Neural-Network-Based Digital Predistortion for Active Antenna Arrays under Load Modulation

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27 Citations (Scopus)
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Abstract

In this letter, we propose an efficient solution to linearize mmWave active antenna array transmitters that suffer from beam-dependent load modulation. We consider a dense neural network that is capable of modeling the correlation between the nonlinear distortion characteristics among different beams. This allows providing consistently good linearization regardless of the beamforming direction, thus avoiding the necessity of executing continuous digital predistortion parameter learning. The proposed solution is validated, conforming to 5G new radio transmit signal quality requirements, with extensive over-the-air RF measurements utilizing a state-of-the-art 64-element active antenna array operating at 28-GHz carrier frequency.

Original languageEnglish
Pages (from-to)843-846
Number of pages4
JournalIEEE Microwave and Wireless Components Letters
Volume30
Issue number8
DOIs
Publication statusPublished - 1 Aug 2020
Publication typeA1 Journal article-refereed

Funding

Manuscript received May 8, 2020; revised June 4, 2020; accepted June 12, 2020. Date of publication July 1, 2020; date of current version August 7, 2020. This work was supported in part by the Academy of Finland under Project 304147, Project 301820, and Project 319994; in part by Nokia Bell Labs; and in part by the Tampere University Doctoral School. (Corresponding author: Mikko Valkama.) The authors are with the Department of Electrical Engineering, Tampere University, 33100 Tampere, Finland (e-mail: [email protected]). Data is available on-line at https://doi.org/10.5281/zenodo.3904473. Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LMWC.2020.3004003

Keywords

  • 5G new radio (NR)
  • digital predistortion (DPD)
  • load modulation
  • mmWave
  • neural networks (NNs)
  • nonlinear distortion

Publication forum classification

  • Publication forum level 2

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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