Browsing by Author "Shiferaw, Yesuf"

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    Comparative Performance Study on Wavelet Based Orthogonal Frequency Division Multiplexing (OFDM) Using Different Wavelets
    (Addis Ababa University, 2007-03) Shiferaw, Yesuf; Ayele, Hailu (PhD)
    As we move in to the future there is a rising demand for high performance, high capacity and high bit rate wireless communication systems to integrate wide variety of communication services such as high-speed data, video and multimedia traffic as well as voice signals. As proven by the success of orthogonal frequency division multiplexing (OFDM), it provides an efficient means to handle high-speed data streams over a multipath fading environment .Conventional OFDM implementation uses Fourier filters for data modulation and demodulation , via the inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) respectively. Much research suggests wavelet OFDM implementation provides performance gains over Fourier based OFDM, due to superior spectral containment properties of wavelet filters. All the characteristics of OFDM modulated signals are directly dependent on the set of waveforms of which it makes use. Several authors have foreseen wavelet theory as good plat form on which to build OFDM waveform bases. In this work the performance of five different most widely used Wavelet bases OFDM schemes over wireless channels is studied and wavelet basis that will be suitable for OFDM, for its optimum performance gains will be investigated. The bit error rate (BER) versus signal-to-noise ratio (SNR) and an elapsed time for simulation of wavelet OFDM are used as a measure of the system performance. The results show that the wavelet based orthogonal frequency division multiplexing (OFDM) system operates at its optimum performance with wavelets of Daubechies family.