A Low-Complexity Companding Transform for Peak-To-Average Power Ratio Reduction in OFDM Systems

The high peak-to-average power ratio (PAPR) feature is one main drawback associated with orthogonal frequency division multiplexing (OFDM) systems. To overcome this problem, many approaches have been presented in the literature, such as the selected mapping technique, the partial transmit sequence technique, the linear nonsymmetrical transform (LNST), and the exponential companding transform (Exp-CT). However, most of them involve high computational complexity. In this paper, we propose a new low-complexity companding transform scheme for PAPR reduction. From computer simulations, the proposed low-complexity scheme can successfully reduce the PAPR value with a lower bit error rate than the Exp-CT scheme and smaller spectrum side-lobe generation than the LNST and Exp-CT schemes. It is useful for physical realization of an OFDM system.

1. INTRODUCTION

Orthogonal frequency division multiplexing (OFDM) is a promising technique for high-bit-rate transmission since its robustness to multipath fading and high spectral utilization efficiency. It has been adopted in many standards of wireline/wireless applications, such as very-high-rate digital subscriber lines (VDSL) [1], terrestrial digital video broadcasting (DVB) [2], and the IEEE 802.11a wireless local area network [3]. One major drawback associated with an OFDM system is that the transmitter's output signal may have a high peak-to-average ratio (PAPR). The high PAPR feature will cause poor efficiency of power consumption, inband distortion, and spectral spreading when an OFDM signal is passed through a nonlinear power amplifier.