Research And Design On Improving The PAPR Technology In OFDM System

Due to the advantages of high spectral efficiency,combat frequency selective fading and simple realization,OFDM technology has been widely used in broadband wireless communication system and was identified as one of the key technologies of 4G. But as a highly efficient multi-carrier transmission technology,OFDM has two major drawbacks,one of which is the high Peak-to-Average Power Ratio(PAPR). High PAPR will increase the cost of the transmitter, reduce the efficiency of the power amplifier and affect the use of mobile terminal. Therefore, how to effectively reduce PAPR has become a research hotspot.The paper mainly focuses on how to improve the PAPR technology in OFDM system,proposes a new method to generate phase sequences based on three dimensional chaotic system and improves the traditional selective mapping(SLM) method by introducing the three dimensional chaotic phase sequence.The paper first introduces and analyzes the background and current status of the subject, the basic principles of OFDM system and some key technologies.Then three PAPR reduction categories are introduced with some analysis and simulation,where the SLM method in probabilily method is mainly studied in the paper.Chaotic systems with randomness and ergodicity, have been applied and developed in a number of areas. The paper proposes a method to generate phase sequences based on three dimensional chaotic system, and then analyzes the generation process and the performance of phase sequence.An improved SLM method, whose random phase sequences produced by three dimensional chaotic system, is proposed to reduce side information and the complexity of the system.According to the characteristics of chaos, chaotic phase sequences,proposed in the fourth chapter,is introduced for improveing the PAPR reduction performance in SLM. Studies and simulations show that the improved SLM method not only saves transmission resources and improves the PAPR performance of the system, but also has more number of sequences, and easy to be generated.