Modeling On High Speed Rail Train-to-ground Wireless Communication Channel

In recent years, high-speed rail technology is developing rapidly. As of October 26, 2014, Chinese high-speed railway operating mileage has more than 12,000 kilometers, about 50% of the world’s high-speed rail total operation mileage, and the high-speed rail network already has the world’s largest scale and highest operating speed. Nowadays high-speed rail has become one of the most important ways for passenger travel. With the train safety monitor, passenger information services and other needs disappearing, the requirements for stability and rapidity to train-to ground wireless communications is increasing. However, with the speed of the train is accelerating, the Doppler effect caused by high speed and the multipath effects caused by scene complexity, have serious impact on the quality of wireless communication. Traditional narrow-band GSM-R is unable to meet the high demand of data transfer rate and can not guarantee the broadband mobile communication services in high-speed environments. To solve the sharp decline in passenger communication quality caused by the train speed’s significantly improvement, detection information is not real-time return and other issues, we need to build broadband wireless private network based on LTE-R, to completely solve the high-speed rail train-to-ground communication problems through a range of key technologies.Establish reasonable and reliable wireless channel model is the basis for train-to-ground communication system design. Research on high-speed rail train-to-ground broadband wireless communication channel modeling approach is a very important part to solve the current communication problems. High-speed rail operating environment’s complexity, the Doppler shift, channel switching frequency and other issues bring great difficulties to wireless channel modeling. Traditional modeling methods include deterministic modeling, statistical modeling and semi-deterministic modeling. Different modeling methods have their advantages and disadvantages. To solve the above problems, combining the advantages of a variety of different modeling methods, a new method of channel modeling is proposed in this paper.In this paper, we combine theoretical modeling and field measurements. Firstly, based on geometric random scattering theory, analyze the characteristics of three typical high-speed rail scenarios including field, mountain and city, then establish channel model and divided derived the AoD probability density distribution and temporal correlation properties. Next, measure the high-speed wireless channel and data processing, and extract the channel parameters including multipath, delay and so on according to the PDP distribution. Finally, make the self-built model simulation and verification. The measurement parameters and theoretical models are combined, creating a complete channel model. In AoD probability density and space-time correlation characteristics two aspects, to field, mountain and city three sceneries, compare Winner Ⅱ classic model, self-built model and the measured values to verify the validity and accuracy of channel model established in this article.The result shows that the channel model established in this paper fits better with the measured data, more effective and accurate. It is of great significance for the train-to-ground wireless communication quality improvement, for meeting train safety monitoring, passenger information services and other needs, for enhancing the wireless communication system stability and rapidity, and for setting up LTE-R-based broadband wireless private network to solve the high-speed railway train-to-ground communication problems.