Logistic映射混沌扩频序列的奇/偶相关特性分析

本文简要分析了Logistic映射混沌扩频序列的奇/偶相关特性以及序列的有限长度效应对奇/偶相关特性的影响;提出了一种EOE Logistic映射混沌扩频序列的构造方法.理论分析表明,EOE Logistic映射有限长度扩频序列的奇/偶相关特性较原序列有所改善.计算机仿真结果验证了理论分析的正确性.     

基于Chebyshev映射的混沌特性及其性能分析

分析Chebyshev映射的混沌产生机制,计算了其李雅普诺夫指数。推导其产生的混沌序列统计特性的数学表达式,说明其与白噪声的统计特性一致,适合作为扩频地址码。分析映射混沌序列的奇、偶相关特性,分别导出序列的有限长度与最大奇、偶相关特性和有限长度与自相关旁瓣、互相关均方根的数据拟合关系式,并给出了针对此扩频序列的每个信息比特所含的合适切普数。仿真结果表明该映射产生的混沌序列具有理想的线性复杂度及良好的平衡特性。     

最佳屏蔽二进序列偶在低/零相关区中的应用研究

将最佳屏蔽二进序列偶应用于低/零相关区中,提出最佳屏蔽低/零相关序列偶集的概念,给出了3种构造低/零相关序列偶集的方法,即奇数长最佳屏蔽二进序列偶与Hadamard矩阵相结合组成ZCZ(零相关区)序列集,偶数长最佳屏蔽二进序列偶与改造后的Hadamard矩阵组成LCZ(低相关区)序列集,以及任意长度最佳屏蔽二进序列偶与正交矩阵构成ZCZ序列集。利用这些构造方法,扩展了原有低/零低相关区存在的长度范围,扩大了序列集的容量,可以更好地满足工程应用的需要。     

二元二值周期自相关序列偶的应用研究

该文提出了正交矩阵偶的概念,它是正交矩阵的一种扩展,尤其二元正交矩阵偶不受阶数应为2的幂次的限制。应用二元二值周期自相关序列偶,提出了一种构造二元正交矩阵偶的方法和一种构造正交序列偶集的方法,还提出了一种利用正交矩阵偶或正交矩阵结合正交序列偶集交织构造适于准同步码分多址通信系统应用的二元零相关区序列偶集的新方法,通过对二元二值周期自相关序列偶的选择可使构造的零相关区序列偶集获得高的能量效率,并可使集合的序列偶数量,零相关区长度及序列偶长度参数接近最大理论限。     

Logistic映射扩频序列的相关分布

本文由Ｌｏｇｉｓｔｉｃ映射产生用于直扩码分多址（ＤＳ／ＣＤＭＡ）系统的扩频序列,证明了周期为Ｎ的此类扩频序列的偶相关和奇相关均服从均值为０、方差为Ｎ的高斯分布,采用混沌扩频序列的ＣＤＭＡ系统的容量怀传统扩频序列相同。     

基于有限状态的全周期序列混沌映射的研究

在有限长度的数字计算机中，混沌迭代序列是一个有限周期序列，其相关性能远远低于理想序列。基于skew tent映射，提出一种离散化的有限状态混沌映射，它允许精确的数值计算，没有舍入误差，通过选择合适的参数，映射能产生全周期长度的序列。仿真实验表明，归一化的序列平均周期对计算机精度不敏感，生成的二进制序列具有良好的相关性能。     

构造大的零相关区的序列偶集方法研究

在准同步CDMA系统中,使用零相关区(ZCZ)序列能够避免共信道冲突和多址干扰。提出了一种新的ZCZ二元序列偶集的构造方法,通过选择合适的正交矩阵,利用扩展方法构造出的新的ZCZ序列偶集合,可以生成长度大于原序列偶的零相关区,不但序列偶长度增加,而且也具有良好的自相关和互相关性能,同时也能满足多用户系统需求。仿真结果表明,它的性能优良,适于作准同步CDMA系统的扩频序列。     

基于交织的零相关区序列偶集构造方法研究

移位序列的设计是交织法构造零相关区序列集的核心问题.该文根据相关函数分析了移位序列的约束条件,并据此条件提出一种基于交织构造零相关区序列集的方法.文中通过选择不同基序列和满足约束条件的移位序列,能够得到具有灵活零相关区长度的序列偶.该文将此序列偶和正交矩阵相结合,构造出具有一定序列长度和数目的零相关区序列偶集.该方法扩展了交织法的应用,可以构造具有一定容量和灵活零相关区的序列集.     

