Input sequence envelope scaling in PAPR reduction of OFDM

Orthogonal frequency division multiplexing or OFDM is a form of multi-carrier modulation technique. High spectral efficiency, robustness to channel fading, immunity to impulse interference, uniform average spectral density, capability of handling very strong echoes and less non linear distortion are among the favorite properties of OFDM. Even though there are many advantages of OFDM it has two main drawbacks: high peak to average power ratio (PAPR) and frequency offset. In this paper, the issue of PAPR in OFDM is discussed. A new algorithm is proposed to reduce PAPR by scaling the input envelope for some sub carriers before they are sent to IFFT. Simulation results show that the PAPR can be reduced by 4 dB.