Research On OFDM Peak - To - Average Ratio Reduction Based On Threshold Vector Circle And FPGA Implementation

The rapid development ot wireless communication technology makes the already scarce spectrum resources become more tense. OFDM signal’s spectrum utilization is high, but its high peak-to-average power ratio feature aggravates the contradiction between effiency and linearity of the nonlinear device in the RF systems. To solve this problem, the PAPR value of OFDM signal must be reduced.In this paper, the PAPR reduction technique of OFDM signals based on threshold vector circle and the FPGA implementation of this method in OFDM baseband communication system has been studied. First, some PAPR suppression techniques such as clipping and filterings tone reservation-. active constellation extension and vector hole punching are analyzed and MATLAB simulation results are presented. On this base, a novel OFDM PAPR reduction method-Threshold vector circle technology has been proposed as the error vector magnitude(EVM)be a constraint. The main idea of this method is set the radius of threshold circle in constellation diagram based on EVM requirement and adjust the amplitude and phase of the constellation points after clipping method to the threshold circle. Then it can ensure that the OFDM signal after PAPR reduction is still able to meet the requirement of EVM indicator. Simulation results show that after the threshold vector circle algorithm, the PAPR value of OFDM signal reduces from 10.98dB to 7.502 dB, and EVM reduces from 13.8% to 11.23% compared to clipping and filtering algorithm. Then, the OFDM signal based on IEEE802.11a physical layer protocols on Xilinx FPGA platform were designed. After this, a deep study of FPGA implementation in novel PAPR reduction technology based on threshold vector circle algorithm was developed. Finally, the OFDM baseband communication transmitter system including PAPR reduction module was completed and the hardware implementation results were measured. The results show that the PAPR value of OFDM signal was reduced sharply based on the EVM performance requirement of IEEE802.11a protocols.