The trend towards personalized ubiquitous computing has led to the advent of a new generation of wireless technologies, namely wireless body area networks (WBANs), which connect the wearable devices into the Internet-of-Things. This thesis considers the problems of relay selection and power control in fading WBANs with energy-efficiency and security considerations. The main body of the thesis is formed by two papers. Ideas from probability theory are used, in the first paper, to construct a performance measure signifying the energy efficiency of transmission, while in the second paper, information-theoretic principles are leveraged to characterize the transmission secrecy at the wireless physical layer (PHY). The hypothesis is that exploiting spatial diversity through multi-hop relaying is an effective strategy in a WBAN to combat fading and enhance communication throughput. In order to analytically explore the problems of optimal relay selection and power control, proper tools from game theory are employed. In particular, non-cooperative game-theoretic frameworks are developed to model and analyze the strategic interactions among sensor nodes in a WBAN when seeking to optimize their transmissions in the uplink. Quality-of-service requirements are also incorporated into the game frameworks, in terms of upper bounds on the end-to-end delay and jitter incurred by multi-hop transmission, by borrowing relevant tools from queuing theory. The proposed game frameworks are proved to admit Nash equilibria, and distributed algorithms are devised that converge to stable Nash solutions. The frameworks are then evaluated using numerical simulations in conditions approximating actual deployment of WBANs. Performance behavior trade-offs are investigated in an IEEE 802.15.6-based ultra wideband WBAN considering various scenarios. The frameworks show remarkable promise in improving the energy efficiency and PHY secrecy of transmission, at the expense of an admissible increase in the end-to-end latency.

Made available in DSpace on 2014-12-17T15:47:04Z (GMT). No. of bitstreams: 1 CaioSVB_TESE.pdf: 3239738 bytes, checksum: 3948060aee2b57cbd69e34e39277bb29 (MD5) Previous issue date: 2014-02-06 / Context-aware applications are typically dynamic and use services provided by several sources, with different quality levels. Context information qualities are expressed in terms of Quality of Context (QoC) metadata, such as precision, correctness, refreshment, and resolution. On the other hand, service qualities are expressed via Quality of Services (QoS) metadata such as response time, availability and error rate. In order to assure that an application is using services and context information that meet its requirements, it is essential to continuously monitor the metadata. For this purpose, it is needed a QoS and QoC monitoring mechanism that meet the following requirements: (i) to support measurement and monitoring of QoS and QoC metadata; (ii) to support synchronous and asynchronous operation, thus enabling the application to periodically gather the monitored metadata and also to be asynchronously notified whenever a given metadata becomes available; (iii) to use ontologies to represent information in order to avoid ambiguous interpretation. This work presents QoMonitor, a module for QoS and QoC metadata monitoring that meets the abovementioned requirement. The architecture and implementation of QoMonitor are discussed. To support asynchronous communication QoMonitor uses two protocols: JMS and Light-PubSubHubbub. In order to illustrate QoMonitor in the development of ubiquitous application it was integrated to OpenCOPI (Open COntext Platform Integration), a Middleware platform that integrates several context provision middleware. To validate QoMonitor we used two applications as proofof- concept: an oil and gas monitoring application and a healthcare application. This work also presents a validation of QoMonitor in terms of performance both in synchronous and asynchronous requests / Aplica??es cientes de contexto s?o tipicamente din?micas e caracterizam-se por utilizar servi?os providos por v?rias fontes, com diferentes n?veis de qualidade. A qualidade de uma informa??o de contexto ? expressa atrav?s dos metadados de Qualidade de Contexto (QoC), como precis?o, corretude, atualidade, resolu??o. Por sua vez, a qualidade de um servi?o ? expressa atrav?s dos metadados de Qualidade de Servi?o (QoS), como tempo de resposta, taxa de erro, disponibilidade e tempo m?dio entre falhas. Para garantir que uma aplica??o est? utilizando servi?os e informa??es de contexto com n?veis de QoS e QoC que satisfa?am seus requisitos, ? essencial que elas estejam continuamente cientes desses metadados. Para tanto, ? necess?rio utilizar um mecanismo de monitoramento de QoS e QoC que atenda aos seguinte requisitos: (i) forne?a suporte a aferi??o e monitoramento de metadados de QoS e QoC; (ii) opere de forma s?ncrona como tamb?m de forma ass?ncrona, permitindo que a aplica??o especifique uma condi??o e o monitor informe quando ocorre algum evento que satisfa?a a condi??o;; (iii) use ontologias para representa??o da informa??o de forma a evitar interpreta??es amb?guas. Este trabalho prop?e o QoMonitor, um m?dulo para monitoramento de metadados de QoS e QoC que atende a tais requisitos. A arquitetura e a implementa??o do QoMonitor s?o discutidos. Para requisi??es ass?ncrona o QoMonitor usa dois protocolos: JMS e Light-PubSubHubbub. De forma a ilustrar o uso do QoMonitor no contexto do desenvolvimento de aplica??es ub?quas ele foi integrado ao OpenCOPI (Open COntext Platform Integration), uma plataforma integradora de diferentes Middleware de provis?o de contexto que fornecem servi?os e seus respectivos metadados. Para validar o uso do QoMonitor s?o utilizados duas aplica??es como provas de conceito que exploram as capacidades do monitor: uma aplica??o da ind?stria de petr?leo e g?s, e uma aplica??o de healthcare. Esse trabalho tamb?m apresenta uma avalia??o do QoMonitor em termos de desempenho tanto no contexto de requisi??es s?ncronas como ass?ncronas

