Ad Hoc Networks : Technologies and Protocols - University of ...

Ad Hoc Network Applications 9
The development of the Internet in the Sky hinges on three essential technologies:
1 Robust wireless connectivity and dynamic networking of autonomous
unmanned vehicles and agents.
2 Intelligent agents including: mobile codes, distributed databases and
libraries, robots, intelligent routers, control protocols, dynamic services,
semantic brokers, message-passing entities.
3 Decentralized hierarchical agent-based organization.
As Figure 1.1 illustrates, the autonomous agents have varying domains of
responsibility at different levels of the hierarchy. For example, clusters of
UAVs operating at low altitude (1K-20K feet) may perform combat missions
with a focus on target identification, combat support, and close-in weapons
deployment. Mid-altitude clusters (20-50K feet) could execute knowledge acquisition,
for example, surveillance and reconnaissance missions such as detecting
objects of interest, performing sensor fusion/integration, coordinating
low-altitude vehicle deployments, and medium-range weapons support. The
high altitude cluster(s) (50K-80K feet) provides the connectivity. At this layer,
the cluster(s) has a wide view of the theater and would be positioned to provide
maximum communications coverage and will support high-bandwidth robust
connectivity to command and control elements located over-the-horizon from
the littoral/targeted areas.
We use this example to focus on mission oriented communications and more
precisely on a particular aspect of it, team multicast. In team multicast the
multicast group does not consist of individual members, rather, of teams. For
example, a team may be a special task force that is part of a search and rescue
mission. The message then must be broadcast to the various teams that are part
of the multicast group, and, to all UVs within each team. For example, a weapon
carrying airborne UV may broadcast an image of the target (say, a poison gas
plant) to the reconnaissance and sensor teams in front of the formation, in
order to get a more precise fix on the location of the target. The sensor UV
team(s) that has acquired such information will return the precise location. As
another example, suppose N teams with chemical sensors are assessing the
“plume” of a chemical spill from different directions. It will be important for
each team to broadcast its findings step by step to the other teams using team
multicast. In general, team multicast will be common place in ad hoc networks
designed to support collective tasks, such as occur in emergency recovery or in
the battlefield.