Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interference Reduction in Multi-Cell Massive MIMO Systems II: Downlink
  Analysis for a Finite Number of Antennas   Sharing global channel information at base stations (BSs) is commonly assumed
for downlink multi-cell precoding. In the context of massive multi-input
multi-output (MIMO) systems where each BS is equipped with a large number of
antennas, sharing instant fading channel coefficients consumes a large amount
of resource. To consider practically implementable methods, we study in this
paper interference reduction based on precoding using the large-scale fading
coefficients that depend on the path-loss model and are independent of a
specific antenna. We focus on the downlink multi-cell precoding designs when
each BS is equipped with a practically finite number of antennas. In this
operation regime, pilot contamination is not the dominant source of
interference, and mitigation of all types of interference is required. This
paper uses an optimization approach to design precoding methods for equal
qualities of service (QoS) to all users in the network, i.e.,maximizing the
minimum signal-to-interference-plus-noise ratios (SINRs) among all users. The
formulated optimization is proved to be quasi-convex, and can be solved
optimally. We also propose low-complexity suboptimal algorithms through uplink
and downlink duality. Simulation results show that the proposed precoding
methods improve 5% outage rate for more than 1000 times, compared to other
known interference mitigation techniques.

18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
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The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol