Traffic modelling on ns-3 network Simulator - ns-3

Question

I am trying to simulate traffic of voice, video, and data in order to check the differences between EDCF and traditional CSMA/CA.
I am using an on off helper based on the example of http://www.scielo.org.co/pdf/dyna/v84n202/0012-7353-dyna-84-202-00055.pdf
for the video but on setAttribute(“OffTime”, StringValue(“ns3::LogNormalRandomVariable[Mu=0.4026,Sigma=0.0352]”));
I get error 'Attribute value "0.4026,Sigma=0.0352" is not properly formatted'
Any ideas for the error or suggestions on how to model the three types of traffic?
Thanks for your time

Answer 1

I couldn't find the version of ns3 in your provided reference. Also, the reference paper was published in September 2017. I think, they have used ns3.26 probably.
So, I've tried with ns3.29 and couldn't reproduce the above error. I've got somewhat different error. But I could fixed it by putting a space before '['.
The second solution I found by using Mu and Sigma separately.
onoff.SetAttribute ("OffTime", StringValue("ns3::LogNormalRandomVariable[Mu=0.4026]"));
onoff.SetAttribute ("OffTime", StringValue("ns3::LogNormalRandomVariable[Sigma=0.0352]"));

Answer 2

a4arshad's answer's compile and run, but they are not correct. The reason a4arshad's solution does not work is that the second SetAttribute call sets the OffTime attribute as a LogNormalRandomVariable with Sigma=0.0352. The second call does not add to the existing LogNormalRandomVariable with Mu=0.4026. The second call overwrites the first one.
a4arshad also suggested putting a space between LogNormalRandomVariable and [, but that doesn't work either; this will just cause ns-3 to ignore all parameters.
The correct way to set the attribute as the linked paper is to delimit parameters using a pipe, |. You should do something like
onoff.SetAttribute("OffTime", StringValue("ns3::LogNormalRandomVariable[Mu=0.4026|Sigma=0.0352]"));
I don't know when ns-3 switched to using a pipe to instead of a comma, but I am using the most recent release version, ns-3.30.1.
You can use the following program to check whether setting an attribute worked. The last lines are the relevant ones; the rest is boilerplate to set up the simulation. In the last lines, we extract the Attribute from the Application, and print the Mu and Sigma values. Try commenting/uncommenting the correct/incorrect methods and look at the different outputs. According to the documentation of LogNormalRandomVariable, the default values of Mu and Sigma are 0 and 1, respectively.
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
// setting a LogNormalRandomVariable with multiple parameters as the OffTime
// of an OnOffApplication
// https://stackoverflow.com/questions/60791009
// Author: Sagar
#include "ns3/core-module.h"
#include "ns3/internet-module.h"
#include "ns3/point-to-point-module.h"
#include "ns3/ipv4-global-routing-helper.h"
#include "ns3/applications-module.h"
using namespace ns3;
NS_LOG_COMPONENT_DEFINE("RandomVariableAttirbuteTest");
int
main(int argc, char *argv[]) {
NodeContainer nodes;
nodes.Create(2);
PointToPointHelper p2pLink;
NetDeviceContainer devices = p2pLink.Install(nodes);
InternetStackHelper stack;
stack.InstallAll();
// assign IP addresses to NetDevices
Ipv4AddressHelper address ("10.1.1.0", "255.255.255.0");
Ipv4InterfaceContainer ipInterfaces = address.Assign(devices);
Ipv4GlobalRoutingHelper::PopulateRoutingTables();
// configure and install server app
int serverPort = 8080;
UdpServerHelper serverApp (serverPort);
serverApp.Install(nodes.Get(0));
Address serverAddress = InetSocketAddress(ipInterfaces.GetAddress(0), serverPort);
// configure and install client apps
OnOffHelper onoff ("ns3::UdpSocketFactory", serverAddress);
// incorrect (two separate SetAttribute calls)
// onoff.SetAttribute("OffTime", StringValue("ns3::LogNormalRandomVariable[Mu=0.4026]"));
// onoff.SetAttribute("OffTime", StringValue("ns3::LogNormalRandomVariable[Sigma=0.0352]"));
// also incorrect (adding a space)
// onoff.SetAttribute("OffTime", StringValue("ns3::LogNormalRandomVariable [Mu=0.4026,Sigma=0.0352]"));
// correct
onoff.SetAttribute("OffTime", StringValue("ns3::LogNormalRandomVariable[Mu=0.4026|Sigma=0.0352]"));
onoff.Install(nodes.Get(1));
// print Attirbutes to check if they were correctly set
Ptr<Application> app = nodes.Get(1)->GetApplication(0);
PointerValue pv;
app->GetAttribute("OffTime", pv);
Ptr<LogNormalRandomVariable> rv = pv.Get<LogNormalRandomVariable>();
NS_LOG_UNCOND("Mu = " << rv->GetMu());
NS_LOG_UNCOND("Sigma = " << rv->GetSigma());
return 0;
}