Subject: Is there suitable SIMULATOR for AD HOC NETWORKING?

From: Seoung-Bum Lee <[email-masked]>
Date: Tue, 14 Oct 1997 09:44:17 -0400 (EDT)

Hello respectable member of manet members.

I am curently testing some of the ideas for wireless & mobile ad hoc
networks. I am also trying to find a suitable simulator which suits the ad
hoc environment but I feel that some of the well known simulators are
incapable of carrying out the simulation. Can anyone suggest a simulator
which is flexible enough to simulate ad hoc networking? (Or, is everybody
building the testbed from the scatch?) 
  
Thank you in advance for your help.

 Seoung-Bum Lee
 COMET Group, CTR
 Graduate Student, Columbia University
 e-mail : [email-masked]

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From: [email-masked] (Samir Ranjan Das)
Date: Tue, 14 Oct 1997 09:59:51 -0500 (CDT)

Seoung-Bum Lee writes > 
> building the testbed from the scatch?) 

As far as I can tell, there is nothing out there that will directly let
you simulate ad-hoc networks. The choice of simulators is sometimes
religious, and sometimes particularly geared towards what sort of
details is important to you. Some have simulated ad-hoc networks from
scratch, may be using some discrete-event simulator. Some simulators
provide you with some network or channel models, such as OPNET
(commercial), Maisie (developed in UCLA), NS-2 (UCB/ISI/LBL joint
project). I don't think any of them gives you mobility models or any
dynamic routing models, but you could always supply these models by
finding appropriate hooks.

If you do not need high-fidelity models of network or MAC protocols or
model of radio etc, you could try MaRS (from Maryland).  MaRS has been
used to experiment with dynamic routing on wide-area internetworks.
There are already some dynamic routing protocols (such as link-state,
distributed Bellman-Ford etc.) supplied with the distribution, thus
providing enough example for you to model your own routing. However,
you will be limited by very simple models of network protocols and
there is no easy way to model MAC or radio. You have to model mobility
also, but that is real easy as link up/down events are known to the
main simulator.

My conclusion: MaRS is an excellent short-cut. But if you are interested
in complete protocol stack, evaluate NS-2 or OPNET, may be Maisie too,
and take your pick (won't be an easy decision).

I will be interested in knowing about any other simulator I might
have missed.

Samir Das

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From: Lee Chee Jwai <[email-masked]>
Date: Wed, 15 Oct 1997 17:11:39 +0800 (SGT)

Where could one get the NS-2 simulator? I think BONeS can be used to
simulate network protocols also, though one might have to design the
wireless links. I've also heard that they've quite a sophisticated model
for satellite to ground links. 

_____________________________________________________________________
Dr. Cheejwai LEE  			 Email: [email-masked]
DSO National Laboratories			Tel  : (65) 3732061
24th Storey, Defence Technology Tower A,	Fax  : (65) 2728418	 
Depot Road					
Singapore 109679 

Mailing Address: DSO National Laboratories
		 20 Science Park Drive, Singapore 118230 
_____________________________________________________________________

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From: "Alessio Casati" <[email-masked]>
Date: Wed, 15 Oct 1997 14:19:28 +0100

On 15 Oct 97 at 17:11, Lee Chee Jwai wrote:

> Where could one get the NS-2 simulator?

look at http://www-mash.cs.berkeley.edu/ns

Bye

  Alessio Casati

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From: Zygmunt Haas <[email-masked]>
Date: Fri, 17 Oct 1997 10:53:52 -0300 (ADT)

We have been using OPNET for our ad hoc (and other) mobile network
simulation. Although there is some non trivial amount of time that you need 
to invest in learning the tool, it is nevertheless extremely robust. You
can also buy the TMM - Terrain Modeler Module with it. The best news is that 
the company (MIL3) has an excellent educational price.

Good Luck.

Zygmunt Haas.
==-=-==-=-=-=-=
~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
Prof. Zygmunt J. Haas             tel: +1-607-255-3454
Wireless Networks Laboratory
323 Frank Rhodes Hall             fax: +1-607-255-9072
School of Electrical Engineering  
Cornell University                e-mail: [email-masked]
Ithaca, N.Y. 14853                
U.S.A                             http://www.ee.cornell.edu/~haas/wnl.html
~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

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From: [email-masked] (George Aggelou)
Date: Wed, 22 Oct 1997 16:54:23 +0100 (BST)

> >  e-mail : [email-masked]

I believe your choice should be dependent on the layer(s) your investigation 
involves.  For example, for TCP and IP layer I used an "easy-going" simulator, 
called MAISIE-created by UCLA. This is an event driven simulator where you can
perform some valuable study on  dynamic routing.
You can freely download it from Internet where valuable guidance is provided for
beginners. 

