bug? ConstantVelocityMobilityModel paused after creation

[Marco Porsch]

Hello Group,

After creating a ConstantVelocityMobilityModel with the appropiate Helper it is set to paused as standard.

Example code:

MobilityHelper mobility;
mobility.SetMobilityModel ("ns3::ConstantVelocityMobilityModel",
"Position", Vector3DValue (Vector3D (5, 0, 0)),
"Velocity", Vector3DValue (Vector3D (-100, 0, 0)));
mobility.Install (wifiNodes.Get(0));

If the simulation is started like this the node 0 will be stationary.
It is always neccessary to re-set the velocity with:

Ptr <ConstantVelocityMobilityModel> myConstantVelocityMobilityModel = wifiNodes.Get(dst)->GetObject<ConstantVelocityMobilityModel>();
myConstantVelocityMobilityModel->SetVelocity(Vector3D (-100, 0, 0));

I think this is a bug.

Possibility 1:

ConstantVelocityHelper::ConstantVelocityHelper (const Vector &position,
const Vector &vel)
: m_position (position),
m_velocity (vel),
m_paused (true)
{
}

here change m_paused to false

Possibility 2:
add a further Attribute 'Pause' similar to ns3::RandomWaypointMobilityModel.

What do you think?

Regards

[Enrico Zamagni]

I can confirm this bug on ns-3.17

The following code:

m_mobility.SetMobilityModel ("ns3::ConstantVelocityMobilityModel",

      "Position", Vector3DValue(Vector3D (0, 0, 0)),

      "Velocity", Vector3DValue(Vector3D(-16.0, 0.0, 0.0)));

m_mobility.Install (n); // here, n is a Node ptr

yields a still node, no mobility whatsoever. Need to correct with

Ptr <ConstantVelocityMobilityModel> cv =v->GetObject<ConstantVelocityMobilityModel>();

cv->SetVelocity(Vector3D(-16.0, 0.0, 0.0));

to get the node to move as expected.

[Piotr Wąsek]

What is  variable "v" in the line: Ptr <ConstantVelocityMobilityModel> cv =v->GetObject<ConstantVelocityMobilityModel>(); ?

[Enrico Zamagni]

Sorry for not pointing that out: v is a pointer to a Node object (Ptr<Node>).

Actually, it's called v because i'm dealing with vehicles in my simulation (an area of research with wich ns3 is not always so friendly, in my opinion)

2013/5/30 Piotr Wąsek <piotr...@gmail.com>

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[李窦哲]

I also suffer from this problem, and I go through  the code of ConstantVelocityMobilityModel, I didn't find any attribute like Position or Velocity in this model. That means the only way to change the velocity is through SetVelocity method. 

And another, the Position problem, the MobilityHelper only use the position in the PositionAllocator, so may be the initial position should be set via PositionAllocator or SetPosition.

The initial velocity and position problem of ConstantVelocityMobilityModel is very upset.

[Achmad Rizal Danisya]

thank you for the clue, Guys !

[Mitch Watrous]

Can someone please post an example script that demonstrates the bug and shows that the velocity is zero at time zero?

Thanks,
Mitch

[Achmad Rizal Danisya]

here you go, Mr Mitch
please check in the NetAnim to know the bug in node allocation
I made a simple LTE scenario
Internet Host--PGW--eNodeB.............UE Node approaching with 25 mps from 1 Km of eNodeB

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[Mitch Watrous]

Thank you for the example code.

The bug has been confirmed and is in the bug tracker:

    https://www.nsnam.org/bugzilla/show_bug.cgi?id=1717

We will work on a solution and will update the bug tracker with any new information.

Mitch