Esta tese propõe uma interpretação sobre a relevância da segregação residencial como dimensão estruturante das relações raciais no Brasil, a partir da análise de dados da Região Metropolitana de São Paulo. Comparações com situações de segregação racial típicas de cidades norte-americanas, aliadas a narrativas de dissimulação das manifestações do racismo no Brasil, têm alimentado discursos que desprezam a importância da segregação para as relações raciais, argumentando que em nossas cidades ocorre segregação apenas por classe social. Esta pesquisa posiciona-se contrariamente a tais discursos e apresenta evidências da segregação residencial por raça nos diferentes estratos sociais. Por um lado, através de abordagens quantitativas mais tradicionais que partem dos diferenciais de localização das residências de grupos sociais, constatamos pequenos níveis de segregação racial em camadas sociais mais baixas que se tornam significativos nas camadas médias e altas. Os brancos de classes médias e superiores residem nas áreas mais privilegiadas da metrópole, estando muito isolados e distantes de todos os outros grupos, até mesmo de negros de classe média e alta. Trata-se, portanto, de segregação residencial por raça e classe. Por outro lado, a partir de uma crítica das formas como a própria noção de segregação residencial tem sido mobilizada pela sociologia, propomos uma abordagem mais aprofundada que revele em que medida a separação das moradias se associa a diferenciais de integração social e acesso à cidade. Para tanto, empreendemos uma estratégia empírica baseada no mapeamento de trajetos e locais frequentados pelos indivíduos no espaço da cidade e na espacialização de suas redes pessoais de relações. As informações foram coletadas através de pesquisa qualitativa na qual entrevistamos 28 indivíduos de classe média negros e brancos, mulheres e homens em três diferentes áreas da cidade de São Paulo: São Miguel Paulista, Tatuapé e Itaim Bibi. Demostramos a importância do local de residência na medida em que a maior parte dos relacionamentos pessoais e dos locais frequentados localizam-se no entorno do distrito no qual residem os entrevistados. Ou seja, na medida em que negros e brancos estão residencialmente segregados, são segregadas também suas redes pessoais e locais frequentados. Além disso, nossos resultados apontam que brancos, independentemente do local de residência, possuem redes pessoais compostas preponderantemente por outros brancos e frequentam mais as áreas nobres da metrópole. Nossos achados realçam o papel do espaço urbano em processos de fechamento social que reforçam barreiras à integração de negros nas classes médias. Ademais, argumentamos que as classes médias se organizam como grupos de status cujas fronteiras são fortemente baseadas, não apenas em características raciais, mas também no espaço urbano (habitado e frequentado). / This thesis proposes an interpretation on the relevance of residential segregation as a structuring dimension of race relations in Brazil, based on the data from the Metropolitan Region of São Paulo. Comparisons with cases of racial segregation typical of North American cities, coupled with narratives that disguise manifestations of racism in Brazil, have fueled discourses that despise the importance of segregation for race relations, arguing that in our cities segregation occurs only by social class. This research opposes such discourses and presents evidence of residential segregation by race in the different social strata. On the one hand, through more traditional quantitative approaches based on the differentials of location of residences, we find small levels of racial segregation in lower social strata that become significant in the middle and upper classes. The white middle and upper classes reside in the most privileged areas of the metropolis, being very isolated and distant from all other groups, even from middle and upper-class blacks. This is, therefore, residential segregation by race and class. On the other hand, from a critique of the ways in which the very notion of residential segregation has been mobilized by sociology, we propose a more in-depth approach that reveals the extent to which the separation of housing is associated with differentials of social integration and access to the city. Therefore, we undertook an empirical strategy based on mapping of paths and places frequented by individuals in the city space and on the spatial distribution of their personal networks of relationships. The information was collected through qualitative research in which we interviewed 28 middle class individuals blacks and whites, women and men in three different areas of the city of São Paulo: São Miguel Paulista, Tatuapé and Itaim Bibi. We demonstrate the importance of place of residence to the extent that most of the personal relationships and the places attended are located around the district in which the respondents reside. That is, to the extent that blacks and whites are residentially segregated, their personal networks and urban paths are also segregated. In addition, our results indicate that whites, regardless of their place of residence, have personal networks that are predominantly composed of other whites and frequent more the elite areas of the metropolis. Our findings highlight the role of urban space in social closure processes that reinforce barriers to the integration of blacks in the middle classes. Furthermore, we argue that the middle classes are organized as status groups whose boundaries are strongly based not only on racial characteristics, but also in urban space (inhabited and frequented).

