Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Unified Relay Framework with both D-F and C-F Relay Nodes   Decode-and-forward (D-F) and compress-and-forward (C-F) are two fundamentally
different relay strategies proposed by (Cover and El Gamal, 1979).
Individually, either of them has been successfully generalized to multi-relay
channels. In this paper, to allow each relay node the freedom of choosing
either of the two strategies, we propose a unified framework, where both the
D-F and C-F strategies can be employed simultaneously in the network. It turns
out that, to fully incorporate the advantages of both the best known D-F and
C-F strategies into a unified framework, the major challenge arises as follows:
For the D-F relay nodes to fully utilize the help of the C-F relay nodes,
decoding at the D-F relay nodes should not be conducted until all the blocks
have been finished; However, in the multi-level D-F strategy, the upstream
nodes have to decode prior to the downstream nodes in order to help, which
makes simultaneous decoding at all the D-F relay nodes after all the blocks
have been finished inapplicable. To tackle this problem, nested blocks combined
with backward decoding are used in our framework, so that the D-F relay nodes
at different levels can perform backward decoding at different frequencies. As
such, the upstream D-F relay nodes can decode before the downstream D-F relay
nodes, and the use of backward decoding at each D-F relay node ensures the full
exploitation of the help of both the other D-F relay nodes and the C-F relay
nodes. The achievable rates under our unified relay framework are found to
combine both the best known D-F and C-F achievable rates and include them as
special cases.

25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat