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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

Enhancing the energy efficiency of radio base stations

Holtkamp, Hauke Andreas January 2014 (has links)
This thesis is concerned with the energy efficiency of cellular networks. It studies the dominant power consumer in future cellular networks, the Long Term Evolution (LTE) radio Base Station (BS), and proposes mechanisms that enhance the BS energy efficiency by reducing its power consumption under target rate constraints. These mechanisms trade spare capacity for power saving. First, the thesis describes how much power individual components of a BS consume and what parameters affect this consumption based on third party experimental data. These individual models are joined into a component power model for an entire BS. The component model is an essential step in analysis but is too complex for many applications. It is therefore abstracted into a much simpler parameterized model to reduce its complexity. The parameterized model is further simplified into an affine model which can be applied in power minimization. Second, Power Control (PC) and Discontinuous Transmission (DTX) are identified as promising power-saving Radio Resource Management (RRM) mechanisms and applied to multi-user downlink transmission. PC reduces the power consumption of the Power Amplifier (PA) and is found to be most effective at high traffic loads. DTX mostly reduces the power consumption of the Baseband (BB) unit while interrupting transmission and is better applied in low traffic loads. Joint optimization of these two techniques is found to enable additional power-saving at medium traffic loads and to be a convex problem which can be solved efficiently. The convex problem is extended to provide a comprehensive power-saving Orthogonal Frequency Division Multiple Access (OFDMA) frame resource scheduler. The proposed scheduler is shown to reduce power consumption by 25-40% in computer simulations, depending on the traffic load. Finally, the thesis investigates the influence of interference on power consumption in a network of multiple power-saving BSs. It discusses three popular alternative distributed uncoordinated methods which align DTX mode between neighbouring BSs. To address drawbacks of these three, a fourth memory-based DTX alignment method is proposed. It decreases power consumption by up to 40% and retransmission probability by around 20%, depending on the traffic load.
2

L'effet de la consommation de passage sur le développement et l'intégration métropolitaine des territoires en Ile-de-France / The effect of same-day consumers on community development and city region economies : a Paris case study

Ruault, Jean-François 11 December 2014 (has links)
L'importance du tourisme dans l'économie locale renseigne généralement le rôle de l'importation de demande finale dans le développement territorial ; ce rôle est objectivé dans le cadre d'enquêtes et d'outils statistiques permettant d'appréhender et chiffrer les transferts de richesses induits par la consommation des touristes. Pour autant, parmi les consommateurs qui visitent un territoire et y consomment, tous ne sont pas des touristes au sens de l'Insee : ils ne dorment pas sur place, ils rentrent chez eux le soir. Cette consommation non portée par des touristes, que nous nommons « consommation de passage », n'a aujourd'hui que peu de réalité, n'étant ni définie officiellement ni repérée à quelque échelle territoriale que ce soit ; elle est ainsi largement méconnue, dans son ampleur et ses effets sur les transferts de richesses interterritoriaux. Avec la région capitale pour cadre empirique, la thèse privilégie ici un terrain soumis à de multiples mobilités pour soulever deux hypothèses. La consommation de passage des Franciliens en Ile de France serait tout d'abord un vecteur de développement territorial non négligeable au niveau infrarégional. Ensuite, en connectant les territoires, la consommation de passage contribuerait à l'intégration métropolitaine. Afin de tester la validité des deux hypothèses, ce travail adopte une approche circulaire de l'économie, et développe une méthode de suivi des richesses, depuis la dépense initiale jusqu'à la rémunération salariale en bout de course. L'exercice nous conduit in fine à chiffrer les retombées économiques de la consommation de passage et à mesurer l'intensité des liens interterritoriaux qu'elle produit / Tourism gives an overview about the role that imported final demand can play in regional economics in general and, in particular, as an engine to community development. This role can be observed through surveys and statistical tools that enable us to understand and quantify generated money flows. However amongst external consumers some of them are not tourists in a classical sense: they do not stay overnight but instead go back home at night. Contrary to world tourism organization, we are less concerned about the unusual environment criterion to define and observe same-day consumers: any money inflows provided by external consumers spendings contribute to community development, unusual environment or not. Therefore we use the term “passing trade” to talk about all same-day consumers. This thesis is about the economic impacts of passing trade. Empirical analyses took place in Paris Region due to its metropolitan favourable context for mobility activities, in particular shopping trips. The thesis then provides support for two hypothesis. The first one is that passing trade can be a significant factor for community development at subregional levels. By connecting areas, the second hypothesis is that passing trade can contribute to metropolitan integration. In order to test these hypotheses, we adopted a circular economy approach, and developed a method for tracking money flows, from the initial spendings to the final wages. In the end, this study led us to quantify money flows amounts, economic impacts and the intensity of spatial interlinkages generated by passing trade

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