Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Piecewise Digital Predistortion fo mmWave Active Antenna Arrays:
  Algorithms and Measurements   In this paper, 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, that 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,
non-iterative, pruning algorithm is introduced, which allows to significantly
reduce the amount 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 inband 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.

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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg