OFDM Baseband System Simulation And Study About Papr Reduction

WIMAX is a broadband wireless technique which has a widely application future based on IEEE802.16 standard. As one of the main technique of IEEE802.16, OFDM has been extensive used into the physical layer of WIMAX system. The basic principle of OFDM is distributing the high bit rate data stream into many orthogonal sub signal carriers, and then transmit the data. So it has less effect of frequency-selective fading and higher bandwidth efficiency.But OFDM has one serious defect due to the formation of the OFDM signal. It can have very high PAPR (Peak-to-Average Power Ratio). The defect will limit this technique application directly.This paper will do the detail research on how to reduce the PAPR of OFDM system. Firstly, analysis OFDM signal character, explain the reason of high PAPR procucing and its effect to the whole OFDM system. Then study the techniques of reducing the system PAPR, compare the benefit and defect of every technique, and put the important on the signal pre-distortion technique, this technique reduce the system PAPR by doing the distortion transform to the OFDM signal directly. This kind of technique includes the clipping technique and companding transform technique.In this paper, some reduce system PAPR techniques have been simulated on the OFDM model based on 802.16e standard. Compare the real effect of every technique, especially the effect of some kinds of companding transform technique.