Low complexity PAPR reduction in SLM-OFDM system using time domain sequence separation

Abstract

Selected mapping (SLM) algorithm has been widely used for reducing high peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signal. One of the factors affecting SLM performance is high computational complexity. To overcome this effect, in this paper, the time domain signals available at the output of IFFT blocks are separated into real odd, real even, imaginary odd and imaginary even subsequences using Fourier transform properties. To generate more candidates, the subsequences corresponding to each time-domain signals are swapped to get M4 candidates from M IFFT operation as swapped SLM. Then the real subsequences are retained and the imaginary subsequences are transformed into time reversed, circularly shifted and time-reversal of circularly shifted subsequences. Therefore, the proposed scheme generates 4M4 candidates by combining different real subsequences and imaginary subsequences using only M IFFT operations. The simulation results illustrate that the proposed SLM scheme offers an improved PAPR reduction performance than other existing algorithms. Also, the proposed algorithm achieves 97% computational complexity reduction in terms of multiplications and 67% in terms of additions when compared to CSLM. Similarly, it provides 75% complexity reduction in terms of multiplications and 20% in terms additions when compared to swapped SLM. Keywords: CCRR, OFDM, SLM, CCDF, PAPR, Swapped SLM