This paper investigates the processing techniques for non-linear high power amplifiers (HPA) using neural networks (NNs). Several applications are presented: Identification and Predistortion of the HPA. Various Neural...
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This paper investigates the processing techniques for non-linear high power amplifiers (HPA) using neural networks (NNs). Several applications are presented: Identification and Predistortion of the HPA. Various Neural Network structures are proposed to identify and predistort the HPA. Since a few decades, NNs have shown excellent performance in solving complex problems (like classification, recognition, etc.) but usually they suffer from slow convergence speed. Here, we propose to use the naturalgradient instead of the classical ordinary gradient in order to enhance the convergence properties. Results are presented concerning identification and predistortion using classical and naturalgradient. Practical implementations issues are given at the end of the paper. Copyright (C) 2002 John Wiley Sons, Ltd.
In this paper, we use natural gradient algorithm to control the shape of the conditional output probability density function for the stochastic distribution systems from the viewpoint of information geometry. The cons...
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In this paper, we use natural gradient algorithm to control the shape of the conditional output probability density function for the stochastic distribution systems from the viewpoint of information geometry. The considered system here is of multi-input and single output with an output feedback and a stochastic noise. Based on the assumption that the probability density function of the stochastic noise is known, we obtain the conditional output probability density function whose shape is only determined by the control input vector under the condition that the output feedback is known at any sample time. The set of all the conditional output probability density functions forms a statistical manifold (M), and the control input vector and the output feedback are considered as the coordinate system. The Kullback divergence acts as the distance between the conditional output probability density function and the target probability density function. Thus, an iterative formula for the control input vector is proposed in the sense of information geometry. Meanwhile, we consider the convergence of the presented algorithm. At last, an illustrative example is utilized to demonstrate the effectiveness of the algorithm. (c) 2013 Elsevier B.V. All rights reserved.
A new approach to blind source separation of cyclostationary sources is introduced which incorporates a cyclic pre-whitening operation within the teaming rule, and thereby provides a new member of the family of natura...
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A new approach to blind source separation of cyclostationary sources is introduced which incorporates a cyclic pre-whitening operation within the teaming rule, and thereby provides a new member of the family of natural gradient algorithms. The technique improves the convergence properties of the natural gradient algorithm for complex valued, cyclostationary signals. Simulations show the improved convergence speed of the approach.
Blind source separation has become a dominant domain of artificial neural network. It attempts to recover unknown independent sources from a given set of observed mixtures. The natural gradient algorithm is a very imp...
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ISBN:
(纸本)1424400600
Blind source separation has become a dominant domain of artificial neural network. It attempts to recover unknown independent sources from a given set of observed mixtures. The natural gradient algorithm is a very important approach for blind source separation (BSS). The selection of activation function is the key to the algorithm. The aim of this paper is to investigate the blind source separation of a linear mixture of independent communication signals by using the natural gradient algorithm. We compare various activation functions for the algorithm and propose a better one. Simulation results not only demonstrate the algorithm can effectively separate the two kinds of random mixing signals, but also show that the algorithm with proposed activation function converges faster than other activation functions.
This paper provides a novel knowledge-increasable artificial neural network model and learns parameters by using probability model. Conventional gradientalgorithm is normally adopted to learn parameters in KI network...
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ISBN:
(纸本)7900081585
This paper provides a novel knowledge-increasable artificial neural network model and learns parameters by using probability model. Conventional gradientalgorithm is normally adopted to learn parameters in KI network, but its performance isn't the best This paper uses the natural gradient algorithm that takes the Riemannian metric of parameter space to define the parameters. This method can adaptively modify the parameters based on Riemannian metric and achieve the approximate best performance.
Blind source separation has become a dominant domain of artificial neural network. It attempts to recover unknown independent sources from a given set of observed mixtures. The natural gradient algorithm is a very imp...
详细信息
Blind source separation has become a dominant domain of artificial neural network. It attempts to recover unknown independent sources from a given set of observed mixtures. The natural gradient algorithm is a very important approach for blind source separation (BSS). The selection of activation function is the key to the algorithm. The aim of this paper is to investigate the blind source separation of a linear mixture of independent communication signals by using the natural gradient algorithm. We compare various activation functions for the algorithm and propose a better one. Simulation results not only demonstrate the algorithm can effectively separate the two kinds of random mixing signals, but also show that the algorithm with proposed activation function converges faster than other activation functions.
The natural gradient algorithm is the most basic independent component analysis (ICA) algorithm. Because the traditional natural gradient algorithm adopts fixed-step-size, the choice of step size directly affects the ...
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ISBN:
(纸本)9781424467129
The natural gradient algorithm is the most basic independent component analysis (ICA) algorithm. Because the traditional natural gradient algorithm adopts fixed-step-size, the choice of step size directly affects the convergence speed and steadystate performance. This paper proposes an improved natural gradient algorithm by using the difference between the separation matrixes to control the factor of step size. The algorithm is a good solution to the trade-offs problems of convergence speed and steady-state performance. Meanwhile, the complexity of the algorithm is lower than the algorithm of reference [2] and reference [11]. The computer simulations have proved the effectiveness of the algorithm.
This paper provides a novel knowledge-increasable artificial neural network model and learns parameters by using probability *** gradientalgorithm is normally adopted to learn parameters in KI network,but its perform...
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This paper provides a novel knowledge-increasable artificial neural network model and learns parameters by using probability *** gradientalgorithm is normally adopted to learn parameters in KI network,but its performance isn't the *** paper uses the natural gradient algorithm that takes the Riemannian metric of parameter space to define the *** method can adaptively modify the parameters based on Riemannian metric and achieve the approximate best performance.
This paper describes a novel modification to the well-known naturalgradient or INFOMAX algorithm for blind source separation that largely mitigates its divergence problems. The modified algorithm imposes an a posteri...
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ISBN:
(纸本)1424407281
This paper describes a novel modification to the well-known naturalgradient or INFOMAX algorithm for blind source separation that largely mitigates its divergence problems. The modified algorithm imposes an a posteriori scalar gradient constraint that adds little computational complexity to the algorithm and exhibits fast convergence and excellent performance for fixed step size values that are largely independent of input signal magnitudes and initial separation matrix estimates. Evaluation of the approach for the separation of instantaneous and convolutive source mixtures using both time-and frequency-domain implementations shows its excellent separation behavior.
In this paper, the Riemannian gradientalgorithm and the natural gradient algorithm are applied to solve descent direction problems on the manifold of positive definite Hermitian matrices, where the geodesic distance ...
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In this paper, the Riemannian gradientalgorithm and the natural gradient algorithm are applied to solve descent direction problems on the manifold of positive definite Hermitian matrices, where the geodesic distance is considered as the objective function. The first proposed problem is the control for positive definite Hermitian matrix systems whose outputs only depend on their inputs. The geodesic distance is adopted as the difference of the output matrix and the target matrix. The controller to adjust the input is obtained such that the output matrix is as close as possible to the target matrix. We show the trajectory of the control input on the manifold using the Riemannian gradientalgorithm. The second application is to compute the Karcher mean of a finite set of given Toeplitz positive definite Hermitian matrices, which is defined as the minimizer of the sum of geodesic distances. To obtain more efficient iterative algorithm than traditional ones, a natural gradient algorithm is proposed to compute the Karcher mean. Illustrative simulations are provided to show the computational behavior of the proposed algorithms.
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