Distributed systems like e-commerce and e-market places, peer-to-peer networks, social networks, and mobile ad hoc networks require cooperation among the participating entities to guarantee the formation and sustained existence of network services. The reliability of interactions among anonymous entities is a significant issue in such environments. The distributed entities establish connections to interact with others, which may include selfish and misbehaving entities and result in bad experiences. Therefore, trustworthiness evaluation using trust management techniques has become a significant issue in securing these environments to allow entities decide on the reliability and trustworthiness of other entities, besides it helps coping with defection problems and stimulating entities to cooperate. Recent models on evaluating trustworthiness in distributed systems have heavily focused on assessing trustworthiness of entities and isolate misbehaviours based on single trust metrics. Less effort has been put on the investigation of the subjective nature and differences in the way trustworthiness is perceived to produce a composite multidimensional trust metrics to overcome the limitation of considering single trust metric. In the light of this context, this thesis concerns the evaluation of entities’ trustworthiness by the design and investigation of trust metrics that are computed using multiple properties of trust and considering environment. Based on the concept of probabilistic theory of trust management technique, this thesis models trust systems and designs cooperation techniques to evaluate trustworthiness in mobile ad hoc networks (MANETs). A recommendation based trust model with multi-parameters filtering algorithm, and multidimensional metric based on social and QoS trust model are proposed to secure MANETs. Effectiveness of each of these models in evaluating trustworthiness and discovering misbehaving nodes prior to interactions, as well as their influence on the network performance has been investigated. The results of investigating both the trustworthiness evaluation and the network performance are promising.

Made available in DSpace on 2016-06-02T19:05:27Z (GMT). No. of bitstreams: 1 1680.pdf: 2540055 bytes, checksum: 6068982fae71ad51efe5f0ebb3308784 (MD5) Previous issue date: 2006-12-15 / The advent of grid computing made possible to access distributed resources, even when they are geographically spread or belong to different organizations. The most used environment for accessing these distributed resources is the Internet, a worldwide computer network based in TCP/IP architecture. Grid computing provides the infrastructure necessary for managing and communicating with the resources offered by different organizations. These organizations are also known as virtual organizations (VO's). Some of the applications used in these collaborating environments may have minimum requirements by quality of service (QoS). However, the "best effort" service, which is offered by Internet, is not capable to satisfy these QoS requirements. In this case, a different solution is needed, in order to provide guarantees related to the traffic in communication channels. This master thesis aims to apply the concepts of quality of service for networks in grid computing, providing end-to-end quality of service between grid computing applications. In order to achieve this goal, we investigate the use of commutation infrastructure provided by MPLS networks. Using traffic engineering mechanisms for routes determination, we aim to provide better control of data flows, improving the performance of distributed applications in geographically highly spread environments. / O surgimento da computação em grade possibilitou o acesso a recursos distribuídos que podem estar dispersos geograficamente e pertencer a diferentes organizações. O meio mais utilizado para prover acesso a tais recursos é a Internet, uma rede de computadores de alcance mundial baseada na arquitetura TCP/IP. As grades computacionais fornecem a infra-estrutura necessária à comunicação e ao gerenciamento dos recursos fornecidos por estas organizações, também conhecidas por organizações virtuais (VOs) . Algumas das aplicações utilizadas nestes ambientes colaborativos podem possuir requisitos mínimos de qualidade de serviço (QoS). Entretanto, o serviço de melhor esforço oferecido pela Internet não é capaz de satisfazer tais exigências, sendo preciso utilizar outra forma para se obter garantias em relação à capacidade de tráfego dos canais de comunicação. Este trabalho de mestrado objetiva aplicar os conceitos de qualidade de serviço de redes para o provimento de qualidade de serviço fim-a-fim nas comunicações entre aplicações para grades computacionais. Para tanto, investiga o uso da infra-estrutura de comutação provida pelas redes MPLS. Usando mecanismos de determinação de rotas em Engenharia de Tráfego, busca-se prover melhor controle dos fluxos de dados, beneficiando aplicações distribuídas em ambientes de grande dispersão física.