Pulse or digital communications – Systems using alternating or pulsating current – Plural channels for transmission of a single pulse train
Reexamination Certificate
2006-11-21
2006-11-21
Ghayour, Mohammed (Department: 2611)
Pulse or digital communications
Systems using alternating or pulsating current
Plural channels for transmission of a single pulse train
C375S259000, C455S059000
Reexamination Certificate
active
07139322
ABSTRACT:
The present invention provides a technique to reduce peak-to-average power ratio (PAR) of multi-carrier transmission systems. A non-empty subset of the subcarriers includes “PAR subcarriers.” The PAR subcarriers have constellations obtained by reducing a constellation that is higher than binary and invariant under multiplication by −1, so that an element is in the reduced constellation if and only if its negative is not. In this way, only one bit per PAR subcarrier is used for PAR reduction. The technique addressed in this invention multiplies a subset of the PAR subcarriers by −1 to reduce PAR at each multi-carrier symbol transmission. A method or apparatus is operated to select the subset of PAR subcarriers to be rotated. The receiver identifies the PAR subcarriers and estimates the subcarriers multiplied by −1 according to the reduced constellations and the received samples.
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A novel peak power reduction scheme for OFDM, Muller, S.H.; Personal, Indoor and Mobile Radio Communications, 1997. ‘Waves of the Year’. PIMRC '97., The 8th IEEE International Symposium on vol. 3, Sep. 1-4, 1997 pp. 1090-1094 v.3.
File Erin M.
Ghayour Mohammed
National Semiconductor Corporation
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