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

/*

 * Copyright (c) 2011 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>

 */

#include "lr-wpan-spectrum-value-helper.h"

#include <ns3/log.h>

#include <ns3/spectrum-value.h>

#include <cmath>

NS_LOG_COMPONENT_DEFINE ("LrWpanSpectrumValueHelper");

namespace ns3 {

Ptr<SpectrumModel> g_LrWpanSpectrumModel;

class LrWpanSpectrumModelInitializer

{

public:

  LrWpanSpectrumModelInitializer (void)

  {

    NS_LOG_FUNCTION (this);

    Bands bands;

    // 1 MHz resolution, with center frequency of 2400, 2401, ... 2483

    // overall frequency span of 2399.5 MHz through 2483.5 MHz (83 bands)

    for (int i = -1; i < 83; i++)

      {

        BandInfo bi;

        bi.fl = 2400.5e6 + i * 1.0e6;

        bi.fh = 2400.5e6 + (i + 1) * 1.0e6;

        bi.fc = (bi.fl +  bi.fh) / 2;

        bands.push_back (bi);

      }

    g_LrWpanSpectrumModel = Create<SpectrumModel> (bands);

  }

} g_LrWpanSpectrumModelInitializerInstance;

LrWpanSpectrumValueHelper::LrWpanSpectrumValueHelper (void)

{

  NS_LOG_FUNCTION (this);

  m_noiseFactor = 1.0;

}

LrWpanSpectrumValueHelper::~LrWpanSpectrumValueHelper (void)

{

  NS_LOG_FUNCTION (this);

}

Ptr<SpectrumValue>

LrWpanSpectrumValueHelper::CreateTxPowerSpectralDensity (double txPower, uint32_t channel)

{

  NS_LOG_FUNCTION (this);

  Ptr<SpectrumValue> txPsd = Create <SpectrumValue> (g_LrWpanSpectrumModel);

  txPower = pow (10., (txPower - 30) / 10);

  // The effective occupied bandwidth of the signal is modelled to be 2 MHz.

  // 99.5% of power is within +/- 1MHz of center frequency, and 0.5% is outside.

  // There are 5 bands containing signal power.  The middle (center) band

  // contains half of the power.  The two inner side bands contain 49.5%.

  // The two outer side bands contain roughly 0.5%.

  double txPowerDensity = txPower / 2.0e6;

  NS_ASSERT_MSG ((channel >= 11 && channel <= 26), "Invalid channel numbers");

  // The channel assignment is in section 6.1.2.1

  // Channel 11 centered at 2.405 GHz, 12 at 2.410 GHz, ... 26 at 2.480 GHz

  (*txPsd)[2405 + 5 * (channel - 11) - 2400 - 2] = txPowerDensity * 0.005;

  (*txPsd)[2405 + 5 * (channel - 11) - 2400 - 1] = txPowerDensity * 0.495;

  (*txPsd)[2405 + 5 * (channel - 11) - 2400] = txPowerDensity; // center

  (*txPsd)[2405 + 5 * (channel - 11) - 2400 + 1 ] = txPowerDensity * 0.495;

  (*txPsd)[2405 + 5 * (channel - 11) - 2400 + 2 ] = txPowerDensity * 0.005;

  // If more power is allocated to more subbands in future revisions of

  // this model, make sure to renormalize so that the integral of the

  // txPsd still equals txPower

  return txPsd;

}

Ptr<SpectrumValue>

LrWpanSpectrumValueHelper::CreateNoisePowerSpectralDensity (uint32_t channel)

{

  NS_LOG_FUNCTION (this);

  Ptr<SpectrumValue> noisePsd = Create <SpectrumValue> (g_LrWpanSpectrumModel);

  static const double BOLTZMANN = 1.3803e-23;

  // Nt  is the power of thermal noise in W

  double Nt = BOLTZMANN * 290.0;

  // noise Floor (W) which accounts for thermal noise and non-idealities of the receiver

  double noisePowerDensity = m_noiseFactor * Nt;

  NS_ASSERT_MSG ((channel >= 11 && channel <= 26), "Invalid channel numbers");

  (*noisePsd)[2405 + 5 * (channel - 11) - 2400 - 2] = noisePowerDensity;

  (*noisePsd)[2405 + 5 * (channel - 11) - 2400 - 1] = noisePowerDensity;

  (*noisePsd)[2405 + 5 * (channel - 11) - 2400] = noisePowerDensity;

  (*noisePsd)[2405 + 5 * (channel - 11) - 2400 + 1] = noisePowerDensity;

  (*noisePsd)[2405 + 5 * (channel - 11) - 2400 + 2] = noisePowerDensity;

  return noisePsd;

}

double

LrWpanSpectrumValueHelper::TotalAvgPower (Ptr<const SpectrumValue> psd)

{

  NS_LOG_FUNCTION (psd);

  double totalAvgPower = 0.0;

  // numerically integrate to get area under psd using

  // 1 MHz resolution from 2400 to 2483 MHz (center freq)

  totalAvgPower = Sum (*psd * 1.0e6);

  return totalAvgPower;

}

} // namespace ns3