Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: NOMA in the Uplink: Delay Analysis with Imperfect CSI and Finite-Length
  Coding   We study whether using non-orthogonal multiple access (NOMA) in the uplink of
a mobile network can improve the performance over orthogonal multiple access
(OMA) when the system requires ultra-reliable low-latency communications
(URLLC). To answer this question, we first consider an ideal system model with
perfect channel state information (CSI) at the transmitter and long codewords,
where we determine the optimal decoding orders when the decoder uses successive
interference cancellation (SIC) and derive closed-form expressions for the
optimal rate when joint decoding is used. While joint decoding performs well
even under tight delay constraints, NOMA with SIC decoding often performs worse
than OMA. For low-latency systems, we must also consider the impact of
finite-length channel coding, as well as rate adaptation based imperfect CSI.
We derive closed-form approximations for the corresponding outage or error
probabilities and find that those effects create a larger performance penalty
for NOMA than for OMA. Thus, NOMA with SIC decoding may often be unsuitable for
URLLC.

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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: stat
10
The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: cond-mat
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The categories of this paper are: astro-ph
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The categories of this paper are: q-alg
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The categories of this paper are: physics