  Recently, swarms or formations of drones have received increased interest
both in the literature and in applications. To dynamically adapt to their
operating environment, swarm members need to communicate wirelessly for control
and coordination tasks. One fundamental communication pattern required for
basic safety purposes, such as collision avoidance, is beaconing, where drones
frequently transmit information about their position, speed, heading, and other
operational data to a local neighbourhood, using a local broadcast service. In
this paper, we propose and analyse a protocol stack which allows to use the
recurring-beaconing primitive for additional purposes. In particular, we
propose the VarDis (Variable Dissemination) protocol, which creates the
abstraction of variables to which all members of a drone swarm have (read)
access, and which can naturally be used for centralized control of a swarm,
amongst other applications. We describe the involved protocols and provide a
mainly simulation-based performance analysis of VarDis.
