The effect of reference distance on path loss prediction based on the measurements in high-speed railway viaduct scenarios

This paper presents the narrowband measurements taken along “Zhengzhou-Xi´an” high-speed railway of China at 930 MHz. The detailed measurements and data processing methods are given using the present GSM-Railways (GSM-R) network, which can be used as the guide method to conduct the narrowband measurements in high-speed railway viaduct scenarios. Based on the log-normal shadowing path loss model, the investigation is made on the effect of reference distance on path loss exponent and standard deviation, which are not well-covered by existing models. The values of path loss exponents and standard deviations calculated with different reference distances are compared. A novel model is proposed to describe the relation of them. It applies to high-speed railway viaduct scenarios, with base antenna heights higher or lower than 25 meters. It raises path loss prediction accuracy and gives the suggestion on large scale modeling considering the effect of reference distance.