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

/* 

 * Copyright (c) 2009 Duy Nguyen 

 * 

 * 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: Duy Nguyen <duy@soe.ucsc.edu> 

 */

#ifndef MINSTREL_WIFI_MANAGER_H

#define MINSTREL_WIFI_MANAGER_H

#include "wifi-remote-station-manager.h"

#include "wifi-mode.h"

#include "ns3/nstime.h"

#include <vector>

/**

 * \author Duy Nguyen

 * \brief Implementation of Minstrel Rate Control Algorithm 

 *

 * Porting Minstrel from Madwifi and Linux Kernel 

 * http://linuxwireless.org/en/developers/Documentation/mac80211/RateControl/minstrel

 */

namespace ns3 {

struct MinstrelWifiRemoteStation;

/**

 * A struct to contain all information related to a data rate

 */

struct RateInfo

{

  /**

   * Perfect transmission time calculation, or frame calculation

   * Given a bit rate and a packet length n bytes

   */

  Time perfectTxTime;

  uint32_t retryCount;  ///< retry limit

  uint32_t adjustedRetryCount;  ///< adjust the retry limit for this rate

  uint32_t numRateAttempt;  ///< how many number of attempts so far

    uint32_t numRateSuccess;  ///< number of successful pkts

  uint32_t prob;  ///< (# pkts success )/(# total pkts)

  /**

   * EWMA calculation

   * ewma_prob =[prob *(100 - ewma_level) + (ewma_prob_old * ewma_level)]/100

   */

  uint32_t ewmaProb;

  uint32_t prevNumRateAttempt;  ///< from last rate

  uint32_t prevNumRateSuccess;  ///< from last rate

  uint64_t successHist;  ///< aggregate of all successes

  uint64_t attemptHist;  ///< aggregate of all attempts

  uint32_t throughput;  ///< throughput of a rate

};

/**

 * Data structure for a Minstrel Rate table

 * A vector of a struct RateInfo

 */

typedef std::vector<struct RateInfo> MinstrelRate;

/**

 * Data structure for a Sample Rate table

 * A vector of a vector uint32_t

 */

typedef std::vector<std::vector<uint32_t> > SampleRate;

class MinstrelWifiManager : public WifiRemoteStationManager

{

public:

  static TypeId GetTypeId (void);

  MinstrelWifiManager ();

  virtual ~MinstrelWifiManager();

  virtual void SetupPhy (Ptr<WifiPhy> phy);

private:

  // overriden from base class

  virtual WifiRemoteStation *DoCreateStation (void) const;

  virtual void DoReportRxOk (WifiRemoteStation *station, 

                             double rxSnr, WifiMode txMode);

  virtual void DoReportRtsFailed (WifiRemoteStation *station);

  virtual void DoReportDataFailed (WifiRemoteStation *station);

  virtual void DoReportRtsOk (WifiRemoteStation *station,

                              double ctsSnr, WifiMode ctsMode, double rtsSnr);

  virtual void DoReportDataOk (WifiRemoteStation *station,

                               double ackSnr, WifiMode ackMode, double dataSnr);

  virtual void DoReportFinalRtsFailed (WifiRemoteStation *station);

  virtual void DoReportFinalDataFailed (WifiRemoteStation *station);

  virtual WifiMode DoGetDataMode (WifiRemoteStation *station, uint32_t size);

  virtual WifiMode DoGetRtsMode (WifiRemoteStation *station);

  virtual bool IsLowLatency (void) const;

  /// for estimating the TxTime of a packet with a given mode  

  Time GetCalcTxTime (WifiMode mode) const;

  void AddCalcTxTime (WifiMode mode, Time t);

  /// update the number of retries and reset accordingly

  void UpdateRetry (MinstrelWifiRemoteStation *station);

  /// getting the next sample from Sample Table

  uint32_t GetNextSample (MinstrelWifiRemoteStation *station);

  /// find a rate to use from Minstrel Table

  uint32_t FindRate (MinstrelWifiRemoteStation *station);

  /// updating the Minstrel Table every 1/10 seconds

  void UpdateStats (MinstrelWifiRemoteStation *station);

  /// initialize Minstrel Table

  void RateInit (MinstrelWifiRemoteStation *station);

  /// initialize Sample Table

  void InitSampleTable (MinstrelWifiRemoteStation *station);

  /// printing Sample Table

  void PrintSampleTable (MinstrelWifiRemoteStation *station);

  /// printing Minstrel Table

  void PrintTable (MinstrelWifiRemoteStation *station);

  void CheckInit (MinstrelWifiRemoteStation *station);  ///< check for initializations

  typedef std::vector<std::pair<Time,WifiMode> > TxTime;

  MinstrelRate m_minstrelTable;  ///< minstrel table

  SampleRate m_sampleTable;  ///< sample table

  TxTime m_calcTxTime;  ///< to hold all the calculated TxTime for all modes

  Time m_updateStats;  ///< how frequent do we calculate the stats(1/10 seconds)

  double m_lookAroundRate;  ///< the % to try other rates than our current rate 

  double m_ewmaLevel;  ///< exponential weighted moving average

  uint32_t m_segmentSize;  ///< largest allowable segment size

  uint32_t m_sampleCol;  ///< number of sample columns

  uint32_t m_pktLen;  ///< packet length used  for calculate mode TxTime  

  uint32_t m_nsupported;  ///< modes supported

};

}// namespace ns3

#endif /* MINSTREL_WIFI_MANAGER_H */