Research And Implementation Of OFDM System Peak-to-Average Ratio Reduction Technology Base On Zero Interme-Diate Frequency Architecture

Orthogonal frequency division multiplexing(Orthogonal Frequency Division Multiplexing,OFDM)technology has become a mainstream technology in the communication field because of its advantages of high communication bandwidth,simple modulation and demodulation implementation,and good robustness under multipath channels.It is widely used in digital TV broadcasting,wireless LAN,4G mobile communication and other fields.In the coming 5G era,OFDM is still a very competitive core technology.Although OFDM technology has many advantages,it also has the disadvantage of Peak to Average Power Ratio(PAPR).The OFDM signal with peak to average power ratio reduces the working efficiency of the power amplifier,and it is easy to cause signal distortion,resulting in system bit error rate rise.Solving the problem of peak-to-average ratio is a prerequisite for further expanding the application scenarios of OFDM technology.This paper analyzes the existing various peak-to-average ratio suppression technologies,and simulates the suppression effects of different technologies.Based on a comprehensive understanding of the advantages and disadvantages of different technologies,a linear optimal time-domain selection and limiting joint algorithm is proposed for the shortcomings of traditional peak-to-average ratio suppression technology,such as greater system overhead and scheme complexity,suppression performance and poor bit error rate And implement FPGA implementation of zero-IF architecture.The main research contents of this article include:(1)A fixed phase sequence is used to replace the random phase sequence of the traditional selective mapping method.At the same time,the fixed phase sequence is grouped at the sending end.The system only needs to transmit a small amount of packet number data,and the suppression algorithm can be translated at the receiving end.code.(2)Introducing the linear nature of Inverse Fast Fourier Transform(IFFT),splitting the signal into real and imaginary parts for separate operations,and combining to generate more candidate signals to improve peak average Than suppression effect.Compared with the traditional method,in the case of obtaining the same candidate signal,this method greatly reduces the computational complexity,which is beneficial to the realization of hardware.(3)Combining probabilistic technology and amplitude limiting technology,and simulation verification shows that the joint algorithm is not only beneficial to enhance the system's peak-to-average ratio suppression capability,but also improves the traditional amplitude limiting technology due to signal nonlinear distortion,resulting in bit errors The problem is too high.(4)On the OFDM system with zero intermediate frequency architecture,FPGA(Field Programmable Gate Array)design and implementation of the proposed joint algorithm.The zero-IF architecture uses Zedboard and AD9361 as development platforms.AD9361 implements the signal spectrum shift,and Zedboard implements all the functions of the algorithm and baseband logic mentioned in the paper.(5)Through the tools of spectrum analyzer,oscilloscope and Matlab,it is verified that the optimal time-domain selection and limiting joint algorithm has a peak-to-average ratio suppression performance that is 2.2d B and 0.8d B better than the performance of the traditional selection mapping method and the limiting method;In terms of hardware resource consumption,compared to the traditional selection mapping method,it can save 8% of lookup table resources,9% of LUTRAM resources,7% of register resources,and 13% of block RAM resources.