Research And Design For Papr Reduction In OFDM System

OFDM is a special kind of multicarrier transmission technology which is effective against multipath fading, and it has high frequency spectrum utilization ratio to achieve data transmission efficiency. But now, in the OFDM system, there are still a lot of key problems which have not got a good solution, such as peak power ratio, frequency deviation sensitivity and so on. To a certain extent this restrict the application range of OFDM technology. This paper mainly discusses the problem of how to reduce PAPR in OFDM system.First of all, this paper introduces the research background of the chosen topic. The OFDM system is introduced, the development features and the present situation of the technology are described. Then the paper makes a brief description on the advantages and disadvantages of OFDM system, illustrating the necessity of the research on PAPR reduction.Secondly, this paper introduces the basic principle of OFDM system in detail, including the OFDM system realization model, subcarrier modulation and the realization of the DFT, protect interval and cycle prefix paper, and the peak of OFDM system than the average power to carry on the detailed description, then introduces the PAPR of pressing method which is divided into three categories, including signal preliminary distortion technology, coding class technology and probability class methods.According to the improved GA-PTS algorithm to reduce PAPR algorithm and algorithm based on the thought, using Matlab software of the corresponding simulation program, set up corresponding simulation parameters, the corresponding simulation, get the corresponding simulation results. According to the improved GA-PTS algorithm to reduce PAPR of simulation results, the corresponding simulation contrast, through the original PTS algorithm and improved GA-PTS algorithm simulation results contrast with the improved GA, found PTS algorithm can effectively reduce PAPR.Finally, when using the original PTS algorithm, according to the problem of the necessity for sending sideband information, the paper puts forward a PTS algorithm which based on the pilot tone of modified low complexity endless information transmission. Based on the original algorithm, the new algorithm can estimate the phase factort of the sender through further calculating the sum of the received pilot tone’s real part and the imaginary part under conditions of expanding phase factors, resulting in the stronger ability to reduce PAPR. At the same time, the new algorithm won’t significantly influence the system BER performance, and won’t significantly increase the complexity of the system, so that the ability of the improved method to reduce PAPR is stronger than the old one.At last the paper makes a simulation of the proposed algorithm, and the results have proved that the proposed algorithm has better performance than the existing algorithm.