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-26T17:46:31Z No. of bitstreams: 1 GustavoNogueiraAlves_DISSERT.pdf: 7390589 bytes, checksum: 622ffc2952552ee8688415a6acdb97f1 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-28T17:44:43Z (GMT) No. of bitstreams: 1 GustavoNogueiraAlves_DISSERT.pdf: 7390589 bytes, checksum: 622ffc2952552ee8688415a6acdb97f1 (MD5) / Made available in DSpace on 2016-01-28T17:44:43Z (GMT). No. of bitstreams: 1 GustavoNogueiraAlves_DISSERT.pdf: 7390589 bytes, checksum: 622ffc2952552ee8688415a6acdb97f1 (MD5) Previous issue date: 2015-01-28 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Computa??o em Nuvem ? um paradigma computacional que possibilita o acesso de forma simples e pervasiva, via rede, a recursos compartilhados e configur?veis de computa??o. Tais recursos s?o oferecidos sob demanda para o usu?rio atrav?s de um modelo de uso em que s? se paga pelo uso do recurso. Com o avan?o desse paradigma, um ?nico servi?o oferecido por uma plataforma de nuvem pode n?o ser suficiente para prover todos os requisitos dos clientes, sendo necess?rio uma composi??o de servi?os providos por diferentes plataformas de nuvem. No entanto, as plataformas de nuvem atuais n?o s?o implementadas usando padr?es comuns, cada uma possui sua pr?pria API e ferramenta de desenvolvimento, o que dificulta a cria??o da composi??o. Para facilitar a cria??o de composi??es existe o Cloud Integrator, uma plataforma de middleware orientada a servi?os que prov? um ambiente que facilita o desenvolvimento e a execu??o de aplica??es. Essas aplica??es s?o composi??es de servi?os de diferentes plataformas de nuvem e representadas atrav?s de workflows abstratos. No entanto, o Cloud Integrator possui algumas limita??es: (i) as aplica??es criadas s?o executadas localmente; (ii) usu?rios n?o podem especificar a aplica??o apenas pelas suas entradas e sa?das, e; (iii) os usu?rios n?o podem selecionar diretamente qual os servi?os que v?o executar as atividades do workflow. A fim de tratar essas limita??es, esse trabalho prop?e o Cloud Stratus, uma plataforma de middleware que estende o Cloud Integrator e oferece diferentes formas de especificar aplica??es, permitindo se definir um workflow abstrato ou fluxo de execu??o completo ou parcial. A plataforma possibilita a implanta??o da aplica??o em m?quinas virtuais na nuvem, de forma que v?rios usu?rios podem acess?-la atrav?s da Internet. O Cloud Stratus ainda realiza o acesso e gerenciamento de m?quinas virtuais de diferentes plataformas de nuvem e fornece mecanismos para monitoramento de servi?os e aferi??o de par?metros de QoS. A valida??o do Cloud Stratus ? realizada atrav?s de um estudo de caso que consiste de uma aplica??o que utiliza diversos servi?os de nuvem providos por diferentes plataformas de nuvem. O Cloud Stratus ainda ? avaliado atrav?s de experimentos computacionais que analisam o desempenho de seus processos. / Cloud Computing is a paradigm that enables the access, in a simple and pervasive way, through the network, to shared and configurable computing resources. Such resources can be offered on demand to users in a pay-per-use model. With the advance of this paradigm, a single service offered by a cloud platform might not be enough to meet all the requirements of clients. Ergo, it is needed to compose services provided by different cloud platforms. However, current cloud platforms are not implemented using common standards, each one has its own APIs and development tools, which is a barrier for composing different services. In this context, the Cloud Integrator, a service-oriented middleware platform, provides an environment to facilitate the development and execution of multi-cloud applications. The applications are compositions of services, from different cloud platforms and, represented by abstract workflows. However, Cloud Integrator has some limitations, such as: (i) applications are locally executed; (ii) users cannot specify the application in terms of its inputs and outputs, and; (iii) experienced users cannot directly determine the concrete Web services that will perform the workflow. In order to deal with such limitations, this work proposes Cloud Stratus, a middleware platform that extends Cloud Integrator and offers different ways to specify an application: as an abstract workflow or a complete/partial execution flow. The platform enables the application deployment in cloud virtual machines, so that several users can access it through the Internet. It also supports the access and management of virtual machines in different cloud platforms and provides services monitoring mechanisms and assessment of QoS parameters. Cloud Stratus was validated through a case study that consists of an application that uses different services provided by different cloud platforms. Cloud Stratus was also evaluated through computing experiments that analyze the performance of its processes.

