Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Nearest Neighbor Decoding and Pilot-Aided Channel Estimation for Fading
  Channels
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th