Scheduling of Millimeter Wave Communications for Ultra-High-Speed Vacuum Tube Train

The vacuum tube train can break through the difficulties of wheel-rail resistance, air resistance and noise of traditional wheel-rail railways. It can reach ultra-high speed of more than 600 km/h, and greatly shorten the world distance. However, the vacuum tube has extremely high penetration losses to radio waves, and the ultra-high-speed movement of trains can also cause more serious problems such as group handover and Doppler effect than traditional high-speed train communication. In this paper, we focus on the train-to-ground millimeter wave (mmWave) communication scheduling problem of vacuum tube trains. We propose an effective multi-hop out-pipe communication architecture. The ground communication adopts a novel centralized base band unit (BBU) resource pool and distributed radio remote unit (RRU). A radio-over-fiber (RoF) technology is used to build mobile cells to achieve handover-free and improve the efficiency of train-to-ground communication. The wireless transmission within the pipeline uses specially designed leaky waveguides to overcome the Doppler spread caused by the flying movement of ultra-high-speed trains. This cleverly avoids the stubborn problems in high-speed railways. In addition, we also propose a scheduling scheme to maximize the number of successfully scheduled user request flows within a superframe. By discretizing the continuous superframes into multiple time slot segments, the complexity of the scheduling algorithm is lowered. The simulation results show that even at a speed of 1,000 km/h or higher, the proposed communication architecture and scheduling algorithm have optimal performance, including the number of completed flows and system throughput.