Quick Gateway Switching for Reliable Data Collection in Multi-Gateway UAV Networks With Gateway Failures

In some UAV networks (Unmanned Aerial Vehicle networks), data is sent from UAVs to a backend server through gateway UAVs in real time. To avoid a single point of failure, using multiple gateways is preferred so that a UAV can switch to another one if a gateway fails. However, we find that the combination of current routing protocols and the IP protocol stack leads to slow switching, usually over 20 seconds. In this paper, we propose a Quick Gateway Switching approach (QGSwitch) for UAV networks with multiple gateways. QGSwitch uses the Batman-adv routing protocol, a built-in module in the Linux kernel, to establish an ad hoc network. With QGSwitch, UAVs do not need to change their IP settings when a gateway fails because the switching is done at the data link layer. To reduce the delay caused by passive failure detection, QGSwitch improves neighbor discovery and its link with the routing protocol. We implement QGSwitch on Raspberry Pi computers and conduct evaluations in both indoor and outdoor environments. Results show that QGSwitch reduces the average gateway switching delay to 1.24 seconds, which is quicker than Batman-adv with 36.48 seconds and OLSR with 20.43 seconds. It also outperforms both baselines in terms of packet loss and throughput.