The Research On PAPR Reduction Technology In OFDM Systems

Orthogonal Frequency Division Multiplexing(OFDM) is regarded as the key technology of physical layer in the next generation mobile communication systems for its robustness effective against multipath channel effect.OFDM has been applied to many wireless communication systems.However,a major drawback of OFDM signals is their high Peak-to-Average-Power Ratio(PAPR), which makes the inter-modulation distortion occur due to the nonlinearity of the high power amplifier.The distortion severely deteriorates the performance of the OFDM systems.So,how to effectively reduce the PAPR of the input OFDM signal is an important issue,which needs to be addressed in OFDM systems. According to the problems mentioned above,this dissertation focuses on the reducing PAPR algorithms design for OFDM systems,and being testified with Matlab software.Start with the basic theory of OFDM technology,the thesis analyses various key techniques of OFDM systems.The paper makes deep analysis on simulation, and summarizes the most popular three kinds of PAPR reducing techniques. Particularly,strong emphasis is cast on partial transmit sepuences(PTS),which belongs to the non-distorting technology.Though,the PTS method possesses the advantages of anti distortion,not being limited by the number of carriers,less loss of frequency spectrum.However,the most serious flaw of PTS is the heavy complexity of computation,which strongly restricts the application of PTS method.Thus,it is very significant to propose improved methods,which could not only reduce the PAPR of OFDM systems effectively,but also possess low complexity of computation.Around the issue of how to reduce the calculation complexity in PAPR reducing methods.Based on different angles,several well accepted improvd schemes are deeply analyzed and researched,which could not only reduce the computational complexity,but also keep good performance of OFDM systems.In the end in order to reducing the calculation of PAPR in PTS, the method of using similar iterative scheme to replace the calcuation of PAPR is proposed.An improved method is proposed by using similar iterative scheme to replace from the point of simplifying the calculation of PAPR in PTS-OFDM, proposes the methoc of using.In this paper,the simulation and analysis of these algorithms by using Matlab are made,the feasibility,technical characteristics and application scope of these algorithms are testified.