Simulate high speed train environment using ns3

[Sjk]

Hi, I am new to ns3 (entirely new in simulation field)

My project is related to handover in high speed mobile environment. Planning to implement using ns3.

My doubt is whether it is possible to simulate high speed train scenario in NS3 ? 

Thanks in advance

[Tommaso Pecorella]

Hi,

the answer is yes, it is possible. There's a catch tho: it's not easy.

The problem is that the current models aren't tuned for such scenario and/or there's no support for the special standard variants envisaged for high speed trains.

Moreover, it really depends on the technology you want to use.

As an example, you can find LTE and WiMAX in ns-3 (I wouldn't suggest to use WiMAX, it's old and it's not used anymore in real world). You will not find GSM or UMTS, let alone GSM-R or similar. If you need one of those, the only possibility is to develop the model, and this isn't easy at all (it requires skills and time).

As a consequence, it's possible, but it depends on the scenario you want to simulate.

Cheers,

T.

PS: I'd start with the tutorial and by reading the first manual chapters, especially if you are new to simulations. Plus, don't underestimate the statistical analysis required to post.process the simulation data.

[Sjk]

Thank you for your response.

Planning to use LTE.  what about using LTE?

Actually I am just starting project work and currently gone through different technical papers regarding handover management in high speed train in LTE and no exposure to ns3 unless gone through some tutorial videos available.

Can you please tell me why It is not easy. whether it is because of being a fresher or simulating high speed mobile terminal is highly skilled task?

Sorry if I am asking something wrong,I didnt ever worked using ns3. what I meant is whether it can be simulated by going through tutorials  or need to create something entirely new using ns3?

[Tommaso Pecorella]

Hi,

the question isn't wrong per-se, don't worry. You're choosing your tool, so it's ok to ask if ns-3 is suitable for you.

Using LTE should ease your work a LOT, since it's already at a good implementation phase. What could be missing is the specialized handover mechanisms, as I guess that the standard ones will not work in high speed environments.

Moreover, I think you'll have to triple check if the actual models take into account the doppler effect in such a high speed environment. Well, probably you'll want to check the whole channel fading models anyway.

As for the node speed, that's not a problem at all, the pre-built models are more than enough to simulate a whole nation-wide railway (speed, direction, etc.)

Cheers,

T.

[Sjk Sj]

Thank you for reply.

My project purpose is to implement basic handover scenario to avoid frequent and unnecessary handovers. (Not specially targeted in high speed only because I am not sure on implementing it based on the above suggestions). 

Actually I am confused  whether it is possible to implement handover either within LTE to UMTS or WiFi to UMTS/WiMax/4G.

The above mentioned technologies are not finalized yet.

My requirement is to use different algorithms, with different set of parameters, and thereby reduce the handover delay or other handover related problems(basic handover challenges).

My doubt is whether these things are possible to implement using ns3.

Sorry for asking these kind of doubts because I am confused with some technical related matters that you have mentioned and I am not clear about these things while going through documentation.

Thanks again in advance.

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[Tommaso Pecorella]

Hi,

1st things first. In ns-3 there's no model for UMTS. LTE, Wi-Fi, WiMAX yes, but no UMTS.

Handover: horizontal and vertical. You can safely (up to a certain point) simulate horizontal handovers, e.g., between two LTE cells or two Wi-Fi access points. Vertical handover is a bit more complex, as it depends on protocols that are not implemented in ns-3, but that can be often used through DCE (Direct Code Execution, i.e., using a linux kernel).

The hysteresis techniques (i.e., the one to avoid unnecessary handovers) are very dependent on the type of handover you consider. As a consequence, you should first decide that.

About what is possible to simulate in ns-3, it really depends on the technology (LTE, Wi-Fi, etc.) and the type of handover. It's not possible to know how hard it would be such an analysis without knowing the exact scenario.

My suggestion is to take your time and read the relevant ns-3 manual sections, especially the ones about Wi-Fi and LTE.

Cheers,

T.

[newns3user]

Hi tommaso,
i am reading this discussion about simulating High speed train using ns3 and i have a question.
I tried to simulate a simple scenario with 1 ue and 3 enbs placed at fixed distance, i used COST231 propagation loss model and 43 dbm TXpower for the enb, 23 for UE, and i was using the A3RSRPhandover algorithm. These are the main parameters for the scenario.
When i increase the velocity of the UE up to 40 m/s i have the x2-handover and everything works, instead for upper velocity , i noticed that i never had handover between the cells so i lost communication. I tried to edit the Hysteresys and TimeToTrigger Value but i don't have any results.
So what i would like to ask is if there is any limitation about the UE velocity for handle the automatic handover using the implemented algorithm in such a scenario using COST231propagation loss because if i use FRIISpropagationloss i have the handover correctly for every ue velocity.
If not can you help me in order to understand what is wrong with me.
I hope to be clear and receive some suggestions, maybe it could be useful for others users too.

[Tommaso Pecorella]

Hi,

you've been very clear, indeed. Unfortunately I have no answer, I've never had the opportunity (or need) to work with LTE handover, so I really have no idea.

If you can post the script we can try to see what's going on, but the best people to answer are the LTE maintainers. They don't read the group everyday, but they DO read it.

Anyway, post the script, perhaps we can figure it out.

Cheers,

T.

[newns3user]

ok thanks. 

i attache my script. 

maybe i solved this trouble. 

i was using the     Config::SetDefault ("ns3::LteHelper::UseIdealRrc", BooleanValue (false)); and with this settings it doesn't work. 

now i tried to change with TRUE IDEAL RRC and i have the handover.