共查询到20条相似文献,搜索用时 171 毫秒
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用于跳频码分多址通信的混沌跳频序列 总被引:36,自引:2,他引:34
最近提出的混沌跳频序列具有均匀性、保密性好的优点,但存在较大的汉明相关值,本文给出了一种减小混沌跳频序列汉明相关值的方法,该方法的构造的跳频序列是帆努利随机序列,汉明相关函数服从Poisson分布,在跳频码分多址(FH/CDMA)系统中,,这种混沌跞频序列的系统容量与常规跳频序列基本相同。 相似文献
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Cunsheng Ding Fuji-Hara R. Fujiwara Y. Jimbo M. Mishima M. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(7):3297-3304
Frequency hopping spread spectrum and direct sequence spread spectrum are two main spread coding technologies in communication systems. Frequency hopping sequences are needed in frequency hopping code-division multiple-access (FH-CDMA) systems. In this paper, four algebraic and a combinatorial constructions of optimal sets of frequency hopping sequences with new parameters are presented, and a number of bounds on sets of frequency hopping sequences are described. 相似文献
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一种基于Logistic映射的混沌跳频序列 总被引:15,自引:2,他引:13
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. 相似文献
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Optimal frequency hopping sequences: a combinatorial approach 总被引:3,自引:0,他引:3
Fuji-Hara R. Ying Miao Mishima M. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2004,50(10):2408-2420
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. 相似文献
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A blind hopping phase estimator is proposed for the demodulation of received signals in frequency‐hopping spread spectrum systems. The received signals are assumed to be bandwidth limited with a shaping filter, modulated as frequency modulation (FM) or binary frequency shift keying (BFSK), and hopped by predetermined random frequency sequences. In the demodulation procedure in this paper, the hopping frequency tracking is accomplished by choosing a frequency component with maximum amplitude after taking a discrete Fourier transform, and the hopping phase estimator performs the conjugated product of two consecutive signals and moving‐average filtering. The probability density function and Cramer‐Rao low bound (CRLB) of the proposed estimator are evaluated. The proposed scheme not only is very simple to implement but also performs close to the CRLB in demodulating hopped FM/BFSK signals. 相似文献
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Maximal length sequences for frequency hopping 总被引:2,自引:0,他引:2
Normally, frequency hopping sequences for spread-spectrum communication systems are obtained by selecting groups of elements of binary m sequences. An alternative to using groups of binary m -sequence elements is developed. It involves obtaining nonbinary m sequences with the number of desired hopping frequencies equal to the number of symbols in the finite field which the nonbinary m sequence is over. The grouping of elements of binary m sequences does not necessarily have the m sequences. In addition, the autocorrelation function of the nonbinary m sequence has a maximal period, whereas the frequency hopping sequences obtained from the grouping of elements of binary m sequences may not have a maximal period 相似文献
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For the anti-jamming purpose, frequency hopping sequences are required to have a large linear span. In this paper, we firstly give the linear span of a class of optimal frequency hopping sequences. The results show that the linear span is very small compared with their periods. To improve the linear span, we transform these optimal frequency hopping sequences into new optimal frequency hopping sequences with large linear span by using a general type of permutation polynomials over a finite field. Furthermore, we give the exact values of the linear span of the transformed optimal frequency hopping sequences. 相似文献
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Udaya P. Siddiqi M.U. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1998,44(4):1492-1503
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 相似文献
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The cross-correlation of frequency hopping sequences obtained from non-binary m-sequences represented as vector m-sequences is developed. Preferred pairs of these vector m-sequences then yield vector or frequency hopping m-sequences which are shown to have small three-and four-level cross-correlation values. Modified preferred pairs are developed that yield frequency hopping m-sequences with reduced peak cross-correlation. 相似文献
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为提高跳频通信系统的被截获性能,该文以跳频周期和跳频间隔为研究对象,提出一种基于最大条件熵的跳频周期、跳频间隔射频隐身联合设计方法。该方法以跳频系统先验数据为样本空间,以拉格朗日乘子为优化粒子,利用混合混沌粒子群优化(HCPSO)算法对最大条件熵的对偶规划进行优化计算。与单阈值方法(STM)和双阈值方法(DTM)的对比仿真结果表明:该文提出的最大熵方法(MEM)具有最大的跳频周期、跳频间隔不确定性和最小的截获概率,且针对不同威胁因子具有较高的环境区分度。因此,MEM具有较好的射频隐身性能,可以有效提高搭载平台的生存能力。 相似文献
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Based on the idea of no hit zone (NHZ) in frequency hopping (FH) systems, new sequences with three no hit zones (T-NHZ) in
time-frequency hopping (TFH) systems are presented. With the T-NHZ in the time- frequency (TF) correlation functions, the
proposed T-NHZ sequences can be directly employed in time-frequency hopping code division multiple access (TFH-CDMA) communication
systems to reduce or eliminate multipath interference. Simulation results show that T-NHZ sequences can achieve much better
bit error performance than the NHZ sequences and the traditional FH sequences.
相似文献
Xianyang JiangEmail: |
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介绍了跳频通信原理及跳频通信具有的特点,并重点论述了跳频图案的设计、同步技术、频率合成技术、跳频组网及自适应跳频等跳频通信中的关键技术,总结了跳频技术的应用,分析了跳频技术的发展趋势. 相似文献
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An error probability bound for protocol sequences is derived for frame asynchronous access on a slow frequency hopping channel. This bound depends on the maximum and average cyclic Hamming correlation properties of the protocol sequences used. Constructions of protocol sequences with good cyclic correlation properties are given. 相似文献