stations et enfin (iv) la réduction du coût d'une telle infrastructure. La première partie de la thèse présente notre réseau de contenu dont l'objectif principal est de transporter de larges volumes de données. Nous montrons pour cela qu'il suffit de déployer des bornes sans-fil aux terminus des lignes de bus. Ce résultat provient de l'analyse des réseaux de transports publics des villes de Toulouse, Helsinki et Paris. Connaissant les horaires et la topologie de ces réseaux de transports, nous proposons de pré-calculer les routes pour transmettre les données dans ce réseau. Nous montrons que ce routage statique permet de réduire drastiquement le nombre de réplications de messages quand on le compare à un routage épidémique. La seconde contribution de cette thèse s'intéresse à l'échange des messages au niveau des bornes sans-fil déployées aux terminus des lignes de bus. En effet, les protocoles d'accès actuels partagent équitablement la bande passante entre les bus et le point d'accès. Dans notre cas, il en résulte une congestion importante que nous proposons de résoudre en introduisant un codage réseau XOR de proche en proche. Les flux qui se croisent sont alors combinés par la borne. Les bus transportent des paquets codés qui seront décodés au prochain saut par la borne suivante. Une analyse théorique de ce mode de communication montre que la probabilité de réception des messages peut-être augmentée au maximum de 50% et la surcharge diminuée au maximum de 50%. Pour les 3 villes européennes considérées, nous montrons par simulation que ce protocole permet d'augmenter de 35% à 48% le nombre de messages reçus. La dernière partie de cette thèse a pour objectif de réduire le coût de déploiement d'une telle architecture. Elle classifie les terminus des lignes de bus en trois ensembles qui sont équipés par des bornes sans fil de nature différentes. Les résultats de simulation montrent que pour les trois villes il est possible de garantir la connectivité de bout-en-bout tout en réduisant les coûts de déploiement d'un facteur 3. Cette architecture, dénommée 3-tier, transporte 30% plus de messages que le déploiement basique proposé en première partie. Nous montrons qu'il est possible de décharger un grand volume de données avec notre architecture. Par exemple, pour Paris, notre architecture permet de / Mobile data traffic is increasing at an exponential rate with the proliferation of mobile devices and easy access to large contents such as video. Traffic demand is expected to soar in the next 5 years and a new generation of mobile networks (5G) is currently being developed to address the looming bandwidth crunch. However, significant 5G deployments are not expected until 2020 or even beyond. As such, any solution that offloads cellular traffic to other available networks is of high interest, the main example being the successful offloading of cellular traffic onto WiFi. In this context, we propose to leverage public transportation networks (PTNs) created by regular bus lines in urban centers to create another offloading option for delay tolerant data such as video on demand. This PhD proposes a novel content delivery infrastructure where wireless access points (APs) are installed on both bus stops and buses. Buses act as data mules, creating a delay tolerant network capable of carrying content users can access while commuting using public transportation. Building such a network raises several core challenges such as: (i) selecting the bus stops on which it is best to install APs, (ii) efficiently routing the data, (iii) relieving congestion points in major hubs and (iv) minimizing the cost of the full architecture. These challenges are addressed in the three parts of this thesis. The first part of the thesis presents our content delivery infrastructure whose primary aim is to carry large volumes of data. We show that it is beneficial to install APs at the end stations of bus lines by analyzing the publicly available time tables of PTN providers of different cities. Knowing the underlying topology and schedule of PTNs, we propose to pre-calculate static routes between stations. This leads to a dramatic decrease in message replications and transfers compared to the state-of-the-art Epidemic delay tolerant protocol. Simulation results for three cities demonstrate that our routing policy increases by 4 to 8 times the number of delivered messages while reducing the overhead ratio. The second part of the thesis addresses the problem of relieving congestion at stations where several bus lines converge and have to exchange data through the AP. The solution proposed leverages XOR network coding where encoding and decoding are performed hop-by-hop for flows crossing at an AP. We conduct a theoretical analysis of the delivery probability and overhead ratio for a general setting. This analysis indicates that the maximum delivery probability is increased by 50% while the overhead ratio is reduced by 50%, if such network coding is applied. Simulations of this general setting corroborate these points, showing, in addition, that the average delay is reduced as well. Introducing our XOR network coding to our content delivery infrastructure using real bus timetables, we demonstrate a 35% - 48% improvement in the number of messages delivered. The third part of the thesis proposes a cost-effective architecture. It classifies PTN bus stops into three categories, each equipped with different types of wireless APs, allowing for a fine-grained cost control. Simulation results demonstrate the viability of our design choices. In particular, the 3-Tier architecture is shown to guarantee end-to-end connectivity and reduce the deployment cost by a factor of 3 while delivering 30% more packets than a baseline architecture. It can offload a large amount of mobile data, as for instance 4.7 terabytes within 12 hours in the Paris topology.

abstract: Mobile data collection (MDC) applications have been growing in the last decade especially in the field of education and research. Although many MDC applications are available, almost all of them are tailor-made for a very specific task in a very specific field (i.e. health, traffic, weather forecasts, …etc.). Since the main users of these apps are researchers, physicians or generally data collectors, it can be extremely challenging for them to make adjustments or modifications to these applications given that they have limited or no technical background in coding. Another common issue with MDC applications is that its functionalities are limited only to data collection and storing. Other functionalities such as data visualizations, data sharing, data synchronization and/or data updating are rarely found in MDC apps. This thesis tries to solve the problems mentioned above by adding the following two enhancements: (a) the ability for data collectors to customize their own applications based on the project they’re working on, (b) and introducing new tools that would help manage the collected data. This will be achieved by creating a Java standalone application where data collectors can use to design their own mobile apps in a userfriendly Graphical User Interface (GUI). Once the app has been completely designed using the Java tool, a new iOS mobile application would be automatically generated based on the user’s input. By using this tool, researchers now are able to create mobile applications that are completely tailored to their needs, in addition to enjoying new features such as visualize and analyze data, synchronize data to the remote database, share data with other data collectors and update existing data. / Dissertation/Thesis / Masters Thesis Computer Science 2016

This work deals with user satisfaction with mobile data service. The main part is devoted to the development of a mobile application that provides testing network parameters to evaluate and use online databases shared with other users. Discussed the possibility of distributing applications among users over its testing and then to the App Store.

Yes / Sensing coverage and network connectivity are two of the most fundamental issues to ensure that there are effective environmental sensing and robust data communication in a WSN application. Random positioning of nodes in a WSN may result in random connectivity, which can cause a large variety of key parameters within the WSN. For example, data latency and battery lifetime can lead to the isolation of nodes, which causes a disconnection between nodes within the network. These problems can be avoided by using mobile data sinks, which travel between nodes that have connection problems. This research aims to design, test and optimise a data collection system that addresses the isolated node problem, as well as to improve the connectivity between sensor nodes and base station, and to reduce the energy consumption simultaneously. In addition, this system will help to solve several problems such as the imbalance of delay and hotspot problems. The effort in this paper is focussed on the feasibility of using the proposed methodology in different applications. More ongoing experimental work will aim to provide a detailed study for advanced applications e.g. transport systems for civil purposes. / European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424.

The goal of this thesis is to design and implement a library for data synchronization between multiple client's devices in the context of the ecosystem of a single application targeting the iOS, iPadOS or MacOS operating system. The work focuses on the simple integration of the library into existing applications using the Realm database system and on the simple way to connect the user interface with the synchronization process. I solved the chosen problem by designing a synchronization protocol primarily based on log synchronization to distribute changes between the client and the server, implementing a library to monitor changes in the client's database and distribute them to the server, and implementing a server library to integrate received changes and distribute them with help of notifications. The solution provides an easy way to implement data synchronization between multiple devices using custom database server and with the ability to define how to handle new changes of objects presented in the user interface during the synchronization. Created library can be quickly and easily integrated and thus effectively speed up the application development process.

In this dissertation research, we design and analyze integrated mobility and service management for network cost minimization in Wireless Mesh Networks (WMNs). We first investigate the problem of mobility management in WMNs for which we propose two efficient per-user mobility management schemes based on pointer forwarding, and then a third one that integrates routing-based location update and pointer forwarding for further performance improvement. We further study integrated mobility and service management for which we propose protocols that support efficient mobile data access services with cache consistency management, and mobile multicast services. We also investigate reliable and secure integrated mobility and service man agement in WMNs, and apply the idea to the design of a protocol for secure and reliable mobile multicast. The most salient feature of our protocols is that they are optimal on a per-user basis (or on a per-group basis for mobile multicast), that is, the overall network communication cost incurred is minimized for each individual user (or group). Per-user based optimization is critical because mobile users normally have vastly different mobility and service characteristics. Thus, the overall cost saving due to per-user based optimization is cumulatively significant with an increasing mobile user population. To evaluate the performance of our proposed protocols, we develop mathematical models and computational procedures used to compute the network communication cost incurred and build simulation systems for validating the results obtained from analytical modeling. We identify optimal design settings under which the network cost is minimized for our mobility and service management protocols in WMNs. Intensive comparative performance studies are carried out to compare our protocols with existing work in the literature. The results show that our protocols significantly outperform existing protocols under identical environmental and operational settings. We extend the design notion of integrated mobility and service management for cost minimization to MANETs and propose a scalable dual-region mobility management scheme for location-based routing. The basic design concept is to use local regions to complement home regions and have mobile nodes in the home region of a mobile node serve as location servers for that node. We develop a mathematical model to derive the optimal home region size and local region size under which overall network cost incurred is minimized. Through a comparative performance study, we show that dual-region mobility management outperforms existing mobility management schemes based on static home regions. / Ph. D.

When implementing an intelligent transportation system (ITS), stakeholders often overlook the importance of evaluating the system once it is in place. Determining the extent to which the objectives of an investment have been met is important to not only the agency involved, but also to other agencies, so that lessons are learned and mistakes are not repeated in future projects. An effective evaluation allows a transit provider to identify and address areas that could use improvement. Agencies implementing ITS investments often have different goals, needs, and concerns that they hope their project will address and consequently the development of a generic evaluation plan is difficult to develop. While it is recognized that the U.S. Department of Transportation has developed guidelines to aid agencies in evaluating such investments, this research is intended to complement these guidelines by assisting in the evaluation of a site specific ITS investment. It presents an evaluation framework and plan that provides a systematic method for assessing the potential impacts associated with the project by defining objectives, measures, analysis recommendations, and data requirements. The framework developed specifically addresses the ITS investment on the OmniLink local route deviation bus service in Prince William County, Virginia, but could be used as a basis for the evaluation of similar ITS investments. The OmniLink ITS investment includes an automatic vehicle location (AVL) system, mobile data terminals (MDTs), and computer-aided dispatch (CAD) technology. / Master of Science