Abstract

In this thesis, the sum-rate capacity of a noncoherent, regular
multiple-access general fading channel is investigated, where each
user has an arbitrary number of antennas and the receiver has only one
antenna. The transmitted signal is subject to additive Gaussian noise
and fading. The fading process is assumed to be general and
memoryless, i.e., it is not restricted to a specific distribution like
Rayleigh or Rician fading. While it is memoryless (i.e., independent
and identically distributed IID) over time, spacial memory is allowed,
i.e., the fading affecting different antennas may be dependent. On
the transmitter side cooperation between users is not allowed, i.e.,
the users are assumed to be statistically independent.

Based on known results about the capacity of a single-user fading
channel, we derive the exact expression for the asymptotic
multiple-user sum-rate capacity. It is shown that the capacity grows
only double-logarithmically in the available power. Futhermore, the
second term of the high-SNR asymptotic expansion of the sum-rate
capacity, the so-called fading number, is derived exactly and
shown to be identical to the fading number of the single-user channel
when all users apart from one is switched off at all times.

The result holds for three different power constraints. In a first
scenario, each user must satisfy its own strict peak-power constraint;
in a second case, each user's power is limited by an average-power
constarint; and in a third situation — somewhat unrealistically —
it is assumed that the users have a common power supply and can share
power (even though they still cannot cooperate on a signal basis).

The proof is based on a duality-based upper bound on mutual
information and on the concept of input distributions that escape to
infinity, meaning that when the available power tends to infinity, the
input must use symbols that also tend to infinity.



-||-   _|_ _|_     /    __|__   Stefan M. Moser
[-]     --__|__   /__\    /__   Senior Researcher & Lecturer, ETH Zurich, Switzerland
_|_     -- --|-    _     /  /   Adj. Professor, National Chiao Tung University (NCTU), Taiwan
/ \     []  \|    |_|   / \/    Web: http://moser-isi.ethz.ch/


Last modified: Mon Aug 19 11:34:52 UTC+8 2013