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dc.contributor.advisorZhou, Guotong
dc.contributor.authorYu, Zhenhua
dc.date.accessioned2014-05-22T15:20:46Z
dc.date.available2014-05-22T15:20:46Z
dc.date.created2014-05
dc.date.issued2014-04-01
dc.date.submittedMay 2014
dc.identifier.urihttp://hdl.handle.net/1853/51784
dc.description.abstractAlong with the rapidly increasing demand for wireless data while more and more crowded radio frequency (RF) spectrum, optical wireless communications (OWC) become a promising candidate to complement conventional RF communications, especially for indoor short and medium range data transmissions. Orthogonal frequency division multiplexing (OFDM) is considered for OWC due to its ability to boost data rates. However, the average emitted optical power and dynamic range of driving signals of LEDs are two major constraints in OWC. OFDM waveforms exhibits high upper and lower peak-to-average power ratios (PAPRs), which make OFDM signals optical power inefficient and easy to violate the dynamic range of LEDs, resulting clipping and nonlinear distortions. In this dissertation, we analyze and design optical power and dynamic range constrained OWC systems, for which OFDM is our major subject. We first derive distributions of upper PAPR and lower PAPR of OWC-OFDM signals. Then we analyze the clipped OFDM signals in term of error vector magnitude (EVM), signal-to-distortion ratio (SDR), and achievable data rates under both optical power and dynamic range constraints. The next part of this dissertation is the OFDM system design for visible light communications (VLC) considering illumination requirement. We investigate the illumination-to-communication efficiency (ICE) in VLC-OFDM, and design the brightness control and flickering mitigation schemes for VLC-OFDM. In the end, to reduce the complexity of driving circuits of LEDs , we propose using delta-sigma modulators in VLC-OFDM systems to convert continuous magnitude OFDM symbols into two-level LED driver signals without loss of the communication theory advantages of OFDM.
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technology
dc.subjectOptical wireless communications (OWC)
dc.subjectVisible light communications (VLC)
dc.subjectOrthogonal frequency division multiplexing (OFDM)
dc.subjectOptical power
dc.subjectDynamic range
dc.subjectPeak-to-average power ratio (PAPR)
dc.subject.lcshWireless communication systems
dc.subject.lcshOptical communications
dc.subject.lcshOrthogonal frequency division multiplexing
dc.titleOptical wireless communications with optical power and dynamic range constraints
dc.typeDissertation
dc.description.degreePh.D.
dc.contributor.departmentElectrical and Computer Engineering
thesis.degree.levelDoctoral
dc.contributor.committeeMemberChang, Gee-Kung
dc.contributor.committeeMemberMa, Xiaoli
dc.contributor.committeeMemberBarry, John R.
dc.contributor.committeeMemberBaxley, Robert J.
dc.contributor.committeeMemberTuell, Grady
dc.date.updated2014-05-22T15:20:46Z


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