propagation.cc

ns2下用于802.11的无线传输模型的代码 增加了基于信噪比计算差错率等功能

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 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
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 propagation.cc
 $Id: propagation.cc,v 1.5 2000/10/02 20:22:43 yewei 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::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) return Pt;	//Added by Wu Xiuchao

  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);

	return Pr;
}