Data Transmission through OFDM System by using Discrete Wavelet Transform Techniques

Abstract

The efficient use of data transmission is main problem in advanced type communication systems. Many
technologies are used for higher data rates, in this process the OFDM system plays main role compared to the
technologies. The OFDM system is one type of multicarrier modulation technique, in this system the original signal can
be divided into many number sub carriers. The same process is also done in other type of modulation techniques, but in
OFDM system orthogonality condition is existed between the subcarriers. In OFDM system two types of interferences
will be there, they are Inter Carrier Interference (ICI) and Inter Symbol Interference (ISI) and these are occurred due to
the orthogonality loss between the subcarriers, to overcome this problem cyclic prefix (CP) is used. CP is a guard band
in OFDM system that uses 20% of required subcarrier. Wavelet based OFDM system provides better orthogonality
between subcarriers. Signal to Noise Ratio (SNR) of the message signal improved by the wavelet transform techniques.
Wavelet based OFDM system doesn’t require cyclic prefix, so bandwidth can’t be wasted. Compare the obtained results
of 16QAM, 64QAM and 256 QAM with conventional DFT method. This is the one advantage to improve the utilization of
the spectrum. OFDM system based on wavelet transform is proposed in the place of Discrete Fourier Transform (DFT)
based OFDM in LTE. Comparing performance of Bit Error Rate (BER) in wavelet transform based techniques with DFT
based OFDM.