propagation.cc

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 *  This product includes software developed by the Computer Systems
 *  Engineering Group at Lawrence Berkeley Laboratory.
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 propagation.cc
 $Id: propagation.cc,v 1.7 2005/02/03 20:15:00 haldar Exp $
*/

#include <stdio.h>

#include <topography.h>
#include <propagation.h>
#include <wireless-phy.h>

class PacketStamp;
int
Propagation::command(int argc, const char*const* argv)
{
  TclObject *obj;  

  if(argc == 3) 
    {
      if( (obj = TclObject::lookup(argv[2])) == 0) 
    {
      fprintf(stderr, "Propagation: %s lookup of %s failed\n", argv[1],
          argv[2]);
      return TCL_ERROR;
    }

      if (strcasecmp(argv[1], "topography") == 0) 
    {
      topo = (Topography*) obj;
      return TCL_OK;
    }
    }
  return TclObject::command(argc,argv);
}
 

/* As new network-intefaces are added, add a default method here */

double
Propagation::Pr(PacketStamp *, PacketStamp *, Phy *)
{
    fprintf(stderr,"Propagation model %s not implemented for generic NetIF\n",
      name);
    abort();
    return 0; // Make msvc happy
}


double
Propagation::Pr(PacketStamp *, PacketStamp *, WirelessPhy *)
{
    fprintf(stderr,
        "Propagation model %s not implemented for SharedMedia interface\n",
        name);
    abort();
    return 0; // Make msvc happy
}

double
Propagation::getDist(double Pr, double Pt, double Gt, double Gr, double hr,
             double ht, double L, double lambda)
{
    fprintf(stderr,
        "Propagtion model %s not implemented for generic use\n", name);
    abort();
    return 0;
}

double
Propagation::Friis(double Pt, double Gt, double Gr, double lambda, double L, double d)
{
        /*
         * Friis free space equation:
         *
         *       Pt * Gt * Gr * (lambda^2)
         *   P = --------------------------
         *       (4 * pi * d)^2 * L
         */
    if (d == 0.0) //XXX probably better check < MIN_DISTANCE or some such
        return Pt;
  double M = lambda / (4 * PI * d);
  return (Pt * Gt * Gr * (M * M)) / L;
}


// methods for free space model
static class FreeSpaceClass: public TclClass {
public:
    FreeSpaceClass() : TclClass("Propagation/FreeSpace") {}
    TclObject* create(int, const char*const*) {
        return (new FreeSpace);
    }
} class_freespace;


double FreeSpace::Pr(PacketStamp *t, PacketStamp *r, WirelessPhy *ifp)
{
    double L = ifp->getL();     // system loss
    double lambda = ifp->getLambda();   // wavelength

    double Xt, Yt, Zt;      // location of transmitter
    double Xr, Yr, Zr;      // location of receiver

    t->getNode()->getLoc(&Xt, &Yt, &Zt);
    r->getNode()->getLoc(&Xr, &Yr, &Zr);

    // Is antenna position relative to node position?
    Xr += r->getAntenna()->getX();
    Yr += r->getAntenna()->getY();
    Zr += r->getAntenna()->getZ();
    Xt += t->getAntenna()->getX();
    Yt += t->getAntenna()->getY();
    Zt += t->getAntenna()->getZ();

    double dX = Xr - Xt;
    double dY = Yr - Yt;
    double dZ = Zr - Zt;
    double d = sqrt(dX * dX + dY * dY + dZ * dZ);

    // get antenna gain
    double Gt = t->getAntenna()->getTxGain(dX, dY, dZ, lambda);
    double Gr = r->getAntenna()->getRxGain(dX, dY, dZ, lambda);

    // calculate receiving power at distance
    double Pr = Friis(t->getTxPr(), Gt, Gr, lambda, L, d);
    printf("%lf: d: %lf, Pr: %e\n", Scheduler::instance().clock(), d, Pr);

    return Pr;
}

double
FreeSpace::getDist(double Pr, double Pt, double Gt, double Gr, double hr, double ht, double L, double lambda)
{
        return sqrt((Pt * Gt * Gr * lambda * lambda) / (L * Pr)) /
                (4 * PI);
}

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