ns2-mobility-helper.cc

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/*
 * Copyright (c) 2007 INRIA
 *               2009,2010 Contributors
 *
 * 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>
 * Contributors: Thomas Waldecker <twaldecker@rocketmail.com>
 *               Martín Giachino <martin.giachino@gmail.com>
 *
 * Brief description: Implementation of a ns2 movement trace file reader.
 *
 * This implementation is based on the ns2 movement documentation of ns2
 * as described in http://www.isi.edu/nsnam/ns/doc/node172.html
 *
 * Valid trace files use the following ns2 statements:
 *
 * $node set X_ x1
 * $node set Y_ y1
 * $node set Z_ z1
 * $ns at $time $node setdest x2 y2 speed
 * $ns at $time $node set X_ x1
 * $ns at $time $node set Y_ Y1
 * $ns at $time $node set Z_ Z1
 *
 */
 
#include "ns2-mobility-helper.h"
 
#include "ns3/constant-velocity-mobility-model.h"
#include "ns3/log.h"
#include "ns3/node-list.h"
#include "ns3/node.h"
#include "ns3/simulator.h"
 
#include <fstream>
#include <map>
#include <sstream>
 
namespace ns3
{
 
NS_LOG_COMPONENT_DEFINE("Ns2MobilityHelper");
 
// Constants definitions
#define NS2_AT "at"
#define NS2_X_COORD "X_"
#define NS2_Y_COORD "Y_"
#define NS2_Z_COORD "Z_"
#define NS2_SETDEST "setdest"
#define NS2_SET "set"
#define NS2_NODEID "$node_("
#define NS2_NS_SCH "$ns_"
 
/**
 * Type to maintain line parsed and its values
 */
struct ParseResult
{
    std::vector<std::string> tokens; //!< tokens from a line
    std::vector<int> ivals;          //!< int values for each tokens
    std::vector<bool> has_ival;      //!< points if a tokens has an int value
    std::vector<double> dvals;       //!< double values for each tokens
    std::vector<bool> has_dval;      //!< points if a tokens has a double value
    std::vector<std::string> svals;  //!< string value for each token
};
 
/**
 * Keeps last movement schedule. If new movement occurs during
 * a current one, node stopping must be cancels (stored in a proper
 * event ID), actually reached point must be calculated and new
 * velocity must be calculated in accordance with actually reached
 * destination.
 */
struct DestinationPoint
{
    Vector m_startPosition; //!< Start position of last movement
    Vector m_speed; //!< Speed of the last movement (needed to derive reached destination at next
                    //!< schedule = start + velocity * actuallyTravelled)
    Vector m_finalPosition; //!< Final destination to be reached before next schedule. Replaced with
                            //!< actually reached if needed.
    EventId m_stopEvent;    //!< Event scheduling node's stop. May be canceled if needed.
    double m_travelStartTime;   //!< Travel start time is needed to calculate actually traveled time
    double m_targetArrivalTime; //!< When a station arrives to a destination
    DestinationPoint()
        : m_startPosition(Vector(0, 0, 0)),
          m_speed(Vector(0, 0, 0)),
          m_finalPosition(Vector(0, 0, 0)),
          m_travelStartTime(0),
          m_targetArrivalTime(0){};
};
 
/**
 * Parses a line of ns2 mobility
 * \param str the string to parse
 * \returns The parsed line
 */
static ParseResult ParseNs2Line(const std::string& str);
 
/**
 * Put out blank spaces at the start and end of a line
 * \param str input line
 * \returns the line trimmed
 */
static std::string TrimNs2Line(const std::string& str);
 
/**
 * Checks if a string represents a number or it has others characters than digits and point.
 * \param s the string to check
 * \returns true if the string represents a number
 */
static bool IsNumber(const std::string& s);
 
/**
 * Check if s string represents a numeric value
 * \param str string to check
 * \param ret numeric value to return
 * \return true if string represents a numeric value
 */
template <class T>
static bool IsVal(const std::string& str, T& ret);
 
