共查询到18条相似文献,搜索用时 156 毫秒
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针对基于扩展信息最大化算法的盲源分离算法在分离超亚高斯混合信号时依赖于信号的峭度估计且对初始分离矩阵和步长较为敏感的问题,提出了一种基于遗传算法的盲源分离算法。该算法以分离信号之间的互信息作为代价函数,采用非多项式函数的逼近方法解决了互信息求解过程中涉及到的负熵的计算问题,用遗传算法代替梯度寻优算法最小化代价函数。仿真结果表明:在分离超亚高斯混合信号时,该算法计算简单,鲁棒性好,迭代100次时性能指数值达到0.025 5,分离性能优于基于扩展信息最大化算法的盲源分离算法。 相似文献
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基于SCS算法的盲自适应多用户检测器 总被引:2,自引:0,他引:2
提出了一种基于SCS(Soft-Constraint-Satisfaction)算法的盲自适应多用户检测器。基于SCS算法的盲自适应多用户检测器只需知道期望用户的扩频码及定时信息,而且通过自动选择用来估计期望信号的非线性函数,可以调节算法的收敛速度和估计误差。仿真实验表明该方法具有较好的抗多址干扰的能力。 相似文献
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空时分组码(STBC)通过使用发射分集策略和空时编码方案可以明显改善系统性能。然而,其接收端必须获得准确的信道状态信息(CSI)才能进行有效的信号检测。而对于复杂的无线通信环境,这种前提条件有时却难以得到满足。独立分量分析(ICA)是一种将一个复杂的数据集合分解为多个独立子集的盲源分离(BSS)技术。通常情况下,即使没有空间信道的任何信息,ICA也可以仅凭接收信号恢复出发射信号。提出了一种利用ICA技术的STBC盲信号检测方案,在建立了适用于ICA的特定通信系统模型后,几种典型的ICA算法被用来进行性能比较。理论分析表明,ICA盲接收技术的应用可以在一定程度上替代基于信道估计的传统方法,增强系统对信道估计错误的顽健性。仿真实验结合了具体的STBC系统,比较了基于ICA的不同方案的性能,并讨论了最优的信号检测方案。 相似文献
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A nonparametric density estimation method is used to directly estimate the score
functions encountered in relative gradient (or natural gradient) adaptation algorithms in
the blind source separation problem. Compared to the method where simple nonlinear
functions are used to replace the unknown score functions, the key advantage of the direct
estimation of the score functions lies in the fact that it enables the algorithm to separate
hybrid mixtures of sources that contain both super-Gaussian and sub-Gaussian signals. The
source statistics required for the choices of the nonlinear functions is no longer needed,
because the score functions are directly estimated. The algorithm is thus expected to be
applicable to more blind cases. 相似文献
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大多数的盲分离算法假设源信号峭度的正负性是己知的,并据此选择相应的非线性函数近似评价函数(score function)。针对源信号峭度的正负性未知的情况,本文提出了一个评价函数的参数估计方法,本算法能有效地分离混合在一起的超高斯信号和亚高斯信号,仿真结果验证了算法的有效性。 相似文献
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有效的自适应波达方向盲估计算法 总被引:5,自引:0,他引:5
本文在分析自适应信号盲分离算法渐近稳定性基础上,提出了一种有效的自适应学习算法用于波达方向盲估计。研究了算法的有界性和渐近稳定性。以渐近稳定性为前提,给出了算法中非线性函数的适当选择。为了抑制噪声和估计信源数,在算法中还增加了白化过程。仿真研究表明,算法是有效的而鲁棒的,其能够从有操声的阵元信号中估计波达方向。 相似文献
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This paper addresses the blind equalization problem for single-input multiple-output nonlinear channels, based on the second-order statistics (SOS) of the received signal. We consider the class of "linear in the parameters" channels, which can be seen as multiple-input systems in which the additional inputs are nonlinear functions of the signal of interest. These models include (but are not limited to) polynomial approximations of nonlinear systems. Although any SOS-based method can only identify the channel to within a mixing matrix (at best), sufficient conditions are given to ensure that the ambiguity is at a level that still allows for the computation of linear FIR equalizers from the received signal SOS, should such equalizers exist. These conditions involve only statistical characteristics of the input signal and the channel nonlinearities and can therefore be checked a priori. Based on these conditions, blind algorithms are developed for the computation of the linear equalizers. Simulation results show that these algorithms compare favorably with previous deterministic methods 相似文献
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In this paper, a new tensorial modeling is first proposed for nonlinear multiple-input multiple-output (MIMO) direct sequence spread spectrum communication systems. The channel is modeled as an instantaneous MIMO Volterra system. Then, a direct data approach for joint blind channel estimation and data recovery is developed using the parallel factor (PARAFAC) decomposition of a third-order tensor composed of received signals, exploiting space, time and code diversities. A blind channel estimation method based on the PARAFAC decomposition of a fifth-order tensor composed of covariances of the received signals is also proposed, considering phase shift keying (PSK) modulated transmitted signals. The proposed estimation algorithms are evaluated by simulating a nonlinear uplink MIMO radio over fiber (ROF) communication system. 相似文献
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Symbol spaced blind channel estimation methods are presented which can essentially use the results of any existing blind equalization method to provide a blind channel estimate of the channel. Blind equalizer's task is reduced to only phase equalization (or identification) as the channel autocorrelation is used to obtain the amplitude response of the channel. Hence, when coupled with simple algorithms such as the constant modulus algorithm (CMA) these methods at baud rate processing provide alternatives to blind channel estimation algorithms that use explicit higher order statistics (HOS) or second-order statistics (subspace) based fractionally-spaced/multichannel algorithms. The proposed methods use finite impulse response (FIR) filter linear receiver equalizer or matched filter receiver based infinite impulse response+FIR linear cascade equalizer configurations to obtain blind channel estimates. It is shown that the utilization of channel autocorrelation information together with blind phase identification of the CMA is very effective to obtain blind channel estimation. The idea of combining estimated channel autocorrelation with blind phase estimation can further be extended to improve the HOS based blind channel estimators in a way that the quality of estimates are improved. 相似文献
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Although the Newton algorithm has been extended to the complex domain in different forms, none of them seems to be directly applicable to blind equalization. Therefore, the objective of this correspondence is to develop an algorithm for blind equalization in the complex domain. We propose a Newton-like algorithm based on a complex Taylor series. Stochastic Newton-like algorithms (SNLA) for two blind equalization cost functions are developed. Simulations show that the new algorithms perform slightly better than the self-orthogonalizing algorithm 相似文献
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The linear mixing model has been considered previously in most of the researches which are devoted to the blind source separation (BSS) problem. In practice, a more realistic BSS mixing model should be the non-linear one. In this paper, we propose a non-linear BSS method, in which a two-layer perceptron network is employed as the separating system to separate sources from observed non-linear mixture signals. The learning rules for the parameters of the separating system are derived based on the minimum mutual information criterion with conjugate gradient algorithm. Instead of choosing a proper non-linear functions empirically, the adaptive kernel density estimation is used in order to estimate the probability density functions and their derivatives of the separated signals. As a result, the score function of the perceptron’s outputs can be estimated directly. Simulations show good performance of the proposed non-linear BSS algorithm. 相似文献