Comparative Study on The Performance of Wavelet-Based and DFT-Based MCM
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Date
2007-01
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Addis Ababa University
Abstract
The demand for wireless networks has been growing rapidly over the recent past due to
improved reliability, higher supported data rates, seamless connectivity between users and the
access point, and low deployment costs relative to wireline infrastructure. This increase in
demand started with the popular IEEE 802.11b wireless local area network standard.
Many recent wireless network standards are now employing DFT based multicarrier
modulation (MCM) popularly termed as OFDM in their design. Multicarrier modulation
reduces the system’s susceptibility to the frequency selective fading channel, due to multipath
propagation, by transforming it into a collection of approximately flat subchannels. As a
result, this makes it easier to compensate for the distortion introduced by the channel. The
effects of the Intersymbol Interference (ISI) and Intercarrier Interference (ICI) are reduced by
the application of cyclic prefix. On the other hand, related research in wavelets points that due
to the high spectral containment of wavelet filters the performance of MCM improves.
This thesis work investigates simulation based performance of the DFT-based and Waveletbased
MCM. The channel model and system models for both MCM schemes are considered.
And using bit error rate (BER) versus signal-to-noise ratio (SNR) as measure of performance,
transmission scenarios are implemented in AWGN channel and time varying multipath
channel models and studied. Channel coding performances and the effects of carrier
frequency offset are investigated.
The performance results obtained by the simulation indicate that the wavelet-based
implementation outperforms that of DFT-based in some channel scenarios. While in other
channel models the DFT-based MCM shows increased performance.
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Keywords
DFT-Based MCM, Wavelet-Based