Companding transform for reduction in peak-to-average power ratio of OFDM signals

A general companding transform method is proposed to effectively reduce peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. By compressing large signals while enhancing small signals along with taking into account their statistical characteristics, this method can achieve significant reduction in PAPR with low implementation complexity. Specifically, we present the design criteria of the transform, which enable effective tradeoff between reduction in PAPR and bit-error rate performance of the OFDM system. It is shown by simulations that the proposed method may significantly improve the performance of OFDM systems in radio channels by carefully choosing the companding form and parameters.

I. Introduction

Orthogonal frequency division multiplexing (OFDM) has been recently seen rising popularity in wireless applications [1]–[3]. On the other hand, one of the major drawbacks of OFDM signal is its large envelope fluctuation, likely resulting in large peak-to-average power ratio (PAPR) [4]. Large PAPR could cause poor power efficiency or serious performance degradation to transmit power amplifier [5].