Multiprotocol Label Switching (MPLS) is a new paradigm in routing architectures which has changed the way Internet Protocol (IP) packet is transferred in a Network. MPLS ensures the reliability of the communication minimizing the delays and enhancing the speed of packet transfer. One important feature of MPLS is its capability of providing Traffic Engineering (TE) which plays a vital role for minimizing the congestion by efficient load, balancing and management of the network resources. The performance evaluation is done considering the network parameters latency, jitter, packet end to end delay, and packet delay variation. Integration of QoS with the MPLS-TE network may enhance the performance of the network. Various scheduling algorithms can be used for implementing QoS on a network, which may vary the performance of the network. In our study, QoS is implemented on top of the MPLS-TE network using Differentiated Service (DiffServ) architecture. Different basic scheduling algorithms are used for the implementation of QoS and to check their impact on the network and to identify the suitable one among them. Performance evaluation is done considering the network parameters latency, jitter, packet end-to-end delay, and Packet Delay Variation. The simulation was done using OPNET modeler 16.0 and the results were analyzed. The simulation result shows that using TE along with QoS in MPLS network decreases the latency, jitter, packet delay variation and end to end packet delay compared to using TE alone for voice traffic. / +46738732963

The service oriented computing paradigm is a new model for distributed computing and due to its simplicity and powerful features, it is being popular and has a wide variety of implementation in different scenarios. The already built system is studies in detail, which was totally implemented using the Grid Technology. The idea of the current work is how we can implement the same functionality in the non-real time environment. The basic idea is to merge the web services and grid services to formulate the unique concept of context dependent quality of service (QoS) for both real time and non-real time solutions. When we merge these different types of services, the main focusing point is to define the service level agreement (SLA) when these different qualified services want to interact with each other. This document discusses and formulates the theoretical aspects, which in future work, can be consider for the practical implementation.

Mobile communication is developing very rapidly with passage of time, new technologies are being introduced to facilitate the mobile users more from the technology. The past technologies are replaced by new ones and needs are growing for the new technologies to be developed. One such development is fourth generation networks. Also called future generation or Next Generation Networks. The introduction of 4G has widened the scope of mobile communication. Now mobile is not only a device used for talking but its more or less a portable computer that can serve different purposes. 4G offers higher data rates with seamless roaming. The mobile user can communicate without any disturbance while switching his coverage network. 4G is still passing through research and therefore there are some problems that need to be fixed in order to benefit the users from it fully. In this report we discuss various challenges 4G is facing and solutions to those problems are discussed. We propose our own way of improving QoS in 4G by using combination of mobility protocol SMIP and SIP. We propose that by using such scheme we can achieve better QoS during the process of handover. / Mobil kommunikation utvecklas mycket snabbt med tiden, är ny teknik införs för att underlätta mobilanvändare mer av tekniken. Det förflutna teknik ersätts av nya och behov ökar för ny teknik som skall utvecklas. En sådan utveckling är fjärde generationens nät. Kallas även kommande generationen eller nästa generations nät. Införandet av 4G har räckvidden för mobil kommunikation. Nu mobil är inte bara en enhet som används för att prata, men dess mer eller mindre en bärbar dator som kan tjäna olika syften. 4G erbjuder högre dataöverföringshastigheter med sömlös roaming. Den mobila användaren kan kommunicera utan störningar samtidigt som du slår sin täckning nätverk. 4G är fortfarande passerar genom forskning och därför finns det vissa problem som behöver rättas till för att gynna användarna av den helt. I denna rapport diskuterar vi olika utmaningar 4G står inför och lösningar på dessa problem diskuteras. Vi föreslår vårt eget sätt att förbättra QoS i 4G genom kombination av mobilitet protokoll SMIP och SIP. Vi föreslår att genom att använda ett sådant system som vi kan uppnå bättre QoS under processen för överlämnandet. / 0044788479520

