satellite-mutual-information-table.cc

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2018 CNES
 *
 * 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: Joaquin Muguerza <joaquin.muguerza@viveris.fr>
 *
 */
 
#include "satellite-mutual-information-table.h"
 
#include "satellite-utils.h"
 
#include "ns3/double.h"
#include "ns3/fatal-error.h"
#include "ns3/log.h"
 
#include <cmath>
#include <fstream>
#include <stdint.h>
#include <string>
 
NS_LOG_COMPONENT_DEFINE("SatMutualInformationTable");
 
namespace ns3
{
 
NS_OBJECT_ENSURE_REGISTERED(SatMutualInformationTable);
 
SatMutualInformationTable::SatMutualInformationTable(std::string mutualInformationPath)
    : m_beta(1.0)
{
    NS_LOG_FUNCTION(this << mutualInformationPath);
    Load(mutualInformationPath);
}
 
SatMutualInformationTable::~SatMutualInformationTable()
{
    NS_LOG_FUNCTION(this);
}
 
void
SatMutualInformationTable::DoDispose()
{
    NS_LOG_FUNCTION(this);
 
    m_snirDb.clear();
    m_symbolInformation.clear();
 
    if (m_ifs != 0)
    {
        if (m_ifs->is_open())
        {
            m_ifs->close();
        }
 
        delete m_ifs;
        m_ifs = 0;
    }
 
    Object::DoDispose();
}
 
TypeId
SatMutualInformationTable::GetTypeId()
{
    static TypeId tid = TypeId("ns3::SatMutualInformationTable")
                            .SetParent<Object>()
                            .AddAttribute("Beta",
                                          "The adjusting factor for the MI function",
                                          DoubleValue(1.0),
                                          MakeDoubleAccessor(&SatMutualInformationTable::m_beta),
                                          MakeDoubleChecker<double>());
    return tid;
}
 
double
SatMutualInformationTable::GetNormalizedSymbolInformation(double snirDb) const
{
    NS_LOG_FUNCTION(this << snirDb);
    NS_LOG_INFO("SatMutualInformationTable::GetNormalizedSymbolInformation - SNIR dB=" << snirDb);
 
    uint16_t n = m_snirDb.size();
 
    NS_ASSERT(n > 0);
    NS_ASSERT(m_symbolInformation.size() == n);
 
    if (snirDb < m_snirDb[0])
    {
        // edge case: very low SNIR, return minimum Symbol Information
        NS_LOG_INFO(this << " Very low SNIR -> Symbol Information = 0.0");
        return 0.0;
    }
 
    uint16_t i = 1;
 
    while ((i < n) && (snirDb > m_snirDb[i]))
    {
        i++;
    }
 
    NS_LOG_DEBUG(this << " i=" << i << " snir[i]=" << m_snirDb[i]
                      << " symbolInformation[i]=" << m_symbolInformation[i]);
 
    if (i >= n)
    {
        // edge case: very high SNIR, return maximum Symbol Information
        NS_LOG_INFO(this << " Very high SNIR -> Symbol Information = 1.0");
        return 1.0;
    }
    else // snirDb <= m_snirDb[i]
    {
        // normal case
        NS_ASSERT(i > 0);
        NS_ASSERT(i < n);
 
        double snir = snirDb;
        double snir0 = m_snirDb[i - 1];
        double snir1 = m_snirDb[i];
        double symbolInformation = SatUtils::Interpolate(snir,
                                                         snir0,
                                                         snir1,
                                                         m_symbolInformation[i - 1],
                                                         m_symbolInformation[i]);
        NS_LOG_INFO(this << " Interpolate: " << snir << " to Symbol Information = "
                         << symbolInformation << "(snir0: " << snir0 << ", snir1: " << snir1
                         << ", symbolInformation0: " << m_symbolInformation[i - 1]
                         << ", symbolInformation1: " << m_symbolInformation[i] << ")");
 
        return symbolInformation;
    }
 
} // end of double SatMutualInformationTable::GetNormalizedSymbolInformation (double snirDb) const
 
double
SatMutualInformationTable::GetSnirDb(double symbolInformationTarget) const
{
    NS_LOG_FUNCTION(this << symbolInformationTarget);
    NS_LOG_INFO("SatMutualInformationTable::GetSnirDb - Symbol Information Target="
                << symbolInformationTarget);
 
    uint16_t n = m_symbolInformation.size();
 
    NS_ASSERT(n > 0);
    NS_ASSERT(m_snirDb.size() == n);
 
    // If the requested Symbol Information is smaller than the smallest Symbol Information entry
    // in the look-up-table. Return small value
    if (symbolInformationTarget <= m_symbolInformation[0])
    {
        NS_LOG_INFO("SatMutualInformationTable::GetSnirDb - SNIR dB=" << -1.0e10);
        return -1.0e10;
    }
 
    // The requested Symbol Information is higher than the highest Symbol Information entry
    // in the look-up-table
    if (symbolInformationTarget > 1.0)
    {
        NS_FATAL_ERROR("The Symbol Information target is set to be too high!");
    }
 
    // The requested Symbol Information is higher than the highest Symbol Information entry
    // in the look-up-table
    if (symbolInformationTarget > m_symbolInformation[n - 1])
    {
        NS_LOG_INFO("SatMutualInformationTable::GetSnirDb - SNIR dB=" << m_snirDb[n - 1]);
        return m_snirDb[n - 1];
    }
 
    double snir = 0.0;
    // Go through the list from end to beginning
    for (uint32_t i = 0; i < n; ++i)
    {
        if (symbolInformationTarget <= m_symbolInformation[i])
        {
            snir = SatUtils::Interpolate(symbolInformationTarget,
                                         m_symbolInformation[i - 1],
                                         m_symbolInformation[i],
                                         m_snirDb[i - 1],
                                         m_snirDb[i]);
            NS_LOG_INFO(this << " Interpolate: " << symbolInformationTarget << " to snir = " << snir
                             << "(symbolInformation0: " << m_symbolInformation[i - 1]
                             << ", symbolInformation1: " << m_symbolInformation[i] << ", snir0: "
                             << m_snirDb[i - 1] << ", snir1: " << m_snirDb[i] << ")");
            return snir;
        }
    }
 
    return snir;
} // end of double SatMutualInformationTable::GetSnir (double symbolInformationTarget) const
 
void
SatMutualInformationTable::Load(std::string mutualInformationPath)
{
    NS_LOG_FUNCTION(this << mutualInformationPath);
 
    // READ FROM THE SPECIFIED INPUT FILE
 
    m_ifs = new std::ifstream(mutualInformationPath.c_str(), std::ifstream::in);
 
    if (!m_ifs->is_open())
    {
        // script might be launched by test.py, try a different base path
        delete m_ifs;
        mutualInformationPath = "../../" + mutualInformationPath;
        m_ifs = new std::ifstream(mutualInformationPath.c_str(), std::ifstream::in);
 
        if (!m_ifs->is_open())
        {
            NS_FATAL_ERROR("The file " << mutualInformationPath << " is not found.");
        }
    }
 
    double lastSnirDb = -100.0;         //-1.0e100; // very low value
    double lastSymbolInformation = 0.0; // minimum value
 
    double snirDb, symbolInformation;
    *m_ifs >> snirDb >> symbolInformation;
 
    while (m_ifs->good())
    {
        NS_LOG_DEBUG(this << " snirDb=" << snirDb << ", symbolInformation=" << symbolInformation);
 
        // SANITY CHECK PART I
        if ((snirDb <= lastSnirDb) || (symbolInformation < lastSymbolInformation))
        {
            NS_FATAL_ERROR("The file " << mutualInformationPath << " is not properly sorted.");
        }
 
        // record the values
        m_snirDb.push_back(snirDb);
        m_symbolInformation.push_back(symbolInformation);
        lastSnirDb = snirDb;
        lastSymbolInformation = symbolInformation;
 
        // get next row
        *m_ifs >> snirDb >> symbolInformation;
    }
 
    m_ifs->close();
    delete m_ifs;
    m_ifs = 0;
 
    // SANITY CHECK PART II
 
    // at least contains one row
    if (m_snirDb.empty())
    {
        NS_FATAL_ERROR("Error reading data from file " << mutualInformationPath << ".");
    }
 
    // SNIR and BLER have same size
    NS_ASSERT(m_snirDb.size() == m_symbolInformation.size());
 
} // end of void Load (std::string mutualInformationPath)
 
} // end of namespace ns3