Utilizing Ground Nodes with Multi-Hop Capabilities to Extend the Range of UAV-BSs

Due to recent technological advancements in the area of unmanned aerial systems, equipping an unmanned aerial vehicle (UAV) with a base station (BS) has been proposed to augment terrestrial base stations and to enhance the performance of 5G and beyond-5G networks. At the same time, advances in multi-hop ad hoc networks have made these networks feasible for supporting communications when fixed infrastructure is unavailable. In this paper, we examine the benefit of combining these two types of networks, utilizing multi-hop ad hoc networks to augment the coverage achievable by a UAV-BS. In particular, we explore the 3D placement problem for multiple UAV-BSs that maximize the number of covered ground nodes both with and without support of multihop ad hoc ground networks. First we present a mathematical formulation of the single UAV-BS placement problem, then we propose a heuristic algorithm that to the best of our knowledge is the first one in the literature to maximize the number of directly and indirectly covered ground nodes considering nodes with the same as well as with different quality of service (QoS) requirements. Simulation results show the merits of our proposed algorithm regarding utilizing the multi-hop capabilities of the ground nodes in terms of reducing the number of UAV-BSs required to cover the nodes compared to a benchmark algorithm that does not take into account the potential of covering nodes indirectly.