別紙41 (課程博士(英文))Date of submission:

Deparunent ofElectrical and Electronic

S加denuD Number

D143229
SupefvisoYS

Information En即neelin旦Jan.7th,2021

Hideyuld uel〕ara
Takashi ohiTa

Kazuld Komatsu

APP11Cant"s nameShuichilchikawa

Abstract (Doctor)
Title ofThesis

A

Nonlinear self・1nterference canceⅡels f01 1n‑Band FUⅡ一Duplex Radios

rox.80o words

As the demand for wileless comlnunications is incTeasin旦 Unabated, tl)e ad)ievement of e缶Cienth'equency utilization is an ongoin曾 CI〕a11enge. 1n・band fU11・duplex (1BFD) techn010gy, which
Simultaneously tlansmits and receives on the same fTequency band and can tl〕em'eticaⅡy acl〕ieve

twice the spectral utilization e缶Ciency of conventional half・duplex systems,is an emerging techniquein recent wireless communications. However, self・interference (SI) intelfa'es si旦ni6Cantly with thedesired si8nal propa菖ated from anotl〕er terminal and distulbs the system capacity, as the distance
between the transmission and reception antennas is extlemely dose compared to the distance
between t11e terminaland anotherterminal. unfortunately のthogonalheq11ency divjsion multiplexed(OFDM) modulation, WI〕jch is comlnonly used in numerous systems at plesent, causes a l〕igl〕
Peak・to・avera8e power ratio and tl〕e nonlinearities of the teTminals have a signi6Cant impact on
the signals. Rlrthennの'e, sl is distの'ted by other tlansceivel non‑idealities, SUCI〕 as imbalances oftl〕e l/Q lnixeTs and the pl〕ase noise ofthe local osdⅡat0鵄. Thus, the lBFD litelature indudes repoTts
Of nonlinear sl canceⅡers that have been developed to achieve ilnproved canceⅡation pa'fonnanceHowevel, nonlineal canceⅡers exhibit certain ploblelns, such as hig11 Computational comp}exity, theIequirement of large training data, and V111nerability to the nonlineality of low・noise alnpli丘田'S(LNAS).八10leover, no theoretical studies have been conducted on the performance of lBFD ladios
W北h nonlineal canceⅡers. T11is thesis plesents studies on nonHnear canceⅡels with regωd to tl〕eabove ploblems
Chapte1 1 Provides a gena'alintroduction to and sumlnary of this tl〕esis. 1t contains tl〕e
bacIくglound of the studies in tl)is t11esis and details of time‑domain paTaⅡel Halnlna'stein canceⅡa'S,Whicl) ale an)on留 the most weⅡ・studied sl canceⅡersIn cl)apte1 2, a frequency・domain HammeTstein canceⅡer is proposed, which achieves low

Computational compleX北y wl〕ile talくin菖 into account the nonlineality of l/Q lnixe鵄 and power
ampli丑a'S (PAS).1n the training period of the pToposed cance11er, discontinU北ies aTe producedin the oFD八I sylnbols W北hout destToying the cydic pre6X structure, and the paralneter estimator
Can estilnate the discontinU北ies ofthe slsi旦nal W北h hi81) acculacy in the frequency domain.1n theCanceⅡation period, the tilne‑domain slsignalis regenerated with the estimated hequency responseby the ove11ap‑save method, T11e performance of the proposed sC11elne is assessed by eq11ivalent
baseband si8nalsimulations of an lBFD transceiver. As a lesult, the l)roposed scheme aC11ieves as1〕igl) sl canceⅡation as time・domain pal'aⅡel Halnmastein canceⅡers with a low computational costf、.11thelmole, the resuHs demonstrate that the conver旦ence performance of the proposed scheme isfaster tl〕an tl)at of the time・domain schemeIn cl〕apter 3, a basis function selection technique is pTesalted to leduce the computational costfurther and to improve the convergence pa'formance ofthe fTequency‑domain Hammerstein canceⅡer,W})ich is presented in chapter 2. TI〕e po、ver spectlal density (PSD) of the nonlinear sl signalistheoreticaⅡy analyzed in detailand a nonlineaT SI PSD estimation lnethod is developed. The proposedSelection tecl)nique determines the basis functions tl〕at ω'e necessaly for canceⅡation and relaxes t11e
Colnputational cost of the hequency・d01〕〕ain Hamma'stein canceⅡer based on the estimated psD of

the sl of eaC11 basis function. TI〕a'eafter, tl〕e silnulation results aTe plesel〕tedl demonstratin冨 t11at thePloposed technique can acl〕ieve similar canceⅡation pafolmance to tl〕e oliσinal h'equency・domain
Hammerstein canceⅡel and a time・domain P釘aⅡel HammeTstein canceⅡeT.1t is also shown t11at thePToposed technique imploves the colnputational cost and convergence performance of the oligil]alh'equency‑domain Hammerstein canceⅡelIn chapter 4, an iterative nonlinear sl canceⅡer is proposed to consider tl〕e nonⅡnealities of not

Only the pA and l/Q mixels, but also tl〕e LNA. The estimation process of tl〕e l)10posed scheme
Consists of t]Uでe sta旦es: t11e c}1anne1 1esponse estilnation,1/Q ilnbalance estimation, and pA andLNA nonlinearity estilnation. The cl〕annelresponse is estimated in the time dolnain, WI〕ereas the1/Q imbalance and nonlinealities ale estimated in the frequency domain by using featules of oFD八1modulation for a more straighぜOTward estimation and superior acculacy.1n tl)e canceⅡation pTocess
Of the proposed scheme, t11e received signalis compensated for wit}〕 tl〕e estin〕ated parameters of theLNA and receiver l/Q imbalance plioT to canceⅡation, because the desired signalis received with ahig11・poweT sl and is distorted by tl〕e Tadio frequency impairments of the leceiver. The simulation
Iesults reveal that the proposed technique can achieve l〕igher canceⅡation performance tl〕an tl〕eHammerstein canceⅡel when the LNA is saturated by sl.八lmでOverltl〕e pelfoTmance ofthe proposed
CanceⅡer converaes much faster than tl〕at of the time・domain paTaⅡel Halnmelstein canceⅡer
In chapterS 2 t04, the developlnent ofcanceⅡers that can achieve l〕ighelcanceⅡation pa'formanceand a lower comP11tational cost is presented, but a more detailed discussion of nonlinear canceⅡa'S
is lequired to implove the perfonnance of lBFD radios f山theT. For a more in・deptl) discussion,CI〕apter 5 Plesents a theoletical analysis technique that takes into account the pA and LNA
nonⅡnearitjes for lBFD Tadios with palaⅡel Hammerstein sl canceⅡels. The envelope of an oFD八1Sjgnal with a sU伍dently la1冨e number of subcarliers can be assumed to f0ⅡOw a complex Gaussian
distribution accolding to the centTa11ilnit tl〕eorem. Thus, the nonlineaT characteristics of tl〕e

System can be expanded by a 旦enelaⅡZed FourieT series using のthonorlnal Laguen'e polynomials
SubsequentlM the canceⅡer perfonnance and system symbol alor Tate (SER) are analyzed using
t11e obtained Fouliel coe伍Cients. The analytica} results aTe compal'ed with t11e silnulation lesults,

demonstrating strong correlation in various situations, from extremely nonlineaT cases t0 昌ood lineaT
FurthennoTe, the results delnonstrate that the sER of the lBFD system is reduced byCases'

moderately nonlinearizing ratha' than linealizin冨 t11e ampli6el
Chapter 6 Concludes this thesis and provides a discussion on f11ture w011くS,