Advances in Signal Processing 1(3): 37-43, 2013 http://www.hrpub.org
DOI: 10.13189/asp.2013.010301
A Novel Floating Point Fast Confluence Adaptive
Independent Component Analysis for Signal Processing
Applications
Jayasanthi Ranjith. M.E.
1
, NJR.Muniraj
2
1
Anna University, Tamil nadu,India
2
Principal,Tejaa Sakthi Institute of Technology for Women,Tamil Nadu, India
*Corresponding Author: mjayasanthi@yahoo.co.in
Copyright © 2013 Horizon Research Publishing All rights reserved.
Abstract Independent component analysis (ICA) is a
technique that separates the independent source signals from
their mixtures by minimizing the statistical dependence
between components. This paper presents a floating point
implementation of a novel fast confluence adaptive
independent component analysis (FCAICA) technique with
reduced number of iterations that provides the high
convergence speed. Fixed point ICA algorithms cover only
smaller range of numbers. To handle large as well as tiny
numbers and hence to improve the dynamic range of the
signal values,floating point operations are performed in ICA.
The high convergence speed is achieved by a novel
optimization scheme that adaptively changes the weight
vector based on the kurtosis value. To validate the
performance of the proposed FCAICA, simulation and
synthesis are performed with super-gaussian mixtures and
sub Gaussian mixtures and experimental results provided.
The proposed FCAICA processor separates the
super-Gaussian signals with a maximum operating
frequency of 2.91MHz with improved convergence speed.
Keywords Adaptive Independent Component Analysis,
Blind Source Separation, Contrast Function Optimization,
Field Programmable Gate Array, Floating Point Independent
Component Analysis, Very Large Scale Integration
1. Introduction
ICA, a statistical signal processing technique, is one of the
most commonly used algorithms in blind source separation.
The term “blind” means that both the original independent
sources and the way the sources were mixed are all unknown.
Estimates of the source signals are found only from the
observed signal mixtures. ICA recovers source signals from
their mixtures by finding a linear transformation that
maximizes the mutual independence or non-gaussianity of
the mixtures regardless of the probability distribution. It
plays an important role in a variety of signal processing,
image processing techniques and communication networks.
Though different ICA algorithms have been reported, the
FastICA algorithm has been shown to have advantages in
terms of convergence speed [1].It measures non-Gaussianity
using kurtosis to find the independent sources from their
mixtures [2]. Algebraic ICA Algorithm performs ICA by
solving simultaneous equations derived from the definition
of the independence. It works very fast for two sources
separation but it becomes extremely complex when the
number of sources goes more than two [3]. Infomax
Estimation is a desirable choice due to its asymptotic
optimality properties when the number of samples is large.
The simplest algorithm for maximizing the likelihood uses
stochastic gradient methods [4]. Maximum likelihood (ML)
estimation is based on the assumption that the unknown
parameters to be estimated are constants or no prior
information is available. Nonlinear Decorrelation Algorithm
has been proposed in order to reduce the computational
overhead and to improve stability [5]. Another approach to
ICA that is related to PCA is the non-linear method. Since
learning rule uses higher order information in the learning
when nonlinearities are introduced, this method indeed
performs ICA, if the data is whitened. Algorithms for exactly
maximizing the nonlinear PCA criteria are introduced in [6].
Simple algorithms are derived from the one-unit contrast
functions using the principle of stochastic gradient descent.
Hebbian like learning rule is obtained by taking the
instantaneous gradient of the contrast function with respect
to w[7] .Joint approximate diagonalization of eigenmatrices
(JADE) is based on the principle of computing several
cumulant Tensors. With low dimensional data, JADE is a
competitive alternative to more popular FastICA algorithms.
Other approaches include maximization of squared
cumulants [8] and fourth-order cumulant based methods
[9].Fourth-order blind identification (FOBI) method deals
with the Eigen value decomposition (EVD) of the weighted