RandomFreqTimeModel.cc

#include "RandomFreqTimeModel.h"


void RandomFreqTimeModel::filterSignal(Signal& s){


  /* At first get a new instance of the default Mapping implementation
   * which is able to represent our attenuation mapping.
   * the first parameter of "createMapping" gets the DimensionSet the
   * Mapping should use as domain and the second parameter sets the
   * interpolation method to be used to calculate the values between
   * two Mapping entries.
   *
   * Note 1: At the moment only LINEAR interpolation is implemented.
   *
   * Note 2: For now the same interpolation method is used for
   * interpolation in every dimension. Later it might be possible
   * to define different interpolation methods for different
   * dimensions. For example: While linear interpolation of time
   * makes sence in this case, using NEAREST for frequency  whould make
   * more sense.
   */
  Mapping* attMapping = MappingUtils::createMapping(dimensions, Mapping::LINEAR);

  /* Get start and end of the signal to avoid unnecessary calculation
   * of attenuation. (Normally we don't wan't to attenuate the signal
   * outside its start and end time since it probably isn't defined there.*/
  simtime_t sStart = s.getSignalStart();
  simtime_t sEnd = sStart + s.getSignalLength();

  simtime_t interval = (sEnd - sStart) / 10.0; //lets divide it into 10 steps

  Argument pos(dimensions); //create an Argument which we will use as parameter
                //to set the values inside the mapping

  for(double freq = 2.412; freq <= 2.472; freq += 0.01){
    //assure attenuation is set at end of freq range
    if(freq > 2.465)
      freq = 2.472;

    pos.setArgValue(frequency, freq*1e9); // update arguments position in frequency dimension

    //create time entries for this frequency
    //the comparision to "sEnd + (interval * 0.5)" is used to avoid floating point errors
    for(simtime_t t = sStart; t <= sEnd - (interval * 0.5); t+=interval){

      pos.setTime(t); // update arguments position in time dimension

      /* Create random attenuation between 0.1 and 1.0.
       * Since the attenuation value is multiplied to the transmission power mapping
       * it should be between 0.0 and 1.0, otherwise it whouldn't be a real
       * attenuation.*/
      double att = (double)rand() / (double)RAND_MAX * 0.9 + 0.1;

      attMapping->setValue(pos, att); //put the attenuation at the current position into the mapping
    }

    //assure that the attenuation is set at the end of the signal
    pos.setTime(sEnd); // update arguments position in time dimension
    double att = (double)rand() / (double)RAND_MAX * 0.9 + 0.1;
    attMapping->setValue(pos, att); //put the attenuation at the current position into the mapping
  }

  //at last add the created attenuation mapping to the signal
  s.addAttenuation(attMapping);
}