NS3- Simulation time inquiry

[Bahaa Hussein]

Hi ns3 group,  I hope you are all safe.

I have read a lot of your research and I have a question about the NS3 simulation tool, if possible:- What are the issues that determine the Simulation time? I mean can we reduce it? can we increase it? who is controlling that?  Also. I have seen that most of the research papers that I have read set the simulation time parameter to 1800 s. why?

With my respect and thanks  in advance, 

BAHAA 

Huazhong University of science and Technology, China

  

[Tom Henderson]

On 8/13/22 21:28, Bahaa Hussein wrote:
> Hi ns3 group,  I hope you are all safe.
>
> I have read a lot of your research and I have a question about the NS3
> simulation tool, if possible:- What are the issues that determine the
> Simulation time? I mean can we reduce it? can we increase it? who is
> controlling that?
>

This is a complicated topic on simulation methodology; ns-3
documentation doesn't really address how to appropriately pick a stop
time, or how to pick a simulation initialization duration. In brief, the
simulation should first run until it has been determined to reach a
steady state, and then data should be collected until the performance
metrics under study have enough samples, and then the simulation should
stop.  The question of 'have enough samples' might depend on an
arbitrary count set by the simulation author, or might depend on trying
to obtain sample variances of an estimator within some bound.  This is a
topic for which it would be best to read some textbooks or tutorials on
stochastic simulations.

For network simulations specifically, there was a paper many years ago
by Kurkowski and Camp that surveyed and critiqued the literature on
MANET simulations; I recommend reading it to understand the many
pitfalls that may arise, and to read the citations that the authors
provided that point to better practices to follow:

https://dl.acm.org/doi/10.1145/1096166.1096174

> Also. I have seen that most of the research papers that I have read
> set the simulation time parameter to 1800 s. why?
>

This value was likely copied from a previous study; there isn't any
fundamental reason why most papers you have read would use such a value
other than copying it from previous related work.

- Tom

[Bahaa Hussein]

  Hi Tom,

Thank you so much for your response.

[Bahaa Hussein]

Hi Tom, 

Does this mean that there is no specific time to complete the simulation and extract the results (Output)?

[Tom Henderson]

On 8/14/22 23:03, Bahaa Hussein wrote:

Hi Tom, 

Does this mean that there is no specific time to complete the simulation and extract the results (Output)?

Yes.

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[Leena Sahoo]

Hi Tom/BHAAA

I need to generate UE and eNB data for my use case implementation. Minimum duration of data I want is of 30 mins. But right now I am getting only 7-10 seconds of data in .txt files. How to generate data for 1800s ? Like what parameter I need to pass in which function, where to increase decrease the time durtaion ?

Thanks.

[Tom Henderson]

On 8/24/22 23:47, Leena Sahoo wrote:
> Hi Tom/BHAAA
>
> I need to generate UE and eNB data for my use case implementation.
> Minimum duration of data I want is of 30 mins. But right now I am
> getting only 7-10 seconds of data in .txt files. How to generate data
> for 1800s ? Like what parameter I need to pass in which function, where
> to increase decrease the time durtaion ?

Check your program to look for calls to 'Stop' the simulator or the
applications, and try to extend the time.

For example, from examples/wireless/wifi-ap.cc

apps.Start (Seconds (0.5));
apps.Stop (Seconds (43.0));

Simulator::Stop (Seconds (44.0));