No description available.

Despite the tremendous bandwidth increase in 3rd generation (3G) Broadband Wireless Networks (BWNs) such as Universal Mobile Telecommunication System (UMTS), maintaining the mobile users’ Quality of Service (QoS) requirements while maximizing the network operators’ revenues is still a challenging issue. Moreover, spatial distribution of network traffic has a negative impact on the overall network performance where network resources are overutilized in parts of the network coverage area while such resources are underutilized in other network coverage areas. Therefore, network congestion and traffic imbalance become inevitable. Hence, efficient Radio Resource Management (RRM) techniques which release congestion and balance network traffic are of utmost need for the success of such wireless cellular systems. Congestion control and load balancing in BWNs are, however, challenging tasks due to the complexity of these systems and the multiple dimensions that need to be taken into consideration. Examples of such issues include the diverse QoS requirements of the supported multimedia services, the interference level in the system, which vary the mobile users and base stations allocated transmission powers and transmission rates to guarantee certain QoS levels during the lifetime of mobile users connections. In this thesis, we address the problem of congestion control and load balancing in BWNs and propose efficient network coverage adaptation solution in order to deal with these issues, and hence enhance the QoS support in these systems. Specifically, we propose a directional coverage adaptation framework for BWNs. The framework is designed to dynamically vary the coverage level of network cells to release system congestion and balance traffic load by forcing mobile users handoff from a loaded cell to its nearby lightly loaded cell. The framework consists of three related components, namely directional coverage adaptation module, congestion control and load balancing protocol, and QoS provisioning module. These components interact with each other to release system congestion, balance network load, maximize network resource utilization, while maintaining the required QoS parameters for individual mobile users. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-04-24 12:15:54.582

Thesis (M. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 107-114).

Thesis (Ph.D.)--University of Texas at Arlington, 2008. / Includes vita. Includes bibliographical references (p. 226-233). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 1994. / Includes bibliographical references (leaves 191-205).

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

No description available.

No description available.

The Internet has become the preferred transport medium for almost every type of communication, continuing to grow, both in terms of the number of users and delivered services. Efforts have been made to ensure that time sensitive applications receive sufficient resources and subsequently receive an acceptable Quality of Service (QoS). However, typical Internet users no longer use a single service at a given point in time, as they are instead engaged in a multimedia-rich experience, comprising of many different concurrent services. Given the scalability problems raised by the diversity of the users and traffic, in conjunction with their increasing expectations, the task of QoS provisioning can no longer be approached from the perspective of providing priority to specific traffic types over coexisting services; either through explicit resource reservation, or traffic classification using static policies, as is the case with the current approach to QoS provisioning, Differentiated Services (Diffserv). This current use of static resource allocation and traffic shaping methods reveals a distinct lack of synergy between current QoS practices and user activities, thus highlighting a need for a QoS solution reflecting the user services. The aim of this thesis is to investigate and propose a novel QoS architecture, which considers the activities of the user and manages resources from a user-centric perspective. The research begins with a comprehensive examination of existing QoS technologies and mechanisms, arguing that current QoS practises are too static in their configuration and typically give priority to specific individual services rather than considering the user experience. The analysis also reveals the potential threat that unresponsive application traffic presents to coexisting Internet services and QoS efforts, and introduces the requirement for a balance between application QoS and fairness. This thesis proposes a novel architecture, the Congestion Aware Packet Scheduler (CAPS), which manages and controls traffic at the point of service aggregation, in order to optimise the overall QoS of the user experience. The CAPS architecture, in contrast to traditional QoS alternatives, places no predetermined precedence on a specific traffic; instead, it adapts QoS policies to each individual’s Internet traffic profile and dynamically controls the ratio of user services to maintain an optimised QoS experience. The rationale behind this approach was to enable a QoS optimised experience to each Internet user and not just those using preferred services. Furthermore, unresponsive bandwidth intensive applications, such as Peer-to-Peer, are managed fairly while minimising their impact on coexisting services. The CAPS architecture has been validated through extensive simulations with the topologies used replicating the complexity and scale of real-network ISP infrastructures. The results show that for a number of different user-traffic profiles, the proposed approach achieves an improved aggregate QoS for each user when compared with Best effort Internet, Traditional Diffserv and Weighted-RED configurations. Furthermore, the results demonstrate that the proposed architecture not only provides an optimised QoS to the user, irrespective of their traffic profile, but through the avoidance of static resource allocation, can adapt with the Internet user as their use of services change.

En se basant sur l’approche des corridors de transport de fret, cette thèse se propose d’étudier les impacts différenciés des politiques d’infrastructures de transport et de télécommunication sur la spécialisation régionale et, par conséquent, sur le développement polycentrique et durable de l’espace européen. Ce faisant, un premier modèle théorique mixte de la NouvelleEconomie Géographique et de l’économie urbaine a été développé. Il montre d’un côté que le commerce interrégional dépend de la taille et des structures internes des zones urbaines ; d’un autre côté, il souligne le fait que l’intégration régionale influence la taille, les structures de ces zones et, par conséquent, leur spécialisation régionale. Ensuite, un deuxième modèle théorique de la Nouvelle Economie Géographique est développé pour étudier les impacts des politiques d’infrastructures de transport et de télécommunication sur la spécialisation régionale. On montre cependant que le secteur technologique joue un rôle essentiel dans la répartition spatiale des activités industrielles et, par conséquent, dans le développement polycentrique de l’espace européen. Enfin, un modèle économétrique basé sur la problématique de couplage est mobilisé pour tester la relation entre la demande de transport maritime international de marchandises et la croissance économique. On souligne ainsi le fait qu’une approche par corridors peut être un outil de découplage, en permettant un système de transport efficace et durable dans la région euro-méditerranéenne. / Based on the freight corridors approach, in this thesis we explore differentiated impacts of transport and telecommunication infrastructure policy on regional specialization and consequently on polycentric and sustainable development of the European area. Within this framework the first mixed theoretical model of New Economic Geography and urban economics was developed. On the one hand it shows that interregional trade depends on the size and internal structure of urban zones; on the other hand it emphasizes that regional integration influences the size and structure of these zones and, as a result, their regionalspecialization. Then the second theoretical model of the New Economic Geography is developed to study the impact of transport and telecommunication infrastructure policy on regional specialization. We demonstrate, however, that technological sector plays an essential role in the spatial distribution of industrial activities, and consequently in the polycentric development of the European space. Finally, an econometric model based on the problem of coupling is applied to test the relation between the demand for international maritime transport and economic growth. Thus it is emphasized that the approach of corridors may beused as an instrument of decoupling, allowing to develop an efficient and sustainable transport system in the Euro-Mediterranean region.