Exponential Companding and Active Constellation Extension Comparisons for PAPR Reduction

One of the major drawbacks of the orthogonal frequency division multiplexing (OFDM) type of communication is the high peak-to-average power ratio (PAPR) of the transmitted signal. Unless carefully tackled, this may cause either reduced energy efficiency or increased nonlinear distortion when the signal is amplified for transmission. For improving energy efficiency, this paper considers PAPR reduction in OFDM based systems. In particular, we study and compare some PAPR reduction approaches including three exponential companding and active constellation extension (ACE) methods. We discuss the trade-offs of the methods. In addition, for the ACE method defined in the ETSI standard, we propose some modifications that give about 1 dB more PAPR reduction without any additional power increase of the transmitted signal. Moreover, if some spectral regrowth due to the PAPR reduction is acceptable, exponential companding approaches can also be used.