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. 30, 1996
Filed:
Oct. 13, 1994
Shlomo Gadot, Ocean Township, Monmouth County, NJ (US);
Gi-Hong Im, Middletown, NJ (US);
Ehud Langberg, Ocean Township, Monmouth County, NJ (US);
Jin-Der Wang, Ocean, NJ (US);
AT&T Corp., Murray Hill, NJ (US);
Abstract
A hybrid type of decision feedback equalizer (DFE) structure that approaches optimal DFE performance is described. The hybrid DFE includes both an intersymbol interference DFE (ISI-DFE) and a noise predictive DFE (NP-DFE). The hybrid DFE structure is designed so that one form of tap values dominates over the other. This allows only the dominate tap values to be used by the transmitter during precoding and reduces the transmitter complexity. In particular, a hybrid DFE is designed so that the I(z) coefficient values dominate over the N(z) coefficient values, where the notation I(z) and N(z), as known in the art, represent the resulting coefficient values after adaptation of the ISI-DFE and the NP-DFE, respectively. A respective Tomlinson precoding scheme in the transmitter uses only the I(z) values. Since only the I(z) values are used in the precoder of the transmitter, the NP-DFE of the receiver is kept active during the communications phase. Conveniently, the continued use of the NP-DFE in the receiver allows the receiver to track small changes in the channel.