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

/*

 * Copyright (c) 2005,2006 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>

 */

#ifndef WIFI_PHY_H

#define WIFI_PHY_H

#include <vector>

#include <list>

#include <stdint.h>

#include "ns3/callback.h"

#include "ns3/event-id.h"

#include "ns3/packet.h"

#include "ns3/object.h"

#include "ns3/callback-trace-source.h"

#include "ns3/nstime.h"

#include "ns3/ptr.h"

#include "ns3/random-variable.h"

#include "wifi-mode.h"

#include "wifi-preamble.h"

namespace ns3 {

class RandomUniform;

class RxEvent;

class TraceContainer;

class WifiNetDevice;

class WifiChannel;

class WifiPhyListener {

public:

  virtual ~WifiPhyListener ();

  /* we have received the first bit of a packet. We decided

   * that we could synchronize on this packet. It does not mean

   * we will be able to successfully receive completely the

   * whole packet. It means we will report a BUSY status.

   * r.end will be invoked later to report whether or not

   * the packet was successfully received.

   */

  virtual void NotifyRxStart (Time duration) = 0;

  /* we have received the last bit of a packet for which

   * rxStart was invoked first. 

   */

  virtual void NotifyRxEndOk (void) = 0;

  virtual void NotifyRxEndError (void) = 0;

  /* we start the transmission of a packet.

   */

  virtual void NotifyTxStart (Time duration) = 0;

  virtual void NotifyCcaBusyStart (Time duration) = 0;

};

/**

 * \brief 802.11 PHY layer model

 *

 * This PHY implements a model of 802.11a. The model

 * implemented here is based on the model described

 * in "Yet Another Network Simulator", 

 * (http://cutebugs.net/files/wns2-yans.pdf).

 *

 * This PHY model depends on a channel loss and delay

 * model as provided by the ns3::PropagationLossModel

 * and ns3::PropagationDelayModel classes.

 * 

 */

class WifiPhy : public Object

{

public:

  /**

   * The state of the PHY layer.

   */

  enum State {

    /**

     * The PHY layer is synchronized upon a packet.

     */

    SYNC,

    /**

     * The PHY layer is sending a packet.

     */

    TX,

    /**

     * The PHY layer has sense the medium busy through

     * the CCA mechanism

     */

    CCA_BUSY,

    /**

     * The PHY layer is IDLE.

     */

    IDLE

  };

  /**

   * arg1: packet received successfully

   * arg2: snr of packet

   * arg3: mode of packet

   * arg4: type of preamble used for packet.

   */

  typedef Callback<void,Packet, double, WifiMode, enum WifiPreamble> SyncOkCallback;

  /**

   * arg1: packet received unsuccessfully

   * arg2: snr of packet

   */

  typedef Callback<void,Packet, double> SyncErrorCallback;

  /**

   * \param device the device which contains this PHY.

   *

   * Create a new PHY layer instance initialized with values

   * coming from \valueref{WifiPhyEnergyDetectionThreshold},

   * \valueref{WifiPhyRxNoise}, \valueref{WifiPhyTxPowerBase},

   * \valueref{WifiPhyTxPowerEnd}, \valueref{WifiPhyTxPowerLevels},

   * \valueref{WifiPhyTxGain}, and, \valueref{WifiPhyRxGain}

   */

  WifiPhy (Ptr<WifiNetDevice> device);

  virtual ~WifiPhy ();

  /**

   * \param channel the channel to connect to.

   */

  void SetChannel (Ptr<WifiChannel> channel);

  /**

   * \param callback the callback to invoke

   *        upon successful packet reception.

   */

  void SetReceiveOkCallback (SyncOkCallback callback);

  /**

   * \param callback the callback to invoke

   *        upon erronous packet reception.

   */

  void SetReceiveErrorCallback (SyncErrorCallback callback);

  /**

   * \param packet the packet to send

   * \param mode the transmission mode to use to send this packet

   * \param preamble the type of preamble to use to send this packet.

   * \param txPowerLevel a power level to use to send this packet. The real

   *        transmission power is calculated as txPowerMin + txPowerLevel * (txPowerMax - txPowerMin) / nTxLevels

   */

  void SendPacket (Packet const packet, WifiMode mode, enum WifiPreamble preamble, uint8_t txPowerLevel);

  /**

   * \param listener the new listener

   *

   * Add the input listener to the list of objects to be notified of

   * PHY-level events.

   */

  void RegisterListener (WifiPhyListener *listener);

  /**

   * \returns true of the current state of the PHY layer is WifiPhy:LCCA_BUSY, false otherwise.

   */

  bool IsStateCcaBusy (void);

  /**

   * \returns true of the current state of the PHY layer is WifiPhy::IDLE, false otherwise.

   */

  bool IsStateIdle (void);

  /**

   * \returns true of the current state of the PHY layer is not WifiPhy::IDLE, false otherwise.

   */

  bool IsStateBusy (void);

  /**

   * \returns true of the current state of the PHY layer is WifiPhy::SYNC, false otherwise.

   */

  bool IsStateSync (void);

  /**

   * \returns true of the current state of the PHY layer is WifiPhy::TX, false otherwise.

   */

  bool IsStateTx (void);

  /**

   * \returns the amount of time since the current state has started.

   */

  Time GetStateDuration (void);

  /**

   * \returns the predicted delay until this PHY can become WifiPhy::IDLE.

   *

   * The PHY will never become WifiPhy::IDLE _before_ the delay returned by

   * this method but it could become really idle later.

   */

  Time GetDelayUntilIdle (void);

  /**

   * \param size the number of bytes in the packet to send

   * \param payloadMode the transmission mode to use for this packet

   * \param preamble the type of preamble to use for this packet.

