To reap the benefits of dense small base station (SBS) deployment, innovative backhaul solutions are needed for scenarios in which high-speed ground backhaul links are either unavailable or limited in capacity. In this paper, a novel backhaul scheme that relies on unmanned aerial vehicles (UAVs) as an on-demand flying network is proposed. The design of the aerial backhaul scheme is formulated as a network formation game among UAVs that seek to form a multi-hop backhaul network in the sky. To solve this game, a myopic network formation algorithm which reaches a pairwise stable network upon convergence, is introduced. The proposed network formation algorithm enables the UAVs to form the necessary multi-hop backhaul network in a decentralized manner thus adapting the backhaul architecture to the dynamics of the network. Simulation results show that the proposed network formation algorithm achieves substantial performance gains in terms of both rate and delay reaching, respectively, up to 380% and 410% compared to the formation of direct communication links with the gateway node (for a network with 15 UAVs). The dense and viral deployment of small base stations (SBSs) is expected to lie at the heart of emerging 5G networks [1] . However, to reap the benefits of SBS deployment, innovative backhaul solutions are needed, as SBSs may be deployed in adverse locations and rural areas in which backhaul access is either inexistent or strictly limited in capacity [2] . Several approaches have been recently proposed for SBS backhauling [1]- [4] . Such solutions include wired and wireless backhauling to and from core network aggregators, cooperation through anchor base stations, and multi-hop over short-range links [1], [2] . Nevertheless, existing solutions do not account for scenarios in which the high-speed ground backhaul is either congested, unavailable, or limited in capacity. In such scenarios, the backhaul connectivity of SBSs can become a bottleneck thus degrading the performance of the radio access network. Therefore, a novel paradigm shift of backhaul network design for 5G networks and beyond is needed. One promising solution for such scenarios is to deploy unmanned aerial vehicles (UAVs) for providing backhaul connectivity to the ground SBSs [5] and [6] . Due to their rapid and flexible deployment capabilities, mobility, ability to fly above obstacles, and relatively low cost, UAVs have received considerable interest for different applications in wireless communications, and in particular, as communication relays [7]-[9]. In this regard, the authors in [4] propose a vertical fronthaul/backhaul framework based on UAVs and free-space optics communication. The authors in [7] consider the formation of a multi-hop relay system based on UAVs in order to extend the communication range of the ground network. In [8] and [9], the authors consider a mobile relay network model in which a UAV serves as a resilient moving relay among the SBSs. In [10], the authors consider the use of UAVs as relays for backhaul connectivity of high altitude balloons in case of temporary
In REF , they proposed a network formation game to solve the problem of connecting SBSs to the core network by multi-hop UAVs devices and to optimize the delay and throughput.
Network Formation in the Sky: Unmanned Aerial Vehicles for Multi-Hop Wireless Backhauling
GLOBECOM 2017 - 2017 IEEE Global Communications Conference
GLOBECOM 2017 - 2017 IEEE Global Communications Conference
Mathematics Computer Science