Abstract: Based on the tunnel geometry size, this paper calculates the cutoff frequency of the radio waves in the tunnel, then uses radio wave propagation path loss and multi-path fading modeling in subway tunnel, and makes a simulation of loss and fading channel for rectangular tunnel. In the end, it concludes that there is a direct path and there is not direct path for receiver signal level of the envelope. The simulation result shows that the received signal intensity is greater than －70 dBm when the AP distance is 400 meters. This conforms to the technical requirements.

Key words: Communication-Based Train Control（CBTC）, train-ground communication, wireless channel, path loss model, multi-path fading model

摘要： 根据隧道几何尺寸计算出无线电波在隧道中的截止频率，利用路径损耗和多径衰落进行地铁矩形隧道中无线信道的建模，对矩形隧道损耗衰落信道进行仿真，得出存在直射路径和不存在直射路径时的接收点接收信号的电平包络，仿真结果表明AP间隔距离为400 m时，接收强度大于－70 dBm，满足技术要求。

关键词: 基于通信的列车控制（CBTC）, 车-地通信, 无线信道, 路径损耗模型, 多径衰落模型