Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: STAR-IOS Aided NOMA Networks: Channel Model Approximation and
  Performance Analysis   Simultaneous transmitting and reflecting intelligent omini-surfaces
(STAR-IOSs) are able to achieve full coverage "smart radio environments". By
splitting the energy or altering the active number of STAR-IOS elements,
STAR-IOSs provide high flexibility of successive interference cancellation
(SIC) orders for non-orthogonal multiple access (NOMA) systems. Based on the
aforementioned advantages, this paper investigates a STAR-IOS-aided downlink
NOMA network with randomly deployed users. We first propose three tractable
channel models for different application scenarios, namely the central limit
model, the curve fitting model, and the M-fold convolution model. More
specifically, the central limit model fits the scenarios with large-size
STAR-IOSs while the curve fitting model is extended to evaluate multi-cell
networks. However, these two models cannot obtain accurate diversity orders.
Hence, we figure out the M-fold convolution model to derive accurate diversity
orders. We consider three protocols for STAR-IOSs, namely, the energy splitting
(ES) protocol, the time switching (TS) protocol, and the mode switching (MS)
protocol. Based on the ES protocol, we derive analytical outage probability
expressions for the paired NOMA users by the central limit model and the curve
fitting model. Based on three STAR-IOS protocols, we derive the diversity gains
of NOMA users by the M-fold convolution model. The analytical results reveal
that the diversity gain of NOMA users is equal to the active number of STAR-IOS
elements. Numerical results indicate that 1) in high signal-to-noise ratio
regions, the central limit model performs as an upper bound, while a lower
bound is obtained by the curve fitting model; 2) the TS protocol has the best
performance but requesting more time blocks than other protocols; 3) the ES
protocol outperforms the MS protocol as the ES protocol has higher diversity
gains.

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The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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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: supr-con
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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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: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: stat
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The categories of this paper are: astro-ph
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The categories of this paper are: q-bio
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The categories of this paper are: econ