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Digital Predistortion for Hybrid MIMO Transmitters

Abdelaziz, Mahmoud; Anttila, Lauri; Brihuega, Alberto; Tufvesson, Fredrik LU and Valkama, Mikko (2018) In IEEE Journal on Selected Topics in Signal Processing
Abstract

This article investigates digital predistortion (DPD) linearization of hybrid beamforming large-scale antenna transmitters. We propose a novel DPD processing and learning technique for an antenna sub-array, which utilizes a combined signal of the individual power amplifier (PA) outputs in conjunction with a decorrelation-based learning rule. In effect, the proposed approach results in minimizing the nonlinear distortions in the direction of the intended receiver. This feature is highly desirable, since emissions in other directions are naturally weak due to beamforming. The proposed parameter learning technique requires only a single observation receiver, and therefore supports simple hardware implementation. It is also shown to clearly... (More)

This article investigates digital predistortion (DPD) linearization of hybrid beamforming large-scale antenna transmitters. We propose a novel DPD processing and learning technique for an antenna sub-array, which utilizes a combined signal of the individual power amplifier (PA) outputs in conjunction with a decorrelation-based learning rule. In effect, the proposed approach results in minimizing the nonlinear distortions in the direction of the intended receiver. This feature is highly desirable, since emissions in other directions are naturally weak due to beamforming. The proposed parameter learning technique requires only a single observation receiver, and therefore supports simple hardware implementation. It is also shown to clearly outperform the current state-of-the-art technique which utilizes only a single PA for learning. Analysis of the feedback network amplitude and phase imbalances reveals that the technique is robust even to high levels of such imbalances. Finally, we also show that the array system out-of-band emissions are well-behaving in all spatial directions, and essentially below those of the corresponding single-antenna transmitter, due to the combined effects of the DPD and beamforming.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
5G, digital predistortion, hybrid beamforming, large-array transmitters, out-of-band emissions, power amplifiers
in
IEEE Journal on Selected Topics in Signal Processing
publisher
IEEE--Institute of Electrical and Electronics Engineers Inc.
external identifiers
  • scopus:85045212003
ISSN
1932-4553
DOI
10.1109/JSTSP.2018.2824981
language
English
LU publication?
yes
id
c724579a-d2f8-4003-ba85-06da4044d500
date added to LUP
2018-04-18 07:55:06
date last changed
2019-01-06 13:51:47
@article{c724579a-d2f8-4003-ba85-06da4044d500,
  abstract     = {<p>This article investigates digital predistortion (DPD) linearization of hybrid beamforming large-scale antenna transmitters. We propose a novel DPD processing and learning technique for an antenna sub-array, which utilizes a combined signal of the individual power amplifier (PA) outputs in conjunction with a decorrelation-based learning rule. In effect, the proposed approach results in minimizing the nonlinear distortions in the direction of the intended receiver. This feature is highly desirable, since emissions in other directions are naturally weak due to beamforming. The proposed parameter learning technique requires only a single observation receiver, and therefore supports simple hardware implementation. It is also shown to clearly outperform the current state-of-the-art technique which utilizes only a single PA for learning. Analysis of the feedback network amplitude and phase imbalances reveals that the technique is robust even to high levels of such imbalances. Finally, we also show that the array system out-of-band emissions are well-behaving in all spatial directions, and essentially below those of the corresponding single-antenna transmitter, due to the combined effects of the DPD and beamforming.</p>},
  author       = {Abdelaziz, Mahmoud and Anttila, Lauri and Brihuega, Alberto and Tufvesson, Fredrik and Valkama, Mikko},
  issn         = {1932-4553},
  keyword      = {5G,digital predistortion,hybrid beamforming,large-array transmitters,out-of-band emissions,power amplifiers},
  language     = {eng},
  month        = {04},
  publisher    = {IEEE--Institute of Electrical and Electronics Engineers Inc.},
  series       = {IEEE Journal on Selected Topics in Signal Processing},
  title        = {Digital Predistortion for Hybrid MIMO Transmitters},
  url          = {http://dx.doi.org/10.1109/JSTSP.2018.2824981},
  year         = {2018},
}