US Patent 8724721 Method and apparatus for crest factor reduction

According to embodiments there is provided a method for reducing the crest factor of an input signal. The method is performed in a part of a transmitter and comprises creating a clipped signal by clipping the input signal using a predetermined clipping threshold and creating a peak signal from the input signal. The peak signal comprises the difference between the input signal and the clipped signal. At least part of the peak signal is convoluted with an inverse Fourier transform of a filtering mask defined in the frequency domain. In this way a filtered signal is created. A subtraction signal is generated by subtracting the filtered signal from the input signal.