Chaotic Digital Code-Division Multiple Access (CDMA) Communication Systems

In this paper, the structure, principle and framework of chaotic digital code-division multiple access ((CD) 2 MA) communication systems are presented. Unlike the existing CDMA systems, (CD) 2 MA systems use continuous pseudo-random time series to spread the spectrum of message signal and the spread signal is then directly sent through a channel to the receiver. In this sense, the carrier used in (CD) 2 MA is a continuous pseudo-random signal instead of a single tone as used in CDMA. We give the statistical properties of the noise-like carriers. In a (CD) 2 MA system, every mobile station has the same structure and parameters, only different initial conditions are assigned to different mobile stations. Instead of synchronizing two binary pseudo-random sequences as in CDMA systems, we use an impulsive control scheme to synchronize two chaotic systems in (CD) 2 MA. The simulation results show that the channel capacity of (CD) 2 MA is twice as large than that of CDMA.