The Research Of Chaotic Sequence Apply In CDMA System

With the high-speed progress of science, in the 21^st century, there is increasing requirement for personal mobile communication while it enter 3G.In the 3^rd generation mobile communication system, CDMA, which based on DS-SS technology has got more and more attention for its superiority. The PN sequence used by a DS-SS direct affects the performance of system. The PN sequence selected is crux of the DS-SS system.The discovery of chaotic dynamic system broad the way of study of PN sequence. Chaos is a convinced and random kind course that appears in the nonlinear system. It is an unperiod and an irregular course. It is not convergence but dose have a bound, while it is sensitive to its initial value .For all these special performance, chaos has an excellent outlook in the application of telecommunication, especially in the generation of PN sequence.In this paper, we have a deep discuss in DS-SS system, analysis the structure of the system, then we come to the PN sequence used in DS-SS system and introduce chaos to the study of PN sequence. We put forward a new kind of chaotic system model-embed chaotic model and analysis its chaotic performance then we apply it and proved Logistic, Tent, Chebyshev, Logistic-Tent, Logistic-2 class Chebyshev chaotic models together with traditional Gold sequence have a comprehensive comparison. In the comparison we study their performance of balance,performance of run , performance of shift , performance of auto-correlation, performance of cross-correlation, performance of sidelobe, performance of peak value. We improve the key performance of chaotic PN sequence by filtration, and get sequence that better than common chaotic sequence and traditional Gold sequence. At last we prove the result on the MATLAB platform. We analysis bit error rate of different PN sequence of MAI and MPI and prove the result of optimize-the performance of chaotic binary SS sequence has been greatly proved after optimize. It is maybe useful in the research of PN sequence of DS-SS system.