Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Techniques for System Information Broadcast in Cell-Free Massive MIMO   We consider transmission of system information in a cell-free massive MIMO
system, when the transmitting access points do not have any channel state
information and the receiving terminal has to estimate the channel based on
downlink pilots. We analyze the system performance in terms of outage rate and
coverage probability, and use space-time block codes to increase performance.
We propose a heuristic method for pilot/data power optimization that can be
applied without any channel state information at the access points. We also
analyze the problem of grouping the access points, which is needed when the
single-antenna access points jointly transmit a space-time block code.

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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: astro-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin