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

/*

 * Copyright (c) 2003,2007 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 "amrr-wifi-manager.h"

#include "ns3/simulator.h"

#include "ns3/log.h"

#include "ns3/uinteger.h"

#include "ns3/double.h"

#define Min(a,b) ((a < b) ? a : b)

namespace ns3 {

NS_LOG_COMPONENT_DEFINE ("AmrrWifiRemoteStation");

/**

 * \brief hold per-remote-station state for AMRR Wifi manager.

 *

 * This struct extends from WifiRemoteStation struct to hold additional

 * information required by the AMRR Wifi manager

 */

struct AmrrWifiRemoteStation : public WifiRemoteStation

{

  Time m_nextModeUpdate;

  uint32_t m_tx_ok;

  uint32_t m_tx_err;

  uint32_t m_tx_retr;

  uint32_t m_retry;

  uint32_t m_txrate;

  uint32_t m_successThreshold;

  uint32_t m_success;

  bool m_recovery;

};

NS_OBJECT_ENSURE_REGISTERED (AmrrWifiManager);

TypeId

AmrrWifiManager::GetTypeId (void)

{

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

    .SetParent<WifiRemoteStationManager> ()

    .SetGroupName ("Wifi")

    .AddConstructor<AmrrWifiManager> ()

    .AddAttribute ("UpdatePeriod",

                   "The interval between decisions about rate control changes",

                   TimeValue (Seconds (1.0)),

                   MakeTimeAccessor (&AmrrWifiManager::m_updatePeriod),

                   MakeTimeChecker ())

    .AddAttribute ("FailureRatio",

                   "Ratio of minimum erroneous transmissions needed to switch to a lower rate",

                   DoubleValue (1.0 / 3.0),

                   MakeDoubleAccessor (&AmrrWifiManager::m_failureRatio),

                   MakeDoubleChecker<double> (0.0, 1.0))

    .AddAttribute ("SuccessRatio",

                   "Ratio of maximum erroneous transmissions needed to switch to a higher rate",

                   DoubleValue (1.0 / 10.0),

                   MakeDoubleAccessor (&AmrrWifiManager::m_successRatio),

                   MakeDoubleChecker<double> (0.0, 1.0))

    .AddAttribute ("MaxSuccessThreshold",

                   "Maximum number of consecutive success periods needed to switch to a higher rate",

                   UintegerValue (10),

                   MakeUintegerAccessor (&AmrrWifiManager::m_maxSuccessThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MinSuccessThreshold",

                   "Minimum number of consecutive success periods needed to switch to a higher rate",

                   UintegerValue (1),

                   MakeUintegerAccessor (&AmrrWifiManager::m_minSuccessThreshold),

                   MakeUintegerChecker<uint32_t> ())

  ;

  return tid;

}

AmrrWifiManager::AmrrWifiManager ()

{

  NS_LOG_FUNCTION (this);

}

WifiRemoteStation *

AmrrWifiManager::DoCreateStation (void) const

{

  NS_LOG_FUNCTION (this);

  AmrrWifiRemoteStation *station = new AmrrWifiRemoteStation ();

  station->m_nextModeUpdate = Simulator::Now () + m_updatePeriod;

  station->m_tx_ok = 0;

  station->m_tx_err = 0;

  station->m_tx_retr = 0;

  station->m_retry = 0;

  station->m_txrate = 0;

  station->m_successThreshold = m_minSuccessThreshold;

  station->m_success = 0;

  station->m_recovery = false;

  return station;

}

void

AmrrWifiManager::DoReportRxOk (WifiRemoteStation *station,

                               double rxSnr, WifiMode txMode)

{

  NS_LOG_FUNCTION (this << station << rxSnr << txMode);

}

void

AmrrWifiManager::DoReportRtsFailed (WifiRemoteStation *station)

{

  NS_LOG_FUNCTION (this << station);

}

void

AmrrWifiManager::DoReportDataFailed (WifiRemoteStation *st)

