Design Of Spatiotemporal Chaos Spread Spectrum Sequences And Its Application In CDMA Communication System

Chaos is an external complex manifestation generated by intrinsic stochastic of deterministic nonlinear system. Chaotic systems exhibit a non-random movement while it looks like random. Spatiotemporal chaos is one type of chaos. Compared with one-dimensional chaos, spatiotemporal chaotic system has both highly sensitive to original condition and boundary conditions. It compresses a complex movement in both time and space domains. The purpose of this paper is to associate the strong points of spatiotemporal chaos and spread spectrum communication. Using the natural characters of spatiotemporal chaotic system, including deterministic, complexity and unpredictability, the new type of secure spread spectrum sequences can be constructed which matches the requirements of spread spectrum sequences.The paper mainly focuses on the following aspects.1 According to the basic theory of spread spectrum sequences and using the character of One-way Coupled Map Lattices, we can design the spread spectrum sequences generation system of digital spatiotemporal chaos. At the same time, we propose the optimal design. By using Matlab7.0, we do some simulations on the characters of the new sequences. The simulation result indicates that the performances of spatiotemporal chaos spread spectrum sequences are better than that of traditional sequences.2 In allusion to the problem of finite-precision effect which is always meet in practical project, we design two dithering approaches to resolve it. The computer simulation and hardware testing show that both approaches are effective, especially the non-periodic feedback dithering approach, which can generate the effective spatiotemporal chaotic-sequences in practical communication systems.3 By using spatiotemporal chaotic-sequences, we design spatiotemporal chaotic spread spectrum communication system base on the principle of the spread spectrum communication. According to Monte Carlo simulation, we test the channel characters under the conditions of multiple access interference, multiple path interference and white noise interference. We compare the result with that of traditional spread spectrum sequences.4 ARM microprocessor and embedded operation system are introduced. Spatiotemporal chaos spread spectrum sequences generator is designed by using LPC2114 and its corresponding software is designed by Visual C++. We complete the design of point to point spread spectrum communication system and user communication software.