Practical implementation of PN scrambler for PAPR reduction in OFDM systems for range extension and lower power consumption

Orthogonal Frequency Division Modulation (OFDM) is an efficient multi-carrier modulation scheme. It is used in many wireless communication systems due to its robustness towards fading channel behavior and a relative ease of implementation coming from computationally efficient Inverse Fast Fourier Transforms (IFFT). However, the OFDM waveform has a very large Peak-to-Average Power Ratio (PAPR). Therefore, to avoid clipping plus nonlinear distortion, the Power Amplifier (PA) needs to be backed off significantly. This paper proposes a novel implementation and analysis of a Pseudorandom Noise (PN) scrambling technique allowing a significant reduction of the OFDM signalpsilas PAPR. The theoretical basis for the technique is presented, and a particular implementation of the technique for the IEEE 802.11a standard is discussed. Both simulations and measurements demonstrate significant benefits of the proposed technique in longer range wireless communications applications that use OFDM.