shadowing.cc

thomson_mesh_modules_Enhanced Wireless Mesh Networking for ns-2 simulator

/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */

/*
 * shadowing.cc
 * Copyright (C) 2000 by the University of Southern California
 * $Id: shadowing.cc,v 1.4 2005/08/25 18:58:09 johnh Exp $
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 *
 *
 * The copyright of this module includes the following
 * linking-with-specific-other-licenses addition:
 *
 * In addition, as a special exception, the copyright holders of
 * this module give you permission to combine (via static or
 * dynamic linking) this module with free software programs or
 * libraries that are released under the GNU LGPL and with code
 * included in the standard release of ns-2 under the Apache 2.0
 * license or under otherwise-compatible licenses with advertising
 * requirements (or modified versions of such code, with unchanged
 * license).  You may copy and distribute such a system following the
 * terms of the GNU GPL for this module and the licenses of the
 * other code concerned, provided that you include the source code of
 * that other code when and as the GNU GPL requires distribution of
 * source code.
 *
 * Note that people who make modified versions of this module
 * are not obligated to grant this special exception for their
 * modified versions; it is their choice whether to do so.  The GNU
 * General Public License gives permission to release a modified
 * version without this exception; this exception also makes it
 * possible to release a modified version which carries forward this
 * exception.
 *
 */

/*
 * Shadowing propation model, including the path-loss model.
 * This statistcal model is applicable for both outdoor and indoor.
 * Wei Ye, [e-mail], 2000
 */


#include <math.h>

#include <delay.h>
#include <packet.h>

#include <packet-stamp.h>
#include <antenna.h>
#include <mobilenode.h>
#include <propagation.h>
#include <wireless-phy.h>
#include <shadowing.h>


static class ShadowingClass: public TclClass {
public:
	ShadowingClass() : TclClass("Propagation/Shadowing") {}
	TclObject* create(int, const char*const*) {
		return (new Shadowing);
	}
} class_shadowing;


Shadowing::Shadowing()
{
	int i;
	// VIVEK
//	printf("Creating shadow_coeff_ array.\n");
	shadow_coeff_ = new double * [MAXNODES];
	for(i=0;i<MAXNODES;i++)
		shadow_coeff_[i] = new double [MAXNODES];

//	bind("pathlossExp_", &pathlossExp_);
//	bind("std_db_", &std_db_);
//	bind("dist0_", &dist0_);
//	bind("seed_", &seed_);
//	bind("num_nodes_", &num_nodes_);
	pathlossExp_ =3.3;
	pathlossConst_ =pow(10.0, -5.3);
	std_db_ =4.0;
	fw_rev_corr_=0.5;
	dist0_ =1.0;
	seed_ =0; //default seed_
	init_seed_ = 0;
	num_nodes_ = -1;
//	ranVar = new RNG;
//	ranVar->set_seed(RNG::PREDEF_SEED_SOURCE, seed_);
}


Shadowing::~Shadowing()
{
	int i;
//	return;
//	printf("Deleting shadow_coeff_ array.\n");
	delete ranVar;
	for(i=0;i<MAXNODES;i++){
		delete [] shadow_coeff_[i];
	}
	delete [] shadow_coeff_;
}

// VIVEK_NEW
void Shadowing::set_seed_(int value){
	int i, j;
	double temp, common_gaussian, gaussian_up, gaussian_down, temp_up, temp_down;
	seed_ = value;
//	return;
// INIT the entire shadowing array of this node
	if(!init_seed_){ // During first pass, set all gains.
		// Ensures repeatability since gains do not depend on the order in which signals were recvd.
		init_seed_ = 1;
		ranVar = new RNG;
//		ranVar->set_seed(RNG::RAW_SEED_SOURCE, ((1+seed_)*1234567)); // Seed
		ranVar->set_seed(RNG::RAW_SEED_SOURCE, seed_+1); // 64 predefined seeds.
//		printf("Setting seed_=%d\n", seed_);
		for(i=0 ; i<MAXNODES ;i++){
			for(j=i+1 ; j<MAXNODES ;j++){//VIVEK_NEW
				//VIVEK_NEW
				//The shadowing over uplink and downlink is about 50-90% correlated.
				//See "Shadow Fading Correlation between Uplink and Downlink," Eldad Perahia, Donald C. Cox, VTC 2001
				//Measurement study in suburban area in 1900MHz band show a correlation of about 0.9 between d/l and u/l
				//Comparison of routing metric paper shows significant difference in fw and rev correlation (MSR paper)
				common_gaussian = ranVar->normal(0.0, std_db_);
				gaussian_up = ranVar->normal(0.0, std_db_);
				gaussian_down = ranVar->normal(0.0, std_db_);
				temp_up   = common_gaussian*pow(fw_rev_corr_, 0.5) + gaussian_up*pow(1.0-fw_rev_corr_, 0.5);
				temp_down = common_gaussian*pow(fw_rev_corr_, 0.5) + gaussian_down*pow(1.0-fw_rev_corr_, 0.5);

