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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Dynamic bandwidth allocation MAC protocols for gigabit-capable passive optical networks

Chang, Ching-Hung January 2008 (has links)
The research initiatives addressed in this thesis are geared towards improving the performance of passive optical networks (PONs) through the development of advanced dynamic bandwidth allocation (DBA) protocols. In particular, the aim of the research undertaken is to enhance the quality of service (QoS) offered by standard PONs by means of providing subscribers with service level agreement (SLA) to fulfil applications and associated bandwidth requirements on demand. To accomplish the research objectives, a novel service and bandwidth focused DBA protocol is developed for standard time division multiplexing (TDM), gigabit-capable PONs (GPONs) by flexibly assigning a guaranteed minimum bandwidth to each optical network unit (ONU),terminated at subscribers premises. Modelling and simulation of the developed algorithms have displayed a tenfold enhancement in network performance, showing a superior performance to other published DBA protocols, in terms of mean packet delay. To accomplish protocol optimisation, the ONU upstream transmission properties of TDM-PONs have been further analysed and subsequently the ONU data transfer order in each communication cycle has been dynamically configured to increase the network upstream throughput by overlapping the upstream transmission period with parts of the bandwidth request-allocation process between OLT and ONUs. In addition, with the objective of extending the application of the developed protocol to long-reach PONs by means of reducing the augmented propagation delays due to the network’s extensive reach, the concept of virtual communication cycles has been incorporated into the optimised DBA algorithm. This approach demonstrates comparable transmission efficiency in the context of subscriber throughput and packet delay as in a standard PON but at much longer distances from the network exchange. To overcome the inevitably limited communication capacity of single wavelength TDM protocols and with the transportation of the ever increasing, time-sensitive, multi-media services in mind, a novel multi-wavelength DBA protocol is then developed to be applied to a wavelength division multiplexing–PON. With this protocol, both the downstream and upstream network capacity is dynamically adjusted according to subscribers’ service level and bandwidth demand in each polling cycle as opposed to a fixed upstream network capacity in TDM-PONs. It therefore also demonstrates improved upstream transmission efficiency.
2

Les politiques publiques face aux changements technologiques / Public policy confronted to technological changes

Hasbi, Maude 17 July 2017 (has links)
Cette thèse aborde plusieurs sujets relatifs à l’impact de la régulation sectorielle sur la concurrence et l’investissement dans le secteur des communications électroniques. En particulier, cette thèse soulève des questions relative à la pertinence de la régulation, lorsque celle-ci est imposée à de technologies anciennes, notamment lorsque des technologies plus efficaces et plus modernes sont disponibles sur le marché à un prix abordable. Cette thèse permet également d’analyser comment la régulation sectorielle affecte la concurrence entre technologies et indirectement l’investissement des opérateurs privés. Des analyses plus complètes sont proposées en ce qui concerne le marché du haut et du très haut débit. J’y estime dans quelle mesure l’impact de la concurrence (via le dégroupage de la boucle locale cuivre) vient affecter les incitations à investir des opérateurs dans les réseaux en fibre optique. Enfin, cette thèse permet d’évaluer l’impact des réseaux très haut débit sur la croissance économique au niveau local, en termes d’impact sur les créations d’entreprises et les créations d’entreprises unipersonnelles. Cette dernière étude a pour objectif de quantifier les bénéfices économiques provenant du déploiement de ces réseaux de nouvelle génération. / This thesis approaches several issues related to the impact of sector-specific regulation on competition and investments in the electronic communication sector. More specifically, it raises the question of the relevance of regulation when applied to an old technology, when enhanced and affordable alternative technologies are available. It also analyzes how regulation affects competition between technologies and indirectly operators’ investments. Further analyses are provided for the fixed broadband market, with an assessment of the effect of competition via local loop unbundling on operators’ incentives to invest into fiber networks. Finally, this thesis evaluates the impact of very high-speed broadband networks on local economic growth, in terms of establishment creation and sole proprietorship creation. It attempts to quantify the economic benefits stemming from the roll-out of next generation access networks
3

Migration Towards Next Generation Optical Access and Transport Networks

Wang, Kun January 2017 (has links)
By 2020 there will be 50 billion connected devices over the Internet. With the fast-increasing data traffic demand in both fixed and mobile networks, network operators need to migrate networks towards next generation solutions. The network migration requires the enormous investment in equipment and infrastructure, while the revenues are not expected to grow significantly. Therefore, one of the main challenges for network operators is to find out a proper cost-effective optical network solution that can match future high capacity demand and flexibly support multiple network services on a common network infrastructure. The first part of the thesis addresses the Active Optical Network (AON) and its migration strategies towards Next Generation Optical Access (NGOA) solutions. Several migration strategies are proposed from the perspective of network topology, data plane and control plane. A general methodology for Techno-Economic analysis has been developed and applied to the Total Cost of Ownership (TCO) calculation of different NGOA solutions. The thesis provides a complete cost evaluation of AON migration paths, which can be used by network operators to assess the economic feasibility of network migration. A converged Optical Transport Network (OTN) that can serve both fixed and mobile network services is beneficial from the cost-saving perspective. However, the different types of services, require different network performance. The second part of the thesis focuses on the investigation of the converged OTN that can be flexibly and timely adjusted to satisfy varying service conditions. A programmable OTN featured with Wavelength Division Multiplexing (WDM) in the data plane and Software Defined Networking (SDN) in control plane has been proposed. To demonstrate the benefits of the converged OTN, the thesis also provides a multi-domain orchestration architecture for the multiple network services.  The resource orchestration, across three network domains: OTN, mobile network and cloud, enables agile service creation and optimized resource allocation among the multiple domains. / <p>QC 20170512</p>

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