/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2005,2006,2007 INRIA

 *

 * 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

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#include "propagation-loss-model.h"

#include "ns3/log.h"

#include "ns3/mobility-model.h"

#include "ns3/static-mobility-model.h"

#include "ns3/double.h"

#include "ns3/pointer.h"

#include <math.h>

NS_LOG_COMPONENT_DEFINE ("PropagationLossModel");

namespace ns3 {

const double FriisPropagationLossModel::PI = 3.1415;

NS_OBJECT_ENSURE_REGISTERED (PropagationLossModel);

TypeId 

PropagationLossModel::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::PropagationLossModel")

    .SetParent<Object> ()

    ;

  return tid;

}

PropagationLossModel::~PropagationLossModel ()

{}

NS_OBJECT_ENSURE_REGISTERED (RandomPropagationLossModel);

TypeId 

RandomPropagationLossModel::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::RandomPropagationLossModel")

    .SetParent<PropagationLossModel> ()

    .AddConstructor<RandomPropagationLossModel> ()

    .AddAttribute ("Variable", "XXX",

                   MakeRandomVariableAccessor (&RandomPropagationLossModel::m_variable),

                   MakeRandomVariableChecker ())

    ;

  return tid;

}

RandomPropagationLossModel::RandomPropagationLossModel ()

{}

RandomPropagationLossModel::~RandomPropagationLossModel ()

{}

double 

RandomPropagationLossModel::GetLoss (Ptr<MobilityModel> a,

				     Ptr<MobilityModel> b) const

{

  double rxc = -m_variable.GetValue ();

  NS_LOG_DEBUG ("attenuation coefficent="<<rxc<<"Db");

  return rxc;

}

NS_OBJECT_ENSURE_REGISTERED (FriisPropagationLossModel);

TypeId 

FriisPropagationLossModel::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::FriisPropagationLossModel")

    .SetParent<PropagationLossModel> ()

    .AddConstructor<FriisPropagationLossModel> ()

    .AddAttribute ("Lambda", 

                   "The wavelength  (default is 5.15 GHz at 300 000 km/s).",

                   MakeDoubleAccessor (&FriisPropagationLossModel::m_lambda),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("SystemLoss", "The system loss",

                   MakeDoubleAccessor (&FriisPropagationLossModel::m_systemLoss),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("MinDistance", 

                   "The distance under which the propagation model refuses to give results (m)",

                   MakeDoubleAccessor (&FriisPropagationLossModel::m_minDistance),

                   MakeDoubleChecker<double> ())

    ;

  return tid;

}

FriisPropagationLossModel::FriisPropagationLossModel ()

{}

void 

FriisPropagationLossModel::SetSystemLoss (double systemLoss)

{

  m_systemLoss = systemLoss;

}

double 

FriisPropagationLossModel::GetSystemLoss (void) const

{

  return m_systemLoss;

}

void 

FriisPropagationLossModel::SetLambda (double frequency, double speed)

{

  m_lambda = speed / frequency;

}

void 

FriisPropagationLossModel::SetLambda (double lambda)

{

  m_lambda = lambda;

}

double 

FriisPropagationLossModel::GetLambda (void) const

{

  return m_lambda;

}

double 

FriisPropagationLossModel::DbmToW (double dbm) const

{

  double mw = pow(10.0,dbm/10.0);

  return mw / 1000.0;

}

double

FriisPropagationLossModel::DbmFromW (double w) const

{

  double dbm = log10 (w * 1000.0) * 10.0;

  return dbm;

}

double 

FriisPropagationLossModel::GetLoss (Ptr<MobilityModel> a,

				    Ptr<MobilityModel> b) const

{

  /*

   * Friis free space equation:

   * where Pt, Gr, Gr and P are in Watt units

   * L is in meter units.

