Analysis and measurement of OFDM-based communication systems considering power amplifier ...

132 Pages·2016·2.99 MB·English

DOCTORAL DISSERTATION
Analysis and measurement of
OFDM-based communication systems
considering power amplifier nonlinearity
パワーアンプの非線形性を考慮したOFDMに基づく
通信システムの測定と解析
Author: Supervisor:
Taewoo LEE ProfessorHideki OCHIAI
Adissertationsubmittedinfulfilmentoftherequirements
forthedegreeofDoctorofEngineering
inthe
DepartmentofPhysics,ElectricalandComputerEngineering
YOKOHAMA NATIONAL UNIVERSITY
DateofSubmission: March2016
横 浜 国 立 大 学
YOKOHAMA National University

Declaration of Authorship
I, Taewoo LEE, declare that this dissertation titled, “Analysis and measurement of
OFDM-based communication systems considering power amplifier nonlinearity” and
theworkpresentedinitaremyown. Iconfirmthat:
(cid:15)
Thisworkwasdonewhollyormainlywhileincandidatureforaresearchdegree
atthisUniversity.
(cid:15)
Where any part of this dissertation has previously been submitted for a degree
oranyotherqualificationatthisUniversityoranyotherinstitution,thishasbeen
clearlystated.
(cid:15)
Where I have consulted the published work of others, this is always clearly at-
tributed.
(cid:15)
Where I have quoted from the work of others, the source is always given. With
theexceptionofsuchquotations,thisdissertationisentirelymyownwork.
(cid:15)
Ihaveacknowledgedallmainsourcesofhelp.
(cid:15)
Where the dissertation is based on work done by myself jointly with others, I
have made clear exactly what was done by others and what I have contributed
myself.
Signed:
Date:
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Abstract
DepartmentofPhysics,ElectricalandComputerEngineering
YOKOHAMANATIONALUNIVERSITY
DoctorofEngineering
AnalysisandmeasurementofOFDM-basedcommunicationsystemsconsidering
poweramplifiernonlinearity
byTaewoo LEE
Orthogonalfrequencydivisionmultiplexing(OFDM)hasbeenadoptedinmanymod-
ern communication systems due to its robustness against frequency-selective fading
channels as well as its near rectangular spectrum that can achieve high spectral effi-
ciency. However,itsmajordrawbackistheresultingsignalwithhighpeak-to-average
power ratio (PAPR), which causes severe nonlinear distortion at the power amplifier
(PA) unless input back off is chosen sufficiently large. The effect of the nonlinear dis-
tortion is two-fold: out-of-band radiation and signal quality degradation. The former
causesadjacentchannelinterferenceandthusdegradesthebandwidthefficiency. The
latter affects the system level performance and is often measured by the error vector
magnitude (EVM). It is thus important for the system designer to analyze the nonlin-
eardistortioncausedbyagivenPAintermsofpowerspectraldensity(PSD)andEVM,
butaccuratecalculationofthesecharacteristicsmaybegenerallyinvolved.
ReductionofPAPRisimportantforsmalllongdistancecommunicationdevicessuch
as user terminals of mobile networks whose power consumption is of significant im-
portance. From this viewpoint, single-carrier frequency division multiple access (SC-
FDMA)isanattractivetechnologymainlyduetoitssignalwithlowerPAPRthanthat
ofOFDM.Nevertheless,anattempttofurtherreducePAPRevenforSC-FDMAsystems
may be desirable since SC-FDMA signal still exhibits relatively high PAPR compared
to the conventional single-carrier signals. Therefore, in this dissertation a new PAPR
reductionschemebasedontrellisshapingisdevelopedforSC-FDMAsystems.
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Acknowledgements
As important as the achievement of my researches itself is to express gratitude to
everyonewhohelpedmethroughoutmylong-termPh.Dcourse. Ihavetosaythatitis
impossibleforanindividualtocompletemyPh.Ddegreewithoutasignificantamount
ofsupportbeitdirectorindirect,technical,financialoremotional. Atthesametimeit
is difficult to mention all those who may have given me such valuable supports. For
thisreason, Iapologizefortheoneswhoarenotmentionedhereinadvance, butyour
assistanceandcontributionaregreatlyappreciated.
Firstly,Iwouldliketoexpressmydeepestgratitudetomyadvisor,professorHideki
Ochiai, for his excellent guidance, caring, patience, and providing me with an excel-
lent atmosphere for doing research. Also, I would also like to thank several graduate
studentswhosefriendshipshavehelpedmetobecomeabetterresearcher.
This work would not be possible without the support from my family. My wife,
Jin has been extremely supportive of me throughout my Ph.D course and has made
incalculable sacrifices to help me get to this point. My son, Sanghwa has continually
providedthemotivationtofinishmydegreewithexpediency.
Finally, my parents deserve special thanks for their continued support and encour-
agement. Theyhavealwaysbeenahugeinspirationtomeandhavealwayssupported
my actions and endeavors whatever they may be. They provided me with all the op-
portunities that anyone could ever dream of, and for this I will always be eternally
grateful. Also, my heartfelt thanks must go to my brother and sisters for their emo-
tionalsupportandencouragement.
Withoutsuchgreatestpeoplebehindme,IdoubtthatIwouldbeinthisplacetoday.
TaewooLEE
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Formysonsandwife.
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