基于混沌的无线跳频通信技术

本文针对跳频通信以及混沌的的特点,研究了混沌跳频序列在跳频通信中的应用,建立了一种混沌序列模型,并对其产生的混沌跳频序列在以无线通信模块SHN2401为核心的家居跳频通信系统进行仿真研究.通过仿真表明该模型产生的混沌跳频序列在抗干扰和通信安全性方面具有良好的效果.     

基于一种特定混沌映射的跳频序列

使用一种简单的分段线性映射构造混沌跳频序列。用于跳频通信中取代传统的伪随机序列（PN序列），分析了此混沌序列的周期性。平衡性，汉明相关特性和线性间隔，最后给出了混沌序列的神经网络实现。仿真和实验结果表明，此序列具有较好的统计特性。应用于跳频多址通信中，可获得较好的抗干扰。抗截获能力。     

MIMO跳频通信系统及其序列设计

在跳频通信系统中应用MIMO技术可以进一步提高数据传输速率和频谱利用率,但是多用户跳频通信系统还受到多址干扰和多径干扰的影响.本文提出一种T-NHZ时频序列的构造方法,应用到MIMO跳频系统中以消除多址干扰和多径干扰,同时由于这种序列的数目较大,有利于进一步提高系统容量.     

一种新的混沌跳频序列设计方法

为了增强跳频通信系统的保密性和安全性,基于Logistic映射和Hybird映射方法的组合,采用相邻组合的方法来产生混沌跳频序列.仿真检测了包括初始敏感性、平衡性、汉明相关性在内的系统性能,结果表明:新跳频序列能够很好地克服有限精度效应,初始敏感性高,汉明相关性好,并具有较高的平衡性能.     

一种基于Logistic映射的混沌跳频序列

基于Logistic映射,提出了一种产生混沌跳频序列的新方法.该方法是先对Logistic映射的轨道点进行多值量化,然后利用比特抽取产生所需的混沌跳频序列.性能分析和数值实验表明,在相同的条件下(频率数目和序列长度相同),其平衡性、跳频间隔和最大汉明相关值与其它方法产生的混沌跳频序列相当,然而其所需的迭代次数却大大减少了,因此非常适合在跳频多址通信中应用.     

基于区间二级划分动态量化宽间隔混沌跳频序列

文章基于对混沌映射区间的二级划分，提出了一种采用旋轮策略动态量化宽间隔混沌跳频序列生成方案。新方案可有效地增加混沌跳频序列的抗重构破译能力。通过对新方案及其它混沌宽间隔跳频序列生成方案比较，结果表明：该方法速度快，生成的跳频序列具有优良的多址性能。     

跳频码分多址系统中混沌跳频序列的优选与仿真

根据跳频码分多址系统的特点，总结了跳频序列的性能分析准则，并据此提出了混沌跳频序列的优选方法。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跳频序列组。与改进型Lempel—Greenberger(L-G)序列相比，优选混沌跳频序列数目多，完全消除频隙滞留现象，而且平均汉明相关特性与之非常接近。为了验证优选混沌序列的性能，在AWGN信道下在跳频异步码分多址系统中进行了仿真，结果证明优选混沌序列的抗多址干扰能力逼近改进型L-G序列。     

用于跳频多址通信的混沌跳频码

跳频码的性能对跳频多址通信起着关键性作用。设计具有良好汉明相关和随机性且数量多的跳频码是非常重要的。本文提出一种利用由混沌映射描述的离散混沌系统设计跳频码的新方法。首先由混沌映射产生混沌时间序列，然后利用量化技术对混沌时间序列进行量化，最后由量化后的混沌时间序列产生伪随机跳频码。为了增大混沌跳频码的周期和非线性复杂度，我们利用多个不同混沌映射组成一个级联混沌映射，并用来设计跳频码。实验表明，混沌跳频码具有非常好的性能。     

超混沌序列对DS-UWB多址性能的改善

利用Roessler超混沌系统构造了一种新的超混沌序列,分析了序列的相关特性,并将其应用于直接序列超宽带（DS—UWB）系统中,以提高它的误码性能。建立了DS-UWB通信系统的模型,以超混沌序列作地址码对高斯白噪声信道中多用户DS—UWB系统误码率进行了分析,并将其与m序列作地址码时的相应性能进行了比较。由分析和仿真可知,构造的新的超混沌序列能较好地改善DS-UWB的多址性能。     

一类混沌跳频序列的性能分析

对一类基于混沌映射,由混沌轨道多值量化和比特抽取相结合产生的跳频序列进行了性能分析。理论分析和统计性能实验表明,该方法构造的跳频序列是贝努利随机序列,其汉明相关函数服从泊松分布。在相同的条件下(频率数目和序列长度相同),其均匀分布性、汉明相关值和线性复杂度与其它方法产生的混沌跳频序列相当,然而其所需的迭代次数却大大减少,从而能够产生更多的跳频序列,非常适合在跳频多址通信中应用。     

Theoretical Bounds and Practical Constructions for Families of One—Coincidence Sequences in FHMA

Theoretical bounds are given for the number of one-coincidence sequences in syn-chronous FHMA systems,and for the number and period of one-coincidence sequences in asyn-chronous FHMA systems.Several practical constructions for families of one-coincidencesequences are surveyed,and a new model for families of one-coincidence sequences is presented.     

Theoretical Bounds and Practical Constructions for Families of One－Coincidence Sequences in FHMA

ＴｈｅｏｒｅｔｉｃａｌＢｏｕｎｄｓａｎｄＰｒａｃｔｉｃａｌＣｏｎｓｔｒｕｃｔｉｏｎｓｆｏｒＦａｍｉｌｉｅｓｏｆＯｎｅ－ＣｏｉｎｃｉｄｅｎｃｅＳｅｑｕｅｎｃｅｓｉｎＦＨＭＡＭｅｉＷｅｎｈｕａ；ＹａｎｇＹｉｘｉａｎ（ＢｅｉｊｉｎｇＡｅｒｏｎａｕｔｉｃａｌ...     

基于分组密码的跳频序列多址接入性能分析

基于3DES迭代型分组密码产生的跳频序列,构造了一种跳频组网的随机多址接入方案模型。在此基础上分析了跳频码分多址的系统接入性能,从理论上推导出跳频图案碰撞引起的误分组率、跳频组网的吞吐量和归一化吞吐率,证明数据分组长度M与可用频隙数q的比值是决定跳频码分多址系统性能的重要因素。计算机仿真结果验证了理论的正确性,同时也证明了基于分组密码的跳频序列具有较好的跳频多址组网性能。     

基于分组密码的跳频序列族构造

基于迭代型分组密码的理论体系,本文从工程实现的角度提出了一种用于跳频码分多址通信系统的新型跳频序列族构造方法.该算法基于密码学的加密机制,具有好的安全性和高的计算复杂度;算法的设计遵循了密码学的"混淆"和"扩散"准则,生成序列具有各项优异的性能指标.本文从安全性、随机性、均匀性、复杂度、组网特性及跳频间隔特性等各方面对产生的跳频序列进行了全面的理论分析,证明该算法具有理想的综合系统性能指标.在此基础上,利用VHDL语言设计并开发出相应的跳频加密芯片.经测试其性能稳定、运算速度快、输入方式灵活多样,已应用于实际的高速跳频通信系统中.     

Analysis of FHMA performance on block cipher based frequency-hopping sequences

Based on the triple Data Encryption Standard (DES) block cipher frequency-hopping (FH) sequences, a kind of packet protocol for frequency-hopping multiple-access (FHMA) network is suggested in this paper. In theory, the performances of both the packet error and the throughput are derived, which shows that the ratio of the packet length M to the frequency slots number q is most key parameter to determine the FHMA system performance under the condition of large user number. Computer simulation results of 3-DES FH sequences compared with those of the chaotic FH sequences are also included to support our developments.     

Optimal frequency hopping sequences: a combinatorial approach

Frequency hopping multiple access (FHMA) spread-spectrum communication systems employing multiple frequency-shift keying (MFSK) as data modulation technique are investigated from a combinatorial approach. A correspondence between optimal frequency hopping (FH) sequences and partition-type difference packings is first established. By virtue of this correspondence, FHMA systems with a single optimal FH sequence each are constructed from various combinatorial structures such as affine geometries, cyclic designs, and difference families. Combinatorial recursive constructions are also presented. Many new infinite series of optimal FH sequences are thus obtained. These new FH sequences are also useful in ultra wideband (UWB) communication systems.     

Optimal large linear complexity frequency hopping patterns derivedfrom polynomial residue class rings

We construct new sequences over finite rings having optimal Hamming correlation properties. These sequences are useful in frequency hopping multiple-access (FHMA) spread-spectrum communication systems. Our constructions can be classified into linear and nonlinear categories, both giving optimal Hamming correlations according to Lempel-Greenberger (1974) bound. The nonlinear sequences have large linear complexity and can be seen as a generalized version of GMW sequences over fields     

Performance of one-hop/symbol FHMA for cellular mobilecommunications

This paper is concerned with the bit-error rate (BER) performance of a cellular one-hop/symbol frequency-hopping multiple-access (FHMA) system operating through a multipath Rayleigh fading channel. M-ary frequency shift keying modulation with noncoherent square-law envelope demodulation and Reed-Solomon (RS) coding is considered. The multiple-access and adjacent cell interference of the cellular FHMA system has been studied. In order to illustrate how sensitive both systems are to the near/far problem, performance of the FHMA system is compared with that of a direct-sequence code-division multiple-access system for an equal system bandwidth. Also, this paper investigates the effect of the values of frequency reuse factor (N) on the system capacity of the cellular frequency-hopping system     

跳频序列设计理论的研究进展

跳频技术具有抗干扰和多址组网性能，在军事无线电通信、民用移动通信、现代雷达和声纳等电子系统中具有重要的应用。跳频序列用于控制载波频率随机时间的变化规律，其性能对跳频系统的性能有重大影响。本文综述跳频序列设计理论的研究成果，并指出今后的发展方向。     

Frequency-hopped multiple-access communications with multicarrier on-off keying in Rayleigh fading channels

We propose the multicarrier on-off keying (MC-OOK) as a bandwidth-efficient modulation method for frequency-hopped multiple-access (FHMA) communications. The motivation for using MC-OOK is that a more bandwidth-efficient modulation scheme allows a larger number of frequency slots, and thus provides a higher immunity against multiple-access interference in FHMA systems. We analyze the average bit-error probability in slow frequency-nonselective Rayleigh fading channels with background noise. We find that the capacity gain that MC-OOK/FHMA system provides over the MFSK/FHMA system in an interference-limited region is more than 2.5 when the modulation alphabet size M is 8, and even a higher capacity gain can be obtained with a larger M.