高铁列车通信中无线衰落分析

Wireless fading analysis in high-speed train communication

为在高铁列车通信中应用无线宽带接入技术拓展车地无线通信系统,分析在此场景下的衰落模型.在高速铁路车地无线通信基本架构的基础上,分别从无线信道自由空间模型、两径模型、简化路径损耗模型等方面研究高铁无线信道的路径损耗、阴影衰落模型.通过实测数据分析和建模衰落信道,表明车地通信中无线信号传播在大尺度范围内近似于服从自由空间模型.基于实测数据,推导高铁车地通信中的中断概率表明,无线信道参数决定中断概率曲线、最低接收功率决定车地通信最大距离.与中断概率一样,小区覆盖范围曲线也由无线信道主要参数决定,但最大车地无线通信距离值与中断概率下的取值约有10%的差距.

In order to make communication systems in high-speed train adopt wireless broadband-access technologies, the fading models for the scenario were analyzed to develop train-to-ground wireless commu- nication （TGWC） system. Based on the fundamental architecture in TGWC for high-speed railway, the wireless fading models of path loss and shadow effect were studied among free space model, two-ray model and simplified path loss model. The results of analyzing the measured data and modeling fading channel show that the wireless transmission in TGWC approximately obeys free space model in large-scale propaga- tion. In view of the measured data, the deviation of outage probability in TGWC illustrates that the curve is determined by the parameters of wireless channel while the maximal train-to-ground distance is decided by the minimal receipt power. Similar to the outage-probability curve, the curve of cell coverage is also de- cided by the wireless fading channel, but the maximal train-to-ground distance makes 10% difference to the value in outage probability.