Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Degrees of Freedom of the Broadcast Channel with Hybrid CSI at
  Transmitter and Receivers   In general, the different links of a broadcast channel may experience
different fading dynamics and, potentially, unequal or hybrid channel state
information (CSI) conditions. The faster the fading and the shorter the fading
block length, the more often the link needs to be trained and estimated at the
receiver, and the more likely that CSI is stale or unavailable at the
transmitter. Disparity of link fading dynamics in the presence of CSI
limitations can be modeled by a multi-user broadcast channel with both
non-identical link fading block lengths as well as dissimilar link CSIR/CSIT
conditions. This paper investigates a MISO broadcast channel where some
receivers experience longer coherence intervals (static receivers) and have
CSIR, while some other receivers experience shorter coherence intervals
(dynamic receivers) and do not enjoy free CSIR. We consider a variety of CSIT
conditions for the above mentioned model, including no CSIT, delayed CSIT, or
hybrid CSIT. To investigate the degrees of freedom region, we employ
interference alignment and beamforming along with a product superposition that
allows simultaneous but non-contaminating transmission of pilots and data to
different receivers. Outer bounds employ the extremal entropy inequality as
well as a bounding of the performance of a discrete memoryless multiuser
multilevel broadcast channel. For several cases, inner and outer bounds are
established that either partially meet, or the gap diminishes with increasing
coherence times.

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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-lat
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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: acc-phys
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The categories of this paper are: nucl-th
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph