OFDM PAR reduction by substituting original in-band subcarriers after clipping

摘要

A peak-to-average ratio (PAR) of a signal is reduced by clipping the signal at a threshold level and replacing desired frequency tones of the clipped signal with set of frequency tones of the signal. In one embodiment, the PAR of a signal is reduced by adding a peak cancellation signal to the received signal. The peak cancellation signal is generated by clipping the received signal at a threshold level and generating a difference signal by subtracting the received signal from the clipped signal. The peak cancellation signal thus generated is scaled by a scaling factor and added to the received signal to reduce the PAR of the received signal. The scaling factor is adjusted to maintain the desired quality of the received signal. In one embodiment, the PAR of an orthogonal frequency division multiplexed (OFDM) signal may be reduced.

主权项

1. A method comprising:
Orthogonal frequency division multiplexed (OFDM) modulating a first signal having a first peak-to-average ratio (PAR) to provide a first central band of subcarriers, a first band of unused subcarriers, and a second band of unused subcarriers, the first and second bands of unused subcarriers being on either side of the first central band of subcarriers; clipping the first signal at a threshold level to generate a clipped signal; forming from the clipped signal a second central band of subcarriers, a third band of unused subcarriers, and a fourth band of unused subcarriers, the third and fourth bands of unused subcarriers being on either side of the second central band of subcarriers; and forming a second signal with a second PAR, which is less than the first PAR, from the third and fourth bands of unused subcarriers and substituting the first central band of subcarriers for the second central band of subcarriers.