Abstract: Between mobile terminals, the direct communication channel of train to train is the Rice which has the Line-Of-Sight（LOS） component. This paper analyzes the Doppler shift and Doppler power spectrum, showing the pure frequency shift and significant Doppler transition without apparent Doppler spread. How the parameters, especially Rice factor and train speed, affect channel fading properties is analyzed by math model. The calculated result of the level crossing rate and average duration of fades, shows that anti-fading techniques are in great need to reduce the signal fading because of the high frequency of the direct communication channel fading.

Key words: train to train communication, Rice fading, fading properties of channel, mobile to mobile channel

摘要： 列车间超短波直接通信信道是伴有视距分量的移动终端到移动终端的莱斯衰落信道。分析了多普勒频移和功率谱，得出该信道中呈现多普勒特性，但无明显的多普勒扩展。利用信道模型，讨论了信道参数特别是莱斯因子和列车运行速度对信道特性的影响。通过计算电平通过率及平均衰落持续时间，得出该信道衰落频度较大，很有必要采取抗衰落技术，以减小信号的衰落。

关键词: 列车直接通信, 莱斯衰落, 信道衰落特性, 移动端到移动端信道