/*

 * 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 "arf-wifi-manager.h"

#include "ns3/assert.h"

#include "ns3/log.h"

#include "ns3/uinteger.h"

NS_LOG_COMPONENT_DEFINE ("ns3::ArfWifiManager");

namespace ns3 {

struct ArfWifiRemoteStation : 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 (ArfWifiManager);

TypeId

ArfWifiManager::GetTypeId (void)

{

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

    .SetParent<WifiRemoteStationManager> ()

    .AddConstructor<ArfWifiManager> ()

    .AddAttribute ("TimerThreshold", "The 'timer' threshold in the ARF algorithm.",

                   UintegerValue (15),

                   MakeUintegerAccessor (&ArfWifiManager::m_timerThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("SuccessThreshold",

                   "The minimum number of sucessfull transmissions to try a new rate.",

                   UintegerValue (10),

                   MakeUintegerAccessor (&ArfWifiManager::m_successThreshold),

                   MakeUintegerChecker<uint32_t> ())

  ;

  return tid;

}

ArfWifiManager::ArfWifiManager ()

{

}

ArfWifiManager::~ArfWifiManager ()

{

}

WifiRemoteStation *

ArfWifiManager::DoCreateStation (void) const

{

  ArfWifiRemoteStation *station = new ArfWifiRemoteStation ();

  station->m_successThreshold = m_successThreshold;

  station->m_timerTimeout = m_timerThreshold;

  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

ArfWifiManager::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

ArfWifiManager::DoReportDataFailed (WifiRemoteStation *st)

{

  ArfWifiRemoteStation *station = (ArfWifiRemoteStation *)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

          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

          if (station->m_rate != 0)

            {

              station->m_rate--;

            }

        }

      if (station->m_retry >= 2)

        {

          station->m_timer = 0;

        }

    }

}

void

ArfWifiManager::DoReportRxOk (WifiRemoteStation *station,

                              double rxSnr, WifiMode txMode)

{

}

void ArfWifiManager::DoReportRtsOk (WifiRemoteStation *station,

                                    double ctsSnr, WifiMode ctsMode, double rtsSnr)

{

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

}

void ArfWifiManager::DoReportDataOk (WifiRemoteStation *st,

                                     double ackSnr, WifiMode ackMode, double dataSnr)

{

  ArfWifiRemoteStation *station = (ArfWifiRemoteStation *) 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 == m_successThreshold

       || station->m_timer == m_timerThreshold)

      && (station->m_rate < (station->m_state->m_operationalRateSet.size () - 1)))

    {

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

      station->m_rate++;

      station->m_timer = 0;

      station->m_success = 0;

      station->m_recovery = true;

    }

}

void

ArfWifiManager::DoReportFinalRtsFailed (WifiRemoteStation *station)

{

}

void

ArfWifiManager::DoReportFinalDataFailed (WifiRemoteStation *station)

{

}

WifiMode

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

{

  ArfWifiRemoteStation *station = (ArfWifiRemoteStation *) st;

  return GetSupported (station, station->m_rate);

}

WifiMode

ArfWifiManager::DoGetRtsMode (WifiRemoteStation *st)

{

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

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

  ArfWifiRemoteStation *station = (ArfWifiRemoteStation *) st;

  return GetSupported (station, 0);

}

bool

ArfWifiManager::IsLowLatency (void) const

{

  return true;

}

} // namespace ns3