Mohamed Ehab Mahmoud, Hashima Sherief
Department of Electrical Engineering, College of Engineering in Wadi Addawasir, Prince Sattam Bin Abdulaziz University, 11991, Wadi Addawasir, Saudi Arabia.
Computational Learning Theory Team, RIKEN-Advanced Intelligence Project, Fukuoka, 819-0395, Japan.
Sci Rep. 2025 Jan 27;15(1):3343. doi: 10.1038/s41598-024-84354-8.
Providing continuous wireless connectivity for high-speed trains (HSTs) is challenging due to their high speeds, making installing numerous ground base stations (BSs) along the HST route an expensive solution, particularly in rural and wilderness areas. This paper proposes using multiple unmanned aerial vehicles (UAVs) to deliver high data rate wireless connectivity for HSTs, taking advantage of their ability to fly, hover, and maneuver at low altitudes. However, autonomously selecting the optimal UAV by the HST is challenging. The chosen UAV should maximize the HST's achievable data rate and provide an extended HST coverage period to minimize frequent UAV handovers constrained by the UAV's limited battery capacity. The optimization challenge arises from accurately estimating each UAV's expected coverage period for the HST, given both are moving at high speeds and the UAV's flying altitude is unknown to the HST. This paper utilizes the estimated HST-UAV channel parameters in the delay-doppler (DD) domain, employing orthogonal time frequency space (OTFS) modulation, to estimate the relative speeds between the HST and UAVs, as well as the UAVs' flying altitudes. Based on these estimates, HST can predict the maximum coverage period each UAV provides, allowing for selecting the best UAV while considering their remaining battery capacities. Numerical analysis demonstrates the effectiveness of the proposed approach compared to other benchmarks in various scenarios.
由于高速列车（HST）速度极高，为其提供持续无线连接颇具挑战，这使得沿高速列车线路安装大量地面基站（BS）成为一种昂贵的解决方案，尤其是在农村和偏远地区。本文提出利用多架无人机（UAV）为高速列车提供高数据速率的无线连接，利用无人机在低空飞行、悬停和机动的能力。然而，高速列车自主选择最优无人机具有挑战性。所选无人机应使高速列车可实现的数据速率最大化，并提供更长的高速列车覆盖期，以尽量减少受无人机有限电池容量限制的频繁无人机切换。由于高速列车和无人机都在高速移动且高速列车不知道无人机的飞行高度，准确估计每架无人机对高速列车的预期覆盖期会引发优化挑战。本文利用延迟 - 多普勒（DD）域中估计的高速列车 - 无人机信道参数，采用正交时频空间（OTFS）调制，来估计高速列车与无人机之间的相对速度以及无人机的飞行高度。基于这些估计，高速列车可以预测每架无人机提供的最大覆盖期，从而在考虑无人机剩余电池容量的同时选择最佳无人机。数值分析表明，与各种场景下的其他基准相比，该方法是有效的。
