Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Study of Trade-off between Opportunistic Resource Allocation and
  Interference Alignment in Femtocell Scenarios   One of the main problems in wireless heterogeneous networks is interference
between macro- and femto-cells. Using Orthogonal Frequency-Division Multiple
Access (OFDMA) to create multiple frequency orthogonal sub-channels, this
interference can be completely avoided if each sub-channel is exclusively used
by either macro- or a femto-cell. However, such an orthogonal allocation may be
inefficient. We consider two alternative strategies for interference
management, opportunistic resource allocation (ORA) and interference alignment
(IA). Both of them utilize the fading fluctuations across frequency channels in
different ways. ORA allows the users to interfere, but selecting the channels
where the interference is faded, while the desired signal has a good channel.
IA uses precoding to create interference-free transmissions; however, such a
precoding changes the diversity picture of the communication resources. In this
letter we investigate the interactions and the trade-offs between these two
strategies.

5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg