The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 24, 2001
Filed:
Jun. 10, 1998
Shin'ichi Koike, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An adaptive filter which is realized as an FIR filter employing stochastic gradient algorithm comprises a step size controller for controlling step size &agr;,so as to minimize the mean squared estimation error &egr;,at each time n. The step size controller regards a step size &agr;,which satisfies &dgr;&egr;,/&dgr;&agr;,=0 at each time n as a theoretical optimum step size, and sets the step size &agr;,at each time n so as to be approximately equal to the theoretical optimum step size &agr;,. For example, when the adaptive filter employs stochastic gradient sign algorithm as the tap weight control algorithm, the step size controller provided with a leakage accumulator calculates a vector q,one by one according to the update equation: q,=(1−&rgr;)q,+&rgr;sgn(e,+&ugr;,)(|e,+&ugr;,|),a,(&rgr;: leakage coefficient, e,: an error signal sequence component, &ugr;,: an additive noise sequence component, a,: an input signal sequence vector), and sets the step size &agr;,at each time n as: &agr;,=&bgr;∥q,∥,(&bgr;=1.07870520/trace(Ra,), Ra=E[a,a,]). By the step size controller, both faster convergence of the adaptive filter and smaller residual mean squared estimation error after convergence can be attained.