Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Improving the Coverage and Spectral Efficiency of Millimeter-Wave
  Cellular Networks using Device-to-Device Relays
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin