Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hierarchical Cellular Structures in High-Capacity Cellular Communication
  Systems   In the prevailing cellular environment, it is important to provide the
resources for the fluctuating traffic demand exactly in the place and at the
time where and when they are needed. In this paper, we explored the ability of
hierarchical cellular structures with inter layer reuse to increase the
capacity of mobile communication network by applying total frequency hopping
(T-FH) and adaptive frequency allocation (AFA) as a strategy to reuse the macro
and micro cell resources without frequency planning in indoor pico cells [11].
The practical aspects for designing macro- micro cellular overlays in the
existing big urban areas are also explained [4]. Femto cells are inducted in
macro / micro / pico cells hierarchical structure to achieve the required QoS
cost effectively.

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The categories of this paper are: atom-ph
3
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: bayes-an
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The categories of this paper are: stat
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio