Research On PAPR Reduction Schemes 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 transmis sion and multimedia data transmission. This technology has been regarded as the core technology of 4G wireless communications system in the future. However, it has high peak-to-average power ratio (PAPR) , which is its inherent disadvantage. This disadvantage in OFDM systems has limited OFDM'S wide applications and has not been solved yet. This paper has mainly researched on the methods of PAPR reduction for OFDM and has obtained some results by MATLAB simulations.The fundamental principle of DFT-based OFDM system and its techniques are introduced in this thesis. Then, the distributions of PAPR are analyzed by simulation. In signal distortion techniques, clipping is analyzed in terms of two performance measures:complementary cumulative distribution function(CCDF) and bit error rate (BER). In order to reduce the large computation complexity of partial transmit sequence (PTS) an improved method has been analyzed and compared with customary PTS via computer simulation. The result of simulation shows that the PAPR is decreased..Finally, the relative research and simulation about the whole paper is summarizes, meanwhile, the further practically research in future is expected.