Influence Analysis of Typical Objects in Rural Railway Environments at 28 GHz

Millimeter wave (mmWave) is a key to realize high data-rate communication and enable smart railway services. There are more and more research works focusing on the algorithm and system design for railway communications in the mmWave band. A correct understanding of the mmWave channel characteristics for railway scenario is important to the estimation and evaluation of designed technologies. In this paper, the influence of typical objects in rural railway environment to the mmWave propagation channel is analyzed. Based on the channel measurement conducted at 28 GHz with train-to-infrastructure deployment in the rural railway environment, a ray tracing (RT) simulator is calibrated in terms of environment modeling and electromagnetic (EM) calculation. The dominant multi-path components of the measurement are tracked and matched with corresponding objects in the propagation environment. Accordingly, dominant propagation mechanisms (direct, penetration, reflection, scattering, etc.) are determined, the 3D environment model and the EM parameters of different objects are calibrated. To overcome the constraints of the measurement and analyze the influence more practically, the measurement campaign is extended to four different environment cases and four T2I deployments. With the predetermined dominant propagation mechanisms and calibrated EM parameters, reliable RT simulations are conducted. The influence of typical objects are analyzed for the considered environment cases and deployments. The analysis of this work not only helps to understand the important influential factors of propagation channel at the object level, but also can be useful in guiding deployment of mmWave communication system. The provided EM parameters and environment modeling suggestions will enable reliable RT based channel realization in rural railway environments.