A New PAPR reduction Technique based on Precoding and Gamma Companding Technique for OFDM system

Abstract

Multi-carrier modulation is less sensitive to time dispersion of the channel. In particular, Orthogonal Frequency Division Multiplexing (OFDM) has gained more attention in the last decade owing to rising power of digital signal processing. In spite of the several difficulties that entails during implementation of OFDM system, one of the major drawbacks in OFDM is high peak to average power ratio. Hence it is mandate to research on the characteristics of the PAPR in association with its distribution and reduction in OFDM systems. Myriad of techniques were introduced to reduce Bit error rate and PAPR. Amidst these techniques, precoding gives best solution for reducing PAPR. But in this technique, more null subcarriers are incorporated which leads to out-of-band power emission and in turn reduces the transmission rate. In order to minimize OOB power emission, we combine precoding in frequency domain and gamma companding technique in time domain. The gamma compander promotes OOB power emission. Simulation results reveals a trade off between OOB power emission and PAPR reduction.