The Analysis Of Chaotic Behavior Of Cellular Neural Networks And Its Application In CDMA Spread Spectrum Code

Nowadays, with the rapid development of mobile radio communication, it is required to achieve high capacity by simultaneously and gain high quality of the performance of the system. Thus CDMA obtains more and more attention due to its high capacity. CDMA is a kind of spread spectrum multiple access, which need spread spectrum signals to multiply the narrowband message signal. Owing to the complex randomicity and enormous amount of chaotic signal, Chaotic CDMA communication system can be applied to spread spectrum system effectively. Chaos is a kind of phenomenon and behavior, and neural network is a kind of topology with specific compute mode. They have their own characters and similar nonlinear characters. The Cellular Neural Network (CNN) is a kind of nonlinear system, which is easy to be obtained by VLSI. With proper parameters, the dynamical behavior of a simple CNN system will show interesting bifurcation and complex chaos. This paper analyzes the relationship between the weight parameters of CNN system and the dynamical behavior. The dynamical property is controlled via adjusting certain weight parameters. The results indicate that the structure of the attractor depends sensitively on the alteration of a parameter, and the dynamical behavior of CNN shows the chaotic attractor with a larger extent of parameters. Using this chaotic behavior of CNN, when given proper parameters, the system will show chaos. Afterward, we can gain spread spectrum sequence by sampling and quantizing the analog chaotic signals. Because of the superior performance and high capacity of this kind of system, it will open up prospects for the super-high capacity of spread spectrum communication in the future. In this paper, we introduce a new multi-valued pseudorandom code which is produced by a four-cell chaotic CNN system, and put forward a multifunction circuit. Simulates indicate that this multi-valued spread spectrum sequence with excellent randomicity can meet the requirement of high capacity in CDMA system, and this leads to a new method to acquire spread spectrum sequence in spread spectrum communication.