Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Joint Power Control and LSFD for Wireless-Powered Cell-Free Massive MIMO   This paper considers wireless uplink information and downlink power transfer
in cell-free massive multiple-input multiple-output systems. The single-antenna
user equipments (UEs) utilize the energy harvested in the downlink to transmit
uplink pilot and information signals to the multiple-antenna access points
(APs). We consider Rician fading and maximum ratio processing based on either
linear minimum mean-squared error (LMMSE) or least-squares (LS) channel
estimation. We derive the average harvested energy by using a practical
non-linear energy harvesting circuit model for both coherent and non-coherent
transmission schemes. Furthermore, the uplink spectral efficiency (SE) is
derived for all the considered methods and the max-min fairness problem is cast
where the optimization variables are the AP and UE power control coefficients
together with the large-scale fading decoding vectors. The objective is to
maximize the minimum SE of the UEs' under APs' and UEs' transmission power
constraints. A novel alternating optimization algorithm with guaranteed
convergence and improvement at each step is proposed to solve the
highly-coupled non-convex problem.

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The categories of this paper are: physics
31
The categories of this paper are: ao-sci
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The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
30
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: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin