Studies on Trade-off Between Throughput and Reliability in Wireless Systems
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Date
2007-12-20T21:38:09Z
Authors
Ansari Sadrabadi, Mehdi
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
In the first part of the thesis, we study the trade-off between the transmission reliability and data
rate in high signal-to-noise ratio regime in ad-hoc wireless
networks. Bandwidth allocation plays a significant role in this
trade-off, since dividing bandwidth reduces the number of users on
each band and consequently decreases the interference level, however
it also decreases the data rate. Noting that the interference power
is substantially influenced by the network density, this trade-off
introduces a measure for appropriate bandwidth allocation among
users considering the network density. The diversity-multiplexing trade-off
is derived for a one-dimensional regular ad-hoc
network.
In the second part of the thesis, we study the performance of point-to-point and broadcast systems
with partial channel state information at the transmitter in a time-varying environment.
First, the capacity of time-varying channels with
periodic feedback at the transmitter is evaluated. It is assumed that the
channel state information is perfectly known at the receiver
and is fed back to the transmitter at the regular time-intervals. The system capacity is investigated in two cases: i) finite state Markov channel, and
ii) additive white Gaussian noise channel with time-correlated fading. In a multiuser scenario, we consider a downlink system in which a single-antenna base
station communicates with single antenna users, over a
time-correlated fading channel. It is assumed that
channel state information is perfectly known at each receiver, while
the rate of channel variations and the fading
gain at the beginning of each frame are known to the transmitter. The asymptotic throughput of the
scheduling that transmits to the user with the maximum signal to
noise ratio is examined applying variable code rate and/or variable
codeword length signaling. It is shown that by selecting a fixed codeword
length for all users, the order of the maximum possible throughput (corresponding to quasi-static fading) is achieved.
Description
Keywords
Diversity-multiplexing, time-varying channel