Synchronization in Cognitive Overlay Systems

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Poikonen, Jussi
dc.contributor.author Hassen, Tewodros Wolde
dc.date.accessioned 2012-11-23T06:36:30Z
dc.date.available 2012-11-23T06:36:30Z
dc.date.issued 2012
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/6103
dc.description.abstract The 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.mimetype application/pdf
dc.language.iso en en
dc.title Synchronization in Cognitive Overlay Systems en
dc.type G2 Pro gradu, diplomityö fi
dc.contributor.school Sähkötekniikan korkeakoulu fi
dc.contributor.department Tietoliikenne- ja tietoverkkotekniikan laitos fi
dc.subject.keyword synchronization en
dc.subject.keyword cognitive radio en
dc.subject.keyword spectrum sharing en
dc.subject.keyword interweave en
dc.subject.keyword overlay en
dc.subject.keyword Gnu radio en
dc.subject.keyword DVB-T en
dc.subject.keyword LTE en
dc.identifier.urn URN:NBN:fi:aalto-201211243398
dc.type.dcmitype text en
dc.programme.major Tietoliikennetekniikka fi
dc.programme.mcode S-72
dc.type.ontasot Diplomityö fi
dc.type.ontasot Master's thesis en
dc.contributor.supervisor Tirkkonen, Olav
dc.location P1 fi


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