PAPR Distribution Analysis at the Output of Nonlinear PAPR Reducers

Désiré Guel,Jacques Palicot

doi:10.4236/jsip.2012.34059

Abstract

Nonlinear PAPR reducers, such as clipping and companding techniques, are some simple methods used to reduce the Peak-to-Average Power Ratio (PAPR). In this paper, assuming that the baseband OFDM signal is characterized as a band-limited complex Gaussian process, we investigate the PAPR distribution of an OFDM signal when it is passed through a nonlinear PAPR reducer. The obtained PAPR distribution depends on the nonlinear function which characterizes the PAPR reducer. Later in this paper, we apply the obtained PAPR distribution in the clipping case. The comparisons made between the proposed distribution and that obtained thanks to computer simulations show good agreement.

Highlights

Orthogonal Frequency Division Multiplexing (OFDM) is an attractive modulation technique for the generation of high bit rate wireless transmission due to its high robustness to multipath fading and its great simplification of channel equalization [1]
In this paper, assuming that the baseband OFDM signal is characterized as a band-limited complex Gaussian process, we investigate the Peak-to-Average Power Ratio (PAPR) distribution of an OFDM signal when it is passed through a nonlinear PAPR reducer
In the same way as (5), we show that the PAPR distribution of the ouput signal y could be approximated by Equation (6): Complementary Cumulative Distribution Function (CCDF) y =

Summary

Introduction

Orthogonal Frequency Division Multiplexing (OFDM) is an attractive modulation technique for the generation of high bit rate wireless transmission due to its high robustness to multipath fading and its great simplification of channel equalization [1]. One of the main problems of the OFDM modulation technique is the large peak-to-average power ratio (PAPR) of the transmitting signals. Several PAPR reduction techniques have been proposed [2] to reduce the PAPR of OFDM signals To well understand this PAPR problem and to predict possible gain thanks to reduction techniques, many papers were interested in the PAPR distribution analysis. The pionneer work was the work of R. van Nee and A. de Wild in [3] This expression was obtained at the Nyquist frequency and did not represent a realistic value of the continuous signal PAPR distribution. Louet and Hussain in [6] proposed a new expression for continuous baseband OFDM signals.

Characterization of Nonlinear PAPR Reducers

PAPR Distribution Analysis

Pr yn Py

PAPR Distribution in the Soft Envelope Clipping Technique’s Case

Conclusions