PAPR Reduction for OFDM

A major drawback of OFDM systems is its high peak-to-average power ratio (PAPR) of the transmit signal. In this book, we describe the design, working principle, advantage and disadvantage of OFDM. A comprehensive analysis of different PAPR reduction methods is presented. The DFT-Spread method, which is the most effective and efficient PAPR reduction technique, is identified. A very detailed theoretical analysis to the DFT-Spread method is provided with regard to the PAPR, both for single user case and multi-user case, with localized subcarrier mapping and distributed subcarrier mapping. For the multi-user case, the analysis is novel and has not been seen anywhere in any publications. A theoretical relationship is derived for the DFT-Spread method with distributed subcarrier mapping, which reveals the PAPR as a function of the modulation order and the number of users. In addition, a novel signal scrambling method is proposed to reduce the PAPR by using space-time block codes. Detailed simulation investigations and analyses are carried out to evaluate the PAPR performance of the DFT-Spread method and the proposed space-time block code signal scrambling method. Simulation investigation is also carried out to investigate the impact of DFT-Spread on the receiving performance.