   *

   *    P     Gt * Gr * (lambda^2)

   *   --- = ---------------------

   *    Pt     (4 * pi * d)^2 * L

   *

   * Gt: tx gain (unit-less)

   * Gr: rx gain (unit-less)

   * Pt: tx power (W)

   * d: distance (m)

   * L: system loss

   * lambda: wavelength (m)

   *

   * Here, we ignore tx and rx gain and the input and output values 

   * are in dbm:

   *

   *                           lambda^2

   * rx = tx +  10 log10 (-------------------)

   *                       (4 * pi * d)^2 * L

   *

   * rx: rx power (dbm)

   * tx: tx power (dbm)

   * d: distance (m)

   * L: system loss

   * lambda: wavelength (m)

   */

  double distance = a->GetDistanceFrom (b);

  if (distance <= m_minDistance)

    {

      return 0.0;

    }

  double numerator = m_lambda * m_lambda;

  double denominator = 16 * PI * PI * distance * distance * m_systemLoss;

  double pr = 10 * log10 (numerator / denominator);

  NS_LOG_DEBUG ("distance="<<distance<<"m, attenuation coefficient="<<pr<<"dB");

  return pr;

}

NS_OBJECT_ENSURE_REGISTERED (LogDistancePropagationLossModel);

TypeId

LogDistancePropagationLossModel::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::LogDistancePropagationLossModel")

    .SetParent<PropagationLossModel> ()

    .AddConstructor<LogDistancePropagationLossModel> ()

    .AddAttribute ("Exponent",

                   "The exponent of the Path Loss propagation model",

                   MakeDoubleAccessor (&LogDistancePropagationLossModel::m_exponent),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("ReferenceDistance",

                   "The distance at which the reference loss is calculated (m)",

                   MakeDoubleAccessor (&LogDistancePropagationLossModel::m_referenceDistance),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("ReferenceModel",

                   "The reference model at the reference distance.",

                   MakePointerAccessor (&LogDistancePropagationLossModel::m_reference),

                   MakePointerChecker<PropagationLossModel> ())

    ;

  return tid;

}

LogDistancePropagationLossModel::LogDistancePropagationLossModel ()

{}

void 

LogDistancePropagationLossModel::SetPathLossExponent (double n)

{

  m_exponent = n;

}

void 

LogDistancePropagationLossModel::SetReferenceDistance (double referenceDistance)

{

  m_referenceDistance = referenceDistance;

}

void 

LogDistancePropagationLossModel::SetReferenceModel (Ptr<PropagationLossModel> model)

{

  m_reference = model;

}

double 

LogDistancePropagationLossModel::GetPathLossExponent (void) const

{

  return m_exponent;

}

double 

LogDistancePropagationLossModel::GetLoss (Ptr<MobilityModel> a,

                                          Ptr<MobilityModel> b) const

{

  double distance = a->GetDistanceFrom (b);

  if (distance <= m_referenceDistance)

    {

      return 0.0;

    }

  /**

   * The formula is:

   * rx = 10 * log (Pr0(tx)) - n * 10 * log (d/d0)

   *

   * Pr0: rx power at reference distance d0 (W)

   * d0: reference distance: 1.0 (m)

   * d: distance (m)

   * tx: tx power (db)

   * rx: db

   *

   * Which, in our case is:

   *      

   * rx = rx0(tx) - 10 * n * log (d/d0)

   */

  static Ptr<StaticMobilityModel> zero = 

    CreateObject<StaticMobilityModel> ("Position", 

  static Ptr<StaticMobilityModel> reference = 

    CreateObject<StaticMobilityModel> ("Position", 

  double ref = m_reference->GetLoss (zero, reference);

  double pathLossDb = 10 * m_exponent * log10 (distance / m_referenceDistance);

  double rxc = ref - pathLossDb;

  NS_LOG_DEBUG ("distance="<<distance<<"m, reference-attenuation="<<ref<<"dB, "<<

		"attenuation coefficient="<<rxc<<"dbm");

  return rxc;

}

} // namespace ns3