   * \returns the total amount of time this PHY will stay busy for

   *          the transmission of these bytes.

   */

  Time CalculateTxDuration (uint32_t size, WifiMode payloadMode, enum WifiPreamble preamble) const;

  /**

   * \returns the number of transmission modes supported by this PHY.

   */

  uint32_t GetNModes (void) const;

  /**

   * \param mode index in array of supported modes

   * \returns the mode whose index is specified.

   */

  WifiMode GetMode (uint32_t mode) const;

  /**

   * \returns the number of tx power levels available for this PHY.

   */

  uint32_t GetNTxpower (void) const;

  /* return snr: W/W */

  /**

   * \param txMode the transmission mode

   * \param ber the probability of bit error rate

   * \returns the minimum snr which is required to achieve

   *          the requested ber for the specified transmission mode.

   */

  double CalculateSnr (WifiMode txMode, double ber) const;

private:

  class NiChange {

  public:

    NiChange (Time time, double delta);

    Time GetTime (void) const;

    double GetDelta (void) const;

    bool operator < (NiChange const &o) const;

  private:

    Time m_time;

    double m_delta;

  };

  typedef std::vector<WifiMode> Modes;

  typedef std::list<WifiPhyListener *> Listeners;

  typedef std::list<Ptr<RxEvent> > Events;

  typedef std::vector <NiChange> NiChanges;

private:

  // inherited from ns3::Object.

  virtual Ptr<TraceResolver> GetTraceResolver (void) const;

  void Configure80211aParameters (void);

  void PrintModes (void) const;

  void Configure80211a (void);

  void ConfigureHolland (void);

  char const *StateToString (enum State state);

  enum WifiPhy::State GetState (void);

  double GetEdThresholdW (void) const;

  double DbmToW (double dbm) const;

  double DbToRatio (double db) const;

  Time GetMaxPacketDuration (void) const;

  void CancelRx (void);

  double GetPowerDbm (uint8_t power) const;

  void NotifyTxStart (Time duration);

  void NotifyWakeup (void);

  void NotifySyncStart (Time duration);

  void NotifySyncEndOk (void);

  void NotifySyncEndError (void);

  void NotifyCcaBusyStart (Time duration);

  void LogPreviousIdleAndCcaBusyStates (void);

  void SwitchToTx (Time txDuration);

  void SwitchToSync (Time syncDuration);

  void SwitchFromSync (void);

  void SwitchMaybeToCcaBusy (Time duration);

  void AppendEvent (Ptr<RxEvent> event);

  double CalculateNoiseInterferenceW (Ptr<RxEvent> event, NiChanges *ni) const;

  double CalculateSnr (double signal, double noiseInterference, WifiMode mode) const;

  double CalculateChunkSuccessRate (double snir, Time delay, WifiMode mode) const;

  double CalculatePer (Ptr<const RxEvent> event, NiChanges *ni) const;

  void EndSync (Packet const packet, Ptr<RxEvent> event);

  double Log2 (double val) const;

  double GetBpskBer (double snr, uint32_t signalSpread, uint32_t phyRate) const;

  double GetQamBer (double snr, unsigned int m, uint32_t signalSpread, uint32_t phyRate) const;

  uint32_t Factorial (uint32_t k) const;

  double Binomial (uint32_t k, double p, uint32_t n) const;

  double CalculatePdOdd (double ber, unsigned int d) const;

  double CalculatePdEven (double ber, unsigned int d) const;

  double CalculatePd (double ber, unsigned int d) const;

  double GetFecBpskBer (double snr, double nbits, 

                        uint32_t signalSpread, uint32_t phyRate,

                        uint32_t dFree, uint32_t adFree) const;

  double GetFecQamBer (double snr, uint32_t nbits, 

                       uint32_t signalSpread,

                       uint32_t phyRate,

                       uint32_t m, uint32_t dfree,

                       uint32_t adFree, uint32_t adFreePlusOne) const;

  double GetChunkSuccessRate (WifiMode mode, double snr, uint32_t nbits) const;

  /* rxPower unit is Watt */

  void ReceivePacket (Packet packet,

                      double rxPowerDbm,

                      WifiMode mode,

                      WifiPreamble preamble);

private:

  uint64_t m_txPrepareDelayUs;

  uint64_t m_plcpLongPreambleDelayUs;

  uint64_t m_plcpShortPreambleDelayUs;

  WifiMode m_longPlcpHeaderMode;

  WifiMode m_shortPlcpHeaderMode;

  uint32_t m_plcpHeaderLength;

  Time     m_maxPacketDuration;

  double   m_edThresholdW; /* unit: W */

  double   m_txGainDb;

  double   m_rxGainDb;

  double   m_rxNoiseRatio;

  double   m_txPowerBaseDbm;

  double   m_txPowerEndDbm;

  uint32_t m_nTxPower;

  bool m_syncing;

  Time m_endTx;

  Time m_endSync;

  Time m_endCcaBusy;

  Time m_startTx;

  Time m_startSync;

  Time m_startCcaBusy;

  Time m_previousStateChangeTime;

  Ptr<WifiChannel> m_channel;

  Ptr<WifiNetDevice> m_device;

  SyncOkCallback m_syncOkCallback;

  SyncErrorCallback m_syncErrorCallback;

  Modes m_modes;

  Listeners m_listeners;

  EventId m_endSyncEvent;

  Events m_events;

  UniformVariable m_random;

  CallbackTraceSource<Time,Time,enum WifiPhy::State> m_stateLogger;

};

} // namespace ns3

#endif /* WIFI_PHY_H */