混沌序列在准同步码分多址系统中的应用  

Application of chaotic sequences in QS-CDMA systems

作　　者：张琪[1] 郑君里[1] 孙守宇[1] 

机构地区：[1]清华大学电子工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2003年第4期453-456,共4页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目 ( 60 0 72 0 0 1) ;国家教育振兴计划

摘　　要：为了获取适用于准同步码分多址系统的混沌序列 ,提出一种用于准正交序列性能分析的优选准则 ,并通过系统仿真对优选混沌序列进行了验证。在准同步码分多址系统中 ,影响系统性能的是零时延附近的部分扩频序列相关函数 ,而且奇相关函数和偶相关函数发挥同等重要的作用。据此对初值不同的 L ogistic映射序列进行筛选 ,得到了混沌准正交序列组。采用 Monte Carlo的方法 ,在 AWGN信道下对采用混沌优选序列的准同步码分多址系统进行了仿真。结果表明 :优选的混沌序列具有优秀的准正交性 。A method is presented to optimize the chaotic sequences for spreading codes of quasi synchronous code division multiple access (QS CDMA) systems. In a QS CDMA system, the relative delay between the signals of different users is random but restricted to a specified time range, so correlation functions around the origin influence system performance and odd function are as important as the even functions. Chaotic sequences generated from a logistic map with different initial values were checked using the quasi orthogonal criteria to select the qualified sequences. Monte Carlo simulations of the QS CDMA system with optimized chaotic sequences as spreading codes on additive white Gaussian noise (AWGN) channel show that these sequences are quasi orthogonal and suitable for application in the QS CDMA system.

关 键 词：准同步码分多址系统 混沌序列 准正交序列 扩频序列 相关函数 优选准则 

分 类 号：TN914.53[电子电信—通信与信息系统] O415.5[电子电信—信息与通信工程]