modulation.cc

fso antenna model for ns2

/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1997 Regents of the University of California.
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 * 3. All advertising materials mentioning features or use of this software
 *    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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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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/* Ported from CMU/Monarch's code, nov'98 -Padma.*/

#include <math.h>
#include <stdlib.h>
#include <random.h>
//#include <debug.h>
#include <modulation.h>
#include <iostream>

using namespace std;

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

/* ======================================================================
   Binary Phase Shift Keying
   ====================================================================== */

// begin RPI FSO Extensions
// methods for free space model
static class BPSKClass: public TclClass {
public:
	BPSKClass() : TclClass("Modulation/BPSK") {}
	TclObject* create(int, const char*const*) {
		return (new BPSK);
	}
} class_bpsk;
   
// RPI - taken out because it just sets it to zero!
/*
BPSK::BPSK()
{
	Rs = 0;
}

BPSK::BPSK(int S)
{
	Rs = S;
}
*/
// end RPI FSO Extensions

int
BPSK::BitError(double Pr, int Size)
{
	double Pe;			// probability of error
	double x;
	int nbit = 0;			// number of bit errors tolerated

	if(nbit == 0) {
		Pe = ProbBitError(Pr);
	}
	else {
		Pe = ProbBitError(Pr, nbit);
	}

	// quick check
	if(Pe == 0.0)
		return 0;		// no bit errors

	// begin RPI FSO Extensions
	// scale the error probabilty
	// Pe *= 1e3;
	// scale the probably by the number of bits in the packet.
	Pe *= Size * 4;

	RandomNumberGenerator_.set_seed(0.0l);
	x = RandomNumberGenerator_.uniform(0.0l,1.0l);

	// x = (double)(((int)Random::uniform()) % 1000);
	// end RPI FSO Extensions

	if(x < Pe)
		return 1;		// bit error
	else
		return 0;		// no bit errors
}

double
BPSK::ProbBitError(double Pr)
{
	// begin RPI FSO Extensions
	double Noise = 0.0001; // AWGN (Watts)
	double SNR = Pr/Noise;
	if(SNR < 1.0)
	{
		return 1.0;
	}
	double SNRdB = 4.342944819 * log(SNR); // 10 * ln(SNR)/ln(10)
	double x = sqrt(SNRdB);
	double Qx = 1/(x*2.506628275) * exp(-((x*x)/2));
	return Qx;
	// end RPI FSO Extensions
}

double
BPSK::ProbBitError(double Pr, int n)
{
	double Pe = 0.0;

	return Pe;
}