Reducing the PAR In OFDM Systems by Clipping Scheme

Orthogonal frequency division multiplexing (OFDM) signals suffer from a large peak-to-average-power-ratio, which requires large power back-offs in the transmitter and receiver. This paper studies a digital post-processing method that mitigates clipping by the analog-to-digital converter in the receiver. The peak to average power ratio (PAR) is baneful in OFDM systems. The clipping signal scheme, which is a useful and simple method to reduce the PAR, but introduces additional noise that degrades the systems performance. An oversampling scheme, which can be used to recover the original signal and to eliminate clipping artifacts at receiver, is proposed by using finite impulse response (FIR) filter. Coefficients of the filter are obtained by correlation function of the received signal and the oversampling information at receiver. The performance of the proposed technique is evaluated for frequency selective channel. Results show that the proposed scheme can mitigate the clipping noise significantly for OFDM systems and in order to maintain the systems capacity.