Research On Reduction PAPR Of OFDM

Orthogonal frequency division multiplexing (OFDM) is a special multicarrier transmission technology. It can strongly combat mufti-path delay and transmit high-rate data with high bandwidth efficiency. However, many key problems of an OFDM system have not been solved yet, such as sensitivity of frequency offset and high peak-to-average power ratio (PAPR), which limit OFDM's wide applications. This thesis mainly focuses on the techniques of PAPR reduction, and obtains some results by MATLAB simulations.Firstly, the principle of DFT based OFDM system, its key techniques, advantages and disadvantages of OFDM technology are analyzed in this thesis. Secondly, the definition and distribution of PAPR are introduced, and various techniques on reducing the PAPR are summarized. Thirdly, signal scrambling techniques are analyzed, including Selective Mapping (SLM) and Partial Transmit Sequences PTS).Two novel algrithom- signal aberration SLM algorithm and IG PTS algorithm is proposed to reduce the peak-to-average power ration. The algorithm of signal aberration SLM combined the signal aberration method with SLM algorithm overcome the influence of simply signal aberration method. The algorithm of signal aberration SLM control the PAPR in expected scope excellently. In the paper, IGA is applied to choose PTS phase factor. IG PTS algorithm is not only simplify the operation but also optimize phase factor. The computer simulation verified the efficiency of the new method.