I Introduction
Orthogonal frequency division multiplexing (OFDM) has grown in popularity to become the modulation of choice for many high data-rate communication systems. The spectral efficiency of OFDM is based on the observation that the orthogonality of subcarriers provides a way to pack more subchannels into the same channel spectrum in order to accommodate multiple users [1], [2]. In OFDM, the subcarriers are generated using the computationally-efficient inverse discrete Fourier transform (IDFT) and can thus exploit the well-known circular convolution properties of the DFT in order to implement low-complexity frequency-domain equalization techniques. Despite its many advantages, however, OFDM has the disadvantage of having large fluctuations in its signal amplitude, which gives it a high peak-to-average-power ratio (PAPR).