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dc.contributor.advisorEager, Derek L.en_US
dc.creatorCarlsson, Niklasen_US
dc.date.accessioned2006-12-15T08:54:40Zen_US
dc.date.accessioned2013-01-04T05:10:36Z
dc.date.available2006-12-15T08:00:00Zen_US
dc.date.available2013-01-04T05:10:36Z
dc.date.created2006-12en_US
dc.date.issued2006-12-15en_US
dc.date.submittedDecember 2006en_US
dc.identifier.urihttp://hdl.handle.net/10388/etd-12152006-085440en_US
dc.description.abstractScalable on-demand content delivery systems, designed to effectively handle increasing request rates, typically use service aggregation or content replication techniques. Service aggregation relies on one-to-many communication techniques, such as multicast, to efficiently deliver content from a single sender to multiple receivers. With replication, multiple geographically distributed replicas of the service or content share the load of processing client requests and enable delivery from a nearby server.Previous scalable protocols for downloading large, popular files from a single server include batching and cyclic multicast. Analytic lower bounds developed in this thesis show that neither of these protocols consistently yields performance close to optimal. New hybrid protocols are proposed that achieve within 20% of the optimal delay in homogeneous systems, as well as within 25% of the optimal maximum client delay in all heterogeneous scenarios considered.In systems utilizing both service aggregation and replication, well-designed policies determining which replica serves each request must balance the objectives of achieving high locality of service, and high efficiency of service aggregation. By comparing classes of policies, using both analysis and simulations, this thesis shows that there are significant performance advantages in using current system state information (rather than only proximities and average loads) and in deferring selection decisions when possible. Most of these performance gains can be achieved using only “local” (rather than global) request information.Finally, this thesis proposes adaptations of already proposed peer-assisted download techniques to support a streaming (rather than download) service, enabling playback to begin well before the entire media file is received. These protocols split each file into pieces, which can be downloaded from multiple sources, including other clients downloading the same file. Using simulations, a candidate protocol is presented and evaluated. The protocol includes both a piece selection technique that effectively mediates the conflict between achieving high piece diversity and the in-order requirements of media file playback, as well as a simple on-line rule for deciding when playback can safely commence.en_US
dc.language.isoen_USen_US
dc.subjectPeer-assisted streamingen_US
dc.subjectProbabilistic piece selectionen_US
dc.subjectPerformance evaluationen_US
dc.subjectBatchingen_US
dc.subjectContent deliveryen_US
dc.subjectScalable downloaden_US
dc.subjectMulticast protocolsen_US
dc.subjectRequired server bandwidthen_US
dc.subjectService aggregationen_US
dc.subjectReplica selectionen_US
dc.subjectBitTorrent-like systemsen_US
dc.subjectDigital fountainen_US
dc.titleScalable download protocolsen_US
thesis.degree.departmentComputer Scienceen_US
thesis.degree.disciplineComputer Scienceen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophy (Ph.D.)en_US
dc.type.materialtexten_US
dc.type.genreThesisen_US
dc.contributor.committeeMemberSoteros, Chrisen_US
dc.contributor.committeeMemberKeil, J. Marken_US
dc.contributor.committeeMemberGrassmann, Winfried K.en_US
dc.contributor.committeeMemberDeters, Ralphen_US


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