/* -*- 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>

#include "wifi-mode.h"

#include "error-rate-model.h"

#include "dsss-error-rate-model.h"

namespace ns3 {

/**

 * \brief Model the error rate for different modulations.

 * \ingroup wifi

 *

 * 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, WifiTxVector txVector, double snr, uint32_t nbits) const;

private:

  /**

   * Return the logarithm of the given value to base 2.

   *

   * \param val

   *

   * \return the logarithm of val to base 2.

   */

  double Log2 (double val) const;

  /**

   * Return BER of BPSK with the given parameters.

   *

   * \param snr snr value

   * \param signalSpread

   * \param phyRate

   *

   * \return BER of BPSK at the given SNR

   */

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

  /**

   * Return BER of QAM-m with the given parameters.

   *

   * \param snr snr value

   * \param m

   * \param signalSpread

   * \param phyRate

   *

   * \return BER of BPSK at the given SNR

   */

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

  /**

   * Return k!

   *

   * \param k

   *

   * \return k!

   */

  uint32_t Factorial (uint32_t k) const;

  /**

   * Return Binomial distribution for a given k, p, and n

   *

   * \param k

   * \param p

   * \param n

   *

   * \return a Binomial distribution

   */

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

  /**

   * \param ber

   * \param d

   *

   * \return double

   */

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

  /**

   * \param ber

   * \param d

   *

   * \return double

   */

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

  /**

   * \param ber

   * \param d

   *

   * \return double

   */

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

  /**

   * \param snr

   * \param nbits

   * \param signalSpread

   * \param phyRate

   * \param dFree

   * \param adFree

   *

   * \return double

   */

  double GetFecBpskBer (double snr, double nbits,

                        uint32_t signalSpread, uint32_t phyRate,

                        uint32_t dFree, uint32_t adFree) const;

  /**

   * \param snr

   * \param nbits

   * \param signalSpread

   * \param phyRate

   * \param m

   * \param dfree

   * \param adFree

   * \param adFreePlusOne

   *

   * \return double

   */

  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;

};

} //namespace ns3

#endif /* YANS_ERROR_RATE_MODEL_H */