{

  NS_LOG_FUNCTION (this << st);

  AmrrWifiRemoteStation *station = (AmrrWifiRemoteStation *)st;

  station->m_retry++;

  station->m_tx_retr++;

}

void

AmrrWifiManager::DoReportRtsOk (WifiRemoteStation *st,

                                double ctsSnr, WifiMode ctsMode, double rtsSnr)

{

  NS_LOG_FUNCTION (this << st << ctsSnr << ctsMode << rtsSnr);

}

void

AmrrWifiManager::DoReportDataOk (WifiRemoteStation *st,

                                 double ackSnr, WifiMode ackMode, double dataSnr)

{

  NS_LOG_FUNCTION (this << st << ackSnr << ackMode << dataSnr);

  AmrrWifiRemoteStation *station = (AmrrWifiRemoteStation *)st;

  station->m_retry = 0;

  station->m_tx_ok++;

}

void

AmrrWifiManager::DoReportFinalRtsFailed (WifiRemoteStation *station)

{

  NS_LOG_FUNCTION (this << station);

}

void

AmrrWifiManager::DoReportFinalDataFailed (WifiRemoteStation *st)

{

  NS_LOG_FUNCTION (this << st);

  AmrrWifiRemoteStation *station = (AmrrWifiRemoteStation *)st;

  station->m_retry = 0;

  station->m_tx_err++;

}

bool

AmrrWifiManager::IsMinRate (AmrrWifiRemoteStation *station) const

{

  NS_LOG_FUNCTION (this << station);

  return (station->m_txrate == 0);

}

bool

AmrrWifiManager::IsMaxRate (AmrrWifiRemoteStation *station) const

{

  NS_LOG_FUNCTION (this << station);

  NS_ASSERT (station->m_txrate + 1 <= GetNSupported (station));

  return (station->m_txrate + 1 == GetNSupported (station));

}

bool

AmrrWifiManager::IsSuccess (AmrrWifiRemoteStation *station) const

{

  NS_LOG_FUNCTION (this << station);

  return (station->m_tx_retr + station->m_tx_err) < station->m_tx_ok * m_successRatio;

}

bool

AmrrWifiManager::IsFailure (AmrrWifiRemoteStation *station) const

{

  NS_LOG_FUNCTION (this << station);

  return (station->m_tx_retr + station->m_tx_err) > station->m_tx_ok * m_failureRatio;

}

bool

AmrrWifiManager::IsEnough (AmrrWifiRemoteStation *station) const

{

  NS_LOG_FUNCTION (this << station);

  return (station->m_tx_retr + station->m_tx_err + station->m_tx_ok) > 10;

}

void

AmrrWifiManager::ResetCnt (AmrrWifiRemoteStation *station)

{

  NS_LOG_FUNCTION (this << station);

  station->m_tx_ok = 0;

  station->m_tx_err = 0;

  station->m_tx_retr = 0;

}

void

AmrrWifiManager::IncreaseRate (AmrrWifiRemoteStation *station)

{

  NS_LOG_FUNCTION (this << station);

  station->m_txrate++;

  NS_ASSERT (station->m_txrate < GetNSupported (station));

}

void

AmrrWifiManager::DecreaseRate (AmrrWifiRemoteStation *station)

{

  NS_LOG_FUNCTION (this << station);

  station->m_txrate--;

}

void

AmrrWifiManager::UpdateMode (AmrrWifiRemoteStation *station)

{

  NS_LOG_FUNCTION (this << station);

  if (Simulator::Now () < station->m_nextModeUpdate)

    {

      return;

    }

  station->m_nextModeUpdate = Simulator::Now () + m_updatePeriod;

  NS_LOG_DEBUG ("Update");

  bool needChange = false;

  if (IsSuccess (station) && IsEnough (station))

    {

      station->m_success++;

      NS_LOG_DEBUG ("++ success=" << station->m_success << " successThreshold=" << station->m_successThreshold <<

