Wireless Communication Using Unmanned Aerial Vehicles (UAVs): Optimal Transport Theory for Hover Time Optimization
Wireless Communication Using Unmanned Aerial Vehicles (UAVs): Optimal Transport Theory for Hover Time Optimization
复制标题
DOI：
10.1109/twc.2017.2756644
复制
发表时间：
2017-12-01
影响因子：
10.4
通讯作者：
Debbah, Merouane
中科院分区：
文献类型：
--
作者：
Mozaffari, Mohammad;Saad, Walid;Debbah, Merouane
本文研究了飞行时间受限的无人机（UAV）作为飞行基站向地面用户提供无线服务的有效利用问题。特别地，提出了一种用于在发送给用户的平均比特数（数据服务）以及UAV的悬停持续时间（即，飞行时间）。在所考虑的模型中，无人机悬停在一个给定的地理区域，以服务于地面用户分布在该区域内的基础上的任意空间分布函数。在这种情况下，考虑两种实际情况。在第一种情况下，基于无人机的最大可能悬停时间，通过找到与无人机相关联的最佳小区分区，在公平资源分配方案下递送给用户的平均数据服务被最大化。利用最优运输理论的强大的数学框架，这个单元划分问题被证明是等价的凸优化问题。随后，提出了一种基于梯度的算法，用于基于用户的分布，悬停时间和无人机的位置的地理区域的最优划分。在第二种情况下，给定地面用户的负载要求，无人机完全服务于地面用户所需的最小平均悬停时间。为此，首先，提出了一种用于服务用户的最优带宽分配方案。然后，给出了这种最优带宽分配，最优小区分区与无人机推导出利用最优运输理论。仿真结果表明，与传统的加权Voronoi图相比，我们提出的小区划分方法在用户间具有更高的公平性。此外，结果表明，无人机的平均悬停时间可以减少64%，通过采用所提出的最优带宽分配方案以及最优单元划分方法。此外，我们的研究结果揭示了一个内在的权衡之间的悬停时间的无人机和带宽效率，同时服务于地面用户。
In this paper, the effective use of flight-time constrained unmanned aerial vehicles (UAVs) as flying base stations that provide wireless service to ground users is investigated. In particular, a novel framework for optimizing the performance of such UAV-based wireless systems in terms of the average number of bits (data service) transmitted to users as well as the UAVs' hover duration (i.e., flight time) is proposed. In the considered model, UAVs hover over a given geographical area to serve ground users that are distributed within the area based on an arbitrary spatial distribution function. In this case, two practical scenarios are considered. In the first scenario, based on the maximum possible hover times of UAVs, the average data service delivered to the users under a fair resource allocation scheme is maximized by finding the optimal cell partitions associated to the UAVs. Using the powerful mathematical framework of optimal transport theory, this cell partitioning problem is proved to be equivalent to a convex optimization problem. Subsequently, a gradient-based algorithm is proposed for optimally partitioning the geographical area based on the users' distribution, hover times, and locations of the UAVs. In the second scenario, given the load requirements of ground users, the minimum average hover time that the UAVs need for completely servicing their ground users is derived. To this end, first, an optimal bandwidth allocation scheme for serving the users is proposed. Then, given this optimal bandwidth allocation, optimal cell partitions associated with the UAVs are derived by exploiting the optimal transport theory. Simulation results show that our proposed cell partitioning approach leads to a significantly higher fairness among the users compared with the classical weighted Voronoi diagram. Furthermore, the results demonstrate that the average hover time of the UAVs can be reduced by 64% by adopting the proposed optimal bandwidth allocation scheme as well as the optimal cell partitioning approach. In addition, our results reveal an inherent tradeoff between the hover time of UAVs and bandwidth efficiency while serving the ground users.