四相混沌扩频序列的优选与仿真

The optimization of quaternary chaotic spreading sequences and system simulation

根据复数处理的四相异步码分多址系统的特点 ,分析了四相扩频序列的性能准则 ,提出了混沌扩频序列的优选方法。通过对大量不同初值的混沌序列进行筛选 ,得到了性能优异的混沌扩频序列组。混沌优选序列数目多 ,并且都是平衡序列。采用MonteCarlo的方法 ,在AWGN信道下 ,分别采用混沌优选序列和一类四相准最优序列作为扩频序列 ,对复数处理的异步码分多址系统进行了仿真。结果表明 ,优选的混沌序列在抗多址干扰方面与准最优序列非常接近 。

In terms of characteristics of asynchronous CDMA system with complex processing and quaternary data modulation, this paper summarizes the property analysis criteria of quaternary spreading sequences, based on which the optimization of chaotic sequences is presented. The size of optimized chaotic sequences set is large and each element's weight is balanced. Monte Carlo simulations in A CDMA system with complex processing and quaternary data modulation are carried out on AWGN channel, where chaotic sequences and one kind of quasi optimum quaternary sequences are employed to spread spectrum respectively. The simulation results show that the optimized chaotic sequences' ability to restrain multiple access interference is close to that of the quasi optimum quaternary sequences, and the ability to restrain intersymbol interference is much better.