PAPR Reduction For Power Optimization In OFDM

Optimizing the energy consumption of cellular networks is one of the booming challenges the industrialists and academics are facing. In the present energy crisis, it is high time to consider the reduction of energy consumption as it affects the operational and environmental expenditures. One of major problems in OFDM is high peak to average power ratio (PAPR), which makes system performance very sensitive to distortion introduced by nonlinear devices such as power amplifiers (PAs). The basic solution to this problem is to use a linear amplifier or to back-off the operating point into the linear region of the nonlinear HPA. However, power efficiency of HPA becomes very low so that this large back off is not desirable. Another method to avoid the nonlinear distortion is a linearization technique, which is good for the single carrier signal with just 3 dB PAPR. However, this linearization is not enough for the OFDM signal of multi-carrier system as large back-off is still required. There have been many studies on the PAPR reduction methods such as block coding method, clipping method, phase control method, partial transmit sequence (PTS) method and selective mapping (SLM) method. In PTS, the lowest PAPR signal is produced by optimally phase combining of the signal sub blocks.