				//Shadowing gains are rarely above 2 standard deviation. If we generate these gains for all the 
				//node pairs, there are 100*99 such terms, and some of them could be very high (basic probability).
				//Hence we truncate the positive side of these gains within 2 std_db_
				//Approach for larger shadow std dev
//				if(temp_up> 2.0*std_db_)
//					temp_up = 2.0*std_db_;
//				else if(temp_up< -2.0*std_db_)
//					temp_up = -2.0*std_db_;
//
//				if(temp_down> 2.0*std_db_)
//					temp_down = 2.0*std_db_;
//				else if(temp_down< -2.0*std_db_)
//					temp_down = -2.0*std_db_;

				shadow_coeff_[i][j] = pow(10.0, temp_up/10.0);
				shadow_coeff_[j][i] = pow(10.0, temp_down/10.0);
//				if((i==73 && j==91) || (i==91 && j==73))
//					printf("shadow coeff %d -> %d=%f\n", j, i, 10.0*log10(shadow_coeff_[i][j]));
			}
		}
	}
}
// VIVEK_NEW


double Shadowing::Pr(PacketStamp *t, PacketStamp *r, WirelessPhy *ifp)
{
	double Pr, avg_db;
	int myaddr, othernd;

	//VIVEK
	if(num_nodes_ <0){
		printf("Set number of wireless nodes with: \nset prop_inst [$ns_ set propInstance_]\n$prop_inst num_nodes_   $opt(nn);\n");
		exit(0);
	}

	// calculate the receiving power at dist
	double L = ifp->getL();		// system loss
	double lambda = ifp->getLambda();   // wavelength

	double Xt, Yt, Zt;		// loc of transmitter
	double Xr, Yr, Zr;		// loc 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 dist = 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 reference distance
// VIVEK_NEW	double Pr0 = Friis(t->getTxPr(), Gt, Gr, lambda, L, dist0_);
	double c = pathlossConst_; // constant in path loss term
	// Rcvd pwr is is c * dist^{-pathlossExp_) * shadow * fading * Gt * Gr * Txpwr
	// Fading term will come later (parent class).
	double Pr0 = t->getTxPr()*c*Gt*Gr;
	myaddr  = r->getNode()->address();
	othernd = t->getNode()->address();

	avg_db = -10.0 * pathlossExp_ * log10(dist/dist0_); // Path loss
//	printf("myaddr=%d, otherndaddr=%d\n",myaddr, othernd);
	Pr = Pr0 * pow(10.0, (avg_db/10.0)) * shadow_coeff_[myaddr][othernd]; // Cumulative gain (path loss and shdwng)
//	Pr = Pr0 * pow(10.0, (avg_db/10.0)) * pow(10.0, 1.130); // Cumulative gain (path loss and shdwng)
	return Pr;
}


int Shadowing::command(int argc, const char* const* argv)
{
	if ((argc == 3) && (strcmp(argv[1], "num_nodes_") == 0)){
		if(atoi(argv[2]) > MAXNODES)
			return(TCL_ERROR); // Network is too large, need to reconfigure
		else{
			set_num_nodes_(atoi(argv[2]));
			return(TCL_OK);
		}
	}
	if (argc == 4) {
		/* VIVEK_NEW OBSOLETE UNDER COMBINED shdw-fdng MODEL */
		if (strcmp(argv[1], "seed") == 0) {
			int s = atoi(argv[3]);
			if (strcmp(argv[2], "raw") == 0) {
				ranVar->set_seed(RNG::RAW_SEED_SOURCE, s);
			} else if (strcmp(argv[2], "predef") == 0) {
				ranVar->set_seed(RNG::PREDEF_SEED_SOURCE, s);
				// s is the index in predefined seed array
				// 0 <= s < 64
			} else if (strcmp(argv[2], "heuristic") == 0) {
				ranVar->set_seed(RNG::HEURISTIC_SEED_SOURCE, 0);
			}
			return(TCL_OK);
		}
	}
	
	return Propagation::command(argc, argv);
}