OFDM is a multicarrier technique proposed in 1966 by Bell Labs to combat dispersive fading channels. However, OFDM suffers from the PAPR. The large PAPR of OFDM symbols presents a significant challenge in designing power efficient RF front-ends, articularly due to the requirement for nonlinear power amplifiers (PA) with large dynamic range. Instead of increase the non-linear power amplifier back-off, which is costly and not power efficient, an alternative is to treat the OFDM signal such that its PAPR is reduced before passing through the non- linear PA. This research, therefore, focuses on PAPR reduction using three techniques, which are based on the well known selected mapping method without explicit side information to recover the transmitted data block. Consequently, the definition of the main components such as; OFDM, High PA, MIMO, PAPR, have been provided (Chapters 2,3) and the investment solutions have been discussed and analyzed (Chapters 4,5,6). The analysis should be helpful to the professional researchers who interests in the physical layer, or any academic person who studies, or teaches, in the communication and signal processing.