Blind source separation based on generalized gaussian model
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Journal ofHarbin Institute of Technology(New Series),Vo1.14,No.3,2007 Blind source separation based on general ̄ed gaussian model YANG Bin ,KONG Wei ,ZHOU Yue 杨斌, 孔薇, 周越 (1.Information Engineering College of Shanghai Maritime University,Shanghai 200135,China; 2.Institute of Image Processing&Pattern Recognition。Shanghai Jiaotong University,Shanghai 200030。China)
Abstract:Since in most blind source separation(BSS)algorithms the estimations of probability density func・ tion(pdf)of sources are fixed or can only switch between one sup.Gaussian and other sub.Gaussian model, they may not be efficient to separate sources with diferent distributions.So to solve the problem of paf mismatch and the separation of hybrid mixture in BSS,the generalized Gaussian model(GGM)is introduced to model the pdf of the sources since it can provide a general structure of univariate distributions.Its great advantage is that only one parameter needs to be determined in modeling the paf of diferent sources.so it is less complex than Gaussian mixture mode1.By using maximum likelihood(ML)approach,the convergence of the proposed algo・ rithm is improved.The computer simulations show that it is more efficient and valid than conventional methods with fixed paf estimation. Key words:blind source separation;Independent Component Analysis;Generalized Gaussian Model;Maxi・ mum I ikelihood CLC nmber:TP911
Blind source separation(BSS)in signal process— ing has received considerable attention from many re— searchers.It is a fundamental problem in signal pro— cessing with a large number of extremely diverse appli— cations such as multi-user communications,speech sig・ nal processing,array processing and medical signal processing including ECG,MEG and EEG. BSS algorithms for tuning the de—mixing matrix are mainly based on Comon’s ICA【l j(Independent Compo— nent Analysis)theory.The idea is to find the de—mixing matrix so that all the components of the output ale mutu— allv independent.The success of ICA on problems such as BSS and signal analysis results directly from its ability to model the underlying statistical distribution of data.If the source distributions are assumed to be Gaussian.the technique is equivalent to pn‘ncipal component analysis (PCA).In contrast.ICA assumes that the source distri— butions are non.Gaussian.In many ICA algorithms, however.the model of the source distribution iS fixed. Much recent work has been extended so that the form of distribution can be inferred from the source data L2-4]. for example,using Gaussian mixture model or mixtures of predefined sub.Gaussian and super—Gaussian mode1. In this paper,we are interested in modeling difer- ent statistical structures of sources.The generalized Gaussian model(GGM)was proposed here to model the underlying statistical structure of sources.It pro— vides a general method of modeling univariate distribu— tions that have the simply form written as P( )oC Article ID:105 ̄113(2007)03-0362-06 exp(-I ).By inferring q,a wide class of statistical distributions can be characterized including Gaussian, Laplacian.super-Gaussian and sub—Gaussian distribu— tions by putting q 2,q 1,q<2 and q>2 respec— tively.Using GGM in ICA.we show that it can be eas. ily used to infer the degree of non.Gaussian statistical structure for sources with diferent distributions.To a— chieve this proposed ICA algorithm,m ̄imum likeli— hood(MI )approach is used as cost function to get the statistically independent output components from the mixture observations.At the same time the natural gra— dient descent is introduced to speed convergence.Two computer simulations demonstrate that the ICA algo. rithm based on GGM can not only separate homogene— OUS mixtures but also hybrid mixtures which consist of sub—Gaussian and super-Gausssian signals.
1 ICA Based on PDF Estimation The famous infomax learning rule proposed by Bell and Sejnowski L2 J(1995)is well used in blind separa— ting speech and music signals.Because the chosen lo— gistic function pdf is rough estimate for distributions of speech and music signals.But when there is a mis— match between the real source pdf and the logistic func— tion IC・df the infomax will fail to separate signals. On the other hand,since there are no suitable nonlinearities that are available for both sub.Gaussian and super—Gaussian signals,the BSS algorithms with
Received 2OO4—03一l4. Sponsored by the Foundation of CSSC(Grant No.03J3.4.3)and the 863 Hi—tech Research and Development Program of China(No.2006AA09Z210)