Investigation of Optimum Phase Sequence for Reduction of PAPR Using SLM in OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) is able to mitigate the detrimental effects of multipath fading but, OFDM signal suffers from high peak to average power ratio (PAPR). Increase in PAPR, decrease the power amplifier efficiency otherwise leads to in-band distortion and out of band radiation due to signal clipping and spectral broadening respectively. There are many techniques to reduce PAPR and Selective Level Mapping (SLM) is a particularly promising technique. In this technique, array multiplication of data sequence with phase sequence reduces PAPR. The combination with the minimum PAPR is considered for transmission. There are many phase sequences for reduction of PAPR such as Riemann, Rudin Shapiro, Chaotic, Chu, Pseudorandom, Hadamard and Novel phase sequences. The selection of phase sequence is very crucial and it depends on PAPR improvement and simplicity in the recovery of signal. In this paper PAPR improvement for various phase sequences and digital modulation schemes is compared and a new phase sequence is developed.