Peak to average power ratio reduction technique for OFDM using pilot tones and unused carriers

One of major drawbacks of Orthogonal Frequency Division Multiplexing (OFDM) is the high Peak-to-Average Power Ratio (PAPR) of the transmit signal. Due to the non-linear characteristics of the power amplifier (PA), significant out-of- band and in-band distortions occur when high peak signals exceed the saturation level of the PA. In this paper we present a new PAPR reduction technique which exploits the use of unused- carriers as well as the phase information of pilot signals in OFDM systems to reduce the PAPR while not degrading channel estimation or frequency offset. Compared to conventional techniques such as clipping and windowing, this technique introduces much less out-of-band distortions and provides a lower bit-error-rate (BER) since there is no interference to the original data signals. There is also no requirement for side information to be transmitted to the receiver.