Submitted by Clebson Anjos (clebson.leandro54@gmail.com) on 2016-03-01T18:01:39Z No. of bitstreams: 1 arquivototal.pdf: 3568225 bytes, checksum: 5a160c927cafc8b12cef6cc94dc824ec (MD5) / Made available in DSpace on 2016-03-01T18:01:39Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3568225 bytes, checksum: 5a160c927cafc8b12cef6cc94dc824ec (MD5) Previous issue date: 2011-09-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The present study analyzes the process of participatory streaming as part of the development of Information and Communication Technologies (ICTs). Our purpose is to investigate the dynamics present within this process, taking as basis the notions of participation, post-massive functions and media convergence. We tried to find in the studies of theorists who analyze the motivations for a relationship with the media, at different times, such as McLuhan (1981), Wolton (2007), Lemos and Lévy (2010), vectors of a historical progression in media participation interest. We developed a reflection on what is intrinsic to the human being and reconfigures in the media processes, realising participation as a key concept for this analysis, in Diaz Bordenave (1994). Through the concept of massive and post-massive functions by Lemos and Lévy (2010) we seek to understand the transformations that the so-called new media provide to the of mass communication processes, analyzed by Wolf (2005). This confrontation gave us the foundation needed to start the presentation of the concept of horizontal mass media. We also hold in check the concept of media convergence, seeking a broad overview on the subject. From proposed convergence categories, we analyzed three cases of converged participation in participatory streaming: the talk show Roda Viva on the Internet, the band Arcade Fire concert on YouTube Live and a Brazilian soccer team match broadcasting in the website GloboEsporte.com. We concluded that, in the cases analyzed, we detected the formation of a horizontal mass media, established in a kind of convergence that mix media of different functions (massive and post-massive), in a collective experience that at the same time provides direct dialogue among the interactors. / A presente pesquisa analisa o processo das transmissões participativas, como parte do desenvolvimento das Tecnologias de Informação e Comunicação (TICs). Nosso objetivo é investigar as dinâmicas presentes dentro deste processo, tendo como fundamento as noções de participação, funções pós-massivas e convergência midiática. Buscamos em teóricos que analisam as motivações para uma relação com as mídias, em diferentes épocas, como McLuhan (1981), Wolton (2007), Lemos e Lévy (2010), encontrar vetores de uma progressão histórica no interesse pela participação midiática. Desenvolvemos uma reflexão sobre o que é intrínseco ao ser humano e se reconfigura nos processos midiáticos, encontrando a participação como um conceito-chave para esta análise, em Diaz Bordenave (1994). Através da conceituação de funções massivas e pós-massivas da mídia, de Lemos e Lévy (2010) buscamos entender quais transformações as chamadas novas mídias proporcionaram aos processos de comunicação de massa, analisados por Wolf (2005). Este embate nos deu a base necessária para iniciar a apresentação do conceito de mídia de massa horizontal. Detemo-nos também na verificação do conceito de convergência midiática, buscando uma visão ampla sobre o assunto. A partir de categorias de convergência propostas, analisamos três casos de participação convergente em transmissões participativas: o programa Roda Viva na Internet, o show da banda Arcade Fire no YouTube Live e a transmissão de um jogo da seleção brasileira de futebol no portal GloboEsporte.com. Concluímos que, com os casos analisados, detectou-se a formação de uma mídia de massa horizontal, estabelecida num tipo de convergência que mistura mídias de funções diferentes (massivas e pós-massivas), numa experiência coletiva e que, ao mesmo tempo, proporciona diálogos diretos entre os interatores.

Submitted by Hemily Gomes Marciano (hemily.gomes@gmail.com) on 2018-04-17T18:10:25Z No. of bitstreams: 1 versão final.pdf: 751892 bytes, checksum: 22aa973b490af1ca393b304a45758dbb (MD5) / Rejected by Pamella Benevides Gonçalves null (pamella@feg.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: Favor basta apenas Inserir a capa, porém é um elemento obrigatório. Deve conter a identificação do trabalho, na seguinte ordem: • Nome da Instituição (centralizado) • Nome completo do autor (centralizado) • Título do trabalho (centralizado) • Subtítulo: se houver, deve ser precedido de dois pontos, evidenciando a sua subordinação ao título • Número do volume, se houver mais de um • Local (cidade) da instituição onde será apresentado (centralizado) • Ano da entrega (centralizado) Agradecemos a compreensão. on 2018-04-18T13:06:59Z (GMT) / Submitted by Hemily Gomes Marciano (hemily.gomes@gmail.com) on 2018-04-18T16:51:34Z No. of bitstreams: 1 Versão Final Tese.pdf: 803694 bytes, checksum: c2cc93bc2be66aef333d543d606bd2f8 (MD5) / Approved for entry into archive by Pamella Benevides Gonçalves null (pamella@feg.unesp.br) on 2018-04-19T18:58:37Z (GMT) No. of bitstreams: 1 fortes_hgm_dr_guara.pdf: 803694 bytes, checksum: c2cc93bc2be66aef333d543d606bd2f8 (MD5) / Made available in DSpace on 2018-04-19T18:58:37Z (GMT). No. of bitstreams: 1 fortes_hgm_dr_guara.pdf: 803694 bytes, checksum: c2cc93bc2be66aef333d543d606bd2f8 (MD5) Previous issue date: 2018-03-23 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Partículas massivas de spin-2 são usualmente descritas pela conhecida teoria de Fierz-Pauli através de um tensor de rank-2 simétrico hµν = hνµ. Recentemente, tem havido um aumento no interesse por teorias que descrevam esse tipo de partícula, principalmente pela possibilidade de oferecer uma explicação alternativa para o problema da aceleração da expansão do universo, pois se o gráviton tivesse uma pequena massa, a força gravitacional diminuiria a grandes distâncias, produzindo tal aceleração. Trabalhos mais recentes têm trazido à tona outras possibilidades além de Fierz-Pauli para se descrever partículas de spin-2 massivas partindo de um tensor de rank-2 não simétrico eµν 6= eνµ, os chamados modelos L(a1). Tendo em vista que toda partícula deve interagir com a gravitação, no presente trabalho buscamos estudar o acoplamento desses novos modelos com um campo gravitacional de fundo. Para isso, a partir da manipulação das equações de movimento, procuramos obter os vínculos necessários para se ter uma teoria com a contagem de graus de liberdade correta. Fizemos também um estudo preliminar da versão sem massa dos modelos L(a1) no espaço curvo a partir da análise das simetrias de gauge existentes. Identificamos ainda os modelos parcialmente simétricos presentes em L(a1) / Massive spin-2 particles are usually described by the well-known Fierz-Pauli theory via a symmetric rank-2 tensor hµν = hνµ. Recently there has been an increase of interest in theories describing this kind of particle, especially because they can contribute to explain the accelerated expansion of the universe, since if the graviton has a small mass, the gravitational force would decrease at large distances, producing such accelerattion. In recent works other possibilities, besides the Fierz-Pauli model, which describe massive spin-2 particles starting from a non-symmetric rank-2 tensor eµν 6= eνµ have been found, the so-called L(a1) models. Since every particle has to interact with the gravitation, we have studied the coupling of the new models with a background gravitational field. Therefore, from the manipulation of the equations of motion, we seek for the necessary constraints in order to achieve the correct counting of degrees of freedom. We also have done a preliminary study of the massless version of the L(a1) models in the curved space from the analysis of the gauge symmetries of the theory. We also have identified the partially symmetric models present in L(a1). / 2013/25368-0

O rápido desenvolvimento da tecnologia da informação traz oportunidades para área da educação, colocando a educação a distância e aprendizagem online como opções para o modelo tradicional, sobretudo os Massive Open Online Courses (MOOCs), os quais, no contexto do movimento de educação aberta, são apresentados como meio para aumentar o acesso e a qualidade da educação, proporcionando redução dos custos e da desigualdade educacional, sobretudo nos países em desenvolvimento. A revisão sistemática de 74 artigos evidenciou que as IES estão incorporando os MOOCs às suas práticas - em parte, produzindo seus próprios MOOCs, mas também os integrando a seus currículos, tanto para revisar conteúdo do Ensino Médio com alunos ingressantes no Ensino Superior quanto para melhorar seus cursos.Assim, considerando que as pesquisas que avaliam a incorporação dos MOOCs aos currículos das IES investigam, sobretudo, o desempenho e o nível de satisfação dos alunos, o objetivo principal desse estudo foi compreender como os MOOCs estão sendo incorporados aos cursos presenciais de graduação e qual o valor funcional percebido pelos alunos com relação a essa prática. Para tal, foi realizada uma revisão sistemática da literatura e um estudo de caso de caráter exploratório e descritivo, que integra os enfoques qualitativo e quantitativo. A unidade de análise do estudo de caso foi a disciplina de Fundamentos de Administração, lecionada no primeiro ano do curso bacharelado em Administração, e quatro fontes de evidências foram utilizadas: documentos sobre o MOOC, documentação sobre a disciplina que utilizou o MOOC, entrevistas com o Chefe de Departamento e os professores responsáveis pela disciplina e levantamento (survey) com 101 alunos. As evidências obtidas nas etapas de investigação documental e entrevistas foram analisadas baseando-se nas questões de pesquisas, enquanto o levantamento com os alunos valeu-se da técnica de análise estatística de modelagem de equações estruturais, utilizando o software R. Os resultados do estudo permitiram identificar que, assim como sugerido pela literatura, o MOOC foi utilizado como recurso online no método blended learning em uma disciplina introdutória e substituindo parte da carga horária presencial, possibilitando o aumento do número de alunos por professor, além de tornar a disciplina mais atrativa para o alunado. Além disso, que o MOOC foi usado como recurso online para apresentação do conteúdo, enquanto os exercícios de fixação, as avaliações e as atividades complementares foram desenvolvidos pelos professores. As hipóteses propostas no estudo foram validadas: valor funcional percebido tem efeito positivo (r=0,801) na intenção de recompra (R2=64,15%), a qualidade percebida com relação ao processo de blended learning e a qualidade percebida com relação ao MOOC têm efeitos positivos (r=0,22e r=0,2929, respectivamente) no valor funcional percebido pelo aluno (R2=20,46%); a preferência e autodisciplina para realização de cursos a distância têm efeito positivo na qualidade percebida com relação ao processo de blended learning (r=0,2636 e R2=6,95%) e com relação ao MOOC (r=0,347 e R2=12,04%). Conclui-se que o valor funcional percebido pelo aluno é favorável, com escore de 4,53 (escala de 7 pontos), e é influenciado pela qualidade percebida com relação ao MOOC e ao processo de blended learning. / The rapid development of information technology brings opportunities for education, putting distance education and online learning as options for the traditional model of education, especially the Massive Open Online Courses (MOOCs), which in the context of the open education are presented as a means to increase access and quality of education, proportionate educational costs and inequality, especially in developing countries. The systematic review of 74 articles showed that HEIs are incorporating MOOCs into their practices. In part, by producing their own MOOCs, but also integrating them into their curricula, both to revise high school content with incoming higher education students and to improve their courses. Thus, considering that research evaluating the incorporation of MOOCs into The main objectives of this study were to understand how the MOOCs are being incorporated into undergraduate courses and what functional value students perceive in relation to this practice. For such, a systematic review of the literature and an exploratory and descriptive case study were carried out, integrating the qualitative and quantitative approaches. The unit of analysis of the case study was the Fundamentals of Administration discipline taught in the first year of the baccalaureate course in Administration and four sources of evidence were used: documents about the MOOC, documentation about the discipline that used the MOOC, interviews with teachers responsible for discipline and survey with the students. The evidence obtained in the documentary analysis and interviews were analyzed based on the research questions while the student lifting was based on the technique of statistical analysis modeling of structural equations using software R. The results of the study allowed to identify, that as suggested by the literature, the MOOC was used as an online resource in the blendedlearning method in an introductory discipline and replacing part of the classroom workload, making it possible to increase the number of students per teacher, in addition to making the course more attractive for the student. The MOOC was used as an online resource for content presentation, while the attachment exercises, assessments, and complementary activities were developed by teachers. The hypotheses proposed in the study were validated: perceived functional value has a positive effect (r = 0.801) on the intention to buy back (R2 = 64.15%), the quality perceived in relation to the blended learning process and perceived quality in relation to the MOOC have positive effects (r = 0.22 and r = 0.2929, respectively) on the functional value perceived by the student (R2 = 20.46%); (r = 0.2636 and R2 = 6.95%) and in relation to the MOOC (r = 0.347 and R 2 = 12), the preference and self-discipline for distance courses have a positive effect on the perceived quality of the blended learning process , 04%).It is concluded that the functional value perceived by the student is favorable, obtaining a score of 4.53 on a 7-point scale, and that this is influenced by the perceived quality in relation to the MOOC and in relation to the process of blended learning.

De nos jours, Le nombre de dispositifs ne cesse d’augmenter ce qui induit une forte demande des applications en données multimédia. Cependant gérer des données massives générées et consommées par les utilisateurs mobiles dans une zone urbaine reste une problématique de taille pour les réseaux cellulaires existants qui sont à la fois limités en termes de cout et de bande passante mais aussi due à la nature de telles données centrées- connexion. D’autre part, l’avancée technologique en matière de véhicules autonomes permet de constituer une infrastructure prometteuse capable de prendre en charge le traitement, la sauvegarde, et la communication de ces données. En effet, Il est maintenant possible de recruter des véhicules intelligents pour des fins de collecte, de stockage, et de partage des données hétérogènes en provenance d’un réseau routier afin de répondre aux demandes des citoyens via des applications. Par conséquent, nous tirons profit de l'évolution récente en « information Centric Networking » ICN afin d'introduire deux nouvelles approches de collecte et de stockage de contenu par les véhicules, nommées respectivement VISIT et SAVING, plus efficaces et plus proches de l'utilisateur mobile en zone urbaine ainsi nous remédions aux problèmes liés à la bande passante et le coût. VISIT est une plate-forme qui définit de nouvelles mesures de centralité basées sur l'intérêt social des citoyens afin d’identifier et de sélectionner l'ensemble approprié des meilleurs véhicules candidats pour la collecte des données urbaines. SAVING est un système de stockage de données sociales, qui présente une solution de mise en cache des données d’une façon collaborative entre un ensemble de véhicules parmi d’autres désignés et recrutés selon une stratégie des théorie des jeux basée sur les réseaux complexes. Nous avons testé ces deux méthodes VISIT et SAVING sur des données simulées pour environ 2986 véhicules avec des traces de mobilité réalistes en zone urbaine, et les résultats ont prouvés que les deux méthodes permettent non seulement une collecte et un stockage efficaces mais aussi bien scalables / The growth in the number of mobile devices today result in an increasing demand for large amount of rich multimedia content to support numerous applications. It is however challenging for the current cellular networks to deal with such increasing demand, both in terms of cost and bandwidth for the ``massive'' content generated and consumed by mobile users in an urban environment due to its connection-centric nature. The technological advancement in modern vehicles allow us to harness their computing, caching and communication capabilities to supplement infrastructure network. It is now possible to recruit smart vehicles to collect, store and share heterogeneous data on urban streets in order to provide citizens with different services. Therefore, we leverage the recent shift towards Information Centric Networking (ICN) to introduce two schemes, VISIT and SAVING for the efficient collection and storage of content at vehicles, closer to the urban mobile user to avoid bandwidth and cost. VISIT is a platform which defines novel centrality metrics based on the social interest of urban users to identify and select the appropriate set of best candidate vehicles to perform urban data collection. SAVING is a social-aware data storage system which exploits complex networks to present game-theoretic solutions for finding and recruiting vehicles adequate to perform collaborative content caching in an urban environment. VISIT and SAVING are simulated for around 2986 vehicles with realistic urban mobility traces and comparison results with other schemes in literature suggest both not only efficient but also scalable data collection and storage systems

Cette thèse présente une étude des coeurs denses et massifs de deux régions de formation d'étoiles massives de notre Galaxie. J'utilise pour ce travail des observations Herschel-HOBYS de NGC 6334 et NGC 6357 complémentées par les sondages GLIMPSE, MIPSGAL, ATLASGAL, MALT90 ainsi que des observations SCUBA-2 et SIMBA. La vision multi-longueur d'onde m'a permis d'identifier spatialement les coeurs les plus denses des deux régions et d'extraire leur distribution spectrale d' énergie. J'ai modélisé l'émission des coeurs pour extraire leurs paramètres physiques et j'ai utilisé des données infrarouge, des catalogues de sources masers et radio, ainsi que des raies mol éculaires pour déterminer leur statut évolutif. Mon travail présente l'extraction des coeurs denses et massifs ainsi que l'analyse de leur distribution spatiale et de leurs paramètres physiques dans le contexte évolutif de la formation d'étoiles massives dans les régions NGC 6334 et NGC 6357. / This thesis aims at studying the massive dense cores found inside two regions of high-mass star formation within our Galaxy. I make use of Herschel observations of NGC 6334 and NGC 6357 from the HOBYS project, complemented with the GLIMPSE, MPISGAL, ATLASGAL, MALT90 surveys as well as observations from SCUBA-2 and SIMBA. The multi-wavelength view allows me to spatially identify the densest cores in both regions and extract their spectral energy distribution. I modelled the emission from the cores to extract their physical parameters and I used infrared data, masers and radio catalogues, and molecular lines to assess their evolutionary status. My study present the extraction of massive dense cores in the regions NGC 6334 and NGC 6357 together with the analysis of their spatial distribution and physical parameters in the evolutionnary context of massivestar formation that is occuring in both regions.

La planète Mars est le siège d'un climat complexe, caractérisé par des cycles du dioxyde de carbone et de l'eau, ainsi qu'un transport de poussière à toutes les échelles. Ces cycles se manifestent par la condensation saisonnière aux pôles de dépôts de glace de CO₂ et d'eau pendant la nuit polaire, et leur sublimation pendant le printemps local. Les cycles du CO₂ , de l'eau et des poussières sur Mars sont intimement liés. Un processus saisonnier actif illustre bien ces liens : les jets de gaz froid, déclenchés par la sublimation saisonnière des dépôts de CO₂ , pouvant mettre en suspension des poussières du régolite de manière durable dans l'atmosphère, et dont l'activité semble être modulée par les échanges d'eau à la surface.L'objectif de cette thèse est de permettre l'utilisation des données d'imagerie hyperspectrale disponibles au maximum de leur potentiel, pour apporter de nouvelles contraintes sur les échanges saisonniers entre surface et atmosphère et sur les interactions entre les différents cycles (CO₂ , eau, poussières), en se focalisant sur les jets de gaz froid. Pour cela, un modèle semi-analytique de transfert radiatif dans les glaces compactes, ainsi qu'une méthode efficace d'inversion ont été développés et validés.Le modèle de transfert radiatif permet de décrire l'interaction de la lumière avec une couche de glace de manière quantitative d'après les paramètres suivants : épaisseur de la couche, proportions volumiques et tailles des impuretés, rugosité de la surface. Il repose sur plusieurs hypothèses majeures : optique géométrique, milieux continus par morceaux, inclusions quasi-sphériques. L'approximation des deux flux est utilisée pour le transfert au sein de la couche mais la réflexion spéculaire en surface est estimée en tenant compte de la variabilité des facettes de la rugosité surfacique. Ce modèle a été validé numériquement et sur des données de laboratoire et des tests numériques. La méthode d'inversion consiste à créer des bases de données synthétiques d’après le modèle de transfert radiatif pour déterminer les jeux de paramètres les plus probables pour reproduire une mesure donnée. L'inversion repose sur le formalisme bayésien : les grandeurs manipulées sont décrites par des densités de probabilités. Ceci permet la prise en compte de manière réaliste des incertitudes sur la donnée et le calcul d'une incertitude a posteriori sur le résultat de l'inversion.Une étude ciblée d'un site d'intérêt a été menée pour tester et démonter l'applicabilité de cette démarche à l'inversion massive de données de spectro-imagerie.Nous avons déterminé l’état de surface du champ de dunes du cratère de Richardson (72°S, 180°W), choisi car il présente de fortes interactions entre cycle de l'eau et du CO₂ , une important activité saisonnière de jets froids mais aussi une grande quantité de données disponible et une haute qualité du suivi temporel. Le suivi des caractéristiques de surface sur ce site montre une diminution de l'épaisseur de la couche de glace pendant le printemps cohérente avec les estimations des modèles de climat. Nous avons pu estimer et faire le suivi du contenu en eau et en poussière pour discuter le scénario de formation des jets froids. Nous avons proposé un nouveau mécanisme de mise en suspension des petits grains d’eau. / Mars has a complex climate, characterized by carbon dioxide and water cycles, and dust transport at all scales. These cycles are mainly controlled by the seasonal condensation of CO₂ and water ice deposits at high latitudes during the polar night and their sublimation during the local spring. There are a lot of interactions between the CO₂ , water and dust cycles on Mars and they influence each other. An active seasonal process illustrates particularly well these links: the cryoventing, cold CO₂ gas jets triggered by seasonal sublimation of CO₂ deposits, which can put dust from the regolith in suspension into the atmosphere durably, and whose activity seems to be modulated by the exchange of water at the surface.The purpose of this thesis is to allow the use of the available hyperspectral imaging data to their full potential, to bring new constraints on seasonal exchanges between surface and atmosphere and the interactions between the different cycles (CO₂ , water , dust), focusing on cold gas jets. To achieve this, a semi-analytical radiative transfer model in compact ices and an effective inversion method were developed and validated.The radiative transfer model describes the interaction of light with a surface quantitatively, using the following parameters: thickness of the layer, volume proportions and grain-sizes of impurities, surface roughness. It is based on several key assumptions: geometrical optics, piecewise-continuous media quasi-spherical inclusions. The two-stream approximation is used for the radiative transfer inside the layer, but the surface specular reflectance is estimated taking into account the variability of the facets orientations from the surface roughness. This model was validated both numerically and on laboratory data.The inversion method consists in exploring synthetic databases generated by the radiative transfer model and determining the most likely sets of parameters to reproduce a given measure. The inversion is based on the Bayesian formalism: the manipulated variables are described by probability density functions. This allows to take into account realistic uncertainties on the data and enables to calculate a posteriori uncertainties on the result of the inversion.A focused study was conducted on a area of particular interest, to test and prove the applicability of this approach to the massive inversion of spectro-imaging data. The dune-field of Richardson Crater (72°S, 180°W) was chosen because it shows strong interactions between the water and CO₂ cycles, a major seasonal cryoventing activity, but also a large amount of data available and a high quality temporal monitoring. The monitoring of surface characteristics on this site shows a decrease in the thickness of the ice during the spring consistently with climate models simulations. We were able to estimate and monitor the content of water and dust in order to discuss the formation scenario of cold jets.

Dans cette thèse, nous avons développé de nouveaux cadres d'analyse pour analyser et optimiser les futurs réseaux cellulaires à l'aide de la géométrie stochastique et des processus ponctuels. Cette thèse fournit quatre contributions techniques principales.Nous analysons d’abord les réseaux émergents capables de communiquer en utilisant la lumière plutôt que les ondes radio. Dans ce contexte, nous proposons un cadre analytique innovant qui nous permet d’estimer la probabilité de couverture et le débit moyen des réseaux distribués dans l’espace, qui sont utilisés pour mieux comprendre l’optimisation du système.Deuxièmement, nous proposons une méthodologie innovante pour modéliser des réseaux cellulaires spatialement corrélés en utilisant des processus ponctuels non homogènes. L'approche proposée est testée par rapport au déploiement pratique de réseaux cellulaires et s'est révélée pratique et précise. Il est appliqué à l'analyse des réseaux de communication à lumière visible et l'impact de la corrélation spatiale est étudié.Troisièmement, nous abordons le problème ouvert de la modélisation de réseaux cellulaires MIMO massifs. Nous étudions les réseaux cellulaires montants et descendants et proposons de nouvelles limites supérieures et inférieures pour l'efficacité spectrale moyenne, ce qui nous permet d'identifier le nombre optimal d'utilisateurs à desservir dans chaque cellule du réseau et l'impact de plusieurs paramètres clés du système.Quatrièmement, nous présentons et analysons les performances d'un nouvel algorithme de planification prenant en compte les interférences pour une application sur la liaison montante des réseaux cellulaires. L’approche proposée consiste à assourdir certains utilisateurs afin de réduire le niveau d’interférence. La performance réalisable et l'équité utilisateur de l'approche proposée sont discutées et quantifiées analytiquement. / In this thesis, we have developed new analytical frameworks for analyzing and optimizing future cellular networks with the aid of stochastic geometry and point processes. This thesis provides four main technical contributions.First, we analyze emerging networks that can communicate by using light instead of radio waves. In this context, we propose an innovative analytical framework that allows us to estimate the coverage probability and the average rate of spatially distributed networks, which are used to gain insight for system optimization.Second, we propose an innovative methodology for modeling spatially correlated cellular networks by using inhomogeneous point processes. The proposed approach is tested against practical deployment of cellular networks and found to be tractable and accurate. It is applied to the analysis of visible light communication networks, and the impact of spatial correlation is studied.Third, we tackle the open problem of modeling Massive MIMO cellular networks. We study uplink and downlink cellular networks and propose new upper and lower bounds for the average spectral efficiency, which allow us to identify the optimal number of user to serve in each cell of the network and the impact of several key system parameters.Fourth, we introduce and analyze the performance of a new interference-aware scheduling algorithm for application to the uplink of cellular networks. The proposed approach is based on muting some users in order to reduce the level of interference. The achievable performance and the user-fairness of the proposed approach are discussed and quantified analytically.

[pt] As comunicações de ondas milimétricas (mmWave) são consideradas uma tecnologia essencial para os sistemas celulares de próxima geração, dado que a enorme largura de banda disponível pode potencialmente fornecer as taxas de vários gigabits por segundo. As técnicas convencionais de pré-codificação e combinação são impraticáveis nos cenários da mmWave devido ao custo de fabricação e ao consumo de energia. As alternativas híbridas foram consideradas uma tecnologia promissora para fornecer um compromisso entre a complexidade do hardware e o desempenho do sistema. Um grande número de projetos de pré-codificadores híbridos têm sido proposto com diferentes abordagens. Uma abordagem possível é procurar minimizar a distância euclidiana entre o pré-decodificador híbrido e o pré-decodificador totalmente digital. No entanto, essa abordagem torna o projeto do pré-codificador híbrido um problema de fatoração da matrices difícil de lidar devido às restrições de hardware dos componentes analógicos. Esta tese de doutorado propõe alguns projetos de pré-codificadores e combinadores híbridos por meio de uma estratégia hierárquica. O problema híbrido de pré-codificação / combinação é dividido em partes analógicas e digitais. Primeiro, o pré-codificador / combinador analógico é projetado. Em seguida, com o pré-codificador / combinador analógico fixo, o précodificador / combinador digital é calculado para melhorar o desempenho do sistema. Além disso, métodos de otimização linear e não linear são empregados para projetar a parte analógica do pré-codificador / combinador. A viabilidade dessas propostas é avaliada usando diferentes técnicas de detecção de dados e analisando o desempenho do sistema em termos de taxa de erros de bits (BER), sum–rate e outras métricas, em cenários internos do mmWave, considerando enlace diretos massivo do MU–MIMO. Além disso, este trabalho propõe um método para encontrar aproximações analíticas bastante restritas ao desempenho obtido no BER. A metodologia proposta exigiria o conhecimento da função densidade de probabilidade (fdp) das variáveis relacionadas que são desconhecidas para os cenários mmWave. Para resolver este problema, são utilizadas as aproximações fdp Gamma. As aproximações analíticas do BER resultaram em diferenças não superiores a 0,5 dB em relação aos resultados da simulação em alto SNR. / [en] Millimeter–wave (mmWave) communications have been regarded as a key technology for the next–generation cellular systems since the huge available bandwidth can potentially provide the rates of multiple gigabits per second. Conventional precoding and combining techniques are impractical at mmWave scenarios due to manufacturing cost and power consumption. Hybrid alternatives have been considered as a promising technology to provide a compromise between hardware complexity and system performance. A large number of hybrid precoder designs have been proposed with different approaches. One possible approach is to search for minimizing the Euclidean distance between hybrid precoder and the full-digital precoder. However, this approach makes the hybrid precoder design becomes a matrix factorization problem difficult to deal due to the hardware constraints of analog components. This doctoral thesis proposes some hybrid precoder and combiners designs through a hierarchical strategy. The hybrid precoding/combining problem is divided into analog and digital parts. First, the analog precoder/combiner is designed. Then, with the analog precoder/combiner fixed, the digital precoder/ combiner is computed to improve the system performance. Furthermore, linear and no-linear optimization methods are employed to design the analog part of the precoder/combiner. The viability of these proposals is evaluated using different data detection techniques and analyzing the system performance in terms of bit error rate (BER), sum rate, and other metrics, in indoor mmWave scenarios considering massive MU-MIMO downlink. Also, this work proposes a method to find fairly tight analytic approximations to the obtained BER performance. The methodology proposed would require the knowledge of the probability density function (pdf) of the variables involved, which are unknown for mmWave scenarios. In order to solve this problem, Gamma pdf approximations are used. The analytic BER approximations resulted in differences no larger than 0.5 dB with respect to the simulation results in high SNR.

Les réseaux de cinquième génération sont en cours de définition et leurs différentes composantes commencent à émerger: nouvelles technologies d'accès à la radio, convergence fixe et mobile des réseaux et virtualization.Le contrôle et la gestion de bout en bout (E2E) du réseau ont une importance particulière pour les performances du réseau. Cela étant, nous segmentons le travail de thèse en deux parties: le réseau d’accès radio (RAN) axé sur la technologie MIMO Massif (M-MIMO) et la connexion E2E du point de vue de la couche transport.Dans la première partie, nous considérons la formation de faisceaux focalisés avec un structure hiérarchique dans les réseaux sans fil. Pour un ensemble de flots donnée, nous proposons des algorithmes efficaces en terme de complexité pour une allocation avec alpha-équité. Nous proposons ensuite des formules exactes pour la performance au niveau du flot, à la fois pour le trafic élastique (avec une équité proportionnelle et équité max-min) et le trafic en continu. Nous validons les résultats analytiques par des simulations.La seconde partie de la thèse vise à développer une fonction de réseau auto-organisant (SON) qui améliore la qualité d'expérience (QoE) des connexions en bout-en-bout. Nous considérons un service de type vidéo streaming et développons une fonctionnalité SON qui adapte la QoE de bout-en-bout entre le serveur vidéo et l'utilisateur. La mémoire-tampon reçoit les données d'un serveur avec une connexion E2E en suivant le protocole TCP. Nous proposons un modèle qui décrit ce comportement et nous comparons les formules analytiques obtenues avec les simulations. Enfin, nous proposons un SON qui donne la qualité vidéo de sorte que la probabilité de famine soit égale à une valeur cible fixée au préalable. / Fifth generation networks are being defined and their different components are beginning to emerge: new technologies for access to radio, fixed and mobile convergence of networks and virtualization.End-to-end (E2E) control and management of the network have a particular importance for network performance. Having this in mind, we segment the work of the thesis in two parts: the radio access network (RAN) with a focus on Massive MIMO (M-MIMO) technology and the E2E connection from a point of view of the transport layer.In the first part, we consider hierarchical beamforming in wireless networks. For a given population of flows, we propose computationally efficient algorithms for fair rate allocation. We next propose closed-form formulas for flow level performance, for both elastic (with either proportional fairness and max-min fairness) and streaming traffic. We further assess the performance of hierarchical beamforming using numerical experiments.In the second part, we identify an application of SON namely the control of the starvation probability of video streaming service. The buffer receives data from a server with an E2E connection following the TCP protocol. We propose a model that describes the behavior of a buffer content and we compare the analytical formulas obtained with simulations. Finally, we propose a SON function that by adjusting the application video rate, achieves a target starvation probability.

In centralized radio access network (C-RAN) architecture, the base-band unit (BBU) is connected to one or more remote radio units (RRUs) via a fronthaul (FH) interface. Upgrading base station antennas in C-RAN to support massive multiple-input multiple-output (MIMO) technology can improve network spectral efficiency and largely boost the capacity of the 5G system. Those great benefits also introduce new challenges to the FH interface since the required FH capacity increases proportionally to the number of transceiver units (TXRUs) for traditional receiver processing at the BBU. To reduce the FH link load, different base-band splitting options between RRUs and BBU are considered in practical C-RAN networks. In this project, we investigate three beamforming algorithms (MRC, DFT and Enhanced) which are expected to reduce the number of streams on FH link, and evaluate their performance for single-user MIMO in different mobility scenarios via system-level simulations. The results show that we successfully reach the goal of reducing the number of streams to one-fourth the number of TXRUs meanwhile maintaining relatively good performance. Additionally, we observe that the Enhanced algorithm performs the best in majority of scenarios. / I en centraliserad nätverksarkitektur för radioåtkomst är basbandsenheten ansluten till en eller flera fjärrradionheter via ett fronthaul-gränssnitt. Genom att uppgradera basstationsantennerna i C-RAN för att stödja massiv multipel input-multipel output-teknik kan man förbättra nätverkets spektraleffektivitet och till stor del öka kapaciteten i 5G-systemet. Dessa stora fördelar medför också nya utmaningar för FH-gränssnittet eftersom den nödvändiga FH-kapaciteten ökar proportionellt mot antalet sändare för traditionell mottagarbearbetning vid BBU. För att minska belastningen på FH-länken övervägs olika alternativ för uppdelning av basbandet mellan RRUs och BBU i praktiska C-RAN-nät. I det här projektet undersöker vi tre strålformningsalgoritmer (MRC, DFT och Enhanced) som förväntas minska antalet strömmar på FH-länken och utvärderar deras prestanda för single-user MIMO i olika mobilitetsscenarier med hjälp av simuleringar på systemnivå. Resultaten visar att vi lyckas uppnå målet att minska antalet strömmar till en fjärdedel av antalet TXRU:s samtidigt som vi behåller en relativt god prestanda. Dessutom kan vi konstatera att den förbättrade algoritmen presterar bäst i de flesta scenarier.