Research On PAPR Reduction Of OFDM

Orthogonal Frequency Division Multiplexing(OFDM) is an effective technique for multi-carrier parallel transmission. It has high bandwidth efficiency and good capability to resist multi-path interference. So it has been widely used in several areas such as Asymmetrical Digital Subscriber Line(ADSL), High Definition TV(HDTV) and Wireless Local-Area Networks(WLAN). It's going to become one of the most important core techniques of the fourth generation mobile communication systems(4G). However, it has an intrinsic weakness of high Peak-to-Average Power Ratio(PAPR) of the transmitted signal. High PAPR is one of main bottlenecks of OFDM technology for practical application. So it has significance to reduce PAPR in OFDM systems.The principles of OFDM and MIMO are introduced in the beginning. We analyze the origin and influence of high PAPR in OFDM systems, then we give out the definition of PAPR and depict the regularities of distribution for statistic characteristics.Then we analyze the PAPR of OFDM and MIMO-OFDM systems. Based on analyzing the previous works of reducing PAPR, we introduce methods of reducing PAPR in category and compare the advantages and disadvantages between them. We focus on improving the effects of two techniques in PAPR reducing. We can conclude from the simulation that the improvements are more feasible and efficient.Finally we improve the Selective Mapping technique and Partial Transmit Sequences technique based on combined and detached methods to narrow the signal power range. The simulations proved that the improvements are more efficient in reducing the PAPR and can save more side information bits. It's hoped that this thesis could bring some help to the further applications of OFDM technology.