Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Achievable Rates and Optimal Resource Allocation for Imperfectly-Known
  Fading Relay Channels   In this paper, achievable rates and optimal resource allocation strategies
for imperfectly-known fading relay channels are studied. It is assumed that
communication starts with the network training phase in which the receivers
estimate the fading coefficients of their respective channels. In the data
transmission phase, amplify-and-forward and decode-and-forward relaying schemes
with different degrees of cooperation are considered, and the corresponding
achievable rate expressions are obtained. Three resource allocation problems
are addressed: 1) power allocation between data and training symbols; 2)
time/bandwidth allocation to the relay; 3) power allocation between the source
and relay in the presence of total power constraints. The achievable rate
expressions are employed to identify the optimal resource allocation
strategies. Finally, energy efficiency is investigated by studying the bit
energy requirements in the low-SNR regime.

17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc