Thèse soutenue

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Auteur / Autrice : Sahar Ghazal
Direction : Jalel Ben Othman
Type : Thèse de doctorat
Discipline(s) : Informatique
Date : Soutenance en 2010
Etablissement(s) : Versailles-St Quentin en Yvelines

Résumé

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IEEE 802. 16 standard is a real revolution in wireless metropolitan area networks (WirelessMANs) that enables high-speed access to data, video, and voice services. Worldwide Interoperability for Microwave Access (WiMAX) is the industry name given to the 802. 16-2004 amendment. The standard supports point-to-multipoint (PMP) as well as mesh mode. In the PMP mode, multiple subscriber stations (SSs) are connected to one base station (BS). The access channel from the BS to the SS is called the downlink (DL) channel, and the one from the SS to the BS is called the uplink (UL) channel. WiMAX is designed to provide inbuilt quality of service (QoS) mainly through the differentiation of five types of traffic flows: unsolicited grant service (UGS), real-time polling service (rtPS), extended realtime polling service (ertPS), non-real-time polling service (nrtPS) and best effort (BE). QoS architecture is defined in the MAC layer that supports classification for the pre mentioned classes and uplink scheduling for only UGS class. The great challenge of research activities in this domain is 1) how to share the bandwidth between the different stations (SS) according to the needed QoS and 2) how to increase the number of users without decreasing the overall QoS? The objective of this thesis is focused on these two points. Our contributions are essentially in admission control, traffic policing, and UL/DL scheduling. A new distributed QoS architecture is proposed, where the SS takes an important part in controlling the QoS through classification, traffic shaping and scheduling. An analytical model based on Markov chains is used to analyse the performance of the AC , where different priorities are assigned between the different traffic classes. This analytical study leads to the design of a self-configuring AC algorithm based on fuzzy logic. To control traffic rate in the network, a traffic policer is implemented in the SS side for each traffic class (multi-policer). And to share the available resources fairly, a real-time adaptive scheduler (RTAS) based on deficit round robin concept is constructed.