A Comparative Performance Analyses of FFT Based OFDM and DWT Based OFDM Systems

While continuously increasing demand for high data rates, to develop more efficient wireless communication systems will always be needed. Orthogonal Frequency Division Multiplexing (OFDM) is a promising multi-carrier wireless communication system for high-speed data transmission with spectral efficiency and fading immunity. Conventional OFDM systems use Fourier filters with the help of the inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT) for modulation and demodulation in transmitter and receiver, respectively. On the other hand, wavelet based OFDM system uses orthonormal wavelets which are derived from a multistage tree-structured wavelet family. Discrete wavelet transform (DWT), reducing inter symbol interference (ISI) and inter carrier interference (ICI), can be used due to better orthogonality and more bandwidth efficiency for OFDM systems. In this paper, performance of the OFDM system based on low complexity DWT (DWT-OFDM) has been compared with FFT based OFDM (FFT-OFDM) system. In DWT based OFDM system, the IFFT and FFT blocks in conventional FFT based OFDM system are simply replaced by an IDWT and DWT, respectively. Computer simulations have been performed to verify the effectiveness of both methods and compare the performance of the DWT-OFDM and FFT-OFDM system in additive white Gaussian noise (AWGN) channel and AWGN plus frequency flat Rayleigh fading channels for different modulation types. The obtained simulation results using HIPERLAN/2 standard have demonstrated that the DWT-OFDM system has considerably better performance than the conventional FFT-OFDM system in all modulation types and also provides high SNR improvement of approximately 6 dB for a BER value of 1E-3.

[1]  Alan R. Lindsey,et al.  Wavelet packet modulation for orthogonally multiplexed communication , 1997, IEEE Trans. Signal Process..

[2]  Mohammad Ghavami,et al.  Comparison between wavelet-based and Fourier-based multicarrier UWB systems , 2008, IET Commun..

[3]  I. Daubechies.  Ten Lectures on Wavelets , 1992 .

[4]  Yesuf Shiferaw.  Comparative Performance Study on Wavelet Based Orthogonal Frequency Division Multiplexing (OFDM) Using Different Wavelets , 2007 .

[5]  Ali N. Akansu,et al.  Wavelet and subband transforms: fundamentals and communication applications , 1997, IEEE Commun. Mag..

[6]  Simon Haykin,et al.  Communication Systems , 1978 .

[7]  Ali N. Akansu,et al.  Orthogonal transmultiplexers in communication: a review , 1998, IEEE Trans. Signal Process..

[8]  C.A. Belfiore,et al.  Decision feedback equalization , 1979, Proceedings of the IEEE.

[9]  John G. Proakis,et al.  Digital Communications , 1983 .

[10]  Michael Frazier.  An introduction to wavelets through linear algebra , 1999 .

[11]  Khaizuran Abdullah.  Interference mitigation techniques for wireless OFDM , 2009 .

[12]  Volkan Kumbasar,et al.  Performance comparison of wavelet based and conventional OFDM systems in multipath Rayleigh fading channels , 2012, Digit. Signal Process..

[13]  S. Qureshi,et al.  Adaptive equalization , 1982, Proceedings of the IEEE.

[15]  H Ayele,et al.  Wavelet based multicarrier code division multiple access communication for wireless environment , 2005 .

[16]  Homayoun Nikookar,et al.  A Review of Wavelets for Digital Wireless Communication , 2006, Wirel. Pers. Commun..

[17]  C. Burrus,et al.  Introduction to Wavelets and Wavelet Transforms: A Primer , 1997 .

[18]  Abbas Hasan Kattoush,et al.  The performance of multiwavelets based OFDM system under different channel conditions , 2010, Digit. Signal Process..

[19]  F. C. Monds,et al.  Equaliser for digital communication , 1971 .

[20]  Manish J. Manglani,et al.  Wavelet Modulation in Gaussian and Rayleigh Fading Channels , 2001 .

[21]  Peter N. Heller,et al.  DMT systems, DWMT systems and digital filter banks , 1994, Proceedings of ICC/SUPERCOMM'94 - 1994 International Conference on Communications.