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:
Nov. 07, 1995
Filed:
Sep. 09, 1992
Lars G Larsson, Stockholm, SE;
Perols B Gudmundson, Sollentuna, SE;
Telefonaktiebolaget LM Ericsson, Stockholm, SE;
Abstract
Radio signals are transmitted over a fading radio channel and are filtered and sampled in a receiver to obtain a digital signal. A channel equalizer has an equalizing filter in which a channel estimate is formed with the aid of a known synchronizing sequence. A Viterbi analyzer decides symbols with the aid of the channel estimate. An estimated time derivative of the channel estimate is formed and adapted with the aid of the decided symbols. The channel estimate is adapted to the radio channel by the derivative estimate and the decided symbols. In the event of fading with rapidly varying signal strength, the channel estimate is adapted slowly and is predicted mainly through the derivative estimate which varies relatively evenly. The digital signal is stored in a memory and an initial value is formed for the derivative estimate as a difference between two known channel estimates divided by a time difference therebetween. The known channel estimate may belong to two separate synchronizing sequences or may belong to one synchronizing sequence and a fading time point in which the channel estimate has zero value.