MinuteMan on the March
By Jeff Goldman, Mon Oct 07 00:00:00 GMT 2002

A project currently underway at UCLA is turning science fiction into reality by creating self-configuring mobile wireless networks to support robots on the move.


In Steven Spielberg's recent blockbuster,
"Minority Report," a swarm of robotic spiders marches through
a tenement in search of our hero, who lies hidden in a bathtub. Working
together, the robots systematically search the building until they track
down their target. It's all pure science fiction, straight from
the mind of Philip K. Dick-but the wireless networks to support those
spiders are currently in development.

The U.S. Navy's
Autonomous Intelligent Network and Systems (AINS) initiative is working
towards the battlefield deployment of swarms of thousands of unmanned
aerial vehicles (UAVs) and unmanned ground vehicles (UGVs), capable of
engaging in everything from surveillance to actual combat. They're
unlikely to look much like Spielberg's robot spiders, but
they'll be similar in many other ways.

Behind the AINS
initiative is UCLA's Multimedia Intelligent Network of Unattended
Mobile Agents (MinuteMan) Project, funded by the Office of Naval
Research. The five-year, $11 million project is focused on developing
protocols and algorithms to support a mobile, flexible "Internet in
the Sky," a wireless network of UAVs able to reconfigure itself
autonomously on the move.

The network is being developed for use
in battlefield situations, but there are a wide variety of potential
commercial applications for this kind of highly flexible solution. From
self-configuring wireless networks to adaptive mobile video
transmission, there's a lot going on in MinuteMan that's worth
watching.

Robots withBrains


Dr. Allen Moshfegh of the Office of Naval
Research, who heads the AINS initiative, explains that the objective is
to provide a wireless infrastructure on the fly using UAVs and UGVs.
"The goal is to be able to spontaneously form networks in an
evolving environment," he said. "We'd like to network
our infrastructure in an intelligent way, so we don't need a
preexisting infrastructure to get things going."

It's
the intelligence, or independence, of that network that's the
central challenge of the MinuteMan Project. To maintain wireless
connectivity between thousands of unmanned platforms, some moving as
fast as 700 miles per hour, the network has to be constantly
reconfiguring itself. Dr. Mario Gerla, who heads the project at UCLA,
points out that the UAVs, therefore, have to be essentially
autonomous.

"It could never work to have a commander
watching all 10,000 assets on a screen and making a decision about each
one," Gerla said. "Suppose a formation of UAVs is flying over
rugged terrain and the front nodes see an obstacle. They start flying
up, they tell the nodes in the back, and the entire swarm moves around
it. You couldn't do that from a command post hundreds of miles
away."

The difference between this and conventional
systems, Gerla explains, is that there's no man in the loop-which
means the UAVs have to be able to determine their own hierarchy.
"For routing, it is important to have some kind of leader," he
said. "And the important thing in our design is that we want to
make the hierarchy completely flexible."

The idea is to
decentralize all decision-making in order to keep the nodes as
autonomous as possible, and to eliminate any single point of failure.
When the UAVs move in clusters, they 'elect' a leader, which
can be automatically replaced if lost. "The leader will be
responsible for maintaining connectivity and routing, but if that
particular leader is shot down, another one will be immediately
elected," Gerla said.

Antennas thatMove


In developing a self-configuring network of
UAVs, Gerla says, additional challenges include scalability and
mobility. The hierarchies discussed above improve scalability by
focusing responsibility on a smaller number of group
'leaders,' but those groups have to be able to change on an
almost continual basis in order to support the degree of mobility the
MinuteMan Project is seeking.

In order to work in such a mobile
environment, the UCLA researchers are developing new protocols and
addressing schemes. "As the node moves from cluster to cluster,
the addressing remains seamless," Moshfegh said. "Every node
is uniquely identified as a contributing member of this mobile wireless
network."

He adds that bandwidth can be increased or
decreased, as needed, by simply moving nodes around. "We're
designing this dynamic mobile backbone to provide the right amount of
bandwidth for a given task," Moshfegh said. "If the existing
cluster does not have sufficient bandwidth, we may bring in other UAVs,
or reposition them, to supply more bandwidth."

On the other
hand, Gerla notes that it's also crucial to make the best possible
use of the bandwidth available. "We're designing very
efficient video encoders to work on this architecture," he said.
"If the connection quality degrades because of enemy jamming, you
can still pipe something back, even at a much slower
rate."

The aim is to give priority to mission-critical
needs. If a soldier urgently needs more bandwidth to transmit or
receive video in the field, the network has to be able to reconfigure
automatically to supply the bandwidth required. "A soldier should
be able to get the right set of network assets configured in a way that
allows him to do his job in a safe manner," Moshfegh said. "We
can't tolerate delay."

A ClearSignal


Finally, Gerla points out, an additional
challenge appears when thousands of drones are transmitting video at
once. "You'll need to have multiple video streams piped all
the way back to the commander, which is something that currently cannot
be done," he said. "Nobody has ever tried to maintain a
networked swarm with many streams."

Key to solving that
problem, Moshfegh says, will be the use of Multiple Input, Multiple
Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM)
technology. "It's a radio concept that allows for very clear
communications with very little noise," Moshfegh said. "It
will really enhance our capability to operate in urban environments, in
caves, and things of that nature."

Yankee Group analyst
John Jackson suggests that a program like MinuteMan is the ideal place
to develop new-and expensive-technologies like OFDM. "It's a
technology that's in a very, very early stage, and it will amount
to 4G," he said. "It's just not commercially viable yet.
The testing that needs to be done to get it working has not been
completed, and nobody can afford it right now."

And what
makes MinuteMan different from many other projects, Moshfegh says, is
that the researchers actually have to prove that their ideas will work.
"We're not just publishing papers," he said. "The
protocols have got to be validated before we go to the next phase of the
program. They have to demonstrate them using the wireless networking
infrastructure they've developed."

In order to do so,
the researchers are developing a hybrid simulation test bed which will
allow them to test thousands of virtual nodes. "The plan is to
have 20 or so nodes connected to the simulator," Gerla said.
"While we're running those nodes in real life, the remaining
thousands of nodes will be simulated through a gateway, so we can
evaluate the performance of the entire system in a very realistic
way."

Into CivilianLife


None of this technology, however, is limited
to military applications: Gerla contends that any network this
autonomous and flexible should have many uses beyond the battlefield.
"I could see civilian applications in emergency recovery, like fuel
spills or nuclear situations where you can't send in people or even
manned vehicles," he said.

Large-scale security operations
in stadiums or arenas could also benefit from these capabilities.
"Instead of a swarm of UAVs, you would have actual people carrying
cell phones and laptops," Gerla said. "They could form a sort
of clique to connect to each other and to the Internet. Once the
technology is inexpensive enough, it will happen."

UCLA
professor John Villasenor, another member of the project team, suggests
that the adaptive network technology could be applied to Wi-Fi
networking as well. "One of the more interesting possible future
uses for 802.11 is to support this kind of adaptive network," he
said. "To the extent that we want to have ubiquitous wireless
connectivity, the technologies we're developing could assist with
that."

Of course, it's not just a matter of deploying
the network as a whole: MinuteMan is also making advances in specific
technology areas. "Many of the components could be pulled out and
used for commercial applications," Gerla said. "The robust
video can be used for anything, including point-to-point communications:
you don't have to justify it only in a thousand-node
network."

And Villasenor points out that the military is an
excellent source for advances like these: with its unique funding and
support, a project like MinuteMan is able to explore possibilities that
the commercial sector can't afford to support. "A commercial
3G system with video is fairly far down the road-whereas the military
has an immediate and growing need for this kind of very sophisticated
imagery," he said.

Jeff
Goldman is a freelance writer covering a wide range of
topics for a number of online journals. He currently writes regular
articles for Internet.com's ISP-Planet. Brought up in Belgium,
Jeff spent the last decade in New York, Chicago and London; he now lives
in Los Angeles.