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dc.contributor.authorSpeer, Ngoc Anh Phanen
dc.date.accessioned2014-03-14T20:10:40Zen
dc.date.available2014-03-14T20:10:40Zen
dc.date.issued2008-04-17en
dc.identifier.otheretd-04242008-112440en
dc.identifier.urihttp://hdl.handle.net/10919/27221en
dc.description.abstractData sensing and retrieval in WSNs have a great applicability in military, environmental, medical, home and commercial applications. In query-based WSNs, a user would issue a query with QoS requirements in terms of reliability and timeliness, and expect a correct response to be returned within the deadline. Satisfying these QoS requirements requires that fault tolerance mechanisms through redundancy be used, which may cause the energy of the system to deplete quickly. This dissertation presents the design and validation of adaptive fault tolerant QoS control algorithms with the objective to achieve the desired quality of service (QoS) requirements and maximize the system lifetime in query-based WSNs. We analyze the effect of redundancy on the mean time to failure (MTTF) of query-based cluster-structured WSNs and show that an optimal redundancy level exists such that the MTTF of the system is maximized. We develop a hop-by-hop data delivery (HHDD) mechanism and an Adaptive Fault Tolerant Quality of Service Control (AFTQC) algorithm in which we utilize "source" and "path" redundancy with the goal to satisfy application QoS requirements while maximizing the lifetime of WSNs. To deal with network dynamics, we investigate proactive and reactive methods to dynamically collect channel and delay conditions to determine the optimal redundancy level at runtime. AFTQC can adapt to network dynamics that cause changes to the node density, residual energy, sensor failure probability, and radio range due to energy consumption, node failures, and change of node connectivity. Further, AFTQC can deal with software faults, concurrent query processing with distinct QoS requirements, and data aggregation. We compare our design with a baseline design without redundancy based on acknowledgement for data transmission and geographical routing for relaying packets to demonstrate the feasibility. We validate analytical results with extensive simulation studies. When given QoS requirements of queries in terms of reliability and timeliness, our AFTQC design allows optimal â sourceâ and â pathâ redundancies to be identified and applied dynamically in response to network dynamics such that not only query QoS requirements are satisfied, as long as adequate resources are available, but also the lifetime of the system is prolonged.en
dc.publisherVirginia Techen
dc.relation.haspartAnhSpeer-Dissertation.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectenergy conservationen
dc.subjectredundancyen
dc.subjectquery processingen
dc.subjecttimelinessen
dc.subjectreliabilityen
dc.subjectquality of serviceen
dc.subjectfault toleranceen
dc.subjectwireless sensor networksen
dc.subjectmean time to failureen
dc.titleDesign and Analysis of Adaptive Fault Tolerant QoS Control Algorithms for Query Processing in Wireless Sensor Networksen
dc.typeDissertationen
dc.contributor.departmentComputer Scienceen
dc.description.degreePh. D.en
thesis.degree.namePh. D.en
thesis.degree.leveldoctoralen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.disciplineComputer Scienceen
dc.contributor.committeechairChen, Ing-Rayen
dc.contributor.committeememberDaSilva, Luiz A.en
dc.contributor.committeememberEgyhazy, Csaba J.en
dc.contributor.committeememberLu, Chang-Tienen
dc.contributor.committeememberMidkiff, Scott F.en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04242008-112440/en
dc.date.sdate2008-04-24en
dc.date.rdate2008-05-02en
dc.date.adate2008-05-02en


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