/* -*- 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 {

/**

 * 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);

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

  Time GetCalcTxTime (WifiMode mode) const;

  void AddCalcTxTime (WifiMode mode, Time t);

private:

  friend class MinstrelWifiRemoteStation;

  virtual class WifiRemoteStation *CreateStation (void);

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

  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

};

class MinstrelWifiRemoteStation : public WifiRemoteStation

{

public:

  MinstrelWifiRemoteStation (Ptr<MinstrelWifiManager> stations);

  virtual ~MinstrelWifiRemoteStation ();

protected:

  /** 

   * when packet is successfully received

   * see wifi-remote-station-manager.h for more documentation

   */

  virtual void DoReportRxOk (double rxSnr, WifiMode txMode);

  /// when RTS timeout expires

  virtual void DoReportRtsFailed (void);

  /**

   *

   * Retry Chain table is implemented here

   *

   * Try |         LOOKAROUND RATE              | NORMAL RATE

   *     | random < best    | random > best     |

   * --------------------------------------------------------------

   *  1  | Best throughput  | Random rate       | Best throughput

   *  2  | Random rate      | Best throughput   | Next best throughput

   *  3  | Best probability | Best probability  | Best probability

   *  4  | Lowest Baserate  | Lowest baserate   | Lowest baserate

   *

   * Note: For clarity, multiple blocks of if's and else's are used

   * After a failing 7 times, DoReportFinalDataFailed will be called

   */

  virtual void DoReportDataFailed (void);

  /// when receive a CTS, associated with an RTS

  virtual void DoReportRtsOk (double ctsSnr, WifiMode ctsMode, double rtsSnr);

  /// when an ACK, associated with a data pkt, is received

  virtual void DoReportDataOk (double ackSnr, WifiMode ackMode, double dataSnr);

  /// after calling ReportRtsFailed if NeedRtsRetransmission returns false

  virtual void DoReportFinalRtsFailed (void);

  /// after calling ReportDataFailed if NeedDataRetransmission returns false

  virtual void DoReportFinalDataFailed (void);

private:

  virtual Ptr<WifiRemoteStationManager> GetManager (void) const;

  /** 

   * returns the transmission mode for sending this packet

   * this function gets called when node is getting ready to send DATA

   * see wifi-remote-station-manager.h for more documentation

   */

  virtual WifiMode DoGetDataMode (uint32_t size);

  /// returns the transmission mode for sending RTS packet

  virtual WifiMode DoGetRtsMode (void);

  /// update the number of retries and reset accordingly

  void UpdateRetry (void);

  /// getting the next sample from Sample Table

  uint32_t GetNextSample (void);

  /// find a rate to use from Minstrel Table

  uint32_t FindRate (void);

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

  void UpdateStats (void);

  /// initialize Minstrel Table

  void RateInit (void);

  /// initialize Sample Table

  void InitSampleTable (void);

  /// printing Sample Table

  void PrintSampleTable (void);

  /// printing Minstrel Table

  void PrintTable (void);

  /**

   * \param packet lenghth 

   * \param current WifiMode

   * \returns calcuated transmit duration 

   */

  Time CalcRatePacket (uint32_t, WifiMode);

  void CheckInit(void);  ///< check for initializations

  Ptr<MinstrelWifiManager> m_stations;

  Time m_nextStatsUpdate;  ///< 10 times every second

  MinstrelRate m_minstrelTable;  ///< minstrel table	

  SampleRate m_sampleTable;  ///< sample table

  /**

   * To keep track of the current position in the our random sample table

   * going row by row from 1st column until the 10th column(Minstrel defines 10)

   * then we wrap back to the row 1 col 1.

   * note: there are many other ways to do this.

   */

  uint32_t m_col, m_index;							

  uint32_t m_maxTpRate;  ///< the current throughput rate 

  uint32_t m_maxTpRate2;  ///< second highest throughput rate

  uint32_t m_maxProbRate;  ///< rate with highest prob of success

  int m_packetCount;  ///< total number of packets as of now

  int m_sampleCount;  ///< how many packets we have sample so far

  bool m_isSampling;  ///< a flag to indicate we are currently sampling

  uint32_t m_sampleRate;  ///< current sample rate

  bool 	m_sampleRateSlower;  ///< a flag to indicate sample rate is slower

  uint32_t m_currentRate;  ///< current rate we are using

  uint32_t m_shortRetry;  ///< short retries such as control packts

  uint32_t m_longRetry;  ///< long retries such as data packets

  uint32_t m_retry;  ///< total retries short + long

  uint32_t m_err;  ///< retry errors

  uint32_t m_txrate;  ///< current transmit rate

  bool m_initialized;  ///< for initializing tables

}; 

}// namespace ns3

#endif /* MINSTREL_WIFI_MANAGER_H */