PAPR Reduction of OFDM System Using Partial Transmit Sequences (PTS) and Firefly Algorithm (FA)

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is an encoding method that are hugely utilized in wireless communication due to its high number of advantages such as tolerance for multipath delay spread, frequency selective fading channels immune and also power efficiency. The bad side of this method is it has high Peak Average Power Ratio (PAPR) that will generate nonlinear distortions and severe power penalty. In this research, Partial Transmit Sequence (PTS) method is proposed to solve the problem of high PAPR but from previous research, it could be seen that in Partial Transmit Sequence, the search complexity increases as the number of phase sequence increase. To solve this issue, Firefly Algorithm (FA) is applied to optimize the function of Partial Transmit Sequence. The modulation method used is Quadrature Phase Shift Keying (QPSK). By the end of the process, CCDF plots are computed. The performance of PAPR reduction in OFDM system are analyzed by different number of subcarriers, phase sequences and iterations using CCDF graphs. By using Partial Transmit Sequence method only, the PAPR values manage to be reduced by 7 to 7.2 dB but with FA-PTS algorithm, the PAPR values can be reduced by 9 to 9.4 dB. With these results, it is concluded that the combination of Partial Transmit Sequence with Firefly Algorithm can help to improve computational complexity in PTS and eventually reduce PAPR value in OFDM system.