Contents I. Introduction
Orthogonal frequency division multiplexing (OFDM) is widely used in high-speed wireless communication systems because of its inherent robustness against multipath fading and resistance to narrow-band interference [1]. However, OFDM suffers from the high peak to average power ratio (PAPR) of the transmitted signal. This issue can cause serious problems including a severe power penalty at the transmitter. Conventional solutions to reduce the PAPR are to use a linear amplifier or to back-off the operating point of a nonlinear amplifier. But both these solutions result in a significant loss of power efficiency. Many methods have thus been proposed to reduce the PAPR by modifying the signal itself. The simplest one is clipping the OFDM signal below a PAPR threshold level [2], [3], but it degrades the bit-error-rate (BER) of the system and results in out-of-band noise and in-band distortion. Coding [4] is another technique. Although it can offer the best PAPR reductions, the associated complexity and data rate reduction limit its application. Selected mapping (SLM) technique [5] and the partial transmit sequence (PTS) [6] are based on multiple signal representation method. These methods [7], [9], [11], [12] improve the PAPR statistics of the OFDM signals, but side information may be transmitted from the transmitter to the receiver, which results in a loss of data throughput.
