  To exploit richer spectrum resources for even better service quality,
millimeter wave (mmWave) communication has been considered for high-speed
railway (HSR) communication systems. In this paper, we focus on scheduling as
many flows as possible while satisfying their QoS requirements. Due to
interference, eavesdropping, or other problems, some flows may not be directly
transmitted from the track-side BS. In this paper, we propose an UAV-assisted
scheduling scheme which utilizes a UAV to serve as relay for such flows. The
proposed scheme also utilize two mmWave bands, one for the BS links and the
other for the UAV links. The proposed algorithm aims to maximize the number of
flows with their QoS requirements satisfied. Simulations demonstrate that the
proposed scheme achieves a superior performance on the number of completed
flows and the system throughput over two baseline schemes.
