Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sectoring in Multi-cell Massive MIMO Systems   In this paper, the downlink of a typical massive MIMO system is studied when
each base station is composed of three antenna arrays with directional antenna
elements serving 120 degrees of the two-dimensional space. A lower bound for
the achievable rate is provided. Furthermore, a power optimization problem is
formulated and as a result, centralized and decentralized power allocation
schemes are proposed. The simulation results reveal that using directional
antennas at base stations along with sectoring can lead to a notable increase
in the achievable rates by increasing the received signal power and decreasing
'pilot contamination' interference in multicell massive MIMO systems. Moreover,
it is shown that using optimized power allocation can increase 0.95-likely rate
in the system significantly.

25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom