Mobilidade distribuida em ambientes dinâmicos

Mestrado em Engenharia Eletrónica e TelecomunicaçõesConventional networks have implemented a specific hierarchical structure, which in many cases deals with centralized mobility anchoring models to ensure IP session continuity. In this context, mobility management demands the existence of a centralized and static anchor point to allow reachability to mobile nodes connected to distinct networks. However, such centralized element is a single point of failures, introducing longer delays and higher management signalling. It may be more vulnerable to attacks, causing problems in the system. For this reason, mobility management addressed to centralized models is a satisfactory and non-optimal solution when mobile networks become less hierarchical. In order to improve mobility management to meet the requirements in mobile network evolution, there have been proposed solutions to distribute the anchor points closer to the end-user. This way, distributed and dynamic mobility anchoring improves scalability and availability, avoiding single points of failure and bottlenecks, as well as enabling transparent mobility support. In this framework, it is idealized and implemented a set of Vehicular scenarios using two different types of mobility management models, one centralized and another distributed. The results shows that the distributed mobility management protocol provides better results in terms of data loss, average data delay, data cost and signaling cost, when compared with the centralized mobility management protocol. The rapid growth of mobile nodes has lead to the increase of mobile data traffic consumption, and they are currently equipped with multiple network interfaces, which in many cases use different access technologies simultaneously. Therefore, session continuity of a certain user's services should be guaranteed independently of the access network technology. Consequently, there is a fundamental change in the network architectures, which is adopting flatten model to cope with users' behaviour and the evolution of the mobile data traffic consumption. Thus, it is specified a distributed mobility management scheme with multihoming support to provide continuity to active sessions when mobile nodes roam between networks/interfaces. This mobility mechanism is evaluated and tested in a real environment, demonstrating the capability to provide uninterrupted sessions for multihomed scenarios, such as the addition/removal of a link, likewise the capability to improve user experience.As redes de telecomunicações sem fios convencionais têm implementada uma estrutura hierárquica específica que em muitos casos lida com entidades centralizadas para garantirem continuidade de sessão e acessibilidade nas comunicações IP. Neste contexto, a gestão de mobilidade exige que haja uma âncora central e estática para permitir que os nós móveis se encontrem acessíveis quando conectados nas diferentes redes. Porém, este elemento central é suscetível a falhas introduzindo maiores atrasos, exigindo uma maior gestão da sinalização, sendo mais vulnerável a ataques o que pode causar problemas no sistema. Por estas razões, à medida que as redes móveis se tornam cada vez menos hierárquicas, a gestão da mobilidade baseada em modelos centralizados torna-se menos otimizada. Para melhorar a gestão de mobilidade tendo em consideração as exigências evolutivas da rede, têm vindo a ser propostas soluções para distribuir as âncoras, colocando-as mais perto do utilizador final com o objetivo de tornar a rede menos hierárquica, descentralizando o processo de gestão de mobilidade de uma forma dinâmica pelos nós da rede. Desta forma, a mobilidade distribuída em ambientes dinâmicos melhora a escalabilidade, acessibilidade e evita pontos centrais de falhas e engarrafamentos. Neste contexto, são idealizados e implementados três cenários de redes veiculares usando dois modelos de gestão de mobilidade, um centralizado e outro distribuído. Os resultados mostram que o protocolo de gestão de mobilidade distribuído apresenta melhores resultados em termos de perda de pacotes, atraso médio por pacote, custo de dados e custo de sinalização quando comparado com o protocolo de gestão de mobilidade centralizado. O rápido crescimento de nós móveis tem levado ao aumento do consumo de trafego de dados e, atualmente, estes estão equipados com múltiplas interfaces que, em muitos casos, utilizam diferentes tecnologias de acesso à rede. No entanto, a continuidade de sessão de um determinado serviço deve ser garantido, independentemente da tecnologia de acesso utilizada. Consequentemente, há uma preocupação em transformar a arquitetura da rede em modelos menos hierárquicos para lidar com o comportamento dos utilizadores e com a evolução do consumo de tráfego de dados móveis. Desta forma, é especificado um esquema de gestão de mobilidade distribuída com suporte a múltiplas interfaces para manter continuidade de sessões quando os nós móveis mudam de rede ou interface. Este mecanismo de mobilidade foi avaliado e testado num cenário real, demonstrando a capacidade de manter as sessões ativas em cenários com múltiplas interfaces melhorando a experiência do utilizador, dando como exemplo cenários de perda de ligação, ligação a outras redes e ligar/desligar uma interface

Acesso banda larga sem fios em ambientes heterogéneos de próxima geração

Doutoramento em Engenharia InformáticaO acesso ubíquo à Internet é um dos principais desafios para os operadores de telecomunicações na próxima década. O número de utilizadores da Internet está a crescer exponencialmente e o paradigma de acesso "always connected, anytime, anywhere" é um requisito fundamental para as redes móveis de próxima geração. A tecnologia WiMAX, juntamente com o LTE, foi recentemente reconhecida pelo ITU como uma das tecnologias de acesso compatíveis com os requisitos do 4G. Ainda assim, esta tecnologia de acesso não está completamente preparada para ambientes de próxima geração, principalmente devido à falta de mecanismos de cross-layer para integração de QoS e mobilidade. Adicionalmente, para além das tecnologias WiMAX e LTE, as tecnologias de acesso rádio UMTS/HSPA e Wi-Fi continuarão a ter um impacto significativo nas comunicações móveis durante os próximos anos. Deste modo, é fundamental garantir a coexistência das várias tecnologias de acesso rádio em termos de QoS e mobilidade, permitindo assim a entrega de serviços multimédia de tempo real em redes móveis. Para garantir a entrega de serviços multimédia a utilizadores WiMAX, esta Tese propõe um gestor cross-layer WiMAX integrado com uma arquitectura de QoS fim-a-fim. A arquitectura apresentada permite o controlo de QoS e a comunicação bidireccional entre o sistema WiMAX e as entidades das camadas superiores. Para além disso, o gestor de cross-layer proposto é estendido com eventos e comandos genéricos e independentes da tecnologia para optimizar os procedimentos de mobilidade em ambientes WiMAX. Foram realizados testes para avaliar o desempenho dos procedimentos de QoS e mobilidade da arquitectura WiMAX definida, demonstrando que esta é perfeitamente capaz de entregar serviços de tempo real sem introduzir custos excessivos na rede. No seguimento das extensões de QoS e mobilidade apresentadas para a tecnologia WiMAX, o âmbito desta Tese foi alargado para ambientes de acesso sem-fios heterogéneos. Neste sentido, é proposta uma arquitectura de mobilidade transparente com suporte de QoS para redes de acesso multitecnologia. A arquitectura apresentada integra uma versão estendida do IEEE 802.21 com suporte de QoS, bem como um gestor de mobilidade avançado integrado com os protocolos de gestão de mobilidade do nível IP. Finalmente, para completar o trabalho desenvolvido no âmbito desta Tese, é proposta uma extensão aos procedimentos de decisão de mobilidade em ambientes heterogéneos para incorporar a informação de contexto da rede e do terminal. Para validar e avaliar as optimizações propostas, foram desenvolvidos testes de desempenho num demonstrador inter-tecnologia, composta pelas redes de acesso WiMAX, Wi-Fi e UMTS/HSPA.Ubiquitous Internet access is one of the main challenges for the telecommunications industry in the next decade. The number of users accessing the Internet is growing exponentially and the network access paradigm of “always connected, anytime, anywhere” is a central requirement for the so-called Next Generation Mobile Networks (NGMN). WiMAX, together with LTE, was recently recognized by ITU as one of the compliant access technologies for 4G. Nevertheless, WiMAX is not yet fully prepared for next generation environments, mainly due to the lack of QoS and mobility crosslayer procedures to support real-time multimedia services delivery. Furthermore, besides the 4G compliant WiMAX and LTE radio access technologies, UMTS/HSPA and Wi-Fi will also have a significant impact in the mobile communications during the next years. Therefore, it is fundamental to ensure the coexistence of multiple radio access technologies in what QoS and mobility procedures are concerned, thereby allowing the delivery of real-time services in mobile networks. In order to provide the WiMAX mobile users with the demanded multimedia services, it is proposed in this Thesis a WiMAX cross-layer manager integrated in an end-to-end all-IP QoS enabled architecture. The presented framework enables the QoS control and bidirectional communication between WiMAX and the upper layer network entities. Furthermore, the proposed cross-layer framework is extended with media independent events and commands to optimize the mobility procedures in WiMAX environments. Tests were made to evaluate the QoS and mobility performance of the defined architecture, demonstrating that it is perfectly capable of handling and supporting real time services without introducing an excessive cost in the network. Following the QoS and mobility extensions provided for WiMAX, the scope of this Thesis is broaden and a seamless mobility architecture with QoS support in heterogeneous wireless access environments is proposed. The presented architecture integrates an extended version of the IEEE 802.21 framework with QoS support, as well as an advanced mobility manager integrated with the IP level mobility management protocols. Finally, to complete the work within the framework of this Thesis, it is proposed an extension to the handover decisionmaking processes in heterogeneous access environments through the integration of context information from both the network entities and the enduser. Performance tests were developed in a real testbed to validate the proposed optimizations in an inter-technology handover scenario involving WiMAX, Wi-Fi and UMTS/HSPA

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Recent Advances in Wireless Communications and Networks

This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters

SLICING-BASED RESOURCE ALLOCATION AND MOBILITY MANAGEMENT FOR EMERGING WIRELESS NETWORKS

The proliferation of smart mobile devices and user applications has continued to contribute to the tremendous volume of data traffic in cellular networks. Moreover, with the feature of heterogeneous connectivity interfaces of these smart devices, it becomes more complex for managing the traffic volume in the context of mobility. To surmount this challenge, service and resource providers are looking for alternative mechanisms that can successfully facilitate managing network resources and mobility in a more dynamic, predictive and distributed manner. New concepts of network architectures such as Software-Defined Network (SDN) and Network Function Virtualization (NFV) have paved the way to move from static to flexible networks. They make networks more flexible (i.e., network providers capable of on-demand provisioning), easily customizable and cost effective. In this regard, network slicing is emerging as a new technology built on the concepts of SDN and NFV. It splits a network infrastructure into isolated virtual networks and allows them to manage network resources based on their requirements and characteristics. Most of the existing solutions for network slicing are facing challenges in terms of resource and mobility management. Regarding resource management, it creates challenges in terms of provisioning network throughput, end-to-end delay, and fairness resources allocation for each slice, whereas, in the case of mobility management, due to the rapid change of user mobility the network slice operator would like to hold the mobility controlling over its clients across different access networks, rather than the network operator, to ensure better services and user experience. In this thesis, we propose two novel architectural solutions to solve the challenges identified above. The first proposed solution introduces a Network Slicing Resource Management (NSRM) mechanism that assigns the required resources for each slice, taking into consideration resource isolation between different slices. The second proposed v solution provides a Mobility Management architecture-based Network Slicing (MMNS) where each slice manages its users across heterogeneous radio access technologies such as WiFi, LTE and 5G networks. In MMNS architecture, each slice has different mobility demands (e.g,. latency, speed and interference) and these demands are governed by a network slice configuration and service characteristics. In addition, NSRM ensures isolating, customizing and fair sharing of distributed bandwidths between various network slices and users belonging to the same slice depending on different requirements of each one. Whereas, MMNS is a logical platform that unifies different Radio Access Technologies (RATs) and allows all slices to share them in order to satisfy different slice mobility demands. We considered two software simulations, namely OPNET Modeler and OMNET++, to validate the performance evaluation of the thesis contributions. The simulation results for both proposed architectures show that, in case of NSRM, the resource blocking is approximately 35% less compared to the legacy LTE network, which it allows to accommodate more users. The NSRM also successfully maintains the isolation for both the inter and intra network slices. Moreover, the results show that the NSRM is able to run different scheduling mechanisms where each network slice guarantee perform its own scheduling mechanism and simultaneously with other slices. Regarding the MMNS, the results show the advantages of the proposed architecture that are the reduction of the tunnelling overhead and the minimization of the handover latency. The MMNS results show the packets delivery cost is optimal by reducing the number of hops that the packets transit between a source node and destination. Additionally, seamless session continues of a user IP-flow between different access networks interfaces has been successfully achieved

Journal of Telecommunications and Information Technology

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Elektroninių paslaugų įgyvendinimo sprendimai

Monografijoje nagrinėjamos elektroninių paslaugų (toliau tekste – ir e. paslaugos) plėtros tendencijos, apžvelgiamos įvairios temos – nuo paprastųjų e. paslaugų infrastruktūros kūrimo iki sudėtingų išmaniųjų paslaugų technologinių sprendimų. Kuriant šiuolaikines dirbtinio intelekto sistemas svarbu, kad jos būtų naudingos vartotojams ir pritaikomos kintančiai aplinkai. Ypač daug dėmesio skiriama išmaniųjų paslaugų kūrimui ir vartotojų įpročių analizei, gyventojų gebėjimams įsisavinti teikiamas paslaugas. Svarbu, kad išmaniosios sistemos leistų daugelį paslaugų valdyti automatiškai, pritaikant jas konkretiems poreikiams. Viena iš tokių sistemų kūrimo sričių – adaptuotosios paslaugos ir nuolat kintantis jų pateikimas. Taip pat aktualu mažinti išteklių sąnaudas, teikti paslaugas tiesioginės kreipties režimu ir reikiamu laiku, kartu siekiant paslaugų kokybės ir kuo mažesnės paklaidų rizikos. Dirbtinio intelekto sistemose, adekvačiai įvertinant paklausą ir gebėjimus valdyti paslaugų teikimo procesus, siūlomos įvairias dalykines sritis siejančios kompiuterinės technologijos. Tai mokslai, susiję su biomedicina, psichologija, kompiuterių inžinerija, lingvistika ir kt