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The micro air vehicle link (MAVLink in short) is a communication protocol for unmanned systems (e.g., drones and robots). It specifies a comprehensive set of messages exchanged between unmanned systems and ground stations. This protocol is used in major autopilot systems, mainly ArduPilot and PX4, and provides powerful features not only for monitoring and controlling unmanned systems missions but also for their integration into the Internet. However, there is no technical survey and/or tutorial in the literature that presents these features or explains how to make use of them. Most of the references are online tutorials and basic technical reports, and none of them presents comprehensive and systematic coverage of the protocol. In this paper, we address this gap, and we propose an overview of the MAVLink protocol, the difference between its versions, and it is potential in enabling Internet connectivity to unmanned systems. We also discuss the security aspects of the MAVLink. To the best of our knowledge, this is the first technical survey and tutorial on the MAVLink protocol, which represents an important reference for unmanned systems users and developers. INDEX TERMS MAVLink, ArduPilot, PX4, Unmanned Aerial Vehicles (UAVs), Ground Control Stations (GCSs).

Recently, user mobility in wireless data networks is increasing because of the popularity of portable devices and the desire for voice and multimedia applications. These applications, however, require fast handoffs among base stations to maintain the quality of the connections. Re-authentication during handoff procedures causes a long handoff latency which affects the flow and service quality especially for multimedia applications. Therefore minimizing re-authentication latency is crucial in order to support real-time multimedia applications on public wireless IP networks. In this paper, we propose two fast re-authentication methods based on the predictive authentication mechanism defined by IEEE 802.11i security group. We have implemented these methods in an experimental test-bed using freeware and commodity 802.11 hardware and we demonstrate that they provide significant latency reductions compared to already proposed solutions. Conducted measurements show a very low latency not exceeding 50 ms under extreme congested network conditions.