Compander Design for OFDM PAPR Reduction Using Optimal Perturbation of Piecewise Linear Segments

In this paper, we develop an optimal perturbation approach to design companders to mitigate the peak-to-average power ratio problem experienced by orthogonal frequency division multiplexing (OFDM) signals. Specifically, we generalize single-linear component design approaches, which modify the Rayleigh-distributed OFDM signal amplitude tail, to use of multiple contiguous piecewise linear components. The new compander design approach defines and solves a constrained optimization problem to optimally perturb a given proposed multicomponent piecewise linear segment set to meet the power and probability density function constraints. The use of multiple piecewise linear components provides greater design flexibility to meet the constraints, thus providing solutions for pairs of inflection points and cutoff values where more rigidly designed companders fail to exist. We present examples of compander design, and demonstrate compander performance through numerical simulation. The new compander design approach can generate companders that offer performance improvements over current companders.

I. Introduction

Companding techniques have proven their use in reducing the large peak-to-average power ratio (PAPR) that occurs in orthogonal frequency division multiplexing (OFDM) signals. Large PAPR results from constructive interference among the OFDM sub-carriers, which accounts for the long tail of the Rayleigh-distributed amplitude values, and can drive the signal amplitude into the power amplifier saturation region.