Compensation of transmitter nonlinearities using predistortion techniques: Case studies of envelope tracking amplifiers and radio-over-fibre links: Dissertation

Atso Hekkala

Research output: ThesisDissertation

Abstract

This thesis studies compensation of nonlinear distortions introduced in the transmitters of wireless communication systems. In particular, adaptive predistortion of the envelope tracking (ET) amplifier and the radio-over-fibre (RoF) link is considered. The main goal is to develop compensation algorithms and architectures for predistortion. By providing a low attenuation and broadband solution, the RoF technology enables using cost-efficient and energy-efficient distributed antenna systems (DASs). Using highly efficient power amplifier (PA) structures, such as the ET amplifiers, energy efficiency of the transmitters is increased. Unfortunately, the RoF links and the ET amplifiers are inherently nonlinear. The results of this thesis indicate that these nonlinearities have to be taken into account when designing wireless communication systems. The nonlinearities can be compensated using the low complex adaptive predistortion techniques proposed in this thesis. In this thesis, a general architecture for the predistortion of the ET amplifier is proposed. Using the architecture, the performance of predistortion is demonstrated. In addition, new time misalignment compensation methods are studied. For the compensation of the RoF link, an extension to the conventional least mean square (LMS) algorithm for the memory polynomial-based predistortion is presented. In addition, different combinations of adaptive algorithms for predistortion are considered. From the compensation architecture point of view, the joint compensation of the RoF link and PA connected in series in the presence of nonlinear feedback is studied. Finally, feasibility of the adaptive predistortion concept is demonstrated by the measurements. The results presented in this thesis can be applied to any wireless communications systems. The performance studies demonstrate that distortions of the RoF link and the ET amplifier can be considerably diminished using a low-complexity design. To get even better results in terms of linearity and energy efficiency, the proposed predistortion techniques can be implemented together with other techniques, such as the peak-to-average power ratio (PAPR) reduction methods.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Oulu
Supervisors/Advisors
  • Katz, Marcos, Supervisor, External person
  • Mämmelä, Aarne, Advisor
Award date4 Apr 2014
Publisher
Print ISBNs978-951-38-8117-7
Electronic ISBNs978-951-38-8118-4
Publication statusPublished - 2014
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

Radio-over-fiber
Transmitters
Communication systems
Power amplifiers
Energy efficiency
Nonlinear distortion
Nonlinear feedback
Adaptive algorithms
Telecommunication links
Compensation and Redress
Polynomials
Antennas
Data storage equipment
Costs

Keywords

  • Adaptive predistortion
  • compensation architecture
  • envelope tracking amplifier
  • LMS
  • power amplifier
  • radio-over-fibre
  • RLS
  • adaptiivinen esivääristys
  • kompensointiarkkitehtuuri
  • kuituoptinen radiolinkki
  • tehovahvistin
  • verhokäyräseuraajavahvistin

Cite this

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title = "Compensation of transmitter nonlinearities using predistortion techniques: Case studies of envelope tracking amplifiers and radio-over-fibre links: Dissertation",
abstract = "This thesis studies compensation of nonlinear distortions introduced in the transmitters of wireless communication systems. In particular, adaptive predistortion of the envelope tracking (ET) amplifier and the radio-over-fibre (RoF) link is considered. The main goal is to develop compensation algorithms and architectures for predistortion. By providing a low attenuation and broadband solution, the RoF technology enables using cost-efficient and energy-efficient distributed antenna systems (DASs). Using highly efficient power amplifier (PA) structures, such as the ET amplifiers, energy efficiency of the transmitters is increased. Unfortunately, the RoF links and the ET amplifiers are inherently nonlinear. The results of this thesis indicate that these nonlinearities have to be taken into account when designing wireless communication systems. The nonlinearities can be compensated using the low complex adaptive predistortion techniques proposed in this thesis. In this thesis, a general architecture for the predistortion of the ET amplifier is proposed. Using the architecture, the performance of predistortion is demonstrated. In addition, new time misalignment compensation methods are studied. For the compensation of the RoF link, an extension to the conventional least mean square (LMS) algorithm for the memory polynomial-based predistortion is presented. In addition, different combinations of adaptive algorithms for predistortion are considered. From the compensation architecture point of view, the joint compensation of the RoF link and PA connected in series in the presence of nonlinear feedback is studied. Finally, feasibility of the adaptive predistortion concept is demonstrated by the measurements. The results presented in this thesis can be applied to any wireless communications systems. The performance studies demonstrate that distortions of the RoF link and the ET amplifier can be considerably diminished using a low-complexity design. To get even better results in terms of linearity and energy efficiency, the proposed predistortion techniques can be implemented together with other techniques, such as the peak-to-average power ratio (PAPR) reduction methods.",
keywords = "Adaptive predistortion, compensation architecture, envelope tracking amplifier, LMS, power amplifier, radio-over-fibre, RLS, adaptiivinen esiv{\"a}{\"a}ristys, kompensointiarkkitehtuuri, kuituoptinen radiolinkki, tehovahvistin, verhok{\"a}yr{\"a}seuraajavahvistin",
author = "Atso Hekkala",
note = "CA2: BA1142 SDA: TIC Project code: 73341 PGN: 56 p. + app. 60 p.",
year = "2014",
language = "English",
isbn = "978-951-38-8117-7",
series = "VTT Science",
publisher = "VTT Technical Research Centre of Finland",
number = "53",
address = "Finland",
school = "University of Oulu",

}

Compensation of transmitter nonlinearities using predistortion techniques : Case studies of envelope tracking amplifiers and radio-over-fibre links: Dissertation. / Hekkala, Atso.

VTT Technical Research Centre of Finland, 2014. 102 p.

Research output: ThesisDissertation

TY - THES

T1 - Compensation of transmitter nonlinearities using predistortion techniques

T2 - Case studies of envelope tracking amplifiers and radio-over-fibre links: Dissertation

AU - Hekkala, Atso

N1 - CA2: BA1142 SDA: TIC Project code: 73341 PGN: 56 p. + app. 60 p.

PY - 2014

Y1 - 2014

N2 - This thesis studies compensation of nonlinear distortions introduced in the transmitters of wireless communication systems. In particular, adaptive predistortion of the envelope tracking (ET) amplifier and the radio-over-fibre (RoF) link is considered. The main goal is to develop compensation algorithms and architectures for predistortion. By providing a low attenuation and broadband solution, the RoF technology enables using cost-efficient and energy-efficient distributed antenna systems (DASs). Using highly efficient power amplifier (PA) structures, such as the ET amplifiers, energy efficiency of the transmitters is increased. Unfortunately, the RoF links and the ET amplifiers are inherently nonlinear. The results of this thesis indicate that these nonlinearities have to be taken into account when designing wireless communication systems. The nonlinearities can be compensated using the low complex adaptive predistortion techniques proposed in this thesis. In this thesis, a general architecture for the predistortion of the ET amplifier is proposed. Using the architecture, the performance of predistortion is demonstrated. In addition, new time misalignment compensation methods are studied. For the compensation of the RoF link, an extension to the conventional least mean square (LMS) algorithm for the memory polynomial-based predistortion is presented. In addition, different combinations of adaptive algorithms for predistortion are considered. From the compensation architecture point of view, the joint compensation of the RoF link and PA connected in series in the presence of nonlinear feedback is studied. Finally, feasibility of the adaptive predistortion concept is demonstrated by the measurements. The results presented in this thesis can be applied to any wireless communications systems. The performance studies demonstrate that distortions of the RoF link and the ET amplifier can be considerably diminished using a low-complexity design. To get even better results in terms of linearity and energy efficiency, the proposed predistortion techniques can be implemented together with other techniques, such as the peak-to-average power ratio (PAPR) reduction methods.

AB - This thesis studies compensation of nonlinear distortions introduced in the transmitters of wireless communication systems. In particular, adaptive predistortion of the envelope tracking (ET) amplifier and the radio-over-fibre (RoF) link is considered. The main goal is to develop compensation algorithms and architectures for predistortion. By providing a low attenuation and broadband solution, the RoF technology enables using cost-efficient and energy-efficient distributed antenna systems (DASs). Using highly efficient power amplifier (PA) structures, such as the ET amplifiers, energy efficiency of the transmitters is increased. Unfortunately, the RoF links and the ET amplifiers are inherently nonlinear. The results of this thesis indicate that these nonlinearities have to be taken into account when designing wireless communication systems. The nonlinearities can be compensated using the low complex adaptive predistortion techniques proposed in this thesis. In this thesis, a general architecture for the predistortion of the ET amplifier is proposed. Using the architecture, the performance of predistortion is demonstrated. In addition, new time misalignment compensation methods are studied. For the compensation of the RoF link, an extension to the conventional least mean square (LMS) algorithm for the memory polynomial-based predistortion is presented. In addition, different combinations of adaptive algorithms for predistortion are considered. From the compensation architecture point of view, the joint compensation of the RoF link and PA connected in series in the presence of nonlinear feedback is studied. Finally, feasibility of the adaptive predistortion concept is demonstrated by the measurements. The results presented in this thesis can be applied to any wireless communications systems. The performance studies demonstrate that distortions of the RoF link and the ET amplifier can be considerably diminished using a low-complexity design. To get even better results in terms of linearity and energy efficiency, the proposed predistortion techniques can be implemented together with other techniques, such as the peak-to-average power ratio (PAPR) reduction methods.

KW - Adaptive predistortion

KW - compensation architecture

KW - envelope tracking amplifier

KW - LMS

KW - power amplifier

KW - radio-over-fibre

KW - RLS

KW - adaptiivinen esivääristys

KW - kompensointiarkkitehtuuri

KW - kuituoptinen radiolinkki

KW - tehovahvistin

KW - verhokäyräseuraajavahvistin

M3 - Dissertation

SN - 978-951-38-8117-7

T3 - VTT Science

PB - VTT Technical Research Centre of Finland

ER -