Performance Enhancement of Discrete Multiwavelet Critical-Sampling Transform-Based OFDM System Using Hybrid Technique Under Different Channel Models

A hybrid technique, which is a combination of the Fast Fourier Transform (FFT) and Sliding Window (SW) technique, is proposed for the development of new structure for Discrete Multiwavelet Critical-Sampling Transform based Orthogonal Frequency Division Multiplexing (DMWCST-OFDM) system under multipath fading channels with the Doppler frequency effect. FFT is utilized to increase the orthogonality of subcarriers against the multipath frequency-selective fading channels. SW technique reduces the fluctuation of signal amplitude, thereby reducing the Doppler frequency effect. This hybrid technique offers a good tradeoff between performance and complexity, where this technique needs more computations. However, it performs better than the standard DMWCST-OFDM system. The performance of the proposed system, called SW-DMWCST-OFDM, was compared to that of the standard DMWCST-OFDM, SW-FFT-OFDM, and FFT-OFDM systems under three channels, namely, additive white Gaussian noise, flat fading, and frequency-selective fading. The simulation results show that the proposed model performs better than the three other models in all types of channels.