/**
 * Checks if the value between brackets is a correct nodeId number
 * \param str string to check
 * \returns true if the string represents a nodeId number
 */
static bool HasNodeIdNumber(std::string str);
 
/**
 * Gets nodeId number in string format from the string like $node_(4)
 * \param str string to de-tokenize
 * \returns A string with the nodeId number
 */
static std::string GetNodeIdFromToken(std::string str);
 
/**
 * Get node id number in int format
 * \param pr the ParseResult to analyze
 * \returns the node ID (as an int)
 */
static int GetNodeIdInt(ParseResult pr);
 
/**
 * Get node id number in string format
 * \param pr the ParseResult to analyze
 * \returns the node ID (as a string)
 */
static std::string GetNodeIdString(ParseResult pr);
 
/**
 * Add one coord to a vector position
 * \param actPos actual position (overwritten)
 * \param coord coordinate (x, y, or z)
 * \param value value of the coordinate
 * \return The vector of the position
 */
static Vector SetOneInitialCoord(Vector actPos, std::string& coord, double value);
 
/**
 * Check if this corresponds to a line like this: $node_(0) set X_ 123
 * \param pr the ParseResult to analyze
 * \returns true if the ParseResult looks like a coordinate without a scheduled time
 */
static bool IsSetInitialPos(ParseResult pr);
 
/**
 * Check if this corresponds to a line like this: $ns_ at 1 "$node_(0) setdest 2 3 4"
 * \param pr the ParseResult to analyze
 * \returns true if the ParseResult looks like a coordinate with a scheduled time and destination
 */
static bool IsSchedSetPos(ParseResult pr);
 
/**
 * Check if this corresponds to a line like this: $ns_ at 1 "$node_(0) set X_ 2"
 * \param pr the ParseResult to analyze
 * \returns true if the ParseResult looks like a coordinate with a scheduled time
 */
static bool IsSchedMobilityPos(ParseResult pr);
 
/**
 * Set waypoints and speed for movement.
 * \param model mobility model
 * \param lastPos last position
 * \param at initial movement time
 * \param xFinalPosition final position (X axis)
 * \param yFinalPosition final position (Y axis)
 * \param speed movement speed
 * \returns A descriptor of the movement
 */
static DestinationPoint SetMovement(Ptr<ConstantVelocityMobilityModel> model,
                                    Vector lastPos,
                                    double at,
                                    double xFinalPosition,
                                    double yFinalPosition,
                                    double speed);
 
/**
 * Set initial position for a node
 * \param model mobility model
 * \param coord coordinate (x, y, or z)
 * \param coordVal value of the coordinate
 * \return The vector of the position
 */
static Vector SetInitialPosition(Ptr<ConstantVelocityMobilityModel> model,
                                 std::string coord,
                                 double coordVal);
 
/**
 * Schedule a set of position for a node
 * \param model mobility model
 * \param at initial movement time
 * \param coord coordinate (x, y, or z)
 * \param coordVal value of the coordinate
 * \return The vector of the position at the given time
 */
static Vector SetSchedPosition(Ptr<ConstantVelocityMobilityModel> model,
                               double at,
                               std::string coord,
                               double coordVal);
 
Ns2MobilityHelper::Ns2MobilityHelper(std::string filename)
    : m_filename(filename)
{
    std::ifstream file(m_filename, std::ios::in);
    if (!(file.is_open()))
    {
        NS_FATAL_ERROR("Could not open trace file " << m_filename
                                                    << " for reading, aborting here \n");
    }
}
 
