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dc.contributor.advisorMarina, Mahesh
dc.contributor.advisorTopham, Nigel
dc.contributor.authorKriara, Lito
dc.date.accessioned2016-06-15T08:51:04Z
dc.date.available2016-06-15T08:51:04Z
dc.date.issued2014-11-27
dc.identifier.urihttp://hdl.handle.net/1842/15871
dc.description.abstractWireless LANs (WLANs), based on the IEEE 802.11 standard, have become the standard means for indoor wireless connectivity. At the same time, the rising number of smart mobile devices, broadband access speeds, and bandwidth hungry applications (e.g., high definition video streaming) have led to an increase not only of usage but also of demand for higher data-rates. This demand for higher rates is being met with newer IEEE 802.11 standards (e.g., 802.11n/ac) that introduce new features and also increase the different possible settings for each feature. Inherent channel variations and the possible interference conditions when operating in unlicensed spectrum necessitate adaptation of the various medium access control (MAC) and physical (PHY) layer features to ensure high performance. Selecting the values of those features to optimise a criterion such as throughput is the link adaptation problem. Link adaptation, the focus of this thesis, can play a key role in improving the performance of 802.11 WLANs. Increasing number of features and feature setting combinations with newer 802.11 standards is not only making link adaptation even more important but also more challenging. The contributions made in this thesis significantly advance the state of the art on link adaptation for 802.11 WLANs along three dimensions. First, we show that not knowing the exact cause of loss is not an impediment to effective link adaptation. Nevertheless, actions taken in response to losses are more crucial and they ought to be holistic and not solely dependent on the exact cause of loss. Second, we make significant methodological contributions for analysing the impact of multiple parameters on a given criterion, based on comprehensive experimental measurements. The application of this methodology on 802.11n measurements, examining the interaction of the protocols various parameters on performance under varying conditions, has lead to several valuable findings on how to perform efficient link adaptation in a complex WLAN scenario like 802.11n and future 802.11 standards. Adaptation should be holistic, based on the channel quality instead of the interference scenario, and independent of loss differentiation. Based on these insights, lastly and most importantly, we propose two novel holistic link adaptation schemes for legacy 802.11a/b/g and 802.11n WLANs, termed Themis and SampleLite, respectively. Both Themis and SampleLite take a hybrid approach relying on easily accessed channel quality information at the sender side to perform holistic adaptation. The hypothesis that adaptation should be holistic is validated by our results, with both Themis and SampleLite outperforming the current state of the art.en
dc.contributor.sponsorEngineering and Physical Sciences Research Council (EPSRC)en
dc.language.isoenen
dc.publisherThe University of Edinburghen
dc.relation.hasversionLito Kriara, Mahesh K. Marina and Arsham Farshad. “Characterization of 802.11n Wireless LAN Performance via Testbed Measurements and Statistical Analysis”. In Proc. IEEE International Conference on Sensing, Communication, and Networking (SECON), New Orleans, LA, June 2013en
dc.relation.hasversionLito Kriara, Sofia Pediaditaki and Mahesh K. Marina. “On the Importance of Loss Differentiation for Link Adaptation in Wireless LANs”. In Proc. IEEE/VDE European Wireless Conference, Poznan, Poland, April 2012en
dc.relation.hasversionLito Kriara, Mujahid Al-Adhami and Mahesh K. Marina. “Impact of 802.11n Link Layer Parameters on Application Performance”. In Proc. ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), Paris, France, May 2011 (poster)en
dc.rightsAttribution-NonCommercial-ShareAlike 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/4.0/*
dc.subjectwireless networksen
dc.titleHolistic and efficient link adaptation for 802.11x wireless LANsen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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