How can we put a varying packet error rate in omnet++

Question

Is there a way to put a varying PER(packet error rate) in the omnet.ini file for a single simulation? I know to simulate for different simulations and compare the graph, but I want one simulation which varies PER. Generally, we put the PER in the ini file as in percentage and have a constant PER but I want is varying one between 1% to 50%.

PER = 0.5 #Generally we do like this to show 50% PER
PER= #(0.1 to 0.5) #I need something like this

Hope I am clear.

Answer 1

There are two ways of achieving your goal.
Method 1

1. In NED declare PER parameter with volatile:

    parameters:
      volatile double PER;
   

2. In omnetpp.ini use a random distribution, for example a uniform distribution:

   **.somemodule.PER = uniform(0.01, 0.50) 
   

3. In C++ code of your module use par("PER") in every place where that value is read.

Thanks to volatile every time that parameter is read, a new random value is chosen. Reference: OMNeT++ Simulation Manual

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Method 2

1. In NED declare two parameters:

    parameters:
      double minPER;
      double maxPER;
   

2. In omnetpp.ini set the values of these parameters:

    **.somemodule.minPER = 0.01
    **.somemodule.maxPER = 0.50
   

3. In initialize() of your C++ class read these parameters, e.g.:

    minPER = par("minPER");
    maxPER = par("maxPER");
   

4. In C++ in the place where PER value is necessary generate the current value using a random distribution, for example:

   double per = uniform(minPER, maxPER);