A Companding Technique for PAPR Reduction in DWT OFDM Systems

Orthogonal frequency division multiplexing (OFDM) technique is considered as a advance technology in realizing high-speed wireless digital communications. However, high peak-to-average power ratio (PAPR) of transmitted signals is a major drawback for multi-carrier modulation systems such as orthogonal frequency division multiplexing and discrete wavelet division multiplexing. In this paper, proposed scheme will be introduced, which combines wavelet transform and companding technique to reduce PAPR. The mu-law companding scheme, which enlarges only small signals so that the average power increases. By using proposed scheme, the PAPR of OFDM signal can be reduced by 6.8 dB over the original system. Wavelet based Multi-Carrier Modulation (WMCM) offers an alternative to the well-established OFDM as an efficient multicarrier modulation technique. The schemes are compared with simulation results.