Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Capacity Approximations for Gaussian Relay Networks   Consider a Gaussian relay network where a source node communicates to a
destination node with the help of several layers of relays. Recent work has
shown that compress-and-forward based strategies can achieve the capacity of
this network within an additive gap. Here, the relays quantize their received
signals at the noise level and map them to random Gaussian codebooks. The
resultant gap to capacity is independent of the SNRs of the channels in the
network and the topology but is linear in the total number of nodes.
  In this paper, we provide an improved lower bound on the rate achieved by
compress-and-forward based strategies (noisy network coding in particular) in
arbitrary Gaussian relay networks, whose gap to capacity depends on the network
not only through the total number of nodes but also through the degrees of
freedom of the min cut of the network. We illustrate that for many networks,
this refined lower bound can lead to a better approximation of the capacity. In
particular, we demonstrate that it leads to a logarithmic rather than linear
capacity gap in the total number of nodes for certain classes of layered
networks. The improvement comes from quantizing the received signals of the
relays at a resolution decreasing with the total number of nodes in the
network. This suggests that the rule-of-thumb in literature of quantizing the
received signals at the noise level can be highly suboptimal.

31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex