混沌序列与一类基于移位寄存器的非线性序列的性能比较

混沌序列与一类基于移位寄存器的非线性序列非线性前馈逻辑(Non-Linear Feed-ForwardLogic,NLFFL)序列都具有非线性、宽带类噪声、大的码族、长的周期且容易产生的特性,通过对它们在产生方式、相关性能、多址性能以及抗相关攻击能力等方面进行分析和仿真研究,说明混沌序列与该类非线性序列在性能上总体相当,但对于短周期序列(N1023),混沌序列的抗相关攻击、抗干扰能力更强,因此更具有实用价值。     

The Construction of GOS Spreading Code Sets and Their Applications into Multi-Rate Multe-Cell QS-CDMA Systems

In this paper, a class of generalized orthogonal sequences (GOS) is presented with the the following characteristics, (1) the cross-correlations in the vicinity of zero shift (zero shift is excluded) between two arbitrary sequences from different GOS sets are zeros; (2) the cross-correlations in the vicinity of zero shift between two arbitrary sequences from different subsets of the same GOS set are zeros; and (3) two arbitrary different sequences from the same subset of the same GOS set are orthogonal. By applying the GOS sets to multi-rate multi-cell quasi-synchronous CDMA (QS-CDMA) system, the system interference is analyzed and compared with that of well-known concatenated orthogonal/PN sequence sets. It is shown that due to the zero correlation properties in the vicinity of zero shift, the interference of system employing GOS sets can achieve a bigger reduction than concatenated orthogonal/PN sequence sets, thus resulting better BER performance than that of latter under the same conditions.     

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     

Fibonacci and Galois representations of feedback-with-carry shiftregisters

A feedback-with-carry shift register (FCSR) with "Fibonacci" architecture is a shift register provided with a small amount of memory which is used in the feedback algorithm. Like the linear feedback shift register (LFSR), the FCSR provides a simple and predictable method for the fast generation of pseudorandom sequences with good statistical properties and large periods. In this paper, we describe and analyze an alternative architecture for the FCSR which is similar to the "Galois" architecture for the LFSR. The Galois architecture is more efficient than the Fibonacci architecture because the feedback computations are performed in parallel. We also describe the output sequences generated by the d-FCSR, a slight modification of the (Fibonacci) FCSR architecture in which the feedback bit is delayed for d clock cycles before being returned to the first cell of the shift register. We explain how these devices may be configured so as to generate sequences with large periods. We show that the d-FCSR also admits a more efficient "Galois" architecture     

Crosscorrelation properties of pseudorandom and related sequences

Binary maximal-length linear feedback shift register sequences (m-sequences) have been successfully employed in communications, navigation, and related systems over the past several years. For the early applications, m-sequences were used primarily because of their excellent periodic autocorrelation properties. For many of the recent systems applications, however, the crosscorrelation properties of such sequences are at least as important as the autocorrelation properties, and the system performance depends upon the aperiodic correlation in addition to the periodic correlation. This paper presents a survey of recent results and provides several new results on the periodic and aperiodic crosscorrelation functions for pairs of m-sequences and for pairs of related (but not maximal-length) binary shift register sequences. Also included are several recent results on correlation for complex-valued sequences as well as identities relating the crosscorrelation functions to autocorrelation functions. Examples of problems in spread-spectrum communications are employed to motivate the choice of correlation parameters that are considered in the paper.     

CCS-FOSSIL and dual-channel system that increases channel capacity per dynamic power range

We design a forest with nodes that represent orthogonal variable spreading factor (OVSF) sequences of different lengths (spreading codes of different lengths that can be used for multi-rate DS-CDMA). In addition to the non-descendant OVSF property exhibited in well-known tree-structured generation of sequences [(F. Adachi, et al., 1997) and (E.H. Dinan and B. Jabbari, 1998)], the sequences represented by the nodes of our forest have useful properties that can be used to achieve multi-channel communication (with a sequence providing a channel) with a lower total peak-to-mean envelope power ratio (PMEPR). These OSVF sequences grouped by our forest structure also have properties that facilitate symbol-by-symbol adaptation of the symbol duration in multi-rate CDMA systems. For example, certain lineages in the forest have the property that any pair of code sequences in the same lineage are shift orthogonal to each other, with the unit shift length being that of the shorter sequence. We present the forest-structured generation of the sequences (spreading codes) and their properties.     

GF(p)上钟控序列

本文利用有限域GF(p)(p2为素数,1为正整数)上二次特征建立了GF(p)上一类互钟控序列,即LSRg[d0,d1,d2]-互钟控序列。讨论了当用作移位时钟控制的前馈函数g(x1,x2,,xn)为二次型时,LSRg[d0,d1,d2]-互钟控序列的周期和线性复杂度的特点。     

Combinational logicfree realisations for high-speed m-sequence generation

A combinational logicfree F.S.R. construction is specified which allows the high speed generation of m-sequences. These constructions are based on characteristic polynomials of the form (1 ? x)q ? xp and they can be designed so as to produce sequences based on primitive trinomial recurrences of the form xn = xn?q ? xn?p at a rate q times as fast as the basic shift pulse rate.     

Information sources using chaotic dynamics

A sequence of binary random variables has found significant applications in modem digital communication systems. For such sequences, several kinds of linear feedback shift register sequences have been proposed. It is, however, well known in probability theory that the Bernoulli shift is a fundamental theoretic model of a sequence of independent identically distributed (i.i.d.) binary random variables. In this paper after reviewing fundamental subjects of chaotic dynamics, in particular a close relationship between information sources and Markov chains, we give the generation method of sequences of i.i.d. binary random variables using chaotic dynamics. Such a generation method is given as a sufficient condition composed of simple symmetric properties for some class of ergodic maps. Furthermore, we give the applications of such sequences: (1) to running-key sequences for stream cipher systems and (2) to a color image communication system through code-division multiple access channels and its extended version, a digital watermarking system. In addition, the performance of spread spectrum codes generated by a Markov chain is theoretically evaluated in asynchronous direct-sequence/code-division multiple access systems     

交织法构造移位不等价的ZCZ/LCZ序列集

本文给出了移位不等价序列集的概念,提出一种移位序列构造方法,并基于这种移位序列,利用交织法得到了多个移位不等价的低零相关区序列集.同以前方法相比扩展了序列集的数量,可以为准同步CDMA通信系统提供更多的扩频序列.通过本文方法还可以利用任意长度的完备序列来构造相互正交的零相关区序列集,放宽了对完备序列长度的限制,从而可以...     

基于混沌和CNN交错反馈产生扩频序列的性能分析

提出了一种基于细胞神经网络和混沌交错反馈产生扩频序列的设计方法,用计算机仿真对该混沌扩频序列的平衡特性、游程特性、位移特性、相关特性和线性复杂度等伪随机特性进行了系统的分析,并分析了该序列的奇/偶相关特性.结果表明,该混沌扩频序列具有理想的伪随机特性,可以作为扩频通信中的扩频码,同时系统的交错加强了通信的保密性.     

New designs for signal sets with low cross correlation, balanceproperty, and large linear span: GF(p) case

New designs for families of sequences over GF(p) with low cross correlation, balance property, and large linear span are presented. The key idea of the new designs is to use short p-ary sequences of period υ with the two-level autocorrelation function together with the interleaved structure to construct a set of long sequences with the desired properties. The resulting sequences are interleaved sequences of period υ². There are υ cyclically shift distinct sequences in each family. The maximal correlation value is 2υ + 3 which is optimal with respect to the Welch bound. Each sequence in the family is balanced and has large linear span. In particular, for binary case, cross/out-of-phase autocorrelation values belong to the set {1, -υ, υ + 2, 2υ + 3, -2υ - 1}, any sequence where the short sequences are quadratic residue sequences achieves the maximal linear span. It is shown that some families of these sequences can be implemented efficiently in both hardware and software     

Application of Zero Correlation Zone Sequences in Quasi-synchronous CDMA Systems

In a quasi-synchronous code division multiple access （QS-CDMA） system, the correlation functions around the origin influence the system performance and odd functions are as important as the even functions. Three kinds of zero correlation zone（ZCZ） sequences are used to analyze and compare the correlation functions. Binary phase shift keying（BPSK） simulations of QS-CDMA system with the three kinds of QS sequences as spreading codes on additive white Gaussian noise（AWGN） channel show that these sequences are quasi-orthogonal, so they are suitable for QS-CDMA system. The correlation between the system performance and the zero correlation zone of the sequence is also proved.     

An analysis of the structure and complexity of nonlinear binary sequence generators

A method of analysis is presented for the class of binary sequence generators employing linear feedback shift registers with nonlinear feed-forward operations. This class is of special interest because the generators are capable of producing very long "unpredictable" sequences. The period of the sequence is determined by the linear feedback connections, and the portion of the total period needed to predict the remainder is determined by the nonlinear feed-forward operations. The linear feedback shift registers are represented in terms of the roots of their characteristic equations in a finite field, and it is shown that nonlinear operations inject additional roots into the representation. The number of roots required to represent a generator is a measure of its complexity, and is equal to the length (number of stages) of the shortest linear feedback shift register that produces the same sequence. The analysis procedure can be applied to any arbitrary combination of binary shift register generators, and is also applicable to the synthesis of complex generators having desired properties. Although the discussion in this paper is limited to binary sequences, the analysis is easily extended to similar devices that generate sequences with members in any finite field.     

交织法构造最佳或几乎最佳低零相关区序列集

该文提出一种新的移位序列的构造方法,通过给移位序列赋予不同的值,得到一类新的移位序列。基于这种移位序列,利用交织法得到了一类具有灵活相关区长度并且参数接近甚至达到理论界限的低零相关区序列集,扩大了交织法的应用范围,得到了更多的适用于准同步CDMA系统的扩频序列集。     

Minimal linear equivalent analysis of a variable-memory binarysequence generator

Starting from a memory-based nonlinear generator due to P.R. Geffe (1973), a binary sequence generator (MEM-BSG), consisting of three linear feedback shift registers and a variable memory, is defined and analyzed. The MEM-BSG is shown to be convenient for generating fast binary sequences of large period and linear complexity, which may be useful in spread-spectrum and cryptographic applications     

Pseudo noise sequences for engineers

Pseudo random binary sequences (PRBSs), also known as pseudo noise (PN), linear feedback shift register (LFSR) sequences or maximal length binary sequences (m-sequences) are widely used in digital communications and the theory involved has been treated extensively in the literature. However, a practising engineer is interested in the fundamentals and the applications of PN sequences, and the methods of generating them with hardware. This paper presents, without the mathematical rigours, some of the interesting characteristics and the use of these characteristics in the generation and acquisition of PN sequences. The series-parallel method of generating PN sequences at high speeds with low-speed devices, which is of interest to hardware designers, is discussed. Some applications of PN sequences in communications and instrumentation are discussed     

一种具有大线性复杂度伪随机序列的构造

 本文提出了一种具有大线性复杂度、低相关性能和序列数目多的新伪随机序列构造方案.这种设计的关键之处在于利用移位序列分析法在理论上对相控序列进行改进,使用交织序列做基础序列代替原来的理想自相关序列,再利用具有理想自相关性的序列和相应的移位序列一起得到新伪随机序列.本文对其相关性能进行了分析,其最大值满足Welch界的要求;新序列的线性复杂度比现有的任意序列都要大;得到的新序列族中的序列有些是平衡的,族的数目和每一族中序列的数目都要多于现有的任意序列.     

Frequency hopping sequences with optimal partial autocorrelation properties

We classify some p/sup k/-ary (p prime, k integer) generalized m-sequences and generalized Gordon-Mills-Welch (GMW) sequences of period p/sup 2k/-1 over a residue class ring R=GF(p)[/spl xi/]/(/spl xi//sup k/) having optimal partial Hamming autocorrelation properties. In frequency hopping (FH) spread-spectrum systems, these sequences are useful for synchronizing process. Suppose, for example, that a transmitting p/sup k/-ary FH patterns of period p/sup 2k/-1 are correlated at a receiver. Usually, the length of a correlation window, denoted by L, is shorter than the pattern's overall period. In that case, the maximum value of the out-of-phase Hamming autocorrelation is lower-bounded by /spl lceil/L/p/sup k/+1/spl rceil/ but the classified sequences achieve this bound with equality for any positive integer L.