Ptr<ConstantVelocityMobilityModel>
Ns2MobilityHelper::GetMobilityModel(std::string idString, const ObjectStore& store) const
{
    std::istringstream iss;
    iss.str(idString);
    uint32_t id(0);
    iss >> id;
    Ptr<Object> object = store.Get(id);
    if (!object)
    {
        return nullptr;
    }
    Ptr<ConstantVelocityMobilityModel> model = object->GetObject<ConstantVelocityMobilityModel>();
    if (!model)
    {
        model = CreateObject<ConstantVelocityMobilityModel>();
        object->AggregateObject(model);
    }
    return model;
}
 
void
Ns2MobilityHelper::ConfigNodesMovements(const ObjectStore& store) const
{
    std::map<int, DestinationPoint> last_pos; // Stores previous movement scheduled for each node
 
    //*****************************************************************
    // Parse the file the first time to get the initial node positions.
    //*****************************************************************
 
    // Look through the whole the file for the the initial node
    // positions to make this helper robust to handle trace files with
    // the initial node positions at the end.
    std::ifstream file(m_filename, std::ios::in);
    if (file.is_open())
    {
        while (!file.eof())
        {
            int iNodeId = 0;
            std::string nodeId;
            std::string line;
 
            getline(file, line);
 
            // ignore empty lines
            if (line.empty())
            {
                continue;
            }
 
            ParseResult pr = ParseNs2Line(line); // Parse line and obtain tokens
 
            // Check if the line corresponds with setting the initial
            // node positions
            if (pr.tokens.size() != 4)
            {
                continue;
            }
 
            // Get the node Id
            nodeId = GetNodeIdString(pr);
            iNodeId = GetNodeIdInt(pr);
            if (iNodeId == -1)
            {
                NS_LOG_ERROR("Node number couldn't be obtained (corrupted file?): " << line
                                                                                    << "\n");
                continue;
            }
 
            // get mobility model of node
            Ptr<ConstantVelocityMobilityModel> model = GetMobilityModel(nodeId, store);
 
            // if model not exists, continue
            if (!model)
            {
                NS_LOG_ERROR("Unknown node ID (corrupted file?): " << nodeId << "\n");
                continue;
            }
 
            /*
             * In this case a initial position is being seted
             * line like $node_(0) set X_ 151.05190721688197
             */
            if (IsSetInitialPos(pr))
            {
                DestinationPoint point;
                //                                                    coord         coord value
                point.m_finalPosition = SetInitialPosition(model, pr.tokens[2], pr.dvals[3]);
                last_pos[iNodeId] = point;
 
                // Log new position
                NS_LOG_DEBUG("Positions after parse for node "
                             << iNodeId << " " << nodeId
                             << " position = " << last_pos[iNodeId].m_finalPosition);
            }
        }
        file.close();
    }
 
    //*****************************************************************
    // Parse the file a second time to get the rest of its values
    //*****************************************************************
 
    // The reason the file is parsed again is to make this helper robust
    // to handle trace files with the initial node positions at the end.
    file.open(m_filename, std::ios::in);
    if (file.is_open())
    {
        while (!file.eof())
        {
            int iNodeId = 0;
            std::string nodeId;
            std::string line;
 
            getline(file, line);
 
            // ignore empty lines
            if (line.empty())
            {
                continue;
            }
 
            ParseResult pr = ParseNs2Line(line); // Parse line and obtain tokens
 
            // Check if the line corresponds with one of the three types of line
            if (pr.tokens.size() != 4 && pr.tokens.size() != 7 && pr.tokens.size() != 8)
            {
                NS_LOG_ERROR("Line has not correct number of parameters (corrupted file?): "
                             << line << "\n");
                continue;
            }
 
            // Get the node Id
            nodeId = GetNodeIdString(pr);
            iNodeId = GetNodeIdInt(pr);
            if (iNodeId == -1)
            {
                NS_LOG_ERROR("Node number couldn't be obtained (corrupted file?): " << line
                                                                                    << "\n");
                continue;
            }
 
            // get mobility model of node
            Ptr<ConstantVelocityMobilityModel> model = GetMobilityModel(nodeId, store);
 
            // if model not exists, continue
            if (!model)
            {
                NS_LOG_ERROR("Unknown node ID (corrupted file?): " << nodeId << "\n");
                continue;
            }
 
            /*
             * In this case a initial position is being seted
             * line like $node_(0) set X_ 151.05190721688197
             */
            if (IsSetInitialPos(pr))
            {
                // This is the second time this file has been parsed,
                // and the initial node positions were already set the
                // first time.  So, do nothing this time with this line.
                continue;
            }
 
            else // NOW EVENTS TO BE SCHEDULED
            {
                // This is a scheduled event, so time at should be present
                double at;
 
                if (!IsNumber(pr.tokens[2]))
                {
                    NS_LOG_WARN("Time is not a number: " << pr.tokens[2]);
                    continue;
                }
 
                at = pr.dvals[2]; // set time at
 
                if (at < 0)
                {
                    NS_LOG_WARN("Time is less than cero: " << at);
                    continue;
                }
 
                /*
                 * In this case a new waypoint is added
                 * line like $ns_ at 1 "$node_(0) setdest 2 3 4"
                 */
                if (IsSchedMobilityPos(pr))
                {
                    if (last_pos[iNodeId].m_targetArrivalTime > at)
                    {
                        NS_LOG_LOGIC("Did not reach a destination! stoptime = "
                                     << last_pos[iNodeId].m_targetArrivalTime << ", at = " << at);
                        double actuallytraveled = at - last_pos[iNodeId].m_travelStartTime;
                        Vector reached = Vector(last_pos[iNodeId].m_startPosition.x +
                                                    last_pos[iNodeId].m_speed.x * actuallytraveled,
                                                last_pos[iNodeId].m_startPosition.y +
                                                    last_pos[iNodeId].m_speed.y * actuallytraveled,
                                                0);
                        NS_LOG_LOGIC("Final point = " << last_pos[iNodeId].m_finalPosition
                                                      << ", actually reached = " << reached);
                        last_pos[iNodeId].m_stopEvent.Cancel();
                        last_pos[iNodeId].m_finalPosition = reached;
                    }
                    //                                     last position     time  X coord     Y
                    //                                     coord      velocity
                    last_pos[iNodeId] = SetMovement(model,
                                                    last_pos[iNodeId].m_finalPosition,
                                                    at,
                                                    pr.dvals[5],
                                                    pr.dvals[6],
                                                    pr.dvals[7]);
 
                    // Log new position
                    NS_LOG_DEBUG("Positions after parse for node "
                                 << iNodeId << " " << nodeId
                                 << " position =" << last_pos[iNodeId].m_finalPosition);
                }
 
                /*
                 * Scheduled set position
                 * line like $ns_ at 4.634906291962 "$node_(0) set X_ 28.675920486450"
                 */
                else if (IsSchedSetPos(pr))
                {
                    //                                         time  coordinate   coord value
                    last_pos[iNodeId].m_finalPosition =
                        SetSchedPosition(model, at, pr.tokens[5], pr.dvals[6]);
                    if (last_pos[iNodeId].m_targetArrivalTime > at)
                    {
                        last_pos[iNodeId].m_stopEvent.Cancel();
                    }
                    last_pos[iNodeId].m_targetArrivalTime = at;
                    last_pos[iNodeId].m_travelStartTime = at;
                    // Log new position
                    NS_LOG_DEBUG("Positions after parse for node "
                                 << iNodeId << " " << nodeId
                                 << " position =" << last_pos[iNodeId].m_finalPosition);
                }
                else
                {
                    NS_LOG_WARN("Format Line is not correct: " << line << "\n");
                }
            }
        }
        file.close();
    }
}
 
ParseResult
ParseNs2Line(const std::string& str)
{
    ParseResult ret;
    std::istringstream s;
    std::string line;
 
    // ignore comments (#)
    size_t pos_sharp = str.find_first_of('#');
    if (pos_sharp != std::string::npos)
    {
        line = str.substr(0, pos_sharp);
    }
    else
    {
        line = str;
    }
 
    line = TrimNs2Line(line);
 
    // If line hasn't a correct node Id
    if (!HasNodeIdNumber(line))
    {
        NS_LOG_WARN("Line has no node Id: " << line);
        return ret;
    }
 
    s.str(line);
 
    while (!s.eof())
    {
        std::string x;
        s >> x;
        if (x.empty())
        {
            continue;
        }
        ret.tokens.push_back(x);
        int ii(0);
        double d(0);
        if (HasNodeIdNumber(x))
        {
            x = GetNodeIdFromToken(x);
        }
        ret.has_ival.push_back(IsVal<int>(x, ii));
        ret.ivals.push_back(ii);
        ret.has_dval.push_back(IsVal<double>(x, d));
        ret.dvals.push_back(d);
        ret.svals.push_back(x);
    }
 
    size_t tokensLength = ret.tokens.size();                     // number of tokens in line
    size_t lasTokenLength = ret.tokens[tokensLength - 1].size(); // length of the last token
 
    // if it is a scheduled set _[XYZ] or a setdest I need to remove the last "
    // and re-calculate values
    if ((tokensLength == 7 || tokensLength == 8) &&
        (ret.tokens[tokensLength - 1][lasTokenLength - 1] == '"'))
    {
        // removes " from the last position
        ret.tokens[tokensLength - 1] = ret.tokens[tokensLength - 1].substr(0, lasTokenLength - 1);
 
        std::string x;
        x = ret.tokens[tokensLength - 1];
 
        if (HasNodeIdNumber(x))
        {
            x = GetNodeIdFromToken(x);
        }
 
        // Re calculate values
        int ii(0);
        double d(0);
        ret.has_ival[tokensLength - 1] = IsVal<int>(x, ii);
        ret.ivals[tokensLength - 1] = ii;
        ret.has_dval[tokensLength - 1] = IsVal<double>(x, d);
        ret.dvals[tokensLength - 1] = d;
        ret.svals[tokensLength - 1] = x;
    }
    else if ((tokensLength == 9 && ret.tokens[tokensLength - 1] == "\"") ||
             (tokensLength == 8 && ret.tokens[tokensLength - 1] == "\""))
    {
        // if the line has the " character in this way: $ns_ at 1 "$node_(0) setdest 2 2 1  "
        // or in this: $ns_ at 4 "$node_(0) set X_ 2  " we need to ignore this last token
 
        ret.tokens.erase(ret.tokens.begin() + tokensLength - 1);
        ret.has_ival.erase(ret.has_ival.begin() + tokensLength - 1);
        ret.ivals.erase(ret.ivals.begin() + tokensLength - 1);
        ret.has_dval.erase(ret.has_dval.begin() + tokensLength - 1);
        ret.dvals.erase(ret.dvals.begin() + tokensLength - 1);
        ret.svals.erase(ret.svals.begin() + tokensLength - 1);
    }
 
    return ret;
}
 
std::string
TrimNs2Line(const std::string& s)
{
    std::string ret = s;
 
    while (!ret.empty() && isblank(ret[0]))
    {
        ret.erase(0, 1); // Removes blank spaces at the beginning of the line
    }
 
    while (!ret.empty() && (isblank(ret[ret.size() - 1]) || (ret[ret.size() - 1] == ';')))
    {
        ret.erase(ret.size() - 1, 1); // Removes blank spaces from at end of line
    }
 
    return ret;
}
 
bool
IsNumber(const std::string& s)
{
    char* endp;
    strtod(s.c_str(), &endp);
    return endp == s.c_str() + s.size();
}
 
template <class T>
bool
IsVal(const std::string& str, T& ret)
{
    if (str.empty())
    {
        return false;
    }
    else if (IsNumber(str))
    {
        std::istringstream s(str);
        s >> ret;
        return true;
    }
    else
    {
        return false;
    }
}
 
bool
HasNodeIdNumber(std::string str)
{
    // find brackets
    std::string::size_type startNodeId = str.find_first_of('('); // index of left bracket
    std::string::size_type endNodeId = str.find_first_of(')');   // index of right bracket
 