Good luck.

--
George Aggelou
Mobile Communications Research Group
Centre for Communications Systems Research
University of Surrey  GU2 5XH  
Guildford UK

Tel:	(+1483) 259484
Fax:	(+1483) 259504
Email: 	[email-masked]

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From: "M. Scott Corson" <[email-masked]>
Date: Wed, 22 Oct 1997 12:58:04 -0400 (EDT)

> and take your pick (won't be an easy decision).

We have used Opnet here at Maryland for some time.  
It's a nice package with lots of capability, but 
the capability comes at a cost which is a bit pricey for some institutions.

Comparing the three *free* packages--MaRS, NS-2 and Maisie--each has its
advantages and disadvantages.  There has probably been more "MANET type"
work performed in Maisie than the other two, so it would be an attractive
and convenient choice in the short term.  However, in considering the 
design of the simulators themselves, their performance, and the flexibility 
and extensibility that can be achieved in protocol modeling, NS-2 is 
probably the simulator with the best design and the brightest long-term 
future.  It's object-oriented design and the ability to create objects
that are a mixture of OTcl (Object-oriented TCL) and C++ gives the 
protocol modeler both ease of coding (via scripting in OTcl) when 
performance is not critical and allows codind in C++ when performance
counts.  It has the additional benefit that many other Internet researchers
from other groups are using the package, which makes incorporation and 
modification of their models (such as TCP or reliable multicast) 
for use in a MANET environment very simple.

Of course, the use of NS-2 would require nearly every MANET group 
participant to encode their protocol in NS (I know of none
currently using it), but this would be a single, one-time shot 
which would put everyone in the same environment. 

Several models and protocols also need to be created for common usage as
well such as:

* a *simple* channel/topology model for determining and maintaining network 
  connectivity 

* a contention-based channel access protocol

* a mobility model for node movement

We here at Maryland would be willing to build/supply the channel model.
Any volunteers for the others, or comments on the idea?

-Scott

*******************************************************************************

M. Scott Corson                                 Institute for Systems Research
[email-masked]                              A.V. Williams Bldg. (115)
Phone: 301-405-6630 (Rm. 2205 AVW)              University of Maryland     
Fax:   301-314-8586                             College Park, MD  20742

*******************************************************************************

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From: [email-masked]
Date: Wed, 22 Oct 1997 11:09:50 PDT

> (nice endorsement of NS-2 clipped)
> 

As one of the ns-2 "developer people", I'd be very interested in helping
facilitate the integration of any models, etc that people in this group would
like to contribute to NS.  On a related item, we recently spent a
fairly large amount of time writing up descriptions
of various parts of the simulator and presenting a workshop at SIGCOMM
about it (see http://www-mash.CS.Berkeley.EDU/ns/ns-documentation.html),
so one thing I would encourage is that
if people would like to contribute modules, documentation and examples
{in addition to code}, would be *highly* appreciated.

Also, if anyone has particular comments as to major but important items
they feel NS lacks for their particular research space, that would be
interesting to hear about...

- Kevin

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From: Kieran Power <[email-masked]>
Date: Thu, 23 Oct 1997 09:27:04 +1000 (EST)

Hi,

While on the topic of simulators, I recently came across a reference
to "MadSim" which claims to be a simulation environment for ad hoc
networks. Apart from the fact that it was developed at the University of
Oklahoma, I know nothing else about this tool. 

Does anybody else know of this simulator and if so what is it like ?

************************************************************************
Kieran Power.                        Room : 63 - G21
Department of Digital Systems,       Tel : +61 3 9905-3234
Monash University, Clayton Campus,   Fax : +61 3 9905-3574 
Wellington Road, Clayton 3168,       E-mail :[email-masked]
AUSTRALIA.    			     WWW : www.dgs.monash.edu.au/~kpower
************************************************************************

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From: Ram Ramanathan <[email-masked]>
Date: Thu, 23 Oct 1997 11:19:48 -0400

> Any volunteers for the others, or comments on the idea?

As part of the DARPA Global Mobility (GloMo) project, our group at BBN has
developed simple models for random node mobility and random path loss.
Both models are in Maisie, and both are available  freely upon request.
The intent in both these models is to simulate the *effects* of mobility
and propagation on network-layer protocols in a *simple* manner, i.e.,
not going into complex equations.

The random mobility model allows control on the randomness of the movement.
It also allows for grouping the nodes and for control on the movement of
each group independently. In other words, you have groups moving independently
and each node within a group also moving randomly but aligned to the 
general direction of the group as a whole. We have used it quite successfully
to model military "reconnaisance" type operations. We have been using
this model for over a year now, and several organizations have borrowed it.

The random propagation model simply randomizes the free-space path loss 
around a mean to model foliage, barriers etc. and models "flutters" in a
link due to multipath, etc. We have just implemented begun testing the impact
of this in our simulations, but already we are seeing some effects not
generated by a free-space model.

More details on both models is given below for those interested. If you
want these models (note: in Maisie), please contact me ([email-masked])
or Regina ([email-masked]) who implemented these models.

See also http://may.cs.ucla.edu/projects/maisie/models.html for other
Maisie models.

-Ram.

---------------------------------

Exponentially Correlated Random Mobility Model

Description

The Exponentially Correlated Random (ECR) mobility model simulates the movement of nodes in
a multihop packet radio network in a tactical setting. The model can have several groups of nodes.
Each group as a whole moves according to the model, and each node within a group also moves
according to the model, but following the trajectory of the group. The idea is to simulate the
movements of multiple networked military units (e.g., brigades). 

The model is controlled by the equation

b(t+1) = b(t)exp(-1/Tau) + sigma * sqrt(1 - (exp(-1/Tau))^2) * r 

where: 
       b(t) is the position (r, theta) of a group or a node 
       Tau is a time constant (regulates the rate of change from 1 time step to the next) 
       Sigma is the variance (regulates range of change) 
       exp is the transcendental number e (~2.7183) 
       r is a random gaussian variable 

Each group is a circle containing nodes initially spread out from the center with a radius R.

Each group's motion is described by moving a certain radius with a certain angle. A set of Tau
and sigma variables are specified for the radius and a second set is specified for the angle of the
group. In general, the smaller the Tau, the more random the movement. Sigma is used to control
what the spread is of the speed or the angle movement is. 

Each node's movement is specified just like a group's. Specifically, all nodes within a group are
given a set of Tau and Sigma variables for the radius and angle. Nodes in different groups may
have different sets of variables.

--------------------------------------

Random Propagation Model

The given area is sectored into subareas of side s each. Attenuation is
calculated between every pair of sectors using a variant of the standard
path loss calculations. In particular, instead of the standard

        path loss = fixed-atten + atten(D),

we do

        path loss = fixed-atten + random( atten(D).(1 - V), atten(D).(1 + V))

where D is the euclidean distance between two nodes in consideration,  
      fixed-atten = 156 - 30*log(AntennaHeight) - 2*AntennaGain
      atten(D) = MAX(40*log(D), 0)
      V is a configured probability, reflecting the severity of terrain,
        foliage, barrier effects. V = 0 reduces to free-space.
      random is log-normal distribution.

Note that now it is not necessarily true that, given two nodes X and Y with
X closer to me than Y, then Y is my neighbor implies that X is too. In
other words, you may  be able to talk to nodes further away from you but
not to a node closer to you (as is the case if there is a barrier between
you and the closer node).

Given two nodes N1 and N2, in order to determine if they are neighbors, we
first find the sectors they are in. Then we find the attenuation between
the sectors as calculated above. Note that this inter-sector attenuation
matrix can be PRE-COMPUTED before the start of the simulation, thereby
saving a lot of running time. If the XmitPower - attenuation is below
the Receiver Capture Threshold, then there is no link. Otherwise, there is
a link with probability 1-FlutterProb. This is to model the case when 
occasionally a link may be lost due to multipath, interference (near-far) etc.

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From: "Andrew T.Campbell" <[email-masked]>
Date: Fri, 24 Oct 1997 14:39:44 -0700

> Any volunteers for the others, or comments on the idea?

We have used ns here for some of the mobile work in the
past and were very happy with some of the features. 

Building a suite of objects (for the channel, access and mobility
patterns)
and using them across the board is a very good idea.
 
Best,
Andrew
--
Andrew T. Campbell  
http://comet.ctr.columbia.edu/~campbell
Wireless Media Systems Project 
http://comet.ctr.columbia.edu/wireless