Subject: Re: MANET application scenarioes

From: Nitin H Vaidya <[email-masked]>
Date: Mon, 6 Mar 2000 09:35:27 -0600 (CST)

>> From [email-masked] Mon Mar  6 01:37:31 2000
  >> 
  >> A light aircraft using ad hoc protocols will be moving at a minimal speed of
  >> about 70 knots and more typically between 100 and 200 knots. That is an 
  >> immediate application for the distribution eg of weather data, approach
  >> charts, safety advisories, local are and terminal traffic status information
  >> and GPS and DGPS position information and updates.

I believe the prior discussion was related to the
issue of routing for MANET, presumably unicast routing.
So please consider my comments in that context.

The application you mention above seems somewhat different
than what the typical ad hoc routing protocol targets.
This application appears more related to the stuff on
"sensor networks" which has become popular with
U.S. academia lately (thanks to DARPA) - correct me if
I am mistaken.

Would these aircrafts want to get the weather data from
a "specific" node, or just any aircraft (node) which happens
to know latest weather? To put it differently, would you
be addressing nodes based on their "IP address", or based
on the kind of data they might be able to provide?
In the latter case, the network
protocols needed are different from the vanilla unicast
protocols, particularly, putting them out of current scope
of MANET working group. (I do believe that the current scope
is terribly narrow, but that is another discussion).

  >> This application has the immediate property of "continuous/fast motion" while
  >> airborne. Also I am sure that you could sell it right now if you had
  >> a working system !

I hope your are right.

Regards.

- nitin

---

From: Carlo Kopp <[email-masked]>
Date: Tue, 7 Mar 2000 07:13:05 +1000 (EST)

On Mon, 6 Mar 2000, Nitin H Vaidya wrote:

> Date: Mon, 06 Mar 2000 09:35:27 -0600 (CST)
> From: Nitin H Vaidya <[email-masked]>
> To: [email-masked]
> Cc: [email-masked]
> Subject: Re: MANET application scenarioes
> 
Nitin,

The model is to tap into a fixed ground network infrastructure which
distributes the data from various FAA ATC and database facilities. The problem
with the conventional approach is that you are limited in bandwidth if
you employ a sat link, and limited in coverage footprint if you use a
simple VHF or UHF ground station network.

Using ad hoc you can limit the number of ground stations and their cost,
by hopping the packets between aircraft over the VHF radio horizon.

You assign a unique IP address to each aircraft. The aircraft do not gather
or provide data, in general, rather they simply act as routing nodes w.r.t.
one another. They may also distribute other data like their own GPS position
for instance, but their primary function as an ad hoc network is to extend
coverage footprint.

The fishing boat scenario is similar, but eg one boat has a satcom link
to tap into sat a met database somewhere over the horizon, on the coast,
and you employ ad hoc to form a network between the boats to distribute
the data which is sent out.

This is in a sense only "one half" of a military application, since the
latter aims to pump data gathered by many moving platforms into a centralised
system, and then distribute to these platforms processed outputs of this
data and other data from centralised wide area surveillance sources.

In civilian applications the emphasis is to make available data from
centralised sources such as weather databases and ATC / GPS data. If the
network is established then you could possibly use it to collect say GPS
position data for tracking, but that is a very low bandwidth signal which
would be insignificant cf the volume of what you are trying to distribute.
Also what you are distributing will not be identical for every aircraft
or fishing boat. While some of what they may want to see may be identical,
in general this is not true. Eg in aircraft they may be looking at weather
advisories, NOTAMs, approach charts etc for different destinations. Therefore
a straight broadcast scheme is both wasteful and cumbersome.

An ongoing problem for instance is currency of maps and charts. If you can 
download the latest map as you approach a destination, this problem goes away.

Collision avoidance is another application, since you can get the same
situational picture as the air traffic controller sees.

I don't see how this diverges from current MANET objectives, insofar as
each platform has a unique IP address and may wish to make unique requests
on ground based data resources. The reason why ad hoc is used is that it
dramatically  reduces the required coverage and thus cost of the supporting
ground infrastructure.

Cheers,

Carlo