关键词: 初等元胞自动机, 耦合映像格, 耦合系数, 扰动, 混沌扩频

Abstract: In order to solve the problem of uneven output distribution of chaotic systems and the degradation of chaotic system dynamics under the limited precision, a pseudo-random coupled map lattice chaotic spreading code generation algorithm is proposed based on the iterative rules of elementary cellular automata and coupled map lattices. First, elementary cellular automata is used to control the coupling objects of each lattice in coupled map lattices. The initial iteration value is generated by the XOR operation of different elementary cellular automata iteration rules. The index is carried out according to the elementary cellular automata iteration results, and the system index rules are designed. Then, the coupling coefficient generation algorithm is designed, and the coupling coefficient value is obtained according to the elementary cellular automata initial value and two secret integers. The lattice index in the coupled map lattices is mapped to the cell index in the elementary cellular automata, and then the corresponding disturbance values and disturbance symbols are returned according to the algorithm rules, which can effectively weaken the degradation of the dynamic characteristics of the chaotic system and enhance the chaotic characteristics of the spatiotemporal chaotic system. Finally, the scheme of chaotic spread spectrum communication system based on pseudo-random coupled image lattice is designed. The pseudo-random coupled map lattice chaotic spread spectrum code is directly spread and modulated by BPSK. The simulation results show that the chaotic spread spectrum code has passed the NIST test and has excellent pseudo-randomness. The proposed scheme has good bit error rate performance and has extensive application prospects in the field of secure communication.

Key words: elementary cellular automata, coupled map lattices, coupling coefficient, disturbance, chaotic spread spectrum