On the use of wideband time-varying signaling for multiuser wireless communications

We propose the use of wideband time-varying signaling in frequency-hopped code division multiple access systems. Specifically, linear chirp signals are highly localized along lines that are spread over the whole bandwidth of a time-frequency hop. As such, many chirps representing different users can be simultaneously transmitted in the same hop without collision. We demonstrate an improved performance in reducing multiple access interference for channels under noise, fading and multipath distortion conditions. The chirp's bandwidth efficiency is further exploited by assigning multiple chirp rates to each user. We also propose time-varying processing methods for estimating the different users' chirp rates at the receiver.