Research On A Monitoring System For Wireless Communication BER Performance Based On APD

With the rapid development of high-speed railways in China,the speed and capacity of trains are constantly upgraded,and the requirements for the safety performance of the railway system are increasingly strict.It is very important to pay attention to the impact of electromagnetic disturbance on train operation.With the development of digital wireless communication,the traditional communication performance evaluation methods,such as quasi-peak detection and RMS detection,are susceptible to the influence of geophone parameters,and can not well adapt to and meet the needs of interference effect evaluation of digital wireless communication transmission.For the relationship between APD statistical results and communication system BER performance,there are many in-depth studies in the academic circle,and APD special measuring instrument is constantly improved.APD can describe the first-order statistical characteristics of disturbance signal amplitude,and can provide more comprehensive statistical characteristics information of electromagnetic disturbance.At the same time,many research conclusions show that APD is closely related to the BER of the communication system,and the effects of disturbance on communication systems can be evaluated based on the measurement results of APD.This paper studies a monitoring system for wireless communication BER performance based on the APD measurement value of electromagnetic disturbance.The main work includes: studying APD measurement technology and mapping algorithm between APD and BER under PAM,PSK and QAM communication systems,using NI hardware platform and LabVIEW software platform to build a monitoring system for wireless communication BER performance based on the APD,and building verification platform under PSK and QAM systems.This paper mainly develops two main function modules of the monitoring system:APD statistics module and BER conversion module.The signal is received through the RF front end and then transmitted to the FPGA.After pre-processing,fast fourier transformation and module calculation,the multi-frequency points were distinguished and the basic statistics of APD were carried out.Then the data processed by FPGA is transferred to the master computer through DMA to realize the final calculation of APD and the conversion of APD to BER,and the final result is displayed through the waveform control.On this basis,the monitoring system was tested and verified by self-built PSK,QAM verification platform and wireless communication integrator.The experimental results verify the effectiveness of the monitoring system.By injecting Gaussian white noise with the same statistical characteristics into the wireless communication transmission channel,the BER results obtained by the three methods proposed in this paper are compared by adjusting the SNR.The deviation between the simulation results of the verification platform and the estimated results of the monitoring system is about 0.09,and the deviation between the measured results of the integrator and the estimated results of the monitoring system is about 0.03,indicating that the BER obtained by using the monitoring system is in good agreement with the simulation BER of the verification platform and the test BER of the integrator.