Characterization of wideband time-varying channels with multipath-scale diversity

In this paper, we present a characterization of wideband time-varying wireless channels based on a discrete time-scale framework that can provide multipath-scale diversity. This is important for systems such as underwater or airborne acoustics for which the narrowband conditions no longer hold, and time-scalings cannot be approximated by constant frequency shifts. We design a spreading waveform for direct-sequence code division multiple-access systems based on wavelet functions to realize orthogonal signaling. Furthermore, we use the orthogonal wavelet decomposition for direct channel estimation and coherent detection.