Esta tese propõe uma interpretação sobre a relevância da segregação residencial como dimensão estruturante das relações raciais no Brasil, a partir da análise de dados da Região Metropolitana de São Paulo. Comparações com situações de segregação racial típicas de cidades norte-americanas, aliadas a narrativas de dissimulação das manifestações do racismo no Brasil, têm alimentado discursos que desprezam a importância da segregação para as relações raciais, argumentando que em nossas cidades ocorre segregação apenas por classe social. Esta pesquisa posiciona-se contrariamente a tais discursos e apresenta evidências da segregação residencial por raça nos diferentes estratos sociais. Por um lado, através de abordagens quantitativas mais tradicionais que partem dos diferenciais de localização das residências de grupos sociais, constatamos pequenos níveis de segregação racial em camadas sociais mais baixas que se tornam significativos nas camadas médias e altas. Os brancos de classes médias e superiores residem nas áreas mais privilegiadas da metrópole, estando muito isolados e distantes de todos os outros grupos, até mesmo de negros de classe média e alta. Trata-se, portanto, de segregação residencial por raça e classe. Por outro lado, a partir de uma crítica das formas como a própria noção de segregação residencial tem sido mobilizada pela sociologia, propomos uma abordagem mais aprofundada que revele em que medida a separação das moradias se associa a diferenciais de integração social e acesso à cidade. Para tanto, empreendemos uma estratégia empírica baseada no mapeamento de trajetos e locais frequentados pelos indivíduos no espaço da cidade e na espacialização de suas redes pessoais de relações. As informações foram coletadas através de pesquisa qualitativa na qual entrevistamos 28 indivíduos de classe média negros e brancos, mulheres e homens em três diferentes áreas da cidade de São Paulo: São Miguel Paulista, Tatuapé e Itaim Bibi. Demostramos a importância do local de residência na medida em que a maior parte dos relacionamentos pessoais e dos locais frequentados localizam-se no entorno do distrito no qual residem os entrevistados. Ou seja, na medida em que negros e brancos estão residencialmente segregados, são segregadas também suas redes pessoais e locais frequentados. Além disso, nossos resultados apontam que brancos, independentemente do local de residência, possuem redes pessoais compostas preponderantemente por outros brancos e frequentam mais as áreas nobres da metrópole. Nossos achados realçam o papel do espaço urbano em processos de fechamento social que reforçam barreiras à integração de negros nas classes médias. Ademais, argumentamos que as classes médias se organizam como grupos de status cujas fronteiras são fortemente baseadas, não apenas em características raciais, mas também no espaço urbano (habitado e frequentado). / This thesis proposes an interpretation on the relevance of residential segregation as a structuring dimension of race relations in Brazil, based on the data from the Metropolitan Region of São Paulo. Comparisons with cases of racial segregation typical of North American cities, coupled with narratives that disguise manifestations of racism in Brazil, have fueled discourses that despise the importance of segregation for race relations, arguing that in our cities segregation occurs only by social class. This research opposes such discourses and presents evidence of residential segregation by race in the different social strata. On the one hand, through more traditional quantitative approaches based on the differentials of location of residences, we find small levels of racial segregation in lower social strata that become significant in the middle and upper classes. The white middle and upper classes reside in the most privileged areas of the metropolis, being very isolated and distant from all other groups, even from middle and upper-class blacks. This is, therefore, residential segregation by race and class. On the other hand, from a critique of the ways in which the very notion of residential segregation has been mobilized by sociology, we propose a more in-depth approach that reveals the extent to which the separation of housing is associated with differentials of social integration and access to the city. Therefore, we undertook an empirical strategy based on mapping of paths and places frequented by individuals in the city space and on the spatial distribution of their personal networks of relationships. The information was collected through qualitative research in which we interviewed 28 middle class individuals blacks and whites, women and men in three different areas of the city of São Paulo: São Miguel Paulista, Tatuapé and Itaim Bibi. We demonstrate the importance of place of residence to the extent that most of the personal relationships and the places attended are located around the district in which the respondents reside. That is, to the extent that blacks and whites are residentially segregated, their personal networks and urban paths are also segregated. In addition, our results indicate that whites, regardless of their place of residence, have personal networks that are predominantly composed of other whites and frequent more the elite areas of the metropolis. Our findings highlight the role of urban space in social closure processes that reinforce barriers to the integration of blacks in the middle classes. Furthermore, we argue that the middle classes are organized as status groups whose boundaries are strongly based not only on racial characteristics, but also in urban space (inhabited and frequented).

