PAPR reduction using clipping and filtering technique for nonlinear communication systems

Orthogonal frequency division multiplexing (OFDM) is one of the widely used modulation techniques for nonlinear communication systems. It offers high data rate, spectral efficiency, robustness to multi path fading, simple receiver design, etc. But, it suffers from high peak-to-average power ratio (PAPR) which causes inband signal distortion and out of band spectral regrowth and results in significant reduction in power efficiency when passed through a nonlinear power amplifier. In this paper, a simple method of PAPR reduction, clipping and filtering is investigated. Effects of clipping and filtering on the performance of OFDM signal such as power spectral density, PAPR, and bit-error rate has been investigated through Matlab simulations. The results obtained indicate that at clipping ratio, CR = 1.4 and 1% of CCDF the reduction in PAPR values are 8.8 dB and 5.4 dB for clipped only and both clipped & filtered signals, respectively. The clipping operation also causes degradation in the BER performance. At 10 dB of signal power and at CR = 1.4, BER values are 1.0×10^-2 for clipped signal, 5.1×10^-3 for both clipped & filtered signals and 7.8×10^-4 for unclipped signal. This increase in BER value is due to distortions caused during the process of clipping and filtering.