I am confused about number of nodes in Vanetcompare file

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Rida Sagheer

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Jan 1, 2022, 5:23:55 PM1/1/22
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Can anybody explain me that what is the purpose of mentioning number of nodes in vanetroutingcompare.cc example when the number of nodes are configured in SUMO and are traced through .tcl file.

If a mobility.tcl file (having upto 500 nodes) shows activity of only 15 nodes upto 10 seconds.
What would be the impact if i set simulation time 10 seconds, and number of nodes MORE Or LESSER than 15??


I want ns3 to follow the sumo simulation just like how OMNET++/Veins does.

please help.

scarpe...@windstream.net

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Jan 1, 2022, 6:56:10 PM1/1/22
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The parameter enables movement for the first n nodes of the total in your mobility file, while keeping all of the other nodes stopped at their initial position.  This may be helpful to pursue a sensitivity study of vehicle density.  For example, suppose that you had initially generated a SUMO mobility file of 100 randomly placed and moving vehicles.  You could run a simulation first with n=10 nodes, then run another study with n=20 nodes, and increasing n (up to the max vehicles / nodes in your mobility file), without having to regenerate a new or different mobility file for each case that you are studying.  That is, by switching from n=10 to n=20 nodes, you will be guaranteed that the first 10 nodes are following the exact same movement pattern (if you are re-using the same mobility file) in both experiments.  When n=10, ,the "next group of 10" would not be moving.  When n=20, then the first 20 nodes would be moving.  I don't recall what happens if you set the nodes to a value greater than the total nodes in your mobility file, but I would guess that it maxes out without any warning.

Rida Sagheer

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Jan 2, 2022, 12:32:54 AM1/2/22
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Hello..
Thanks for the detailed answer. I want ns3 to simulate the mobility file without doing any changes to the nodes. That is.... Vehicles should move as they're moving in sumo.

Now for example my mobility file has 900 around vehicles in total. But it only shows the activity of 10 nodes in first 15 seconds. (I assume others have not departed till then)

In this case when i do the configuration:
Sim time 15 seconds, nodes 10
Sim time 15 seconds, nodes 200

The speed of simulation drastically reduces. I assume that is because all 200 nodes are departing at 0 time (unlike mobility.tcl).
What to do if i want to resist this?? 
I want every vehicle to depart at time whatever is mentioned in mobility file. 



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