Piecewise Digital Predistortion for mmWave Active Antenna Arrays: Algorithms and Measurements
Journal article, 2020

In this article, we describe a novel framework for digital predistortion (DPD)-based linearization of strongly nonlinear millimeter-wave active antenna arrays. Specifically, we formulate a piecewise (PW) closed-loop (CL) DPD solution and low-complexity gradient-adaptive parameter learning algorithms, together with a region partitioning method, which can efficiently handle deep compression of the PA units. The impact of beamsteering on the DPD performance is studied, showing strong beam-dependence, thus necessitating frequent updating of the DPD. In order to facilitate fast adaptation, an inexpensive, noniterative, pruning algorithm is introduced, which allows us to significantly reduce the number of model coefficients. The proposed methods are validated with extensive over-the-air RF measurements on a 64-element active antenna array transmitter operating at 28-GHz carrier frequency and transmitting a 400-MHz 5G new radio (NR) standard-compliant orthogonal frequency-division multiplexing waveform. The obtained results demonstrate the excellent linearization capabilities of the proposed solution, conforming to the new 5G NR requirements for frequency range 2 (FR2) in terms of both in-band waveform quality and out-of-band emissions. The proposed PW-CL DPD is shown to outperform the state-of-the-art PW DPD based on the indirect learning architecture, as well as the classical single-polynomial-based DPD solutions in terms of linearization performance and computational complexity by a clear margin.

digital predistortion (DPD)

Array signal processing

piecewise (PW) processing

5G new radio (NR)

Complexity theory

5G mobile communication

nonlinear distortion

Partitioning algorithms

millimeter-wave (mmWave)


Antenna measurements


over-the-air (OTA) measurements

closed-loop (CL) learning

Antenna arrays

Antenna arrays


Alberto Brihuega

University of Tampere

Mahmoud Abdelaziz

Zewail City of Science and Technology

Lauri Anttila

University of Tampere

Matias Turunen

University of Tampere

Markus Allen

University of Tampere

Thomas Eriksson

Chalmers, Electrical Engineering, Communication and Antenna Systems, Communication Systems

Mikko Valkama

University of Tampere

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN)

Vol. 68 9 4000-4017

Subject Categories


Signal Processing

Other Electrical Engineering, Electronic Engineering, Information Engineering



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