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Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) technology with high spectrum efficiency , anti-interference ability and bandwidth scalability and good range of features , has been in short-distance wireless access has been widely used, is next generation mobile communication system very competitive key technologies. However , OFDM systems is a major bottleneck is the OFDM signal PAPR (Peak to Average Power Ratio, PAPR) is large, this, how to effectively solve the OFDM system the peak to average power ratio is a serious problem . In response to these problems, this paper focuses on how to effectively reduce the PAPR OFDM signal technology issues . First, the paper analyzes the wireless fading channel characteristics are discussed in detail the various propagation characteristics of the mobile radio channel , in which small-scale fading mobile radio channel is the focus of discussion , also discussed the Doppler shift of the transmitted signal. On this basis, the OFDM system introduced the principle of the OFDM system Introduction Several key technologies ( synchronization, channel estimation, the peak to average power ratio , channel coding, etc. ) ; describe the PAPR definition and statistical properties , and Some PAPR reduction scheme was introduced , simulation and analysis. Secondly, the paper describes the limiting filtering the basic principle and its simulation analysis, pointing out the advantages and disadvantages of this approach ; expansion in the traditional compression techniques to reduce PAPR based on the introduction of a new compression expansion technology, and its simulation , simulation results show that this method can be very effective in reducing the PAPR value of the system , its performance is moderate , the method is simple , there is a strong practicality. Finally, the article describes the non- distortion technology to reduce the PAPR methods , focusing on selected mapping (SLM) and Partial Transmit Sequence (PTS) method to conduct a comprehensive study and comparison . After analysis and comparison , the paper pointed out that in practical applications should be based on the specific requirements of the choice of appropriate algorithms to reduce the PAPR, so that the best overall system performance .
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