Subject: Re: A question about the OPNET models of AODV and DSR

From: Jason Ballah <[email-masked]>
Date: Fri, 14 Dec 2001 06:46:10 -0500

Ed,
   The DSR model implements the billiard mobility model, which just 
sends nodes in a random directions until they run into a boundary then 
choose a new random direction.  That was all fine and good except that 
there is not a good way to modify the speed or initial distribution of 
nodes.  The speed is modified by implementing a movement "step" of 0.0 
to 1.0 which tells you nothing about the speed of the nodes unless you 
really understand OPNET and the algorithm by which the nodes were being 
repositioned.

   This is a long way of saying that I would suggest you throw out the 
billiard mobility model and import the random waypoint model from the 
2nd release of the AODV implementation.  It doesn't take too much 
modification to make it work in the DSR model and with it you can set 
all the needed parameters such as maximum speed, and pause time.  It 
also performs the initial uniform distribution of nodes within the 
simulation area.  

Let me know if you have any problems doing this and I can help you out.

- Jason

Edward Hua wrote:

>Hi,
>
>    I downloaded the OPNET models of AODV and DSR from the NIST website a 
>couple of weeks ago, and have recently begun playing with them. I have a 
>question here, specifically for DSR, but would appreciate an answer for 
>AODV as well. I'm a brand new user of OPNET, so don't laugh if this is 
>too simple a question for you guys.
>
>    It seems the default velocity for the nodes in the DSR (initially 
>there are 16 DSR nodes in the model) is 0.16667m/s, which is about 
>0.6km/hr. I'm wondering where in the OPNET DSR model I should look to 
>modify the speed of the nodes. 
>
>   Same question for the AODV model. If you have the answer to that, I 
>really appreciate your correspondence. Thanks in advance. Bye.
>
>-Ed
>
>
>

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From: Fan Bai <[email-masked]>
Date: Fri, 14 Dec 2001 12:02:02 -0800

Jason,

I am wondering whether the billiard model is also a kind of "random mobility
model" just like random waypoint model in ns-2. that is, the selection of
destination (or, direction & speed) for a node will be just random-based.
But compared to random waypoint model, the billiard model has relatively
less flexibility to adjust. Am my understanding right?

Where can i find more detailed description about that billiard model?

Thanks in advance.

Regards,
Fan

---

From: Jason Ballah <[email-masked]>
Date: Sun, 16 Dec 2001 08:04:38 -0500

Fan,
   You are correct with your understanding.  However, I had not seen the 
billiard mobility model before I started working with the NIST DSR model 
in OPNET, so I am not sure where to point you for more information.  

   The biggest difference between the billiard model and the random 
waypoint model is that the billiard model does not go to any particular 
waypoint destination or perform any PAUSE waiting times.  The nodes move 
continuously at a designated speed in a random direction until the node 
encounters the edge of the simulation area, then a new random direction 
is chosen to move in.  This model works good to just keep nodes moveing, 
but I have not seen any research on it as to how realistic of a movement 
model it is or what problems could be encountered due to node spatiality 
or node density.

   Flexibility of node speed and initial distributions is a matter of 
implementation.  This flexibility can be easily built into the model.

- Jason

2.