CHAPTER Time-Scale and Dispersive Processing for Wideband Time-Varying Channels 1 Arizona 2 Grenoble 9 State University, Tempe, AZ, USA Institute of Technology, Grenoble, France Antonia Papandreou-Suppappola 1 , Cornel Ioana 2 , Jun Jason Zhang 1 9.1 INTRODUCTION 9.1.1 Need for Wideband Channel Characterizations Linear time-varying (LTV) channel characterizations have found many successes in mobile wireless communications as they can be effectively used to detect, estimate, and diversify the communica- tion process. As discussed in earlier chapters, one such useful characterization of the channel output