Multiband and multicarrier wavelet packet multiplexing for UWB transmissions

We propose a novel multi-channel modulation scheme for UWB transmissions based on the discrete wavelet packet transform (DWPT) and DWT combined with spread spectrum and multiband approaches (as analogous to multicarrier CDMA and multiband OFDM). Thus, two possible structures are proposed for UWB transmissions. Namely, multiband DWT multiplexing and DWT-CDMA multiplexing. Indeed, the proposed techniques divide UWB channels into a set of parallel channels. Exploiting the properties of wavelets in time and frequency, a set of multi-channel basis functions can be formed such that the corresponding channel-output functions remain nearly orthogonal for any UWB channel. Multiple access can be introduced in the form of time-frequency hopping codes (similar to multiband OFDM) or by introducing spreading codes (similar to multicarrier CDMA). The proposals are compared to multiband OFDM and multicarrier CDMA in terms of BER performance.