Method and apparatus for reducing the peak-to-average ratio in a

Details Method and apparatus for reducing the peak-to-average ratio in a Method and apparatus for reducing the peak-to-average ratio in a

1997-12-01

2000-10-10

Pham, Chi H.

Pulse or digital communications

Transmitters

375285, H04L 2704

Patent

active

061309184

ABSTRACT:
A reduction in a peak-to-mean envelope power ratio of a multicarrier signal, represented as a time domain signal, is achieved by applying (76) an offset, indicative of a difference (74) between a mean signal level and a midpoint level of the time domain signal, to the time domain signal. Alternatively, constellation values of positive and negative frequency components are modified by differing functions to produce a modified data set. Preferably, the negative frequency components are set to a predetermined value (namely zero (124)) to provide an alternate coding scheme Once the multicarrier signal has been converted into a time domain representation, real and imaginary parts (126-128) of the modified data set that consequently only contain positive frequency components and zeros are compared with one another to identify (130) which of the real and imaginary parts has a lower peak-to-average signal ratio (134) for the time domain representation. Then, based upon which of the peak-to-average signal ratios is lowest (136), either the real and imaginary part of the time domain signal is selected for subsequent transmission (138).

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