Chaotic Direct Sequence Spread Spectrum Communication System Simulation And Analysis

The chaotic DSSS (Direct-Sequence Spread-Spectrum) communication has the advantages of both DSSS communications and chaotic dynam. It is so widely used in modern commnications about military, satellite and mobile.Research has showed that conventional PN has low complication,low quantity and low security. In addition, their good correlation property are not many enough.So it is limited for its useness.These problem can be resloved by using chaotic sequence.The paper firstly introduces conventional spread spectrum.Spread spectrum communication transmitter uses much larger bandwidth than required by spreading original information using PN sequences. A spread spectrum receiver then uses the synchronized of the PN sequences to recover the original information. Due to this PN property of the spreading sequences, spread spectrum communication can work at low power spectral density and has many good characters such as anti-noise, anti-interference, anti-multipath effect, multiple access,efficient frequency usage.And then,chaos is produced by deterministic nonlinear systems, its phenomena is pseudo random. Because chaotic systems exhibit sensitivity to initial conditions, they can generate many enough PN sequences with good correlation property.The paper analyses several basic features such as Logistic,Henon,Lorenz maps.The characters of these sequences are also analyzed both auto-correlation property and cross-correlation property.In order to exam the feasibility of chaotic sequences applying for real spread spectrum telecommunications, we analyze the EBR in AWGN channel in theoretics.The feasibility of chaotic sequences are able to be used in spread spectrum communication systems is proved by theoretic calculation and Monte Carlo method simulation using MATLAB.Moreover,the paper analyzes the influence about parameter change of chaotic map and bit rate.Finally, the paper makes a conclusion and makes an expectation of further research.