Channel Equalization for Wavelet Packet Modulation

Abstract

Wavelet Packet Modulation (WPM) is a multicarrier modulation technique like the well-established Orthogonal Frequency Division Multiplexing (OFDM). It has several advantages over OFDM, such as flexibility of operation and excellent localization in frequency. The Channel Equalization for WPM is new and an unexplored research area. It is also different from equalization for OFDM because WPM symbols overlap in time. This thesis work presents a channel equalizer for WPM systems. The algorithm proposed is a pre-detection channel equalizer, which performs time-domain equalization. The equalizer applies the principle of peak distortion criterion where the maximum inter-symbol interference caused by the channel is minimized. The operation of the equalizer is tested under different realistic channels with different taps and characteristics. Furthermore, investigations to understand the impact of the wavelet family, length of the wavelet filters, and the number of equalizer taps on the performance of the equalizer are carried out. Results of the simulation studies illustrate notable performance gains including better Bit Error Rate (BER) performance and lower Inter symbol interference (ISI). Moreover, the different components of interference such as ISI(Inter Symbol Interference), ICI(Inter Carrier Interference) and ISCI(Inter Symbol Carrier Interference) are mathematically analyzed.