Low-complexity modified SLM method for PAPR reduction in OFDM systems

To overcome the multipath fading effect in wireless communications an efficient multicarrier modulation technique OFDM (Orthogonal frequency division multiplexing) is used. The OFDM system has high spectral efficiency and support high data rate wireless transmission without any additional requirement of equalization. So, it is an attractive technology formodern wireless communication systems. One major drawback of OFDM system is high peak-to-average power ratio (PAPR) of transmit signal. There are many methods to reduce PAPR in OFDM system, in which selected mapping (SLM) is one of the best distortion less method. However, it requires a bank of inverse Fast Fourier Transforms (IFFTs). Therefore, the system has more computational complexity. In this paper, we proposed a modified selected mapping (M-SLM) scheme using a perfect sequence /conversion vectors. In this method, the data sequences are equally divided then for the first half of the data sequence IFFT is taken then circular convolutionis performed with perfect sequences. conventional SLM is applied for the second half section to reduce the complexity and PAPR. Finally, the number of candidate signals are doubled from the same IFFT blocks. From the simulation results, the proposed method slightly reducesPAPR. Moreover, the computational complexity of the proposed method reduces much than C-SLM.