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. 09, 2002
Filed:
May. 27, 1998
Christine J. Morrison, Decatur, GA (US);
Errol Reiss, Chamblee, GA (US);
Liliana Aidorevich, Maracay Edo Aragua, VE;
Jong Soo Choi, Taegu, KR;
Ericsson Inc., Research Triangle Park, NC (US);
Abstract
The present invention provides apparatus and methods in which variable delay is provided for channel tracking. In particular, a demodulator having both a hard output (or symbol estimate) and a soft output (or indication of the quality of the symbol estimate) is coupled to a channel tracker. The channel tracker provides a channel estimate used by the demodulator, in part, to correct for fading. The channel tracker updates the channel estimate based on the symbol estimates from the demodulator and the received signal. However, when the soft output indicates a low confidence in the symbol estimate, the symbol estimate is not used to update the channel estimate. This is accomplished by providing a variable delay to the channel estimate calculation performed by the channel tracker depending on the number of consecutive suspect symbol estimates. For example, a single suspect estimate generates a delay of one causing the most recent estimate to not be used, two consecutive suspect estimate generates a delay of two causing the two most recent estimates to not be used and so on. Accordingly, the channel tracker of the present invention utilizes only the most reliable data available locally to generate a channel estimate for use by the demodulator.