Investigation of the Performance of Different Adaptive Space-Time Transmit Diversity Schemes
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Date
2006-12
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Addis Ababa University
Abstract
Transmit diversity techniques provide attractive solutions for increasing
downlink capacity in 3G systems. Open-loop and closed-loop transmit
diversity modes with two transmit antennas have already been included into
3G Partner Project WCDMA (wideband code division multiplexing access),
and schemes exploiting a large number of transmit antennas are being
developed. System capacity can be increased from that of open-loop modes
if the transmitter is equipped with additional side information of the
downlink channel. In a frequency division duplex (FDD) system this means
that the receiver has to provide the information through some feedback
mechanism.
In this work, a scheme which combines a closed-loop and open-loop
transmit diversity (adaptive space-time transmit diversity) is investigated
and the signal-to-noise ratio (SNR) to bit error rate (BER) performance of
this adaptive space-time transmit diversity schemes are evaluated on a flat
Rayleigh fading channel.
The performance results obtained from the simulations show that adaptive
space-time transmit diversity schemes have better error rate performance
than the space-time transmit diversity. Finally, this work has shown that
adaptive power allocation scheme in conjunction with the Alamouti scheme
has an improved error rate than the open loop transmit diversity (Alamouti
scheme) and also adaptive space time modulation has an improved error rate performance than the Alamouti scheme. Moreover, this thesis showed
the tradeoff between schemes combining both adaptive rate and power with
different percentages and increasing the power at the same time reducing
the data rate has an improved error rate performance than reducing the
power at the same time increasing the data rate of the system
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