As globalization facilitates trade across geographical borders, more and more small and medium-sized enterprises (SMEs) take the opportunity to internationalize, sometimes even immediately after their start-up. To enhance our understanding of how SMEs internationalize, this dissertation investigates different means of interaction that SMEs employ in foreign business relationships to develop the experiential knowledge needed for further internationalization. The investigated interaction means are high-commitment internationalization modes, low-commitment internationalization modes, business network relationships, personal network relationships, and personal interaction. Based on qualitative, longitudinal data from eight born global SMEs in the biotech field and a questionnaire survey of 188 SMEs from various industries, results show how different groups of firms apply different interaction means to develop experiential knowledge and internationalize. In particular, the results show that differences in the backgrounds of founders and managers strongly influence the means that different groups of SMEs use when interacting with foreign business counterparts. Moreover, interaction of high quality and quantity, in the form of personal interaction, reduces uncertainties and supports the development of trust and experiential knowledge in internationalizing SMEs. Personal interaction is also shown to be an especially important interaction means for firms that develop new products or new technologies in collaboration with foreign customers. Building on these results, the dissertation contribute to the development of theory about the influence of interaction on the experiential knowledge development and internationalization of SMEs in general and rapidly internationalizing SMEs in particular.

An increasing number of small and medium-sized enterprises (SMEs) expand their businesses into foreign markets. Some SMEs begin to operate abroad soon after their establishment. These so-called born globals demonstrate a more rapid internationalisation compared with other SMEs. This thesis develops a deeper understanding of the internationalisation process of SMEs, by studying how born globals and other SMEs develop foreign market knowledge during the international expansion. The internationalisation process is divided into three phases; the pre-firm internationalisation phase, the initial internationalisation phase and the continued internationalisation phase. Based on a qualitative study of 14 biotech SMEs and a questionnaire survey of 188 SMEs from various industries, new insights on the internationalisation process of SMEs and born globals are presented. By extending the analysis of SMEs’ internationalisation to a phase prior to their establishment and by continuing to follow these firms during their operations in foreign markets, the findings of this thesis show how the knowledge and personal networks of key individuals relate to the firm’s development of foreign market knowledge. The thesis also advances the understanding of how an SME develops foreign market knowledge from its business network relationships. In summary, the result of this thesis shows that a rapid expansion in several foreign markets can hold back an SME’s development of foreign market knowledge and lead to difficulties in developing the firm’s operations in the continued internationalisation phase. / Diss. Stockholm : Handelshögskolan, 2009. Sammanfattning jämte 6 uppsatser

Made available in DSpace on 2015-04-16T15:23:46Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1393799 bytes, checksum: 907f42514d0dae661e8c13f40aa59f9a (MD5) Previous issue date: 2010-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / It deals with information and knowledge as key assets within the organizations, and the prospect of Information Science investigates the properties and behavior of information, the forces that govern the information flow and processing facilities. From this perspective, the objective is to analyze the feasibility of collaborative networks of spontaneous internal personal knowledge between teachers / actors programs Graduate in Business Administration (PPGA) with teachers / actors within the management of the Post Graduate Information Science (PPGCI) UFPB. The choice of search field is on the Programs Graduate Administration and Information Science located at the CCSA / UFPB whose subjects are the teachers of the permanent program. It takes as a tool for data collection curriculum lattes site CNPq. These data were supplemented and annotated in previously created form that includes the following information: name, qualification (undergraduate and graduate) courses taught in graduate school, a research group that works thematically (dissertation and thesis), guidance (graduate). Based on the analysis and interpretation of results, it appears that is appropriate to propose the cooperation networks for the spontaneous sharing of knowledge like that can be applied to the development of programs Postgraduate (PPGA and PPGCI), motivated by learning, where