Research On Peak-to-average Power Ratio Reduction For OFDM System

OFDM (orthogonal frequency division multiplexing) is a parallel transmission scheme of MCM (Multi-Carriers Modulation) . It transmits information through orthogonal multiple sub-carriers and has high utilization of frequency spectrum, good capability of countering multi-path interference. It is also adaptive to high-rate data transmission and multimedia data transmission. This technology has been regarded as the core technology of 4G wireless communications system in the future. However, one of the main implementation disadvantages of OFDM is the high peak-to-average power ratio (PAPR) of the transmitted signals. This thesis mainly focuses on the techniques of PAPR reduction and use MATLAB software to achieve simulation. We have achieved the following work:(1) This thesis first analyze the basic theory of OFDM signal and key technique. Then the paper introduces the orthogonal condition of sub-carrier.(2) This paper deduces the reason of high PAPR and sums up all kinds of methods of reducing PAPR all over the world. Then it analyzes the disadvantage of limited breadth filter and improves the companding method.(3) A coding scheme based on Golay Complementary sequences and Reed-Muller codes is proposed to reduce the PAPR.(4) SLM method and PTS method are particularly presented, and then put forward improvement based traditional SLM method. In farther deep study about parameter and assistant adding power information this paper brings forward new method which may reduce the complexity of OFDM system. Last this thesis uses MATLAB software to simulate the new methods.