Clipping Versus Symbol Switching for PAPR Reduction in Coded OFDM

In multicarrier systems, the transmitted timedomain signal exhibits large amplitude peaks. This peak-toaverage power ratio (PAPR) problem complicates the practical use of multicarrier systems: the amplifier used to transmit the signal saturates because of the large peaks and causes non-linear distortion. As this non-linear distortion frustrates severely the detection of the multicarrier signal, the average power of the multicarrier signal must be reduced such that the system operates in the linear part of the amplifier. However, this power reduction comes at the cost of a reduced capacity of the multicarrier system. Hence, several techniques were investigated to reduce the PAPR. In this paper, we compare two PAPR reduction techniques for coded OFDM using an iterative decoder, i.e. clipping and symbol switching. Clipping outperforms the symbol switching technique as for given PAPR reduction, a lower BER degradation is obtained. However, the clipping technique causes out-of-band radiation whereas the spectrum is not changed when using the symbol switching technique.