Calculating Channel Busy Ratio

[Boong Baang]

I created a function that I call every 100ms and record if the channel was CCA busy or not using the IsStateCcaBusy method. 

 

 void BsmApplication::ifCCAbusy(uint32_t nodeID)
  {
    Ptr<WifiNetDevice> device = DynamicCast<WifiNetDevice>(GetNode(nodeID)->GetDevice(0));
    // more than 1 device can be at each node so take the 1st one

    Ptr<WifiPhy> phy = device->GetPhy ();

    Ptr <YansWifiPhy> wfc = phy->GetObject<YansWifiPhy> ();

    // Ptr <WifiPhyStateHelper> statehelper = phy->GetState();

    PointerValue ptr;
    wfc->GetAttribute("State", ptr);
    Ptr<WifiPhyStateHelper> wpsh = ptr.Get<WifiPhyStateHelper>();

    std::cerr<<"CCA state for node "<<nodeID<<" is "<<wpsh->IsStateCcaBusy()()<<std::endl;

    if (wpsh->IsStateCcaBusy() == true )
    {
      CBRTime[nodeID].push_back(1);
    }
    else
    {
      CBRTime[nodeID].push_back(0);
    }

    CBRreviewInstants[nodeID] = Simulator::Schedule (//recvSink->GetNode ()->GetId (), //BIPLAV
                                      CBRcheckInterval, &BsmApplication::ifCCAbusy, this,
                                      nodeID);
  }

I start with a highly dense scenario of 200 mobile vehicles transmitting at 30 Hz, so I expected the CCA busy to be 1 quite frequently. But it is mostly 0 in my scenario of 300 seconds. Should I use some other methods to evaluate CBR, like the `IsStateIdle`

[Boong Baang]

I used the callback:

 void BsmApplication::LogMyState(const Time start, const Time duration, const WifiPhyState state)
 {
 std::cerr<<"start time = "<<start.GetMilliSeconds()<<" with duration "<<duration.GetMilliSeconds()<<" and state "<<state<<std::endl;
 }

that is called by

 Config::ConnectWithoutContext ("/NodeList/30/DeviceList/0/$ns3::WifiNetDevice/Phy/$ns3::YansWifiPhy/State",MakeCallback (&BsmApplication::LogMyState, this));

and this is also never called. This callback should be called every time the state changes, so can someone please help in finding the mistake.