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

/*

 * Copyright (c) 2010 The Boeing Company

 *

 * 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: Gary Pei <guangyu.pei@boeing.com>

 */

#ifndef DSS_ERROR_RATE_MODEL_H

#define DSS_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

namespace ns3 {

#ifdef ENABLE_GSL

typedef struct FunctionParameterType

{

  double beta;

  double n;

} FunctionParameters;

double IntegralFunction (double x, void *params);

#endif

/**

 * \brief an implementation of DSSS error rate model

 * \ingroup wifi

 *

 * 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.

 *

 *  This model is designed to run with highest accuracy using the Gnu

 *  Scientific Library (GSL), but if GSL is not installed on the platform,

 *  will fall back to (slightly less accurate) Matlab-derived models for

 *  the CCK modulation types.

 *

 *  More detailed description and validation can be found in

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

 */

class DsssErrorRateModel

{

public:

  /**

   * A function DQPSK

   *

   * \param x x

   * \return DQPSK(x)

   */

  static double DqpskFunction (double x);

  /**

   * Return the chunk success rate of the differential BPSK.

   *

   * \param sinr the SINR of the chunk

   * \param nbits the size of the chunk

   * \return the chunk success rate of the differential BPSK

   */

  static double GetDsssDbpskSuccessRate (double sinr, uint32_t nbits);

  /**

   * Return the chunk success rate of the differential encoded QPSK.

   *

   * \param sinr the SINR of the chunk

   * \param nbits the size of the chunk

   * \return the chunk success rate of the differential encoded QPSK.

   */

  static double GetDsssDqpskSuccessRate (double sinr,uint32_t nbits);

  /**

   * Return the chunk success rate of the differential encoded QPSK for

   * 5.5Mbps data rate.

   *

   * \param sinr the SINR of the chunk

   * \param nbits the size of the chunk

   * \return the chunk success rate of the differential encoded QPSK for

   */

  static double GetDsssDqpskCck5_5SuccessRate (double sinr,uint32_t nbits);

  /**

   * Return the chunk success rate of the differential encoded QPSK for

   * 11Mbps data rate.

   *

   * \param sinr the SINR of the chunk

   * \param nbits the size of the chunk

   * \return the chunk success rate of the differential encoded QPSK for

   */

  static double GetDsssDqpskCck11SuccessRate (double sinr,uint32_t nbits);

#ifdef ENABLE_GSL

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

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

#else

protected:

  static const double WLAN_SIR_PERFECT;

  static const double WLAN_SIR_IMPOSSIBLE;

#endif

};

} // namespace ns3

#endif /* DSSS_ERROR_RATE_MODEL_H */