PAPR reduction techniques using Precoding OFDM systems Companding

In recent years, the need for reliable transmission of digital data is increasing rapidly And extend high-speed data networks and wireless networks in public and private business were caused It would be considered.With OFDM multi-carrier modulation and consists of several sub-carrier is modulated have to be perpendicular to each other. The disadvantages of multi-carrier modulation, such as OFDM, greater than Peak-to-Average Power Ratio PAPR at the transmitter output signal is PAPR large signal, causes the amplifier with a wider range of linear functions necessary. That is effective and if the amplifier can be used with low linear operation area, causing distortion in band and out of band signal will be sent radiation. In this paper, both Precoding techniques and Companding μ-law used to reduce PAPR Further studies using different methods and number of sub-carrier modulation is different. A significant decrease in the values of PAPP using these techniques have been. And efficacy compared with each other.