                    " tx_ok=" << station->m_tx_ok << " tx_err=" << station->m_tx_err << " tx_retr=" << station->m_tx_retr <<

                    " rate=" << station->m_txrate << " n-supported-rates=" << GetNSupported (station));

      if (station->m_success >= station->m_successThreshold

          && !IsMaxRate (station))

        {

          station->m_recovery = true;

          station->m_success = 0;

          IncreaseRate (station);

          needChange = true;

        }

      else

        {

          station->m_recovery = false;

        }

    }

  else if (IsFailure (station))

    {

      station->m_success = 0;

      NS_LOG_DEBUG ("-- success=" << station->m_success << " successThreshold=" << station->m_successThreshold <<

                    " tx_ok=" << station->m_tx_ok << " tx_err=" << station->m_tx_err << " tx_retr=" << station->m_tx_retr <<

                    " rate=" << station->m_txrate << " n-supported-rates=" << GetNSupported (station));

      if (!IsMinRate (station))

        {

          if (station->m_recovery)

            {

              station->m_successThreshold *= 2;

              station->m_successThreshold = std::min (station->m_successThreshold,

                                                      m_maxSuccessThreshold);

            }

          else

            {

              station->m_successThreshold = m_minSuccessThreshold;

            }

          station->m_recovery = false;

          DecreaseRate (station);

          needChange = true;

        }

      else

        {

          station->m_recovery = false;

        }

    }

  if (IsEnough (station) || needChange)

    {

      NS_LOG_DEBUG ("Reset");

      ResetCnt (station);

    }

}

WifiTxVector

AmrrWifiManager::DoGetDataTxVector (WifiRemoteStation *st, uint32_t size)

{

  NS_LOG_FUNCTION (this << st << size);

  AmrrWifiRemoteStation *station = (AmrrWifiRemoteStation *)st;

  UpdateMode (station);

  NS_ASSERT (station->m_txrate < GetNSupported (station));

  uint32_t rateIndex;

  if (station->m_retry < 1)

    {

      rateIndex = station->m_txrate;

    }

  else if (station->m_retry < 2)

    {

      if (station->m_txrate > 0)

        {

          rateIndex = station->m_txrate - 1;

        }

      else

        {

          rateIndex = station->m_txrate;

        }

    }

  else if (station->m_retry < 3)

    {

      if (station->m_txrate > 1)

        {

          rateIndex = station->m_txrate - 2;

        }

      else

        {

          rateIndex = station->m_txrate;

        }

    }

  else

    {

      if (station->m_txrate > 2)

        {

          rateIndex = station->m_txrate - 3;

        }

      else

        {

          rateIndex = station->m_txrate;

        }

    }

  uint32_t channelWidth = GetChannelWidth (station);

  if (channelWidth > 20 && channelWidth != 22)

    {

      //avoid to use legacy rate adaptation algorithms for IEEE 802.11n/ac

      channelWidth = 20;

    }

  return WifiTxVector (GetSupported (station, rateIndex), GetDefaultTxPowerLevel (), GetLongRetryCount (station), false, 1, 0, channelWidth, GetAggregation (station), false);

}

WifiTxVector

AmrrWifiManager::DoGetRtsTxVector (WifiRemoteStation *st)

{

  NS_LOG_FUNCTION (this << st);

  AmrrWifiRemoteStation *station = (AmrrWifiRemoteStation *)st;

  uint32_t channelWidth = GetChannelWidth (station);

  if (channelWidth > 20 && channelWidth != 22)

    {

      //avoid to use legacy rate adaptation algorithms for IEEE 802.11n/ac

      channelWidth = 20;

    }

  UpdateMode (station);

  /// \todo can we implement something smarter ?

  return WifiTxVector (GetSupported (station, 0), GetDefaultTxPowerLevel (), GetLongRetryCount (station), false, 1, 0, channelWidth, GetAggregation (station), false);

}

bool

AmrrWifiManager::IsLowLatency (void) const

{

  NS_LOG_FUNCTION (this);

  return true;

}

} //namespace ns3