Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Achievable rate regions for bi-directional relaying   In a bi-directional relay channel, two nodes wish to exchange independent
messages over a shared wireless half-duplex channel with the help of a relay.
In this paper, we derive achievable rate regions for four new half-duplex
protocols and compare these to four existing half-duplex protocols and outer
bounds. In time, our protocols consist of either two or three phases. In the
two phase protocols, both users simultaneously transmit during the first phase
and the relay alone transmits during the second phase, while in the three phase
protocol the two users sequentially transmit followed by a transmission from
the relay. The relay may forward information in one of four manners; we outline
existing Amplify and Forward (AF), Decode and Forward (DF) and Compress and
Forward (CF) relaying schemes and introduce the novel Mixed Forward scheme. The
latter is a combination of CF in one direction and DF in the other. We derive
achievable rate regions for the CF and Mixed relaying schemes for the two and
three phase protocols. In the last part of this work we provide a comprehensive
treatment of 8 possible half-duplex bi-directional relaying protocols in
Gaussian noise, obtaining their respective achievable rate regions, outer
bounds, and their relative performance under different SNR and relay
geometries.

16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat