Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: AoA Estimation for OAM Communication Systems With Mode-Frequency
  Multi-Time ESPRIT Method   Radio orbital angular momentum (OAM) communications require accurate
alignment between the transmit and receive beam directions. Accordingly, a key
feature of OAM receivers is the ability to reliably estimate the angle of
arrival (AoA) of multi-mode OAM beams. Considering the limitations of existing
AoA estimation techniques, in this paper, we propose an easier-to-implement AoA
estimation method based on applying multiple times the estimating signal
parameters via rotational invariance techniques (ESPRIT) algorithm to the
received training signals in OAM mode and frequency domains, which is denoted
as the mode-frequency (M-F) multi-time (MT)-ESPRIT algorithm. With this method,
the misalignment error of real OAM channels can be greatly reduced and the
performance approaches that of ideally aligned OAM channels.

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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn