Summary:
The demand for high data rate wireless multi-media applications has increased
significantly in the past few years. The wireless user’s pressure towards
faster communications, no matter whether mobile, nomadic, or fixed positioned,
without extra cost is nowadays a reality. To fulfill these demands, a new
scheme which combines wireless digital modulation and multiple accesses was
proposed in the recent years, namely, Multicarrier-Code Division Multiple
Access (MC-CDMA).
The Fourier based OFDM uses the complex exponential bases functions and it is
replaced by wavelets in order to reduce the level of interference. It is found
that the Haar-based wavelets are capable of reducing the ISI and ICI, which are
caused by the loss in orthogonality between the carriers. Further performance
gains can be made by looking at alternative orthogonal basis functions and
finding a better transform rather than Fourier and wavelet transform.
In this thesis, there are three proposed models [Model ‘1’ (OFDM based on
In-Place Wavelet Transform, Model ‘2’ (MC-CDMA based on IP-WT and Phase Matrix)
and Model ‘3’ (MC-CDMA based on Multiwavelet Transform)] were created and then
comparison their performances with the traditional models for single user
system were compared under different channel characteristics (AWGN channel,
flat fading and selective fading).
The conclusion of my study as follows, the models (1) was achieved much lower
bit error rates than traditional models based FFT. Therefore these models can
be considered as an alternative to the conventional MC-CDMA based FFT. The main
advantage of using In-Place wavelet transform in the proposed models that it
does not require an additional array at each sweep such as in ordered Fast Haar
wavelet transform, which makes it simpler for implementation than FFT. The
model (2) gave a new algorithm based on In-Place wavelet transform with first
level processing multiple by PM was proposed. The model (3) gave much lower bit
error than other two models in additional to traditional models.
Keywords:
OFDM, MC-CDMA, Wavelet Transform, IP-WT, Phase Matrix
