Subject: [manet] Is it reasonable to use static topology in MAC protocol design for MANET

From: "tanaka atomu" <[email-masked]>
Date: Fri, 19 Nov 2004 16:02:19 +0900

Hi, all:

   Recently i am working on the MAC protocol for MANETs. I have read some 
papers in this filed, and found that in the most of the simulations they 
carried out, the topology is static, that is, all the nodes will not move 
during the simulation. This may be contrast with the most critical future 
of MANET: All the nodes move frequently and rapidly. Thus i am wondering:

1)Is it reasonable to use the static toplogy in the simulation for MANETs 
when simulating MAC protocol?

2)If it is reasonable to use static toplogy for MAC protocols of MANETs, 
will there be some different results occuring between simulating the static 
topology and simulating the dynamic toplogy?  That is, the results obtained 
when simulating static topology are different from that of dynamic 
topology. Is it reasonable?

Thanks in advance.

Tanaka

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From: "John Stine" <[email-masked]>
Date: Fri, 19 Nov 2004 06:10:13 -0500

Tanaka,

	It will depend on the MAC protocol and whether mobility will have an
affect on its performance.  If the MAC does not react to topology changes,
(i.e. track state of the network for its operation), then what purpose does
modeling mobility serve?  It is likely to confound the performance of the
routing protocol with that of the access protocol.  Examples of MAC
protocols that are sensitive to mobility are scheduling access mechanisms,
access mechanisms that use clustering, and access mechanisms that track
power requirements, interference constraints, directionality, etc.  Examples
of access mechanisms that are not sensitive to mobility are most random
access techniques, e.g. aloha, csma, and 802.11.  I personally much rather
read a paper on a MAC protocol that uses static topologies to benchmark the
MAC's performance according to node density and traffic load and then
describes how mobility would affect that performance without regard to
routing.  I do not want to see results that allow the poor choice of a next
hop destination by a routing protocol to affect the results.  An example of
an issue where mobility might be of interest in studying a MAC protocol is
to see the effect of access delay, i.e. the routing protocol makes a good
routing decision but the delay from the time that the packet was forwarded
to the MAC and the packet was transmitted allowed the topology to change.
To study the MAC protocols contribution to this problem might involve
implementing a "perfect" router and parameterizing mobility to identify how
much mobility causes the problem.  In the end, the problem will be most
sensitive to load and node density since this is what causes access delay.

John

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
tanaka atomu
Sent: Friday, November 19, 2004 2:02 AM
To: [email-masked]
Subject: [manet] Is it reasonable to use static topology in MAC protocol
design for MANET

Hi, all:

Thanks in advance.

Tanaka

---

From: "ronan de renesse" <[email-masked]>
Date: Fri, 19 Nov 2004 11:43:12 -0000

Hi,

Maybe this paper could help you:
http://www.tkn.tu-berlin.de/tkn/publications/papers/carlson_paper1.pdf

It's about a MAC reservation protocol called DARE taking mobility into
account in MANETs.

Regards,

Ronan

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of tanaka atomu
Sent: 19 November 2004 07:02
To: [email-masked]
Subject: [manet] Is it reasonable to use static topology in MAC
protocoldesign for MANET

Hi, all:

   Recently i am working on the MAC protocol for MANETs. I have read
some 
papers in this filed, and found that in the most of the simulations they

carried out, the topology is static, that is, all the nodes will not
move 
during the simulation. This may be contrast with the most critical
future 
of MANET: All the nodes move frequently and rapidly. Thus i am
wondering:

1)Is it reasonable to use the static toplogy in the simulation for
MANETs 
when simulating MAC protocol?

will there be some different results occuring between simulating the
static 
topology and simulating the dynamic toplogy?  That is, the results
obtained 
when simulating static topology are different from that of dynamic 
topology. Is it reasonable?

Thanks in advance.

Tanaka

---

From: Brown Tim <[email-masked]>
Date: Fri, 19 Nov 2004 08:39:35 -0700 (MST)

I would go a bit further than John. It is more than whether or not the MAC
protocol is affected by mobility. It also depends on whether the MAC
protocol is trying to solve mobility problems. For instance, a MAC
protocol with an embedded lightweight HELLO mechanism to keep track of
neighbors for the higher layers is much more interesting in a mobile
environment than a static environment. Many 802.11 implementations have
adaptive ACK timeouts to solve the problem that nodes can move further or
closer. And, of course, every radio is sensitive to doppler shifts at high
enough speed.

Some mechanisms may try to treat these issues specifically and so testing
in a mobile environment is imperative.
	Regards,
		Tim

On Fri, 19 Nov 2004, John Stine wrote:

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Timothy X Brown
Interdisciplinary Telecommunications
Electrical and Computer Engineering
ECOT 256 Campus Box 530
University of Colorado
Boulder, CO 80309
Tel: (303) 492-1630
Fax: (303) 492-1112
http://ece.colorado.edu/~timxb