Multi-user Chaotic Spread Spectrum Communication System

Chaos spread-spectrum communication has become a hotspot in thefield of chaotic application research. Combined theoretical analysis withsimulation approaches, the key technologies of multi-user chaotic spreadspectrum communication are analyzed, especially in the generation ofchaotic sequence, the optimizing of the chaotic sequence, the method ofchaotic synchronization, and the Simulation and performance analysis ofthe system.The relation between the performance of balance and the parameterof four typical chaotic maps (Chebyshev, Improved Logistic, Logistic andTent) is studied. The new numeric ranges of initial value and fractalparameter are decided, which provides reference for the generation ofchaotic spread-spectrum sequence.The performance of balance and correlated characteristic of thesefour chaotic sequences with the length of 2000 to 3000 are studied. A newchaotic sequence generation scheme based on improved logistic-map andChebyshev is proposed. Compared with other four chaotic sequences andconventional spreading sequences, it has better performance of balanceand correlated characteristic. Especially in multi-user chaoticspread-spectrum communication system, its error-bit property is bettertoo. The series sequence provides a new idea for the optimizing of thechaotic spread-spectrum sequence.Based on m sequence, a new chaotic sequence synchronizationmethod which has excellent anti-jamming capability is proposed.Through the capture of m sequence, the synchronization of chaoticsequence between transmitter and receiver is realized. This method notonly solves the synchronization of the chaotic sequences with the finitelength, but also founds the technology foundation for the practicalapplication of chaotic spread spectrum communication.Single-user and multi-user chaotic spread spectrum communicationsystems based on Rake reception are designed, and the dynamic visualsimulation system model is established by the Simulink. The error-bit rate performance of these systems with parameter of chaotic maps, signal tonoise ratio, number of users, the length of sequence and number ofmulti-path is investigated, and the results show that it has many merits,such as good anti-interference, low BER, great capacity, ideal secureproperties, and good flexibility.