TDCS Modified Feedback Control Chaotic Basis Function Generation Method

Chaotic degradation occurs when the chaotic basis function is generated digitally in transform domain communication system, which leads to the decrease of the concealment and security of communication. In response to the above problems, a feedback control method for generating chaotic basis functions is proposed. This method is mainly based on the improved feedback control chaotic sequence and generates pseudo-random phase accordingly. Firstly, on the basis of the feedback control chaotic system with Lyapunov index being strictly positive, the minimum operation accuracy required for digitization of the system is obtained. Secondly, the adjustment factor is introduced to make the digital chaotic system consistent with the original chaotic system. Theoretical analysis and simulation experiments show that this method can produce a large number of chaotic basis functions with strong pseudo-randomness and high complexity, and has good comprehensive performance in such aspects as the delay autocorrelation, phase coverage and approximate entropy of the basis functions.