Research On The Reduction Of PAPR In OFDM System

OFDM is a kind of Multi-carrier modulating techniques. It can be good for countering multi-path interference, which realizes high speed data transmission according to very high spectra utilization efficiency. And transmitter and reception configuration are briefness because it uses IFFT. So it is considered as one of core technologies for future4G move communication. However, a major drawback of OFDM technology is its high Peak-to-Average Power Ratio (PAPR), which severely deteriorates the performance of systems. So, how to effectively reduce the higher PAPR of the OFDM signals is rather an important issue. In the thesis, the research is mainly around this problem, especially discussed the Selective Mapping algorithm.In the dissertation, the OFDM system including some fundamental theories and its key technologies are introduced. The definition and distribution of PAPR is presented, so as to the cause of the high PAPR. The paper summarizes the most popular three kinds of PAPR reducing techniques, including pre-distortion technique, coding technique and probability technique. This thesis mainly focuses on the techniques of PAPR reduction and use MATLAB software to achieve simulation. The following work has been down.In the time domain, based on time-domain linear combination of SLM algorithm, combined with dynamic improved SLM algorithm and the repeat clipping and filtering (RCF) algorithm, proposed a new improved algorithm, which is based on dynamic time-domain linear combination improved SLM algorithm. In domain, solve the problem of the high a mount of computation in SLM algorithm. Simulation results show that, in the circumstance of same simulation effect in PAPR reduction, the computation of proposed SLM algorithm is less than the computation of traditional SLM algorithm. With the increase of the number of carriers, the improved algorithm achieves excellent performance in PAPR reduction and less amount of computation.In the frequency domain, to solve the problems of large amount of IFFT module calculation in conventional SLM algorithm, proposed a new SLM improved algorithm (TMSLM), which is based on the transformation matrix. The new SLM improved algorithm will get the time domain sequences in the time domain rather than in the frequency domain. Simulation results show that, the proposed T matrix conventional SLM algorithm needs less computation amount than the traditional SLM algorithm.Finally the paper summarizes content, which expectations more task and direction for investigative practicality.