Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Capacity of Multiple Access and Broadcast Fading Channels with
  Full Channel State Information at Low SNR   We study the throughput capacity region of the Gaussian multi-access (MAC)
fading channel with perfect channel state information (CSI) at the receiver and
at the transmitters, at low power regime. We show that it has a
multidimensional rectangle structure and thus is simply characterized by single
user capacity points. More specifically, we show that at low power regime, the
boundary surface of the capacity region shrinks to a single point corresponding
to the sum rate maximizer and that the coordinates of this point coincide with
single user capacity bounds. Inspired by this result, we propose an on-off
scheme, compute its achievable rate, and show that this scheme achieves single
user capacity bounds of the MAC channel for a wide class of fading channels at
asymptotically low power regime. We argue that this class of fading encompasses
all known wireless channels for which the capacity region of the MAC channel
has even a simpler expression in terms of users' average power constraints
only. Using the duality of Gaussian MAC and broadcast channels (BC), we deduce
a simple characterization of the BC capacity region at low power regime and
show that for a class of fading channels (including Rayleigh fading),
time-sharing is asymptotically optimal.

29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con