we can look for partnerships, to foster relationships through the promotion of events to promote meeting to present projects and research in progress in both programs Graduate, intensify calls for teachers to give lectures in rooms class in each subject correlated with their area and others. / Esta pesquisa aborda a informação e o conhecimento, como ativos fundamentais no âmbito das organizações, e, na perspectiva da Ciência da Informação, investiga as propriedades e o comportamento da informação, as forças que regem o fluxo informacional e os meios de processamento. Nessa perspectiva, objetiva-se analisar a viabilidade de formação de redes colaborativas internas pessoais espontâneas de conhecimentos, entre os docentes/atores dos programas de Pós-graduação em Administração (PPGA), com os docentes/atores da área de gestão do Programa de Pós-graduação de Ciência da Informação (PPGCI) da UFPB. A escolha do campo de pesquisa recai sobre os Programas de Pós-graduação de Administração e de Ciência da Informação, localizados no CCSA/UFPB, cujos sujeitos são os docentes do quadro permanente dos programas. Adota-se como instrumento de coleta de dados o currículo lattes do site do CNPq. Esses dados foram complementados e anotados em formulário previamente elaborado, que contempla os seguintes elementos: nome, qualificação (graduação e pós-graduação), disciplinas ministradas na pós-graduação, grupo de pesquisa em que atua, temática (dissertação e da tese) e orientação (pós-graduação). Com base na análise e na interpretação dos resultados, conclui-se que é oportuno propor redes de cooperação espontâneas para o compartilhamento dos conhecimentos afins, que poderão ser aplicados no desenvolvimento dos programas de Pós-graduação (PPGA e PPGCI), motivados pela aprendizagem contínua, na qual possamos buscar parcerias, no sentido de promover relacionamentos por meio da promoção de eventos; encontro para apresentação de projetos e pesquisas em andamento, nos dois programas de Pós-graduação; intensificar convites aos docentes, para proferirem palestras nas salas de aula em cada disciplina correlata com a sua área, entre outros.

This study analysed the entrepreneurial intentions of academic researchers to create spinoffs in a country where the phenomenon of academic spinoffs is emerging. The study consisted of a quantitative analysis of entrepreneurial intentions, performed within the context of South Africa’s Higher Education Institutions and Science Councils.The study drew from psychological and entrepreneurship research on intentionality to measure the level of entrepreneurial intentions using specific determinants (entrepreneurial self-efficacy, personal networks, perceived role models, number of years spent at the academic institution, number of patents/ copyrights/ designs, type of research, and cooperation with industry) that characterise the emergence of academic entrepreneurial intentions that lead academics to the creation of spinoffs. The study also aimed to determine if there were differences in the entrepreneurial intentions between researchers in technical and non-technical fields of expertise.A quantitative online survey was conducted amongst researchers in higher education institutions and science councils, followed by data analysis using a multiple linear regression to measure the entrepreneurial intentions. Thereafter a determination of factors associated with the higher levels of intention and a comparison of the level of intentions was conducted between researchers from the two study groups using an analysis of coefficients and significance tests respectively.The study showed that the entrepreneurial intentions of researchers in South Africa were very low. It was also shown that entrepreneurial self-efficacy was the strongest predictor of academic entrepreneurial intentions. Furthermore it was found that there was no significant difference in the entrepreneurial intentions between researchers in technical and non technical fields of expertise. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted

This thesis explores the Visit Friends and Relatives (VFR) tourism experiences of highly skilled first-generation Italians and Chinese in Sweden. It focuses on personal networks influence on migrant hosts’ interaction and participation in the place and how the Covid-19 global immobility has changed the dynamics and the feelings towards the place. Data are collected through semi-structured interviews with a participative target sociogram as memory recollection and visualization tool. Results showed that VFR is mainly a within network experience and the interaction with the place and the society is marginal and influenced by hosts’ mediation, their local network structure and composition. The VFR aspect of sharing quality time emerges as central element. The local dimension shapes place interaction and participation dynamics: the migrant host personal relation to the local place, their local network structure and composition, and the difference of having a native member in the network are crucial elements.

The overall purpose of this dissertation is to provide an empirical study of the post-Cold War EastAsian security setting, with the aim of understanding why there is an East Asian peace. The EastAsian peace exists in a region with a history of militarised conflicts, home to many of the world'slongest ongoing militarised problems and a number of unresolved critical flashpoints. Thus, thepost-Cold War East Asian inter-state peace is a paradox. Despite being a region predicted to be ripefor conflict, there have not only been less wars than expected, but the region also shows severalsigns of a development towards a more durable peace. The dominant research paradigm –neorealism – has painted a gloomy picture of post-Cold War East Asia, with perpetual conflictsdominating the predictions. Other mainstream international relations theories, too, fail to accountfully for the relative peace. One of the greatest problems for mainstream theories, is accounting forpeace given East Asia's lack of security organisations or other formalised conflict managementmechanisms. Given this paradox/problem, this dissertation sets out to ask "Why is there a relativepeace in the East Asian security setting despite an absence of security organisations or otherformalised mechanisms to prevent existing conflicts from escalating into violence?" In order to answer this question, the case of East Asian peace is approached by comparingthree embedded case studies within the region: the Taiwan issue, the South China Sea, and theKorean nuclear conflict. It explores the full range of informal and formal processes plus the ConflictPrevention and Peacebuilding Mechanisms (CPPBMs) that have been important for the creation ofa continuing relative peace in East Asia between 1990 and 2008. The study furthermore focuses onChina's role in the three cases, on an empirical basis consisting of interviews conducted with keypersons during more than 1.5 years fieldwork in China. The three cases show that informal processes exist, and that they have furthermore beenimportant for peace, both by preventing conflicts from escalating into war, and by buildingconditions for a stable longer-term peace. Their impact on the persistence of peace has been tracedto a range of different CPPBMs. Returning to the level of the East Asian case, a common feature ofmany of the identified processes is that they can be understood as aspects or manifestations of theEast Asian regionalisation process. Specifically, elite interactions (personal networks, track twodiplomacy), back-channel negotiations, economic interdependence and integration, and functionalcooperation have together with (China's acceptance of) multilateralism and institutionalisation (ofpeaceful relations) been of high importance for the relative peace. Whereas formalised conflictmanagement mechanisms and the U.S. presence have also contributed to peace, this dissertationshows their contribution to be much more limited.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-01T17:19:06Z No. of bitstreams: 1 LORENO FEITOSA DE OLIVEIRA - DISSERTAÇÃO PPGCC 2007..pdf: 5757457 bytes, checksum: b80a82ad9c8975205f58ab024e542115 (MD5) / Made available in DSpace on 2018-08-01T17:19:06Z (GMT). No. of bitstreams: 1 LORENO FEITOSA DE OLIVEIRA - DISSERTAÇÃO PPGCC 2007..pdf: 5757457 bytes, checksum: b80a82ad9c8975205f58ab024e542115 (MD5) Previous issue date: 2007-08-31 / Redes pessoais sem fio, WPANs (WirelessPersonalAreaNetworks), são redes de curto alcance, em torno de 10 m, cujo centro é o usuário. O cenário de uso geral é aquele onde dispositivos dentro da área de cobertura da WPAN comunicam-se diretamente entre si ou com recursos do mundo exterior (recursos fora da WPAN) através de pontos de acesso que ofereçam esse tipo de encaminhamento de dados. WPANs vêm ganhando atenção nos últimos anos principalmente devido ao surgimento de novas tecnologias de transmissão sem fio que viabilizam este tipo de rede, particularmente Bluetooth. De fato, o desenvolvimento das WPANs confunde-se com o desenvolvimento do Bluetooth, que tem sido usado como ponto de partida em diversos estudos e protótipos nesta área. Sendo a mobilidade de usuários a principal característica das WPANs, um número de questões surge quando se pensa no desenvolvimento de aplicações direcionadas para esse novo paradigma. Uma das principais se refere à gerência de handoff. Handoff é o processo pelo qual conexões, rotas de dados, e estados associados à provisão de algum serviço são transferidos entre pontos de acesso à medida que o usuário se move entre suas áreas de cobertura. Apesar de seu alinhamento com o modelo de rede das WPANs, Bluetooth não possui facilidades para o gerenciamento de handoffs além de suas operações padrão para localização e conexão com dispositivos próximos; inquiry e paging respectivamente. Adicionalmente, o tráfego de dados dessas operações pela interface Bluetooth possui prioridade sobre o tráfego de dados das aplicações do usuário. Essa característica possui especial impacto sobre um tipo particular de aplicações: aquelas que demandam transferências de dados em tempo-real, como aplicações de streaming. Ao tornar o canal sem fio indisponível para o tráfego de dados, seja pela temporária perda total de conexão com pontos de acesso durante handoffs ou por preempção da interface para as operações citadas, aplicações de tempo-real têm seus desempenhos comprometidos devido à quebra de requisitos temporais associados às suas trocas de dados. Nesse contexto, neste trabalho é proposto um protocolo para gerência dehandoffs em WPANs Bluetooth. O protocolo apresentado é voltado para o uso com aplicações que demandam transferências de dados em tempo-real, sendo demonstrada nesse trabalho sua adequação para esse tipo de aplicação. O protocolo apresentado foi projetado levando-se em consideração as limitações dos potenciais dispositivos clientes (pequenos dispositivos móveis com pouco poder de processamento, pouca memória, largura de banda restrita, etc). Assim, são transferidas para os pontos de acesso todas as atividades relativas às transições entre pontos de acesso dos dispositivos móveis. O protocolo apresentado descarta ainda a necessidade de sinalizações ou quaisquer outras trocas de mensagens entre dispositivos móveis e pontos de acesso durante os handoffs. Por utilizar apenas operações padronizadas do Bluetooth, viabiliza-se seu uso junto com qualquer dispositivo programável equipado com interface Bluetooth de acordo com a especificação, sendo portanto dispensada a necessidade de, por exemplo, modificar a pilha Bluetooth dos dispositivos. / Wireless personal area networks (WPANs), are a mobile short range wireless network, with typical range of 10 meters, where the user is the center. The general usage scenario is where devices within the WPANs range communicate directly to each other or with resources from the external world (outside the WPAN) through access points which offer routing service. WPANs have been gaining attention over the last few years mainly due the emergence and popularization of novel wireless communication technologies that enable this kind of network, notably Bluetooth. In fact, the development of WPANs is closely related to the development of Bluetooth, which has been used as starting point to several studies and prototypes in this field. As the user mobility is the main feature of WPANs, a number of questions arise when developing applications targeted to this new paradigm. One of the most important refers to the handoff management. Handoff is the process through which network connections, routes, and states associated to services in course are seamlessly transferred between access points as the user moves through their coverage areas. Despite its alignment with the WPAN's network model, Bluetooth has no facilities for aiding the management of handoffs besides its standard operations for querying nearby devices and connect to them, inquiry and paging respectively. Moreover, the data traffic of these operations has priority over user applications' data traffic. This property has special impact for a particular kind of application: those that require real-time data transfer, such as streaming applications. When the wireless channel is unavailable for data transfers, with temporary connection loss with access points during handoffs, or interface preemption for the inquiry and paging operations, real-time applications have their performance compromised in consequence of violation of temporal requirements. In this work, a protocol for managing handoffs in Bluetooth-based WPANs is presented. The protocol is focused on the use of applications that demand real-time data transfers. The adequacy of the protocol to this kind of application is analyzed through a case study for an audio streaming application. The protocol is designed focusing on the limitations of potential client devices (small portable devices with limited computational power, memory, bandwidth, battery life, etc). Therefore, all the handoff management operations are transferred to access points. There is no need of signaling or any other kind of coordination or message exchange between access points and mobile devices during handoffs. Due to the use of standardized Bluetooth operations, any programmable device with a standard complaint Bluetooth interface can be used without changes on any underlying software layer, such as the Bluetooth stack. It is also presented a formal modelling and validation of the protocol to ensure it behaves according to its specification. The formal model is important to understand the protocol, unanbiguous documentation, and to easy the validation of changes and extension by automatic simulation and proof of properties.

En el futuro, los dispositivos digitales formarán parte del entorno en el que las personas se desenvuelvan, participarán en nuestros objetivos y necesidades y nos ayudarán a "hacer más haciendo menos". A través de los dispositivos portátiles o aquellos que estén embebidos a nuestro alrededor el usuario será capaz de interactuar con el futuro universo de servicios e infraestructuras ubicuas. El principal paradigma que se seguirá se basa en que este universo estará centrado en el usuario ya que éste demandará los servicios que más le convengan en cualquier momento y lugar, todo ello preservando nuestra privacidad y seguridad. Este nuevo concepto no sólo se aplica a un entorno de ocio sino que en el campo profesional las redes inalámbricas de próxima generación permitirán incrementar nuestra productividad, reduciendo el peso de tareas repetitivas, poniendo a nuestra disposición la información relevante en el momento adecuado y según sean las necesidades particulares del usuario en ese momento y permitiéndonos trabajar con otras personas independientemente de donde se encuentren. En particular, se intuye que las redes de próxima generación se diseñen de forma que aglutinen todos los servicios disponibles a través de los diferentes sistemas que existan de forma que las posibles deficiencias de alguno de ellos se vean compensadas por otro. Lo que se pretende conseguir es que el usuario pueda disfrutar en todo momento y lugar de los servicios que desee sin que ello suponga un esfuerzo.Este concepto implica diferentes retos tecnológicos y la integración de múltiples sistemas. Dentro de estos retos tecnológicos esta Tesis aborda los siguientes: soporte de la heterogeneidad en lo referente a las tecnologías de acceso radio que existen y que eventualmente aparecerán en el futuro y que coexistirán en un mismo terminal; desarrollo de técnicas de optimización basadas en la cooperación entre diferentes capas de la pila de protocolos; implementación de estrategias de selección de la red que mejor pueda soportar un determinado servicio ante la posibilidad de utilización de múltiples tecnologías de acceso; optimización del uso de recursos energéticos en las comunicaciones dentro de la red; protección de la privacidad y la seguridad de las comunicaciones personales del usuario.Desde el punto de vista de las aportaciones, en esta Tesis se ha contribuido mediante el diseño, implementación y validación de una serie de técnicas de optimización de las comunicaciones en redes de dispositivos móviles basadas en información intercapa. Para ello, se propone una arquitectura de protocolos novedosa que permite soportar la heterogeneidad en términos de tecnologías de acceso dentro del mismo terminal. El concepto de aislar las capas superiores de la pila de protocolos de las tecnologías de acceso subyacentes se consigue a través de una Capa de Convergencia Universal (UCL, en sus siglas en inglés). El diseño y la especificación esta arquitectura así como de los bloques funcionales que la componen son la primera contribución que se hace en esta Tesis. La UCL supone el marco en el que el resto de técnicas de optimización que se presentan han sido desarrolladas.Igualmente, se desarrollan una serie de técnicas basadas en optimización intercapa que permiten una gestión eficiente de los recursos disponibles así como una mejora en el uso de la energía. Finalmente, se implementan los mecanismos de autenticación y encriptación que permiten asegurar las comunicaciones dentro de la red. El diseño, implementación y validación de estos mecanismos supone la segunda contribución en esta Tesis. El empleo de técnicas de optimización basadas en información procedentes de diferentes capas de la pila de protocolos es la base de los dos mecanismos que se han propuesto. El primero de ellos se basa en la selección dinámica de la tecnología de acceso a utilizar para obtener un rendimiento óptimo del sistema. La segunda estrategia de optimización consiste en el uso simultáneo de varias tecnologías de acceso para conseguir una mejora en las prestaciones de la red. Aparte de la optimización en cuanto al rendimiento en términos de ancho de banda y calidad de servicio, se ha evaluado la mejora de la eficiencia energética conseguida gracias a las soluciones propuestas. Los resultados