Research On Reducing Peak-to-Average Ratio In Optical Orthogonal Frequency Division Multiplexing System

Optical Orthogonal Frequency Division Multiplexing(OOFDM)technology has the advantages of high bandwidth,high transmission rate,high spectrum utilization,good security,and resistance to fiber dispersion,which has attracted more and more attention.However,because an orthogonal frequency division multiplexing(OFDM)signal is formed by superimposing sub-carriers,when the phases of adjacent sub-carriers are close,the peak value of the signal will be relatively high,resulting in a relatively high instantaneous peak average of the signal.There are many non-linear components in the OOFDM communication system.When a signal with a high peak-to-average ratio passes through these non-linear components,signal distortion will occur.In order to adapt to the signal with the peak-to-average ratio,the system will have higher requirements for the performance of the components.This increases the cost of the communication system.Therefore,suppressing the peak-to-average ratio of OFDM signals is the key to low-cost,high-quality communication.In this article,in order to suppress the peak-to-average ratio of the signal,the focus is on the optical orthogonal frequency division multiplexing system based on nonlinear compression algorithm.Non-linear compression algorithm refers to a series of processing and cosine operation on the signal before digital-to-analog conversion,which makes the amplitude of the signal change between-1 and 1,thus limiting the amplitude range of the signal.The main work and innovations of this paper are as follows:(1)Deeply understand the principle of OFDM,build an OFDM communication system based on FPGA,including transmitter design,digital-to-analog conversion,and receiver design.(2)A theoretical analysis of the nonlinear compression algorithm is carried out,and the algorithm is implemented in hardware for the first time using coordinate rotation digital calculation(CORDIC),and experiments are carried out on the built OFDM hardware platform.(3)Calculate the original signal and the peak-to-average ratio of different coefficients under the algorithm,test the bit error rate of the communication system,and analyze and compare the experimental results.Experiments show that:After using this algorithm,compared with ordinary OOFDM systems,when the complementary cumulative distribution function(CCDF)is 10^-2,the peak-to-average ratio can be reduced by 5.426d B,and due to the reduced requirements for the quantization bits of the digital-to-analog converter,bit errors rate has also been reduced.