Performance improvement of haar-based wavelet packet modulation in multipath fading environment

In recent years, high-speed and high-quality mobile communications have been demanded. Wavelet packet modulation (WPM) has been proposed as one of the multicarrier transmission methods and applied to the mobile communications. The WPM has an advantage of equalizing performance compared with OFDM (orthogonal frequency division multiplexing) when a frequency domain equalizer (FDE) is applied because of a frequency diversity property. In this paper, we enhance this WPM to improve the performance in multipath fading environments. First, the principle of equalization in WPM is shown with matrix expression. Next, the comparison of performance and complexity between WPM using Haar wavelet and OFDM are considered. Then, the modified WPM using phase rotation and complex Haar function are proposed, and the improved performances are confirmed through the numerical results.