As shown in Chapters 2 and 3, even though the DFT-SC-FDMA and the DCT-SC-FDMA transmitted signals are characterized by low signal envelope fluctuations, the performance degradation due to the nonlinear amplification may substantially affect the link performance of these systems. It has been found that the PAPR of these systems is high, and it is possible to enhance the immunity of these systems to the nonlinear amplification effects by reducing the PAPR using the PAPR reduction methods. In the literature, several methods to reduce the PAPR in OFDM systems have been proposed [52-57]. However, the DFT-SC-FDMA and the DCTSC-FDMA systems are relatively new systems and reducing their PAPR is still an open issue. It is known that applying the PAPR reduction methods directly reduces the PAPR, but it also degrades the BER performance. Therefore, it is urgent to look for an efficient method that aims to reduce the PAPR and simultaneously enhance the BER performance of the DFT-SC-FDMA and the DCT-SCFDMA systems.