text: /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
  /*
   * Copyright (c) 2009 CTTC
   *
   * 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: Nicola Baldo <nbaldo@cttc.es>
   */
  
  #ifndef FRIIS_SPECTRUM_PROPAGATION_LOSS_H
  #define FRIIS_SPECTRUM_PROPAGATION_LOSS_H
  
  
  #include <ns3/spectrum-propagation-loss-model.h>
  
  
  namespace ns3 {
  
  class MobilityModel;
  
  
  /**
   * \ingroup spectrum
   * \brief Friis spectrum propagation loss model
   *
   * The propagation loss is calculated according to a simplified version of Friis'
   * formula in which antenna gains are unitary:
   *
   * \f$ L = \frac{4 \pi * d * f}{C^2}\f$
   *
   * where C = 3e8 m/s is the light speed in the vacuum. The intended
   * use is to calculate Prx = Ptx * G
   */
  class FriisSpectrumPropagationLossModel : public SpectrumPropagationLossModel
  {
  
  public:
    FriisSpectrumPropagationLossModel ();
    ~FriisSpectrumPropagationLossModel ();
  
    /**
     * \brief Get the type ID.
     * \return the object TypeId
     */
    static TypeId GetTypeId ();
  
  
    virtual Ptr<SpectrumValue> DoCalcRxPowerSpectralDensity (Ptr<const SpectrumValue> txPsd,
                                                             Ptr<const MobilityModel> a,
                                                             Ptr<const MobilityModel> b) const;
  
  
    /**
     * Return the propagation loss L according to a simplified version of Friis'
     * formula in which antenna gains are unitary
     *
     * @param f frequency in Hz
     * @param d distance in m
     *
     * @return if Prx < Ptx then return Prx; else return Ptx
     */
    double CalculateLoss (double f, double d) const;
  };
  
  
  
  
  
  
  } // namespace ns3
  
  #endif /* FRIIS_SPECTRUM_PROPAGATION_LOSS_MODEL_H */
  