Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Achieving AWGN Channel Capacity with Sparse Graph Modulation and "In the
  Air" Coupling   Communication over a multiple access channel is considered. Each user
modulates his signal as a superposition of redundant data streams where
interconnection of data bits can be represented by means of a sparse graph. The
receiver observes a signal resulting from the coupling of the sparse modulation
graphs. Iterative interference cancellation decoding is analyzed. It is proved
that spatial graph coupling allows to achieve the AWGN channel capacity with
equal power transmissions.

18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol