Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Practical Considerations in Direct Detection Under Tukey Signalling   The deliberate introduction of controlled intersymbol interference (ISI) in
Tukey signalling enables the recovery of signal amplitude and (in part) signal
phase under direct detection, giving rise to significant spectral efficiency
improvements compared to intensity modulation with direct detection (IMDD). The
use of an integrate-and-dump detector makes precise waveform shaping
unnecessary, thereby equipping the scheme with a high degree of robustness to
nonlinear signal distortions introduced by practical modulators. Signal
sequences drawn from star quadrature amplitude modulation (SQAM) formats admit
an efficient trellis description that facilitates codebook design and
low-complexity near maximum-likelihood sequence detection in the presence of
both shot noise and thermal noise. Under the practical (though suboptimal)
allocation of a 50% duty cycle between ISI-free and ISI-present signalling
segments, at a symbol rate of 50 Gbaud and a launch power of -10 dBm the Tukey
scheme has a maximum theoretically achievable throughput of 225 Gb/s with a
(13,4)-SQAM constellation, while a comparable IMDD scheme achieves about 145
Gb/s using PAM-8.

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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: alg-geom