Показать сокращенную информацию

dc.contributor.advisorAgrawala, Ashoken_US
dc.contributor.authorTas, Nazif Cihanen_US
dc.date.accessioned2010-07-02T06:03:07Z
dc.date.available2010-07-02T06:03:07Z
dc.date.issued2010en_US
dc.identifier.urihttp://hdl.handle.net/1903/10375
dc.description.abstractConventional Link Adaptation Techniques in wireless networks aim to overcome harsh link conditions caused by physical environmental properties, by adaptively regulating modulation, coding and other signal and protocol specific parameters. These techniques are essential for the overall performance of the networks, especially for environments where the ambient noise level is high or the noise level changes rapidly. Link adaptation techniques answer the questions of <italic>What to change?</italic> and <italic>When to change?</italic> in order to improve the present layer performance. Once these decisions are made, other layers are expected to function perfectly with the new communication channel conditions. In our work, we have shown that this assumption does not always hold; and provide two mechanisms that lessen the negative outcomes caused by these decisions. Our first solution, MORAL, is a MAC layer link adaptation technique which utilizes the physical transmission information in order to create differentiation between wireless users with different communication capabilities. MORAL passively collects information from its neighbors and re-aligns the MAC layer parameters according to the observed conditions. MORAL improves the fairness and total throughput of the system through distributing the mutually shared network assets to the wireless users in a fairer manner, according to their capabilities. Our second solution, Data Rate and Fragmentation Aware Ad-hoc Routing protocol, is a network layer link adaptation technique which utilizes the physical transmission information in order to differentiate the wireless links according to their communication capabilities. The proposed mechanism takes the physical transmission parameters into account during the path creation process and produces energy-efficient network paths. The research demonstrated in this dissertation contributes to our understanding of link adaptation techniques and broadens the scope of such techniques beyond simple, one-step physical parameter adjustments. We have designed and implemented two cross-layer mechanisms that utilize the physical layer information to better adapt to the varying channel conditions caused by physical link adaptation mechanisms. These mechanisms has shown that even though the <italic>Link Adaptation</italic> concept starts at the physical layer, its effects are by no means restricted to this layer; and the wireless networks can benefit considerably by expanding the scope of this concept throughout the entire network stack.en_US
dc.titleLINK ADAPTATION IN WIRELESS NETWORKS: A CROSS-LAYER APPROACHen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentComputer Scienceen_US
dc.subject.pqcontrolledComputer Scienceen_US
dc.subject.pquncontrolledCross-layer designen_US
dc.subject.pquncontrolledLink adaptationen_US
dc.subject.pquncontrolledWireless networksen_US


Файлы в этом документе

Thumbnail

Данный элемент включен в следующие коллекции

Показать сокращенную информацию