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

/*

 * Copyright (c) 2004,2005,2006 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>

 */

#include "aarf-wifi-manager.h"

#include "ns3/double.h"

#include "ns3/uinteger.h"

#include "ns3/log.h"

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

#define Max(a,b) ((a > b) ? a : b)

NS_LOG_COMPONENT_DEFINE ("AarfWifiManager");

namespace ns3 {

struct AarfWifiRemoteStation : public WifiRemoteStation

{

  uint32_t m_timer;

  uint32_t m_success;

  uint32_t m_failed;

  bool m_recovery;

  uint32_t m_retry;

  uint32_t m_timerTimeout;

  uint32_t m_successThreshold;

  uint32_t m_rate;

};

NS_OBJECT_ENSURE_REGISTERED (AarfWifiManager);

TypeId

AarfWifiManager::GetTypeId (void)

{

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

    .SetParent<WifiRemoteStationManager> ()

    .AddConstructor<AarfWifiManager> ()

    .AddAttribute ("SuccessK", "Multiplication factor for the success threshold in the AARF algorithm.",

                   DoubleValue (2.0),

                   MakeDoubleAccessor (&AarfWifiManager::m_successK),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("TimerK",

                   "Multiplication factor for the timer threshold in the AARF algorithm.",

                   DoubleValue (2.0),

                   MakeDoubleAccessor (&AarfWifiManager::m_timerK),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("MaxSuccessThreshold",

                   "Maximum value of the success threshold in the AARF algorithm.",

                   UintegerValue (60),

                   MakeUintegerAccessor (&AarfWifiManager::m_maxSuccessThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MinTimerThreshold",

                   "The minimum value for the 'timer' threshold in the AARF algorithm.",

                   UintegerValue (15),

                   MakeUintegerAccessor (&AarfWifiManager::m_minTimerThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MinSuccessThreshold",

                   "The minimum value for the success threshold in the AARF algorithm.",

                   UintegerValue (10),

                   MakeUintegerAccessor (&AarfWifiManager::m_minSuccessThreshold),

                   MakeUintegerChecker<uint32_t> ())

  ;

  return tid;

}

AarfWifiManager::AarfWifiManager ()

{

}

AarfWifiManager::~AarfWifiManager ()

{

}

WifiRemoteStation *

AarfWifiManager::DoCreateStation (void) const

{

  AarfWifiRemoteStation *station = new AarfWifiRemoteStation ();

  station->m_successThreshold = m_minSuccessThreshold;

  station->m_timerTimeout = m_minTimerThreshold;

  station->m_rate = 0;

  station->m_success = 0;

  station->m_failed = 0;

  station->m_recovery = false;

  station->m_retry = 0;

  station->m_timer = 0;

  return station;

}

void

AarfWifiManager::DoReportRtsFailed (WifiRemoteStation *station)

{

}

/**

 * It is important to realize that "recovery" mode starts after failure of

 * the first transmission after a rate increase and ends at the first successful

 * transmission. Specifically, recovery mode transcends retransmissions boundaries.

 * Fundamentally, ARF handles each data transmission independently, whether it

 * is the initial transmission of a packet or the retransmission of a packet.

 * The fundamental reason for this is that there is a backoff between each data

 * transmission, be it an initial transmission or a retransmission.

 */

void

AarfWifiManager::DoReportDataFailed (WifiRemoteStation *st)

{

  AarfWifiRemoteStation *station = (AarfWifiRemoteStation *)st;

  station->m_timer++;

  station->m_failed++;

  station->m_retry++;

  station->m_success = 0;

  if (station->m_recovery)

    {

      NS_ASSERT (station->m_retry >= 1);

      if (station->m_retry == 1)

        {

          // need recovery fallback

          station->m_successThreshold = (int)(Min (station->m_successThreshold * m_successK,

                                                   m_maxSuccessThreshold));

          station->m_timerTimeout = (int)(Max (station->m_timerTimeout * m_timerK,

                                               m_minSuccessThreshold));

          if (station->m_rate != 0)

            {

              station->m_rate--;

            }

        }

      station->m_timer = 0;

    }

  else

    {

      NS_ASSERT (station->m_retry >= 1);

      if (((station->m_retry - 1) % 2) == 1)

        {

          // need normal fallback

          station->m_timerTimeout = m_minTimerThreshold;

          station->m_successThreshold = m_minSuccessThreshold;

          if (station->m_rate != 0)

            {

              station->m_rate--;

            }

        }

      if (station->m_retry >= 2)

        {

          station->m_timer = 0;

        }

    }

}

void

AarfWifiManager::DoReportRxOk (WifiRemoteStation *station,

                               double rxSnr, WifiMode txMode)

{

}

void

AarfWifiManager::DoReportRtsOk (WifiRemoteStation *station,

                                double ctsSnr, WifiMode ctsMode, double rtsSnr)

{

  NS_LOG_DEBUG ("station=" << station << " rts ok");

}

void

AarfWifiManager::DoReportDataOk (WifiRemoteStation *st,

                                 double ackSnr, WifiMode ackMode, double dataSnr)

{

  AarfWifiRemoteStation *station = (AarfWifiRemoteStation *) st;

  station->m_timer++;

  station->m_success++;

  station->m_failed = 0;

  station->m_recovery = false;

  station->m_retry = 0;

  NS_LOG_DEBUG ("station=" << station << " data ok success=" << station->m_success << ", timer=" << station->m_timer);

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

       || station->m_timer == station->m_timerTimeout)

      && (station->m_rate < (GetNSupported (station) - 1)))

    {

      NS_LOG_DEBUG ("station=" << station << " inc rate");

      station->m_rate++;

      station->m_timer = 0;

      station->m_success = 0;

      station->m_recovery = true;

    }

}

void

AarfWifiManager::DoReportFinalRtsFailed (WifiRemoteStation *station)

{

}

void

AarfWifiManager::DoReportFinalDataFailed (WifiRemoteStation *station)

{

}

WifiMode

AarfWifiManager::DoGetDataMode (WifiRemoteStation *st, uint32_t size)

{

  AarfWifiRemoteStation *station = (AarfWifiRemoteStation *) st;

  return GetSupported (station, station->m_rate);

}

WifiMode

AarfWifiManager::DoGetRtsMode (WifiRemoteStation *st)

{

  // XXX: we could/should implement the Aarf algorithm for

  // RTS only by picking a single rate within the BasicRateSet.

  AarfWifiRemoteStation *station = (AarfWifiRemoteStation *) st;

  return GetSupported (station, 0);

}

bool

AarfWifiManager::IsLowLatency (void) const

{

  return true;

}

} // namespace ns3