Nonlinear companding transform technique for reducing PAPR of ODFM signals

In this paper a novel nonlinear companding transform (NCT) scheme based on the inverse hyperbolic sine function is proposed for reducing the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. By introducing the variable companding parameters and an inflexion point in the companding function, it enables more design flexibility and freedom in companding form so that an effective trade-off between the PAPR and bit error rate (BER) performance can be offered. Moreover, the theoretical study reveals that, to approach a desired PAPR threshold, it is preferable for the proposed scheme to make the companding distortion as small as possible with appropriate selection of the companding parameters and forms. The analysis expressions regarding the achievable PAPR reduction, transform gain G, and signal attenuation factor are derived. Simulation results also demonstrate that this scheme can substantially outperform existing NCT techniques.