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

/*

 * Copyright (c) 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>

 */

#ifndef YANS_ERROR_RATE_MODEL_H

#define YANS_ERROR_RATE_MODEL_H

#include <stdint.h>

#ifdef ENABLE_GSL

#include <gsl/gsl_math.h>

#include <gsl/gsl_integration.h>

#include <gsl/gsl_cdf.h>

#include <gsl/gsl_sf_bessel.h>

#endif

#include "wifi-mode.h"

#include "error-rate-model.h"

namespace ns3 {

#ifdef ENABLE_GSL

typedef struct FunctionParameterType

{

 double beta;

 double n;

} FunctionParameters;

double IntegralFunction (double x, void *params);

#endif

/**

 * \brief Model the error rate for different modulations.

 *

 * A packet of interest (e.g., a packet can potentially be received by the MAC) 

 * is divided into chunks. Each chunk is related to an start/end receiving event. 

 * For each chunk, it calculates the ratio (SINR) between received power of packet 

 * of interest and summation of noise and interfering power of all the other incoming 

 * packets. Then, it will calculate the success rate of the chunk based on 

 * BER of the modulation. The success reception rate of the packet is derived from 

 * the success rate of all chunks.

 *

 * The 802.11b modulations:

 *    - 1 Mbps mode is based on DBPSK. BER is from equation 5.2-69 from John G. Proakis

 *      Digitial Communications, 2001 edition

 *    - 2 Mbps model is based on DQPSK. Equation 8 from "Tight bounds and accurate 

 *      approximations for dqpsk transmission bit error rate", G. Ferrari and G.E. Corazza 

 *      ELECTRONICS LETTERS, 40(20):1284-1285, September 2004

 *    - 5.5 Mbps and 11 Mbps are based on equations (18) and (17) from "Properties and 

 *      performance of the ieee 802.11b complementarycode-key signal sets", 

 *      Michael B. Pursley and Thomas C. Royster. IEEE TRANSACTIONS ON COMMUNICATIONS, 

 *      57(2):440-449, February 2009.

 *    - More detailed description and validation can be found in 

 *      http://www.nsnam.org/~pei/80211b.pdf

 */

class YansErrorRateModel : public ErrorRateModel

{

public:

  static TypeId GetTypeId (void);

  YansErrorRateModel ();

  virtual double GetChunkSuccessRate (WifiMode mode, double snr, uint32_t nbits) const;

private:

  double Log2 (double val) const;

  double GetBpskBer (double snr, uint32_t signalSpread, uint32_t phyRate) const;

  double GetQamBer (double snr, unsigned int m, uint32_t signalSpread, uint32_t phyRate) const;

  uint32_t Factorial (uint32_t k) const;

  double Binomial (uint32_t k, double p, uint32_t n) const;

  double CalculatePdOdd (double ber, unsigned int d) const;

  double CalculatePdEven (double ber, unsigned int d) const;

  double CalculatePd (double ber, unsigned int d) const;

  double GetFecBpskBer (double snr, double nbits, 

                        uint32_t signalSpread, uint32_t phyRate,

                        uint32_t dFree, uint32_t adFree) const;

  double GetFecQamBer (double snr, uint32_t nbits, 

                       uint32_t signalSpread,

                       uint32_t phyRate,

                       uint32_t m, uint32_t dfree,

                       uint32_t adFree, uint32_t adFreePlusOne) const;

  double DqpskFunction (double x) const;

  double Get80211bDsssDbpskSuccessRate (double sinr, uint32_t nbits) const;

  double Get80211bDsssDqpskSuccessRate (double sinr,uint32_t nbits) const;

  double Get80211bDsssDqpskCck5_5SuccessRate (double sinr,uint32_t nbits) const;

  double Get80211bDsssDqpskCck11SuccessRate (double sinr,uint32_t nbits) const;

#ifdef ENABLE_GSL

  double SymbolErrorProb16Cck (double e2) const; /// equation (18) in Pursley's paper

  double SymbolErrorProb256Cck (double e1) const; /// equation (17) in Pursley's paper

#else

private:

  static const double WLAN_SIR_PERFECT;

  static const double WLAN_SIR_IMPOSSIBLE;

#endif

};

} // namespace ns3

#endif /* YANS_ERROR_RATE_MODEL_H */