To Route or To Ferry: A Hybrid Packet Forwarding Algorithm in Flying Ad Hoc Networks

The capabilities and roles of unmanned aerial vehicles, a.k.a. drones, have been rapidly evolving as a result of the advances in processing, sensing, communicating, and networking technologies of robotic systems. Because of the versatility, flexibility, easy installation, and relatively small operating expenses of drones, Flying Ad Hoc Networks (FANETs) consisting of a fleet of drones endowed with sensing, computing, and wireless communicating capabilities are promptly proliferating and representing a key enabler for Internet-of-Drones and its applications. Unfortunately, reliable packet forwarding in FANETs is not always guaranteed because of unstable link quality and intermittent connectivity caused by high mobility of drones. In this paper, we propose a hybrid packet forwarding algorithm, named HYBDfwd, to efficiently and reliably deliver data packets to ground destination in FANETs. The HYBDfwd consists of two schemes: end-to-end routing and delay-tolerant forwarding. In end-to-end routing, the drone initiates a route discovery procedure to find an end-to-end routing path to deliver data packets to ground destination. In case no end-to-end routing path exists, delay-tolerant forwarding is applied, where the drone forwards data packets to the ferry drone that is moving to ground destination or it carries data packets and moves to ground destination to deliver data packets. We evaluate the proposed hybrid packet forwarding algorithm through extensive simulation experiments using OMNeT++ and compare its performance with a prior motion-driven packet forwarding algorithm, and experimental results indicate that the proposed hybrid packet forwarding algorithm can be a viable approach in FANETs.