US 7,061,997 B1
Method and apparatus for fine frequency synchronization in multi-carrier demodulation systemsGeneral
US 7,061,997 B1
Method and apparatus for fine frequency synchronization in multi-carrier demodulation systems
Tech Center:
2600 Communications
Examiner:
Stephen Chin
Art Unit:
2611 Computer Graphic Processing, 3D Animation, Display Color Attribute, Object Processing, Hardware and Memory
Inventors:
Ernst Eberlein; Sabah Badri; Stefan Lipp; Stephan Buchholz; Albert Heuberger; Heinz Gerhaeuser
Assignee:
FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN
Priority:
04/14/98
Filed:
04/14/98
Granted:
06/13/06
Expiration:
11/29/20
Abstract
A method and an apparatus relating to a fine frequency synchronization compensating for a carrier frequency deviation from an oscillator frequency in a multi-carrier demodulation system of the type capable of carrying out a differential phase decoding of multi-carrier modulated signals, the signals comprising a plurality of symbols, each symbol being defined by phase differences between simultaneous carriers having different frequencies. A phase difference between phases of the same carrier in different symbols is determined. Thereafter, a frequency offset is determined by eliminating phase shift uncertainties related to the transmitted information from the phase difference making use of a M-PSK decision device. Finally, a feedback correction of the carrier frequency deviation is performed based on the determined frequency offset. Alternatively, an averaged frequency offset can be determined by averaging determined frequency offsets of a plurality of carriers. Then, the feedback correction of the frequency deviation is performed based on the averaged frequency offset.