  We present algorithms for uniformly covering an unknown indoor region with a
swarm of simple, anonymous and autonomous mobile agents. The exploration of
such regions is made difficult by the lack of a common global reference frame,
severe degradation of radio-frequency communication, and numerous ground
obstacles. We propose addressing these challenges by using airborne agents,
such as Micro Air Vehicles, in dual capacity, both as mobile explorers and
(once they land) as beacons that help other agents navigate the region.
  The algorithms we propose are designed for a swarm of simple, identical,
ant-like agents with local sensing capabilities. The agents enter the region,
which is discretized as a graph, over time from one or more entry points and
are tasked with occupying all of its vertices. Unlike many works in this area,
we consider the requirement of informing an outside operator with limited
information that the coverage mission is complete. Even with this additional
requirement we show, both through simulations and mathematical proofs, that the
dual role concept results in linear-time termination, while also besting many
well-known algorithms in the literature in terms of energy use.
