/* -*- 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 */