    // Get de nodeId in a string and in a int value
    std::string nodeId; // node id
 
    // if no brackets, continue!
    if (startNodeId == std::string::npos || endNodeId == std::string::npos)
    {
        return false;
    }
 
    nodeId = str.substr(startNodeId + 1, endNodeId - (startNodeId + 1)); // set node id
 
    //     is number           is integer                                        is not negative
    return IsNumber(nodeId) && nodeId.find_first_of('.') == std::string::npos && nodeId[0] != '-';
}
 
std::string
GetNodeIdFromToken(std::string str)
{
    if (HasNodeIdNumber(str))
    {
        // find brackets
        std::string::size_type startNodeId = str.find_first_of('('); // index of left bracket
        std::string::size_type endNodeId = str.find_first_of(')');   // index of right bracket
 
        return str.substr(startNodeId + 1, endNodeId - (startNodeId + 1)); // set node id
    }
    else
    {
        return "";
    }
}
 
int
GetNodeIdInt(ParseResult pr)
{
    int result = -1;
    switch (pr.tokens.size())
    {
    case 4: // line like $node_(0) set X_ 11
        result = pr.ivals[0];
        break;
    case 7: // line like $ns_ at 4 "$node_(0) set X_ 28"
        result = pr.ivals[3];
        break;
    case 8: // line like $ns_ at 1 "$node_(0) setdest 2 3 4"
        result = pr.ivals[3];
        break;
    default:
        result = -1;
    }
    return result;
}
 
// Get node id number in string format
std::string
GetNodeIdString(ParseResult pr)
{
    switch (pr.tokens.size())
    {
    case 4: // line like $node_(0) set X_ 11
        return pr.svals[0];
    case 7: // line like $ns_ at 4 "$node_(0) set X_ 28"
        return pr.svals[3];
    case 8: // line like $ns_ at 1 "$node_(0) setdest 2 3 4"
        return pr.svals[3];
    default:
        return "";
    }
}
 
Vector
SetOneInitialCoord(Vector position, std::string& coord, double value)
{
    // set the position for the coord.
    if (coord == NS2_X_COORD)
    {
        position.x = value;
        NS_LOG_DEBUG("X=" << value);
    }
    else if (coord == NS2_Y_COORD)
    {
        position.y = value;
        NS_LOG_DEBUG("Y=" << value);
    }
    else if (coord == NS2_Z_COORD)
    {
        position.z = value;
        NS_LOG_DEBUG("Z=" << value);
    }
    return position;
}
 
bool
IsSetInitialPos(ParseResult pr)
{
    //        number of tokens         has $node_( ?                        has "set"           has
    //        double for position?
    return pr.tokens.size() == 4 && HasNodeIdNumber(pr.tokens[0]) && pr.tokens[1] == NS2_SET &&
           pr.has_dval[3]
           // coord name is X_, Y_ or Z_ ?
           && (pr.tokens[2] == NS2_X_COORD || pr.tokens[2] == NS2_Y_COORD ||
               pr.tokens[2] == NS2_Z_COORD);
}
 
bool
IsSchedSetPos(ParseResult pr)
{
    //      correct number of tokens,    has $ns_                   and at
    return pr.tokens.size() == 7 && pr.tokens[0] == NS2_NS_SCH && pr.tokens[1] == NS2_AT &&
           pr.tokens[4] == NS2_SET && pr.has_dval[2] &&
           pr.has_dval[3] // has set and double value for time and nodeid
           && (pr.tokens[5] == NS2_X_COORD || pr.tokens[5] == NS2_Y_COORD ||
               pr.tokens[5] == NS2_Z_COORD) // has X_, Y_ or Z_?
           && pr.has_dval[2];               // time is a number
}
 
bool
IsSchedMobilityPos(ParseResult pr)
{
    //     number of tokens      and    has $ns_                and    has at
    return pr.tokens.size() == 8 && pr.tokens[0] == NS2_NS_SCH &&
           pr.tokens[1] == NS2_AT
           //    time             x coord          y coord          velocity are numbers?
           && pr.has_dval[2] && pr.has_dval[5] && pr.has_dval[6] && pr.has_dval[7] &&
           pr.tokens[4] == NS2_SETDEST; // and has setdest
}
 
DestinationPoint
SetMovement(Ptr<ConstantVelocityMobilityModel> model,
            Vector last_pos,
            double at,
            double xFinalPosition,
            double yFinalPosition,
            double speed)
{
    DestinationPoint retval;
    retval.m_startPosition = last_pos;
    retval.m_finalPosition = last_pos;
    retval.m_travelStartTime = at;
    retval.m_targetArrivalTime = at;
 
    if (speed == 0)
    {
        // We have to maintain last position, and stop the movement
        retval.m_stopEvent = Simulator::Schedule(Seconds(at),
                                                 &ConstantVelocityMobilityModel::SetVelocity,
                                                 model,
                                                 Vector(0, 0, 0));
        return retval;
    }
    if (speed > 0)
    {
        // first calculate the time; time = distance / speed
        double time = std::sqrt(std::pow(xFinalPosition - retval.m_finalPosition.x, 2) +
                                std::pow(yFinalPosition - retval.m_finalPosition.y, 2)) /
                      speed;
        NS_LOG_DEBUG("at=" << at << " time=" << time);
        if (time == 0)
        {
            return retval;
        }
        // now calculate the xSpeed = distance / time
        double xSpeed = (xFinalPosition - retval.m_finalPosition.x) / time;
        double ySpeed = (yFinalPosition - retval.m_finalPosition.y) / time; // & same with ySpeed
        retval.m_speed = Vector(xSpeed, ySpeed, 0);
 
        // quick and dirty set zSpeed = 0
        double zSpeed = 0;
 
        NS_LOG_DEBUG("Calculated Speed: X=" << xSpeed << " Y=" << ySpeed << " Z=" << zSpeed);
 
        // Set the Values
        Simulator::Schedule(Seconds(at),
                            &ConstantVelocityMobilityModel::SetVelocity,
                            model,
                            Vector(xSpeed, ySpeed, zSpeed));
        retval.m_stopEvent = Simulator::Schedule(Seconds(at + time),
                                                 &ConstantVelocityMobilityModel::SetVelocity,
                                                 model,
                                                 Vector(0, 0, 0));
        retval.m_finalPosition.x += xSpeed * time;
        retval.m_finalPosition.y += ySpeed * time;
        retval.m_targetArrivalTime += time;
    }
    return retval;
}
 
Vector
SetInitialPosition(Ptr<ConstantVelocityMobilityModel> model, std::string coord, double coordVal)
{
    model->SetPosition(SetOneInitialCoord(model->GetPosition(), coord, coordVal));
 
    Vector position;
    position.x = model->GetPosition().x;
    position.y = model->GetPosition().y;
    position.z = model->GetPosition().z;
 
    return position;
}
 
// Schedule a set of position for a node
Vector
SetSchedPosition(Ptr<ConstantVelocityMobilityModel> model,
                 double at,
                 std::string coord,
                 double coordVal)
{
    // update position
    model->SetPosition(SetOneInitialCoord(model->GetPosition(), coord, coordVal));
 
    Vector position;
    position.x = model->GetPosition().x;
    position.y = model->GetPosition().y;
    position.z = model->GetPosition().z;
 
    // Schedule next positions
    Simulator::Schedule(Seconds(at), &ConstantVelocityMobilityModel::SetPosition, model, position);
 
    return position;
}
 
void
Ns2MobilityHelper::Install() const
{
    Install(NodeList::Begin(), NodeList::End());
}
 
} // namespace ns3