PAR reduction for DMT systems with unloaded subchannels

The inverse discrete Fourier transform used by discrete multitone modulation produces transmitted signals with a large peak-to-average ratio. Peak-to-average ratio reduction methods allow the transmitter to reduce the probability of clipping, or maintain the same probability of clipping while reducing the dynamic range requirements of the analog front end. In this paper we propose a method of peak-to-average ratio reduction that uses unloaded subchannels to prevent clipping in the transmitted signal. Considerations such as efficient adaptation methods and extensions to compensate for upsampling and filtering are addressed.