PAPR Reduction for OFDM System using DCT Based Modified PTS Technique

Though the OFDM provides high data rate due to its high spectral efficiency, it has high PAPR which results in performance degradation and high out of band radiation due to nonlinearity of the high power amplifier. Partial Transmit sequence is one of the distortions-less PAPR reduction techniques which obtain the minimum PAPR signal by multiplying suitable phase factors with subsequenced subcarriers. In order to reduce PAPR even more, autocorrelation among data should be less. So DCT is applied along with PTS technique which has the property of reduction of autocorrelation. In the proposed method DCT is applied before PTS technique and after the PTS technique. The simulation results show that DCT preceding PTS technique has better performance compared to DCT succeeding PTS technique. The analysis of the both the proposed method is carried out with different subcarriers and sub-blocks are discussed. Key-Words: OFDM, PAPR, IFFT, DCT, IDCT, Modified PTS.