source: proiecte/ptvs/src/vnsim/network/propagation/TwoRay.java @ 31

/************************************************************************************
 * Copyright (C) 2008 by Politehnica University of Bucharest and Rutgers University
 * All rights reserved.
 * Refer to LICENSE for terms and conditions of use.
 ***********************************************************************************/
//Petroaca - two ray propagation model
package vnsim.network.propagation;

import vnsim.map.object.Globals;
import vnsim.network.propagation.FreeSpace;

public class TwoRay
{
        private static double Hr=Globals.AH;
        private static double Ht=Globals.AH;
        private static double crossoverDistance=(4*Math.PI*Ht*Hr)/Globals.DSRC_LAMBDA;
        
        public static double getPr(double Pt,double R)
        {
                if(Pt<=0.0 || R<=0.0)
                        return -1;
                
                if(R<=crossoverDistance)
                {
                        return FreeSpace.getPr(Pt,R);
                }
                else
                {
                        double aux=Math.pow(Ht,2)*Math.pow(Hr,2);
                        double R4=Math.pow(R,4);
                        
                        return (Pt*Math.pow(Globals.ANTENNA_GAIN,2)*aux)/(R4*Globals.SYSTEM_LOSS);
                }
        }
        
        public static double getPrAlt(double Pt,double R)
        {
                if(Pt<=0 || R<=0)
                        return -1;
                
                double pathloss = -(2*Globals.ANTENNA_GAIN);
                double freeSpace = (4.0 * Math.PI * R) / Globals.DSRC_LAMBDA;
                double planeEarth = (R * R) / (Hr*Ht);

                if (planeEarth > freeSpace){
                        pathloss += 20.0 * Math.log10(planeEarth);
                }else{
                        pathloss += 20.0 * Math.log10(freeSpace);
                }
            
                return Pt-pathloss;
        }
}