Research On Malicious Interference Detection And Suppression Technology And Its FPGA Implementation Of OFDM Receiver

For more than a decade,OFDM technology is more widely used in military and civil communications.In the process of broadband wireless communication,it is an important issue to be studied about how to combat the great damage caused by malicious interference to the transmission performance.In this dissertation,several typical time and frequency domain interference detection and suppression techniques and the implementation of FPGA are studied for OFDM receivers.The introduction part of the dissertation introduces the background and significance of the study,and summarizes the content and structure of the research.In the second chapter,this dissertation introduces the interference model and channel model studied firstly,and then introduces the link structure of OFDM which this study is based on.Briefly explain the transceiver processing process of the link,and give the frame structure and related link parameters.In the third chapter,the detection and suppression processing techniques of interference are studied,which are divided into frequency-domain monotone and partial band interference,as well as time-domain Gaussian pulse interference.In terms of frequency domain interference detection and suppression,the FCME and CME detection algorithms,as well as zeroing,limit ingress and scaling suppression algorithms,are introduced.First,for the interference spectrum leakage caused by the time-frequency domain conversion,a method to determine the ideal interference location using 99% power bandwidth is proposed to guide the performance comparison and analysis of the algorithm.Next,in view of interference suppression,the effects of different processing algorithms on sample distribution and OFDM link performance are studied,the algorithms performance is analyzed,and is used to guide the detection processing research.Then,in view of the problem of detecting sample fluctuations,the pre-processing method of sliding average is introduced to achieve smooth data fast.For different interference scenarios,through the simulation of the probability of leakage and the detection error RMSE,the detection results are analyzed in detail.Finally,the performance of OFDM link transmission in different frequency domain interference environment is simulated,and the proposed processing algorithm can improve the antijamming ability of the link.In terms of time domain interference detection and suppression,firstly analyzes the characteristics of sample distribution in different interference environments,verifies the benefit of sliding average,and simulates the performance of direct interference detection for different time domain interference.Then,for the problem that there are more sample points of time domain detection causing difficult hardware implementation,the method of segment detection and averaging is proposed.The causes of leakage from segmentation are studied,and the proper segment detection processing has good performance as well as direct detection while reducing the complexity of processing,verified through simulation.In view of interference suppression,the effects on sample distribution and link performance are analyzed after processing by different suppression algorithms.Finally,the performance of OFDM link transmission is simulated,and the results show that the proposed algorithm can improve the reliability of link transmission in interference environment.In the fourth chapter,the FPGA implementation of interference detection and suppression treatment is studied.Firstly,the implementation structure of the preprocessing part is introduced.For the sliding average,combined with the hardware implementation characteristics,introduce a parallel processing method which can reduce data cache consumption.Then,the implementation structure of FCME and CME algorithms is described in detail.In view of the sorting processing in FCME,32 fork tree heap sorting is introduced,the processing process and control logic of the initial build and reconstruction heap are detailed described,and the stable sorting function of 512 points is realized.For the processing of FCME iterative calculation of judgment thresholds,adjust the processing order,implement parallel processing,and reduce processing latency and cache consumption.Next,the implementation structure and processing process for scaling suppression processing are introduced and the functionality is validated by simulation.Finally,the consumption analysis of hardware resources is given,and the algorithm function of Verilog HDL is verified compared with the result of MATLAB.Briefly introduce the OFDM link hardware test platform,demonstrate and analyze the platform transmission performanceThe last chapter gives the summary and the direction of the follow-up work.