Crest factor reduction system and method for OFDM transmission systems using selective sub-carrier degradation
AssigneePowerwave Technologies, Inc.
InventorRichard Neil Braithwaite
Life of this patent
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Abstract
A system and method for crest factor reduction of OFDM transmission systems using selective sub-carrier degradation, is disclosed. A modulated communications signal comprising a series of symbols is converted into parallel format in groups of plural symbols in the frequency domain. Crest factor reduction reduces a primary peak of the groups of plural symbols by selective sub-carrier degradation, to generate peak reduction symbols. The groups of plural symbols are converted into time domain symbols, and combined with the peak reduction symbols to provide peak reduced symbols in time domain.
Claims22
An OFDM communications system, comprising:
- an input receiving a modulated communications signal comprising a series of symbols;
- a serial-to-parallel converter for converting the symbols into parallel format and providing groups of plural symbols in a frequency domain;
- a circuit that receives said groups of plural symbols and converts them into time domain symbols;
- a crest factor reduction circuit that receives said groups of plural symbols in the frequency domain and reduces a primary peak therein by selective sub-carrier degradation to generate peak reduction symbols;
- a circuit for converting the peak reduction symbols into time domain peak reduction symbols;
- a combiner circuit for combining the peak reduction symbols with the time domain symbols to provide peak reduced symbols in time domain;
- and
- a cyclic extension circuit for performing a cyclic extension operation on the time domain peak reduced symbols.
A method for peak power reduction of an OFDM wireless communications signal, comprising:
- receiving an OFDM signal comprising groups of plural symbols;
- converting the groups of plural symbols into time domain symbols;
- reducing a primary peak in the groups of plural symbols by selective sub-carrier degradation, to generate peak reduction symbols;
- converting the peak reduction symbols into time domain peak reduction symbols;
- combining the peak reduction symbols with the time domain symbols to provide peak reduced symbols in time domain;
- and
- performing a cyclic extension operation on the time domain peak reduced symbols.
Dependencies are inferred from the claim text.