Chebyshev二相混沌扩频序列平衡性

针对直扩码分多址系统中扩频序列不平衡的问题,利用Chebyshev混沌映射产生二相混沌扩频序列,给出了平衡性定义,讨论了与平衡性有关的参数,深入分析了平衡性与分形参数、初始值、序列周期的关系,提出了混沌序列用于码分多址系统时应避开的不平衡点,解决了选取分行参数和周期长度两个关键问题.仿真结果表明:Chebyshev混沌扩频序列具有良好的平衡性,序列中幂级数K对平衡性影响小,不存在峰值;初始值对平衡性的影响在零点处存在峰值,构造序列时要避开这点.当取序列周期在1 000以上时,可满足直扩码分多址系统对平衡性的要求.

Performance of balance base on Chebyshev 2-phasc chaotis spreading sequence

Because the spread spectrum sequences is not balanced in DS-CDMA(Direct Spectrum-Code Division Multiple Access)system. Chaotic spread spectrum sequences of 2-phasc is built up by using Chebyshev-mapping. The definition of performance of balance is given and the parameters related to performance of balance is discussed.The relation between the performance of balance E of the sequence and fractal parameter, initial value, the period of the sequence is analysed thoroughly. Non-balance spot ought to evaded in application of CDMA system is proposed.Two key problems of fractal parameter and length of the period selection are solved. The imitation results show that Chebyshev chaotic sequence has good performance of balance.Power series \%K\% has little influence on performance of balance and there is no peak valuespread for spectrum sequence;Initial value's effect on degree of balance results in the peak points on the spots zero,which should be avoided when structure sequence.Chebyshev chaotic sequence can meet of demand to CDMA system when sequence length is over 1 000.