Synchronization in Cognitive Overlay Systems

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dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.advisorPoikonen, Jussi 
dc.contributor.authorHassen, Tewodros Wolde 
dc.contributor.departmentTietoliikenne- ja tietoverkkotekniikan laitosfi
dc.contributor.schoolSähkötekniikan korkeakoulufi
dc.contributor.supervisorTirkkonen, Olav 
dc.date.accessioned2012-11-23T06:36:30Z
dc.date.available2012-11-23T06:36:30Z
dc.date.issued2012 
dc.description.abstractThe primary purpose of this thesis is to study the effect of synchronization problems in cognitive radio based overlay systems. In such systems the secondary transmitter should know the transmission timing of the primary transmitter for cooperation to take place between the two systems. The thesis also investigates the effect of relaying in overlay systems. By splitting the secondary transmission power into two parts by a ratio alpha, the secondary transmitter can relay the primary transmission while transmitting its own message. Another aim of the thesis is to study the effects of time and frequency offsets in the primary and the secondary systems. Hence, time and frequency synchronization issues are investigated for DVB-T and LTE systems individually. Cell search and selection procedures are also studied for LTE systems. Two N200 Universal Software Radio Peripherals (USRPs) were used to transmit and receive the signal using the Gnu Radio platform and the captured signals were post processed in Matlab to study the effects of time offset and frequency offset of the devices. Moreover, a Matlab simulation was used to investigate the effect of timing offset between primary and secondary transmitters in overlay systems. From the investigation of the overlay scenario with relay, we have found out that the relaying introduce a multi-path effect at the secondary receiver. If there is a delay between the primary and the secondary receivers, the components of the multi-path signal might be added-up in such a way that it is impossible to separate the primary and the secondary signals at the secondary receiver. Hence, we have implemented synchronization and equalization algorithms to estimate the delay and frequency offsets. We observed that the performance of the equalizer at the secondary receiver deteriorates for high delays and low alpha values.en
dc.format.extent[8] + 85 s. 
dc.format.mimetypeapplication/pdf 
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/6103
dc.identifier.urnURN:NBN:fi:aalto-201211243398
dc.language.isoenen
dc.locationP1fi
dc.programme.majorTietoliikennetekniikkafi
dc.programme.mcodeS-72 
dc.rights.accesslevelopenAccess
dc.subject.keywordsynchronizationen
dc.subject.keywordcognitive radioen
dc.subject.keywordspectrum sharingen
dc.subject.keywordinterweaveen
dc.subject.keywordoverlayen
dc.subject.keywordGnu radioen
dc.subject.keywordDVB-Ten
dc.subject.keywordLTEen
dc.titleSynchronization in Cognitive Overlay Systemsen
dc.typeG2 Pro gradu, diplomityöfi
dc.type.dcmitypetexten
dc.type.okmG2 Pro gradu, diplomityö
dc.type.ontasotDiplomityöfi
dc.type.ontasotMaster's thesisen
dc.type.publicationmasterThesis
local.aalto.digifolderAalto_05227
local.aalto.idinssi45419
local.aalto.openaccessyes
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