Abstract: It is most significant that train-to-train direct communication system can reduce the incidence of railway accidents effectively. However the direct communication system in plain environment has been proposed only. A new kind of multiband frequency receiver and transmitter that can be applied in both plain and tunnel environment are designed for direct communication system, then the communication performance in tunnel is analyzed. Firstly, the working frequency band and the communication distance of millimeter waves are decided for railway application requirements in tunnel. In the second place, the multiband frequency receiver and transmitter are proposed for both plain and tunnel environment, then the sensitivity of the designed receiver is computed. Moreover, the propagation mode of electromagnetic wave is analyzed in tunnel. Then the loss model of roughness and different form in tunnel is researched. The corresponding tent law and the multipath effect of propagating of electromagnetic wave are calculated. With all the above methods, the deterministic and statistic model of direct communication channel in single and double line railway tunnel are established. Meanwhile, the simulation results show the feasibility of the proposed 8 mm wave based direct communication scheme between trains.

Key words: millimeter waves, working frequency band, tunnel, direct communication channel, deterministic model, statistic model

摘要： 列车间直接通信对减少铁路交通事故的发生具有重大意义，但是目前只设计出了平原环境下列车间直接通信的通信系统。设计了既适用于平原环境也适用于隧道环境下列车间直接通信的多频段通信系统下并在隧道环境下分析了该通信系统的通信性能。确定了适合隧道环境中通信的毫米波工作频段和通信范围；设计了既可适用于平原环境也可适用于隧道环境下的多频段接收机和多频段发射机，并计算了接收机的灵敏度；最后通过分析电磁波在隧道内的传播方式、隧道壁粗糙度以及不同隧道类型对电磁波的损耗模型、帐篷定律以及隧道环境下电磁波传播的多径效应，分别建立了单线和双线铁路隧道中列车间直接通信信道的确定性模型和统计模型。通过仿真分析得出，所提出的隧道中列车间8?mm波直接通信方案是可行的。

关键词: 毫米波, 工作频段, 隧道, 直接通信信道, 确定性模型, 统计模型