A LOW COMPLEXITY PARTIAL TRANSMIT SEQUENCE SCHEME FOR BETTER PAPR REDUCTION IN OFDM SYSTEMS

Abstract

The main drawback of OFDM system is the high Peak t o Average Power Ratio (PAPR) of the transmitted sig nals. Partial transmit sequence scheme is a promising algorithm to reduce the peak-to-average power ratio (PAPR) in orthogona l frequency division multiplexing (OFDM). The Partial Transmit Sequence (PTS) consist of several inverse fast Fourier trans form (IFFT) operations and complicated calculations to obtain optimum phase se quence which results in increasing the computationa l complexity of PTS. A phase sequence applied to the PTS Scheme reduces its comp lexity but at the expense of slight degradation in PAPR reduction. In this paper, for further reduction of PAPR the peak clipping of the OFDM signal is introduced along with the PTS wi th new phase sequence scheme. Since clipping is one of the simplest techn iques of PAPR reduction, it does not increase the c omplexity of the system much and a better PAPR reduction is obtained with the co mbined effect of clipping and PTS with New Phase Se quence. But the clipping technique introduce some distortion in the signal, however peak clipping of signal below a particular threshold can maintain the BER in the tolerable range. The clipping threshold sele cted will be different for different OFDM systems.