Mu-Law companded PTS for PAPR reduction in OFDM systems

Abstract

Orthogonal Frequency Division multiplexing (OFDM) is a multicarrier modulation technique that offers immunity to multipath propagation effects. However, it suffers from high peak to average power ratio that arises when the subcarrier signal phases are same. The literature survey shows that partial transmit sequence (PTS) is best among the multiple signaling and probabilistic techniques for PAPR reduction. However, the circuit complexity increases with the increase in the number of sub-blocks. Under signal distortion methods of PAPR reduction, mu-Law companding offers better performance. In this paper, a scheme that performs mu-LAW companding operation on partial transmit sequence (PTS) signal is proposed to achieve low circuit complexity while offering better PAPR reduction. The proposed scheme provides better PAPR reduction compared to PTS with four blocks, nearly the same BER performance as PTS with two blocks, least circuit complexity when compared to PTS with four blocks. The performance of the proposed scheme is better than mu-law companding, conventional PTS, SLM and combined versions of SLM, PTS.