Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Precoder Design for Signal Superposition in MIMO-NOMA Multicell Networks   The throughput of users with poor channel conditions, such as those at a cell
edge, is a bottleneck in wireless systems. A major part of the power budget
must be allocated to serve these users in guaranteeing their quality-of-service
(QoS) requirement, hampering QoS for other users and thus compromising the
system reliability. In nonorthogonal multiple access (NOMA), the message
intended for a user with a poor channel condition is decoded by itself and by
another user with a better channel condition. The message intended for the
latter is then successively decoded by itself after canceling the interference
of the former. The overall information throughput is thus improved by this
particular successive decoding and interference cancellation. This paper aims
to design linear precoders/beamformers for signal superposition at the base
stations of NOMA multi-input multi-output multi-cellular systems to maximize
the overall sum throughput subject to the users' QoS requirements, which are
imposed independently on the users' channel condition. This design problem is
formulated as the maximization of a highly nonlinear and nonsmooth function
subject to nonconvex constraints, which is very computationally challenging.
Path-following algorithms for its solution, which invoke only a simple convex
problem of moderate dimension at each iteration are developed. Generating a
sequence of improved points, these algorithms converge at least to a local
optimum. Extensive numerical simulations are then provided to demonstrate their
merit.

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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: eess