GPS L1C信号Weil码相关性能分析

伪码是码分多址信号的基本组成,寻找具有良好相关性能的伪码是基于码分多址的无线通信和无线电导航等信号设计中的重要环节。Weil码是一种基于勒让德序列移位相加形成的伪随机码,具有良好的相关性能,且具有相对灵活的可选序列长度,将在GPS的L1C信号中得到应用。在提出伪码选择方法的基础上,对Weil码的产生方式进行了介绍,并对几种典型的伪码的理论相关性能和序列长度特点进行对比分析,对L1C信号采用的126个Weil码的奇相关和偶相关性能进行仿真,结果表明在10 230的序列长度下Weil码具有良好的相关性能。     

序列偶扩频码的研究

丈中在对最佳二元序列偶进行研究的基础上,对63长以内非2"-1长度上的序列偶进行了搜索,找到了部分相关性能较好的结果,并同Gold序列进行了比较.结果表明,序列偶扩频码在某些长度上有较好的性能,弥补了目前伪随机序列在该长度上的欠缺,给实际工程应用提供了更多选择.     

Design of pseudonoise sequences with good odd and even correlationproperties for DS/CDMA

Proposes and investigates a method for designing pseudonoise (PN) sequences having both good odd and even correlation properties, which are important for acquisition and demodulation in spread spectrum (SS) communications. Odd correlation properties of PN sequences should be designed as well as their even or periodic correlation properties so that the cochannel interference can be reduced as small as possible. Polyphase PN sequences with such good correlation properties can be derived from biphase PN sequences with a good aperiodic correlation property under a certain condition. Absolute values of odd and even correlation functions of these sequences are equal at each shift. The authors evaluated their peak correlations properties and bit error rate performance. Numerical evaluations show that the derived polyphase sequences have lower peaks of correlations and lower bit error rate than their original sequences. Furthermore, the authors defined the generalized odd correlation function for polyphase SS systems, and derived a way to improve the generalized odd correlation properties     

A new polyphase sequence with perfect even and good odd cross-correlation functions for DS/CDMA systems

A class of polyphase signature sequences for direct-sequence code-division multiple-access (DS/CDMA) systems is proposed. The proposed class has zero periodic (=even) cross-correlation (CC) function and approximate maximum magnitude N//spl pi/ of odd cross-correlation (OCC), where N is the length of sequences. Although the maximum magnitude is relatively large, it is observed that the maximum magnitude has little effect on the performance of the DS/CDMA system, since its frequency is very low. The performance of the proposed sequence in DS/CDMA systems is investigated and shown to be better than that of other sequences for an asynchronous additive white Gaussian noise channel environment with and without Rayleigh multipath fading.     

用于混沌扩频保密通信的不等长四相扩频序列

本文重点研究不等长四相混沌扩频序列的广义奇互相关性质。理论分析和仿真实验表明,不等长与等长的四相混沌扩频序列在许多方面具有相似的性质,所获结果为不等长四相混沌扩顺序列在保密通信等方面的应用提供了理论基础。     

GROUP CORRELATION PROPERTIES OF THE BINARY SEQUENCE SETS

The group correlation properties of binary sequences is studied, and a conclusion is drawn that not only the group correlation function of a binary sequence itself is ideal, but also some of its subsets, which code length N is even, is ideal. Finally a general formula of the group correlation of a binary sequence set is derived.     

Impulses concealed by singularities: transmission line theory

The input admittance of a loss-free short-circuited transmission line is generally said to be a cotangent function of frequency, a function that is imaginary and odd. The symmetry implies that the impulse response, which has the admittance function of frequency as its Fourier transform, is also odd. However, there can be no response at negative times preceding the applied impulse. Therefore the cotangent formula for susceptance cannot be correct. A real, even function of frequency representing a conductance term must be added to the imaginary, odd susceptance. Likewise, the familiar formula Z=iZ₀ tan(2πL/λ) is deficient     

用于CDMA的四相混沌扩频序列

本文由混沌映射产生用于直扩码分多址（ＤＳ／ＣＤＭＡ）系统的四相扩频序列，证明了周期为Ｎ的此类扩频序列的四种广义奇相关均服从均方值为Ｎ的瑞利分布。混沌四相序列的相关峰值较混沌二相序列有显著的下降，多址性能与传统四相扩频序列相同。     

二进制序列的群相关特性

本文研究了二进制序列的群相关特性,证明了不仅二进制序列的群相关函数是理想的,而且当码长N是偶数位时,它的某些子集的群相关函数也是理想的。文中还导出了二进制集C的群相关函数的一般形式。