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. 10, 2007
Filed:
Feb. 19, 2001
Janne Väänänen, Espoo, FI;
Janne Väänänen, Espoo, FI;
Tellabs Oy, Espoo, FI;
Abstract
The invention relates to implementing a training phase of adaptive channel equalization on a digital communications path using QAM- or CAP-modulation method and comprising at least one band-stop filter that forms a stop band on a the signal spectrum. Training of adaptive equalizers is performed utilizing a sparse symbol constellation, wherein a number of symbol states (S) is smaller than that of a symbol constellation used in a normal data transmission state. The benefit of the sparse symbol constellation is that a strong intersymbol interference caused by the stop band can thus be reduced to such a low level in regard to a signal power that a linear equalizer may be used to reach a situation, wherein a proportion of correct symbol decisions becomes sufficiently high for training of a decision-feedback equalizer.