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Browsing by Subject "norma IEEE 802.11"

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    Item type:Doctoral Dissertation, Access status: Open Access ,
    An analysis of IEEE 802.11 EDCA ad-hoc networks in the presence of hidden nodes
    (2008-07-01) (Data obrony: 2011-05-25) Kosek-Szott, Katarzyna
    Wydział Elektrotechniki, Automatyki, Informatyki i Elektroniki
    This dissertation deals with quality of service (QoS) provisioning in IEEE 802.11 ad-hoc networks with hidden nodes. In particular, it focuses on the Enhanced Distributed Channel Access (EDCA) function of the Medium Access Control (MAC) layer of the IEEE 802.11 standard. The following thesis was formulated and proved: It is possible to improve the performance of the EDCA (Enhanced Distributed Channel Access) function by modifying the IEEE 802.11 standard in order to improve the efficiency of ad-hoc networks with hidden nodes. Furthermore, in such networks, it is possible to improve the fairness of traffic prioritising for the access categories defined in the IEEE 802.11 standard. The thesis is proved by the proposed BusySiMOn mechanism, which implements an intelligent two-step reservation procedure combined with the advantages of EDCA service differentiation. It is shown that when BusySiMOn is applied, the overall throughput, fairness and maximum frame delay are improved in comparison* to the four-way handshake mechanism. Additionally, a novel mathematical model of the IEEE 802.11 EDCA function is proposed. The proposed model can be used for rapid estimation of throughput of ad-hoc networks for the basic and the four-way handshake based channel access. It is kept reasonably simple to make it attractive to network designers.