obtenidos permiten concluir que las propuestas realizadas en el marco de esta Tesis representan una optimización tanto en parámetros de calidad de servicio como en la eficiencia energética del sistema.El mayor avance respecto del estado del arte se centra en habilitar al usuario para que utilice de manera transparente, eficiente y segura los dispositivos que tiene a su alrededor independientemente de la heterogeneidad que presenten y sin requerir de un conocimiento intensivo de la tecnología. El usuario podrá comunicarse haciendo un uso óptimo de los recursos a su alcance sin preocuparse de tener que gestionarlos él mismo. / In the future, computation will be human-centred: it will enter the human world, handling our goals and needs and helping us to do more by doing less. Next generation wireless systems should provide the user access with a broad range of services in a transparent way, independently of user location, by making the technology invisible and embedded in the natural surroundings. New systems will boost our productivity. They will help us automate repetitive human tasks, control a wide range of physical devices in our environment, find the information we need (when we need it, without obliging us to examine thousands of search-engine hits), and enable us to work together with other people through space and time.The achievement of this paradigm led to the identification of a set of optimizations in intra-cluster communications that were needed to fully support it. Firstly, heterogeneity will be a fundamental characteristic of next generation wireless communications since more and more personal devices are equipped with multiple network access technologies so that the user can have access to the different services that the different operational environments provide. However, Next Generation Networks (NGN) will comprise such a diverse number of possibilities that the users cannot be expected to take technical decisions on their own. It is necessary to provide mechanisms that intelligently select the optimal available access network based on context information such as user preferences, power consumption, link quality, etc. Finally, users need to trust the system that supports their personal communications. Within a personal network the most confidential information might be exchanged and the user need to be sure that this will never be disclosed. If the system fails in these features, NGN in general and PNs in particular will never happen.This Thesis has contributed with the development of the mechanisms that tackle the abovementioned challenges. The design and specification of a convergence framework, the so-called Universal Convergence Layer (UCL), has been the first topic addressed. This framework aims to manage all the network access interfaces with which a device is equipped so that they can be transparently used by upper layers as if the node were equipped with a single access technology. On the other hand, the UCL enables the cross-layer optimization paradigm. Its privileged location within the protocol stack gives the UCL the possibility to support both bottom-up and top-down information flow. In this sense, two different solutions based on cross-layer optimization have been proposed to enhance the performance and energy efficiency of the system. The first one deals with the selection at run-time of the most appropriate wireless interface to be used in order to improve the system performance. The second one leverages the striping concept in order to exploit all the network interfaces available. Finally, the UCL also plays a key role in security issues as an enabler for providing link-layer security mechanisms that ensure data confidentiality and integrity, authenticity and non-repudiation. The techniques implemented for node authentication combined with traffic encryption in ad-hoc networks have been thoroughly assessed and have demonstrated their appropriateness.The biggest advance in the state-of-the-art comes from enabling the user to have easy, affordable and seamless control of their devices over heterogeneous communications networks. They are empowered to communicate efficiently and securely with their selected interaction groups, no matter what kind of access is available for them to use.