A fair comparison platform for OFDM systems with various PAPR reduction schemes

Orthogonal Frequency Division Multiplexing (OFDM) provides a flexible air interface for high data rate transmission which has high spectral efficiency and is robust in the presence of multipath. However, OFDM has a high peak-to-average power ratio (PAPR). If peaks are clipped by the non-linearity of the RF power amplifier (PA), both in-band and out-of-band distortion is produced. In-band distortion increases Bit Error Rates (BER). Backing off the signal level in the PA reduces distortion at the cost of reduced power efficiency, so various PAPR reduction strategies have been proposed. Generally, the effectiveness of PAPR reduction schemes have been reported in terms of their effect on the Cumulative Distribution Function (CDF) of the resulting signal, however, this does not directly relate to achievable BER performance, making comparisons between schemes difficult. By contrast, this paper defines a fair comparison platform based on the BER achieved at optimum back-off. Three schemes are compared. The Active Constellation Extension (ACE) scheme was shown to have the best performance, then Selective Mapping (SLM). A scrambling scheme was the least effective. None of the schemes provide much advantage at poor signal-to-noise ratio (SNR).