Rician fading channel is investigated. In this channel, the

transmitted signal is sub ject to additive Gaussian noise and Rician

fading,

line-of-sight component. On the transmitter side the cooperation

between users is not allowed,

statistically independent.

Based on the known result of the asymptotic capacity of a single-user

fading channel, our work is to generalize it to the multiple-user

sum-rate capacity. We study the single-antenna case only: all

transmitters and the receiver use one antenna. We get a natural upper

bound on the capacity if the constraint of independence between the

users is relaxed, in which case the channel becomes a multiple-input

single-output (MISO) channel. Also, a lower bound can be obtained if

all users apart from one are switched off, which corresponds to a

single-input single-output (SISO) channel. We improve these bounds and

get an exact formula of the asymptotic capacity.

The main concept we use in this thesis is escaping to infinity of

input distributions, which means that when the available power tends

to infinity, the input must use symbols that also tend to infinity. We

propose that in the multiple-access fading channel, at least one

userâ€™s distribution must escape to infinity. Based on this we obtain

the result that the asymptotic sum-rate capacity is identical to the

previously mentioned lower bound: the single-user SISO capacity. We

conclude that in order to achieve the best sum-rate capacity in the

multiple-access system, we have to switch off the users with bad

channels and only allow those with the best channel to transmit.

-||- _|_ _|_ / __|__ 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: Fri Sep 11 06:46:00 UTC+8 2009