复制生成序列的自相关函数研究

介绍了以二进制码为复制信息,用平移复制生成序列的方法。讨论了复制生成序列的性质和复制生成序列的自相关函数的性质。依据序列的复制特性,给出了一个复制生成序列自相关函数的计算公式,并给出了自相关函数值为零的一个充要条件,及相应的数学证明。最后讨论了Paley顺序的离散Walsh函数的自相关函数。     

基于CAZAC序列的突发通信定时同步算法

介绍了一种基于恒包络零自相关序列(CAZAC)为前导字的突发通信定时同步算法。该算法采用最大似然估计准则,利用CAZAC序列的零自相关特性,直接得到定时同步参数的估计值,且该算法所需的计算量较低,适合数字硬件实现。最后,仿真结果验证了该算法的可行性和有效性,并给出了其主要的硬件实现结构。     

一类由交织方式构造的二元ZCZ序列簇

2000年, Tang, Fan和Matsufuji给出(L,M,Zcz)-ZCZ序列簇的理论界为ZczL/M-1 。给定正整数n和L,本文给出一个交织ZCZ序列簇的构造算法,该算法由L条周期为L的正交序列簇生成一类(2n+1L,2L,2n-1)-ZCZ序列簇。若n2且4 |, 该类ZCZ序列簇中编号为奇数的序列与编号为偶数的序列在移位为时相关值为零。此外,选择不同的正交序列簇或不同的移位序列, 经构造算法可以生成不同的ZCZ序列簇。     

沃尔什函数复制理论及其在Rademacher/Walsh变换矩阵中的应用

本文进一步计论了沃尔什函数复制理论,提出了复制距离的新概念及用“异或”运算复制生成结果序列的新看法,并将它应用于Rademacher/Walsh变换矩阵中。本文还指出解决用复制理论一次性复制生成Rademacher/Walsh变换矩阵的关键是正确构成复制信息。     

一种新型的混沌直接扩谱序列

提出了一种基于一维无限折叠混沌映射的直接扩谱序列构造方法。统计测试和仿真结果表明,所产生的二值直接扩谱序为统计独立的均匀分布序列,因而具有理想的二值自相关函数和零互相关函数的特性。     

混合进制广义沃尔什函数的复制生成

本文把二进制、多进制沃尔什函数的复制生成理论推广到了混合进制情形,给出了混合进制广义沃尔什函数的复制生成方法,并对复制生成方法进行了数学分析.它对信号的复制生成理论的深入研究有一定的理论价值.     

频谱理论及其在通信保密技术中的应用研究

文章阐述频谱理论以及频谱理论在通信保密技术当中的应用情况,利用一阶Walsh谱,明确布尔函数相关免疫性以及非线性度的关系,分析布尔函数非线性度、自相关值为零的个数以及谱值为零的个数,阐明三者之间的关系,推广扩散准则概念,着重分析有限域上的频谱理论及其应用。     

GMW序列和WG序列及WG序列间的互相关特性

对于奇数n,研究了Gordon-Mills-Welch（GMW）序列与Welch-Gong（WG）序列（及其某一采样序列）间的互相关函数以及WG序列间的互相关函数。研究表明：GMW序列与WG序列（及其某一采样序列）间的互相关函数以及WG序列间的互相关函数最终均与m-序列与其采样序列间的互相关函数相关;并且在一定条件下,WG序列间的互相关函数可为3-值或5-值的。另外,给出了GMW序列与WG序列间互相关函数的最大峰值。     

QPSK数字化解调中载波同步技术研究

分析了判决辅助载波同步和非判决辅助载波同步的基本原理,研究了基于信号相位的载波频偏估计算法和基于信号自相关函数载波频偏估计算法,提出了基于恒包络零自相关(CAZAC)序列为前导的载波同步算法,并对基于CAZAC序列的载波恢复算法进行了分析和计算机仿真,结果表明该算法性能优良且实现简单。     

密码学函数迭代原理信息论分析

在密码编码学中,经常利用密码学函数迭代技术来实现密码算法,其所依赖的理论基础包括相关免疫理论,扩散准则,雪崩原理等.本文利用信息论原理以及随机过程理论给出了密码学函数迭代原理分析,得到了经过密码学函数迭代之后,输出为均匀分布时,输入输出互信息极限为零的充分必要条件,以及在一定条件下输入输出互信息收敛速度的一个上界.     

Ternary sequence with zero correlation

A method of generating ternary sequences with zero cyclic correlation except for the spike for zero lag is described. The sequences are of length given by (3ⁿ-1)/2 where n is odd. A method of generating uncorrelated sequences derived from the ternary sequence modified by a Hadamard matrix is indicated.     

Design of sequence set with group-wise zero correlation window

Zero correlation window (ZCW) or zero correlation zone (ZCZ) sequence can be used in quasi-synchronous code division multiple access (QS-CDMA) system to eliminate multiple access and multipath interferences. However, as the length of ZCW or ZCZ increases, fewer sequences are available. Recently, a new concept, sequence set with group-wise zero correlation window is introduced, which can increase the number of available sequences for a QS-CDMA system. In this article, a new method for generating sequence set with group-wise zero correlation window is presented. This method is based on a Hadamard matrix of size N×N and a pair of Hadamard matrices of size M×M. Compared with previous methods, the proposed sequence set has a group-wise zero correlation window for both periodic and aperiodic cross-correlation functions.     

关于零相关窗互补码理论界的几点讨论

提出了一类新型的零相关窗互补码，这类新型零相关窗互补码可以表示为三个独立的元素：一对相互正交的互补码、一个正交矩阵和一个标号矩阵的组合。本文重点讨论了这类新型零相关窗互补码的副峰平方之和的理论界，证明了几个重要的定理。这些定理包括：副峰的平方之和只是相对偏移的函数、零相关窗互补码集的一致性、列旋转不变性及列排列不变性等。这些定理对零相关窗互补码的设计具有重要的指导意义。     

一种全数字位同步检测算法

位同步检测是实现全数字接收机开环定时恢复的关键技术。本文推导了基带PAM(脉冲幅度调制)信号的互相关函数,指出基带PAM信号的互相关函数中含有位同步信息,以此为依据得到了一种位同步检测算法。该算法可采用递归结构实现,且与载波相位误差无关。     

A 3-D space vector modulation generalized algorithm for multilevel converters

A three-dimensional (3-D) space vector algorithm of multilevel converters for compensating harmonics and zero sequence in three-phase four-wire systems with neutral is presented. The low computational cost of the proposed method is always the same and it is independent of the number of levels of the converter. The conventional two-dimensional (2-D) space vector algorithms are particular cases of the proposed generalized modulation algorithm. In general, the presented algorithm is useful in systems with or without neutral, unbalanced load, triple harmonics and for generating 3-D control vectors.     

一类新的性能优异的伪随机序列——GMW相控序列

基于交错方法构造出了一类新的伪随机序列,称为GMW相控序列.给出了GMW相控序列的生成算法,证明了GMW相控序列均满足平衡性,具有优良的相关特性和极大的线性复杂度,可适用于CDMA扩频通信和保密通信系统中.     

Spectral factorization of random processes with multiplicity one

A fairly general treatment of the spectral factorization problem for scalar processes is presented. Necessary and sufficient conditions for the existence of a scalar dynamic system generating a given covariance function and equations whose solutions yield the system parameters are given. The processes considered are of second order with zero mean, Gaussian, and continuous in quadratic mean; initial conditions are relaxed.     

Universal noiseless coding

Universal coding is any asymptotically optimum method of block-to-block memoryless source coding for sources with unknown parameters. This paper considers noiseless coding for such sources, primarily in terms of variable-length coding, with performance measured as a function of the coding redundancy relative to the per-letter conditional source entropy given the unknown parameter. It is found that universal (i.e., zero redundancy) coding in a weighted sense is possible if and only if the per-letter average mutual information between the parameter space and the message space is zero. Universal coding is possible in a maximin sense if and only if the channel capacity between the two spaces is zero. Universal coding is possible in a minimax sense if and only if a probability mass function exists, independent of the unknown parameter, for which the relative entropy of the known conditional-probability mass-function is zero. Several examples are given to illustrate the ideas. Particular attention is given to sources that are stationary and ergodic for any fixed parameter although the whole ensemble is not. For such sources, weighted universal codes always exist if the alphabet is finite, or more generally if the entropy is finite. Minimax universal codes result if an additional entropy stability constraint is applied. A discussion of fixed-rate universal coding is also given briefly with performance measured by a probability of error.     

New Algorithms for Designing Unimodular Sequences With Good Correlation Properties

Unimodular (i.e., constant modulus) sequences with good autocorrelation properties are useful in several areas, including communications and radar. The integrated sidelobe level (ISL) of the correlation function is often used to express the goodness of the correlation properties of a given sequence. In this paper, we present several cyclic algorithms for the local minimization of ISL-related metrics. These cyclic algorithms can be initialized with a good existing sequence such as a Golomb sequence, a Frank sequence, or even a (pseudo)random sequence. To illustrate the performance of the proposed algorithms, we present a number of examples, including the design of sequences that have virtually zero autocorrelation sidelobes in a specified lag interval and of long sequences that could hardly be handled by means of other algorithms previously suggested in the literature.