共查询到19条相似文献,搜索用时 468 毫秒
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赵艳丽 《电信工程技术与标准化》2013,(12):77-80
为了解决Gardner定时同步环路式样抖动较大的问题,对现有的各种式样抖动消减算法进行了归类研究,将其划分为算法修正类和波形预处理类两类,并分别从S曲线特性及定时抖动方差等性能对各类算法进行了理论和仿真分析,同时以修正的克拉美罗界(MCRB)作为衡量算法优劣的标准。最后简单总结了各类算法的实际应用场景及未来的研究方向。 相似文献
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本文提出以混沌吸引子作为水印信号的数字水印算法,由混沌吸引子生成的混沌水印信号具有类噪声特性,而其独特的分形自相似结构,及混沌动力学特性,使其作为水印信号比噪声类水印信号更具优良特性.文中以Lorenz混沌吸引子为例,对水印信号生成及检测算法进行了探讨.通过对混沌吸引子水印信号的主分量谱及其分形特性的分析,提出多种水印检测方案,可根据应用场合及攻击特点采用联合检测方法,以实现最优检测.实验给出混沌吸引子水印信号与高斯噪声类水印信号在同样条件下的抗攻击性能比较,实验结果表明,该算法性能上具有明显的优势. 相似文献
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文章以协作多点传输技术为背景,基于信道互异性模型,介绍了3类较为典型的校准算法:基于硬件检测的自校准方法、基于天线自检测反馈的自校准方法、基于校准天线检测反馈的互校准方法。以此为基础,文章分析和研究了各校准算法的特性,评估和仿真了各校准算法协作多点传输技术在各类联合预编码算法下的系统性能,同时预测了校准算法未来的研究进程及可能面临的挑战。 相似文献
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信噪比(SNR)估计是信道估计的重要组成部分,很多先进通信系统和信号处理方法都将信噪比作为先验信息,因此对信噪比估计方法的研究尤为重要。基于多进制相移键控(MPSK)信号模型,对最大似然类、矩估计类和空间分解类算法进行了性能分析和仿真。在一定条件下,上述算法的估计偏差在[0,20] dB区间内均小于1 dB,其中最大似然类算法估计精确度最高,但易受解调误码率影响;矩估计类算法在低信噪比时性能较好,高信噪比时易受算法自噪声影响;空间分解类算法适应性最强,但实时性较差。通过对上述算法一致性和差异性分析,总结了信噪比估计的研究进展和主要问题,明确了复杂调制信号宽范围信噪比估计和空间分解方法的研究方向,为后续研究提供了解决思路和改进措施。 相似文献
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针对数据量大、含有噪声、属性变量较多的数据集群,提出了一种基于消除噪声的聚类算法。该算法对数据进行分析及预处理,接着进行消除噪声处理,之后采用改进聚类算法对数据集进行聚类分析。在实验中,采用10 000条移动用户的手机数据,对通常的聚类方法和消除噪声后的改进聚类算法进行分析比较,发现改进后的算法效率更高、准确度也更好。根据聚类后的数据总结分析移动用户对新业务的使用情况,将有助于指导业务的开展。 相似文献
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对LMS类变步长自适应算法进行讨论和分类,通过仿真实验,分别对各类算法性能进行分析并得出各算法的优缺点。 相似文献
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智能天线自适应波束赋形算法的研究 总被引:1,自引:0,他引:1
智能天线作为3G及未来移动通信的核心技术,是当前通信领域的研究热点。阐述了智能天线的基本原理,并对自适应波束赋形算法进行了分类,较为详细地比较和分析了几种算法的特点及其适用条件。基于算法的现状,提出了未来的研究方向。 相似文献
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位同步技术是空间激光通信和测控一体化的关键技术之一,位同步的精确与否直接影响整个系统的性能。针对空间激光通信位同步技术中基于Gardner定时误差估计算法易受系统自噪声干扰,提出了一种自噪声抑制Gardner算法,同时基于此算法提出一种位同步环路。通过对算法理论分析与环路建模仿真结果表明,在Eb/N0大于9 dB情况下,提出自噪声抑制Gardner算法与位同步环路能够有效地降低同步过程中由于系统自噪声引起的定时抖动,并且拥有更快的位同步建立的时间。 相似文献
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For most symbol synchronizers operating on a PAM waveform corrupted by noise, the timing error consists of a noisedependent term and a data-dependent term. When the signal-to-noise ratio (SNR) is high, the data-dependent term, which is often called self-noise, dominates, and the timing error variance becomes independent of SNR. In this paper we present two types of symbol synchronizers for which self-noise is absent: the modified maximum-likelihood (MML) synchronizer and the minimum mean-square error (MMSE) synchronizer. As a consequence of the absence of self-noise, their timing error variances at high SNR are inversely proportional to the SNR. The performances of these synchronizers are evaluated and compared with the Cramér-Rao bound. 相似文献
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This paper investigates the performance of the digital symbol timing recovery schemes for 16QAM upstream transmission of the DOCSIS standard. Two forms of nonlinearity are considered: the magnitude square operation and the delay multiplication operation, both of which generate the output signal that contains the symbol timing information. The detailed analysis for the magnitude square timing recovery is given in the digital domain, and consequently the symbol timing estimate can be directly obtained by the discrete Fourier transform. The simulation results show that the magnitude square timing recovery and delay multiplication timing recovery algorithms suffer from the same problem that the estimation error is reduced slowly at high signal-to-noise ratios due to the effect of self-noise. To this end, the third scheme, which is the magnitude square timing recovery with prefilter, is examined. This scheme shows a superior performance and a comparison with the results of the other two schemes is made. 相似文献
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Data derived synchronization is plagued by self-noise arising from the randomness of the data stream. Experimental spectrum plots of the in-phase and quadrature self-noise components are given for various channel bandwidth and prefiltering conditions and different types of nonlinear devices. Results bring up features not covered by available theoretical analysis. 相似文献
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Quadrature amplitude-shift keying (QASK) is often used for transmitting two digital data streams in bandwidth-constrained communication systems. Previous analyses of the tracking performance of a decision-feedback carrier tracking loop, which can be used to provide a carrier reference for a QASK signal set, have neglected the effects of the self-noise in the derivation of the loop resonance. The authors incorporate the effects of the self-noise will only result in a conservative assessment of the system's performance, contrary to what might be expected. All results obtained are in closed form and can easily be evaluated numerically for performance prediction purposes 相似文献
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Dongmin Lim 《Communications, IEEE Transactions on》2004,52(10):1643-1647
In this letter, we propose a modified version of the Gardner detector for symbol timing recovery of M-ary phase-shift keying (M-PSK) signals. Simulation results show that the proposed modification leads to significant performance improvement when M-PSK signals are highly bandlimited and M is small. Specifically, the reduction in the level of self-noise due to the modification amounts to 10.7 dB for quaternary phase-shift keying signals with the rolloff factor of 0.25 and the normalized noise-equivalent loop bandwidth of 0.005. In terms of computational complexity involved, the proposed method has an advantage over the known self-noise reduction methods for M-PSK signals with small M. 相似文献