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Key Technologies of Broadband Wireless Communication for Vacuum Tube High-Speed Flying Train

The vacuum tube high-speed flying train (high-speed flying train) is a novel rail transportation technology. The maglev train can run with low mechanical friction, low air resistance and low noise mode at ultra-high-speed (over 1000 km/h) in all weather conditions inside the vacuum tube. In this paper, we describe the unique characteristics associated with the wireless communication of high-speed flying train, such as high Doppler frequency shift, metal waveguide effect and extreme frequent handoff. Therefore, the solution of leaky-wave system is selected to effectively suppress the Doppler effect in the vacuum tube. The simulation results show the even field distribution at the observation point far away from the leaky-wave system, and the uniform phrase distribution along the train motion direction, which can eliminate Doppler frequency shift. Since the simulation indicates that the conventional time-varying frequency-selective fading channel is converted into a stationary channel, we proposed an electromagnetic wave refractive lens system, which together with the leaky wave near-field convergence technology can directly achieve the even wireless signal coverage for passengers inside the train. In addition, in order to deal with the extremely frequent handoff, the solution of moving cell is adopted, which can be realized by the Centralized, cooperative, cloud Radio Access Network (C-RAN).