Subject: [manet] should we have size of MANET as a metric

From: Sukanta Kumar Hazra <[email-masked]>
Date: Fri, 21 Mar 2003 09:48:03 +0800

Hi!

Regarding the comments made by Dave in the MANET meeting today, I tend
to agree with him, that we need an idea of the size of the network that
the different protocols support. That might be an important
consideration. The network model and the traffic model might be somthing
that is difficult to agree on, but would be desirable. I have the need
to evaluate a number of ad hoc routing protocols for network consisting
of up to 10000 nodes, and some idea of which protocol is suitable for
such a network would be great.

- Sukanta

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Sukanta Kumar Hazra <[email-masked]>
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From: "John Mullen" <[email-masked]>
Date: Fri, 21 Mar 2003 08:15:34 -0700

Hi Sukanta,

I agree that this is important, but the trouble with "size" is the
problem of how to describe it.  Certainly, the number of nodes is a
factor, but it is one thing when most nodes can reach their destinations
directly and another when multi-hops are the norm.  The trouble is that
technology, geography, and usage patterns interact.

For example, if the network is over a wide area, but the traffic pattern
is such that 90% of messages are to neighbors, there will be a
relatively small need for relays.  The same situation can arise if the
network is compact enough that most nodes can reach one another
directly, regardless of the traffic pattern.  However, if traffic
patterns or geographical dispersion is greater, then the same number of
nodes presents a more difficult problem.

For another, a network that is working in a large, open, mostly
featureless area will not have the same problems as one working in an
urban environment.

There are other factors that will affect the "size" of the MANET.  For
example, if nodes are highly mobile, it will be necessary to broadcast
Hellos more frequently to retain and distribute knowledge of the
topology, than if the MANET contains only a few mobile nodes or is
relatively stable.  This increases the risk of latency problems and
reduces the BW available for transmitting messages.

Certainly, the size should be a metric, but I feel that "size" needs to
be measured in a way that has some relevance to the MANET problem.  Some
measures that might work are:

1. Total number of nodes, as you suggest, plus
2. Average fraction of the net within one hop, or maybe better yet, the
distribution of the number of hops,
3. The area of the network in terms of the direct-connect radius,
4. The aspect ratio or some other shape parameter of the geographical
coverage

and so on.

Of course, the important thing is the MANET community agree on whatever
measures that are chosen so that people don't end up trying to compare
apples to televisions.

John Mullen

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Sukanta Kumar Hazra
Sent: Thursday, March 20, 2003 6:48 PM
To: Manet WG
Subject: [manet] should we have size of MANET as a metric

Hi!

- Sukanta

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From: "'Sukanta Kumar Hazra'" <[email-masked]>
Date: Mon, 24 Mar 2003 21:42:37 +0800

Hi John,

I agree with the issues that you have pointed out. If we could agree on
a few scenarios, which take into account most the points that you have
raised, that would be good. We could avoid the problems associated with
finding "the one" model that is representative of all the factors that
we want to take into account.

It would then be possible to evaluate the various routing protocols in
these scenarios and thus have some feel for their performance and
suitabililty.

- Sukanta