The Performance Analysis And An Optimal Design Of Chaotic Pn Sequences

The characters such as nonlinearity, sensitivity to initial values and randomness, make chaos systems proper to generate high performance PN sequences. The chaotic PN sequences are highly random and have long periods which mean that it's suitable for secret communication and spreading code generation. After analyzing several chaotic systems, this paper proposes a method to generate different PN sequences useing FPGA technology, and then compares them with each other to decide a better way to generate high quality PN sequence. A novel chaotic system is designed.The main work of this paper includes:(1) DSP Builder Toolbag, which is developed by Altera, is employed to firstly construct chaotic systems in MATLAB. The systems are then coverted into VHDL language and downloaded into FPGA chip. This process shortens the development cycle of chaos hardware realization and makes it possible to analyze a large amount of chaotic PN sequences.(2) As for that there's no quantitative analysis on the finite precision effect of digital chaotic systems, a large amount of data is tested to deduce the quantitative expression of the relation between the cycle and the precision of Logistic map, which makes finite precision effect more detailed and utilizable for practical application.(3) Analysis is made on the PN sequences that are respectively generated from normal chaos systems, switched chaos systems, hyperchaos systems. The conclusion is gained that: the complex behavior of switched and hyperchaos systems are not inherited by the PN sequences during the quantization process. Perturbation or mixing method are suspected to get in use.(4) The 2 methods of perturbation and mixing method are found both of disadvantages. In order to overcome these disadvantages, a novel chaotic system based on these 2 methods is implemented. This system has simple structure but better behaviors...