228 research outputs found

    Asymmetric digital subscriber line technology and the future of remote access networking

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    ISDN at NASA Lewis Research Center

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    An expository investigation of the potential impact of the Integrated Services Digital Network (ISDN) at NASA Lewis Research Center is described. To properly frame the subject, the paper contains a detailed survey of the components of Narrowband ISDN. The principles and objectives are presented as decreed by the Consultative Committee for International Telephone and Telegraph (CCITT). The various channel types are delineated and their associated service combinations are described. The subscriber-access network functions are explained pictorially via the ISDN reference configuration. A section on switching techniques is presented to enable the reader to understand the emergence of the concept of fast packet switching. This new technology is designed to operate over the high bandwidth, low error rate transmission media that characterizes the LeRC environment. A brief introduction to the next generation of networks is covered with sections on Broadband ISDM (B-ISDN), Asynchronous Transfer Mode (ATM), and Synchronous Optical Networks (SONET). Applications at LeRC are presented, first in terms of targets of opportunity, then in light of compatibility constraints. In-place pilot projects and testing are described that demonstrate actual usage at LeRC

    Technology Directions for the 21st Century

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    New technologies will unleash the huge capacity of fiber-optic cable to meet growing demands for bandwidth. Companies will continue to replace private networks with public network bandwidth-on-demand. Although asynchronous transfer mode (ATM) is the transmission technology favored by many, its penetration will be slower than anticipated. Hybrid networks - e.g., a mix of ATM, frame relay, and fast Ethernet - may predominate, both as interim and long-term solutions, based on factors such as availability, interoperability, and cost. Telecommunications equipment and services prices will decrease further due to increased supply and more competition. Explosive Internet growth will continue, requiring additional backbone transmission capacity and enhanced protocols, but it is not clear who will fund the upgrade. Within ten years, space-based constellations of satellites in Low Earth orbit (LEO) will serve mobile users employing small, low-power terminals. 'Little LEO's' will provide packet transmission services and geo-position determination. 'Big LEO's' will function as global cellular telephone networks, with some planning to offer video and interactive multimedia services. Geosynchronous satellites also are proposed for mobile voice grade links and high-bandwidth services. NASA may benefit from resulting cost reductions in components, space hardware, launch services, and telecommunications services

    Journal of Telecommunications in Higher Education

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    This Issue: Student Services & Revenue Generation Student Services: Where Are We Going? UK Positions for the Future Prepaid Calling Cards: Big Deal on Campus Bringing Cable to Campus Interview: Howard Anderson and Bryan VanDussen,The Yankee Group Campus Profile: University of Colorado at Boulde

    Ontwerp en evaluatie van content distributie netwerken voor multimediale streaming diensten.

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    Traditionele Internetgebaseerde diensten voor het verspreiden van bestanden, zoals Web browsen en het versturen van e-mails, worden aangeboden via één centrale server. Meer recente netwerkdiensten zoals interactieve digitale televisie of video-op-aanvraag vereisen echter hoge kwaliteitsgaranties (QoS), zoals een lage en constante netwerkvertraging, en verbruiken een aanzienlijke hoeveelheid bandbreedte op het netwerk. Architecturen met één centrale server kunnen deze garanties moeilijk bieden en voldoen daarom niet meer aan de hoge eisen van de volgende generatie multimediatoepassingen. In dit onderzoek worden daarom nieuwe netwerkarchitecturen bestudeerd, die een dergelijke dienstkwaliteit kunnen ondersteunen. Zowel peer-to-peer mechanismes, zoals bij het uitwisselen van muziekbestanden tussen eindgebruikers, als servergebaseerde oplossingen, zoals gedistribueerde caches en content distributie netwerken (CDN's), komen aan bod. Afhankelijk van de bestudeerde dienst en de gebruikte netwerktechnologieën en -architectuur, worden gecentraliseerde algoritmen voor netwerkontwerp voorgesteld. Deze algoritmen optimaliseren de plaatsing van de servers of netwerkcaches en bepalen de nodige capaciteit van de servers en netwerklinks. De dynamische plaatsing van de aangeboden bestanden in de verschillende netwerkelementen wordt aangepast aan de heersende staat van het netwerk en aan de variërende aanvraagpatronen van de eindgebruikers. Serverselectie, herroutering van aanvragen en het verspreiden van de belasting over het hele netwerk komen hierbij ook aan bod

    Análise técnico-económica de redes de acesso : ferramentas de decisão

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    Mestrado em Engenharia Electrónica e TelecomunicaçõesO recente crescimento de consumo de internet e televisão por cabo desencadeou a necessidade de novas redes de acesso. O mundo das telecomunicações tornou-se num negócio competitivo entre as operadoras. As estratégias de competitividade são agora com baseadas em qualidade do serviço e na acessibilidade dos preços a todas as categorias da população. Para garantir estes requisitos é necessário inovar em equipamentos e meios de distribuição. A implantação de novas redes de acesso tornou-se crucial na sociedade, mas a recente crise económica mundial forçou um dimensionamento cuidado para garantir o máximo lucro possível no negócio. Portanto esta dissertação apresenta uma análise económica e financeira da implementação de uma rede HFC. Mostra a estrutura da rede e as suas características tecnológicas, além disso explica como lidar com problemas no dimensionamento da rede: a incerteza espacial associada ao processo de adesão dos utilizadores e como lidar com consumo em excesso de largura de banda, também causado pelos utilizadores. Por fim realiza o estudo da instalação da rede HFC em três tipos diferentes de cenários e expondo os resultados económicos obtidos, permitindo a conclusão sobre a viabilidade destes projetos.The recent growth in Data Traffic and Cable Tv consumption triggered the need for new access networks and the world of Telecommunications has become a very competitive business among service providers. The strategies of competitiveness are now based on quality of services and affordable prices to all classes of the population. To guarantee these requirements, an equipment and distribution facilities innovation was necessary. The deployment of Next Generation Access Networks (NGA) has become crucial in society, but the recent world economic crisis has forced a careful dimensioning to produce the most profit possible with small investments. This dissertation presents a techno-economic analysis of a HFC network implementation. The network structure and technologic characteristics are presented, along with explanation of how to deal with problems in the network dimensioning: as spatial uncertainty associated with the adhesion process of the users and the surplus consumption of bandwidth by them. Finally, the study of the network implementation in three different sorts of areas is shown and the economic results obtained are exposed, providing the viability of these projects
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