Research And Realization Of The Peak-to-average Power Ratio Reduction Algorithms In OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) is a high-speed parallel transmission scheme of MCM(Multi-Carriers Modulation), which transmits information through multiple orthogonal subcarriers. Owning to the high bandwidth efficiency and resistance to frequency-selective fading, OFDM is considered as one of the most competitive technology of the 4th generation mobile communication. However, the main factor which restricts OFDM is the high peak to average power ratio of the signal, it results in intermodulation distortion when signal pass through the power amplifier's non-linear region, thereby degrading system performance. This paper makes a study and discussion on how to effectively suppress the PAPR of OFDM system.Firstly, this paper summarizes the research topics, and introsuces the basic theory of OFDM system. Secondly, this paper elaborates the inherent problem, which is high PAPR phenomena in OFDM, and introduces the definition of PAPR as well as the description of the statistical characteristics of distribution. Subsequently, this paper classifies and analysis the existing PAPR suppression techniques, By simaulating and comparing these typical technologies, including Clipping-and-Filtering,Golay-Complementary-Sequence,Selective-Mapping and Partial-Transmit-Sequence.According to the problem of high computational complexity cased by the traditional PTS algorithm through all of the phase-coefficient series, this paper proposes a novel PTS based on Discrete Particle Swarm Optimization. Simulation results show that the proposed algorithm can still obtain the performance of PAPR suppression as same as the optimal PTS in the case of greatly reducing the computational complexity. These simulations verify the feasibility of the proposed algorithm.The FPGA architecture of proposed algorithm is given in the paper based on theoretic analysis. Specifically, detailed designs, implementations and testing of each module are given in the paper. In the design, the control path and the data path of the architecture are designed separately whose thought is generated from the algorithm state machine. Finally, an integration of each module is formed; and the testing results show that the implementation of PTS algorithm based on discrete particle swarm optimization can realize good performance of PAPR suppression with low complexity.With the popularity of OFDM technology and the future communications favor to the OFDM, I believe the work of this paper will take some positive role in promoting on design and implementation of PAPR Reduction Algorithm for OFDM system.