There are many disadvantages (cost, lack of security, difficult to manage large networks, support to non-sensitive applications, delay, etc.) associated with traditional networking, IP network, ATM and Frame relay networking. To solve this, an MPLS-based VPN networking is introduced that can work with existing deployed backbones and allow organizations to interconnect the dispersed sites and remote workers through secure links by using public internet. In this thesis, we are trying to build a better understanding to MPLS VPN and we researched to analyze the behavior of OSPF and RIPv2 based MPLS-BGP VPN architectures by using intense VoIP traffic. Then it comes with an OPNET simulation process and scenarios for MPLS-BGP VPN. At last, the conclusion is made: OSPF based MPLS-BGP VPN architecture has lower VPN delay, background traffic Flow delay, LSP delay and point-to-point Queuing delay, and has better performance in VPN load and VPN throughput that can acquire customer satisfaction and confidence as compared to the RIPv2 based MPLS-BGP VPN architecture. / Det finns många nackdelar (kostnader, bristande säkerhet, svåra att hantera stora nätverk, stöd till icke-känsliga tillämpningar, delay, etc.) i samband med traditionella nätverk, IP-nätverk, ATM och Frame Relay nätverk. För att lösa detta, är ett MPLS-baserat VPN nätverk införs som kan arbeta med befintliga sättas samman och låter organisationer för att förbinda de spridda platser och distansarbetare genom säkra länkar genom att använda publika Internet. I denna avhandling försöker vi bygga en bättre förståelse för MPLS VPN och vi forskat för att analysera beteendet hos OSPF och RIPv2 baserad MPLS-VPN BGP arkitekturer med hjälp av intensiv VoIP-trafik. Då kommer med en OPNET simulering process och scenarier för MPLS-BGP VPN. Äntligen är den slutsatsen: OSPF bygger MPLS-VPN BGP arkitektur har lägre VPN dröjsmål bakgrund trafikflödet dröjsmål, LSP dröjsmål och punkt-till-punkt Queuing dröjsmål, och har bättre prestanda i VPN-belastning och VPN som kan få kunden tillfredsställelse och förtroende jämfört med RIPv2 baserad MPLS-VPN BGP arkitektur.

The presence of computer technologies in our daily life is growing by leaps and bounds. One of the recent trends is the use of mobile technologies and cloud services for supporting everyday tasks and the sharing of information between users. The field of education is not absent from these developments and many organizations are adopting Information and Communication Technologies (ICT) in various ways for supporting teaching and learning. The field of Mobile Learning (M-Learning) offers new opportunities for carrying out collaborative educational activities in a variety of settings and situations. The use of mobile technologies for enhancing collaboration provides new opportunities but at the same time new challenges emerge. One of those challenges is discussed in this thesis and it con- cerns with uncertainties related to the dynamic aspects that characterized outdoor M-Learning activities. The existence of these uncertainties force software developers to make assumptions in their developments. However, these uncertainties are the cause of risks that may affect the required outcomes for M-Learning activities. Mitigations mechanisms can be developed and included to reduce the risks’ impact during the different phases of development. However, uncertainties which are present at runtime require adaptation mechanisms to mitigate the resulting risks. This thesis analyzes the current state of the art in self-adaptation in Technology-Enhanced Learning (TEL) and M-Learning. The results of an extensive literature survey in the field and the outcomes of the Geometry Mobile (GEM) research project are reported. A list of uncertainties in collaborative M-Learning activities and the associated risks that threaten the critical QoS outcomes for collaboration are identified and discussed. A detailed elaboration addressing mitigation mechanisms to cope with these problems is elaborated and presented. The results of these efforts provide valuable insights and the basis towards the design of a multi-agent self-adaptive architecture for multiple concerns that is illustrated with a prototype implementation. The proposed conceptual architecture is an initial cornerstone towards the creation of a decentralized distributed self-adaptive system for multiple concerns to guarantee collaboration in M-Learning.