Research On Reduction Of Peak-to-Average Power Ratio In OFDM System

Orthogonal frequency-division multiplexing (OFDM) is a multi-carrier modulation technique with high data rate and high spectrum utilization efficiency, so it is robust to the multipath fading channel and fit for multimedia data transform. It has been regarded and used as one of the core technologies for the fourth generation communication network. But OFDM has inherent drawbacks of high peak-to-average power ratio (PAPR) and it is sensitive to frequency offset. The paper mainly discusses how to reduce PAPR of OFDM system, and there are some simulation results made by MATLAB.Firstly, the basic principle of OFDM is introduced, the distribution of PAPR is analyzed, three methods of reducing PAPR are summarized and basic theory of each method is analyzed in detail. Then selective mapping technique (SLM) which is one of the methods of reducing PAPR is investigated in detail in terms of scrambling sequence designing and SLM algorithm. Finally, performance of some scrambling sequences is simulated and verified, and a modified SLM scheme is proposed and simulation results show that the improved SLM outperforms conventional methods in terms of both reduction of PAPR and complexity of computation.