| With rapid development of high-speed railway, CTCS3 system based on GSM-R network would be used progressively, but domestic test standards and construction standards are still not perfect enough. A test is needed to guarantee that the GSM-R network infrastructure and network performance meet requirements of CTCS3 system under the high-speed mobile environment, and to provide a certain reference to GSM-R network voice testing and network construction. This article combines some testing standards and requirements both at home and abroad to study correlation of RxQual, RxLevel, and Doppler Frequency offset under high speed motion and create a simulation model to predict the evolutional trace of SNR and BER under high-speed motion.Beginning with the CSD voice service requirements of GSM-R system, analyzed the GSM-R network architecture and summarized the requirements and test methods of CSD voice evaluation standards of high-speed railway, puts forward the simulation calculation methods of Doppler frequency offset along high-speed railway line on the basis of the formula of the Doppler frequency offset under the high-speed motion, and analyze the relationship of RxQual and RxLevel to the Hefei-Wuhan-line Doppler Frequency offset according to the basic theory of gray correlation, the simulation results show that RxQual and RxLevel have great correlation under the state of normal working network. Through analysis of characteristics of wireless transmission of multi-path channels, the analysis model of high speed transmission BER with multi-path fading conditions is proposed to simulate the effect of speed to BER, and simulation results show that the higher speed cause the higher BER. Four kinds of radio wave propagation loss models were studied, and a new modified MG model based on McGeeHan-Griffiths model was proposed. By stimulation comparison of actual measured data of the Beijing-Tianjin line field, the results show that the modified MG model is more close to actual measured data. |
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