/* -*-  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 SPECTRUM_INTERFERENCE_H

#define SPECTRUM_INTERFERENCE_H

#include <ns3/object.h>

#include <ns3/packet.h>

#include <ns3/nstime.h>

#include <ns3/spectrum-value.h>

namespace ns3 {

class SpectrumErrorModel;

/**

 * This class implements a gaussian interference model, i.e., all

 * incoming signals are added to the total interference.

 *

 */

class SpectrumInterference : public Object

{

public:

  SpectrumInterference ();

  virtual ~SpectrumInterference ();

  /**

   * set the SpectrumErrorModel to be used.

   *

   * @param e

   */

  void SetErrorModel (Ptr<SpectrumErrorModel> e);

  /**

   * notify that the PHY is starting a RX attempt

   *

   * @param p the packet corresponding to the signal being RX

   * @param rxPsd the power spectral density of the signal being RX

   */

  void StartRx (Ptr<const Packet> p, Ptr<const SpectrumValue> rxPsd);

  /**

   * notify that the RX attempt has ended. The receiving PHY must call

   * this method upon RX end in order to:

   * 1) know if RX was successful or not

   * 2) free up resources that might eventually be used for the

   * calculation of interference. Note that for this reason this

   * method must also be called when RX is aborted.

   *

   *

   * @return true if RX was successful, false otherwise

   */

  bool EndRx ();

  /**

   * notify that a new signal is being perceived in the medium. This

   * method is to be called for all incoming signal, regardless of

   * wether they're useful signals or interferers.

   *

   * @param spd the power spectral density of the new signal

   * @param duration the duration of the new signal

   */

  void AddSignal (Ptr<const SpectrumValue> spd, const Time duration);

  /**

   *

   * @param noisePsd the Noise Power Spectral Density in power units

   * (Watt, Pascal...) per Hz.

   */

  void SetNoisePowerSpectralDensity (Ptr<const SpectrumValue> noisePsd);

protected:

  void DoDispose ();

private:

  void ConditionallyEvaluateChunk ();

  void DoAddSignal  (Ptr<const SpectrumValue> spd);

  void DoSubtractSignal  (Ptr<const SpectrumValue> spd);

  bool m_receiving;

  Ptr<const SpectrumValue> m_rxSignal; /**< stores the power spectral density of

                                  * the signal whose RX is being

                                  * attempted

                                  */

  Ptr<SpectrumValue> m_allSignals; /**< stores the spectral

                                    * power density of the sum of incoming signals;

                                    * does not include noise, includes the SPD of the signal being RX

                                    */

  Ptr<const SpectrumValue> m_noise;

  Time m_lastChangeTime;     /**< the time of the last change in

                                m_TotalPower */

  Ptr<SpectrumErrorModel> m_errorModel;

};

} // namespace ns3

#endif /* SPECTRUM_INTERFERENCE_H */