Wireless CDMA communications using time-varying signals

In this paper, we propose to use time-varying signals in code division multiple access (CDMA) techniques for wireless communication channels. Specifically, we employ linear FM chirp signaling in a frequency hopped (FH) CDMA system with additive white Gaussian noise (AWGN). Every user is characterized not only by a unique pseudo-noise (PN) sequence but also by a unique set of chirp rates. Our multi-rate chirp (MRC) FH-CDMA system has been motivated by the inherent resistance of chirp signals against AWGN. We demonstrate that our system is bandwidth efficient and resistant against AWGN. Simulations successfully demonstrate the increase in performance of the new method as compared to frequency shift keying (FSK) FH-CDMA.