diff --git a/samples/main-grid-topology.cc b/samples/main-grid-topology.cc
index ef0f15d37..7d9f5bbe5 100644
--- a/samples/main-grid-topology.cc
+++ b/samples/main-grid-topology.cc
@@ -41,7 +41,7 @@ int main (int argc, char *argv[])
       Ptr<Object> object = *j;
       Ptr<MobilityModel> position = object->QueryInterface<MobilityModel> (MobilityModel::iid);
       NS_ASSERT (position != 0);
-      Position pos = position->GetPosition ();
+      Vector pos = position->GetPosition ();
       std::cout << "x=" << pos.x << ", y=" << pos.y << ", z=" << pos.z << std::endl;
     }
 
diff --git a/samples/main-random-topology.cc b/samples/main-random-topology.cc
index 608397d53..fe896278d 100644
--- a/samples/main-random-topology.cc
+++ b/samples/main-random-topology.cc
@@ -17,7 +17,7 @@ using namespace ns3;
 static void 
 CourseChange (const TraceContext &context, Ptr<const MobilityModel> position)
 {
-  Position pos = position->GetPosition ();
+  Vector pos = position->GetPosition ();
   std::cout << Simulator::Now () << ", pos=" << position << ", x=" << pos.x << ", y=" << pos.y
             << ", z=" << pos.z << std::endl;
 }
diff --git a/samples/main-random-walk.cc b/samples/main-random-walk.cc
index 45be9b904..2fa095d4e 100644
--- a/samples/main-random-walk.cc
+++ b/samples/main-random-walk.cc
@@ -18,11 +18,11 @@ using namespace ns3;
 static void 
 CourseChange (ns3::TraceContext const&, Ptr<const MobilityModel> mobility)
 {
-  Position pos = mobility->GetPosition ();
-  Speed vel = mobility->GetSpeed ();
+  Vector pos = mobility->GetPosition ();
+  Vector vel = mobility->GetSpeed ();
   std::cout << Simulator::Now () << ", model=" << mobility << ", POS: x=" << pos.x << ", y=" << pos.y
-            << ", z=" << pos.z << "; VEL:" << vel.dx << ", y=" << vel.dy
-            << ", z=" << vel.dz << std::endl;
+            << ", z=" << pos.z << "; VEL:" << vel.x << ", y=" << vel.y
+            << ", z=" << vel.z << std::endl;
 }
 
 int main (int argc, char *argv[])
diff --git a/src/mobility/grid-topology.cc b/src/mobility/grid-topology.cc
index f738a3be2..1e33a70cd 100644
--- a/src/mobility/grid-topology.cc
+++ b/src/mobility/grid-topology.cc
@@ -46,7 +46,7 @@ GridTopology::LayoutOneRowFirst (Ptr<Object> object, uint32_t i)
   Ptr<MobilityModel> mobility = ComponentManager::Create<MobilityModel> (m_positionClassId,
                                                                          MobilityModel::iid);
   object->AddInterface (mobility);
-  mobility->SetPosition (Position (x, y, 0.0));
+  mobility->SetPosition (Vector (x, y, 0.0));
 }
 
 void 
@@ -58,7 +58,7 @@ GridTopology::LayoutOneColumnFirst (Ptr<Object> object, uint32_t i)
   Ptr<MobilityModel> mobility = ComponentManager::Create<MobilityModel> (m_positionClassId, 
                                                                          MobilityModel::iid);
   object->AddInterface (mobility);
-  mobility->SetPosition (Position (x, y, 0.0));
+  mobility->SetPosition (Vector (x, y, 0.0));
 }
 
 
diff --git a/src/mobility/hierarchical-mobility-model.cc b/src/mobility/hierarchical-mobility-model.cc
index d144597ec..a01ba4821 100644
--- a/src/mobility/hierarchical-mobility-model.cc
+++ b/src/mobility/hierarchical-mobility-model.cc
@@ -56,34 +56,34 @@ HierarchicalMobilityModel::GetParent (void) const
   return m_parent;
 }
 
-Position 
+Vector
 HierarchicalMobilityModel::DoGetPosition (void) const
 {
-  Position parentPosition = m_parent->GetPosition ();
-  Position childPosition = m_child->GetPosition ();
-  return Position (parentPosition.x + childPosition.x,
+  Vector parentPosition = m_parent->GetPosition ();
+  Vector childPosition = m_child->GetPosition ();
+  return Vector (parentPosition.x + childPosition.x,
 		   parentPosition.y + childPosition.y,
 		   parentPosition.z + childPosition.z);
 }
 void 
-HierarchicalMobilityModel::DoSetPosition (const Position &position)
+HierarchicalMobilityModel::DoSetPosition (const Vector &position)
 {
   // This implementation of DoSetPosition is really an arbitraty choice.
   // anything else would have been ok.
-  Position parentPosition = m_parent->GetPosition ();
-  Position childPosition (position.x - parentPosition.x,
+  Vector parentPosition = m_parent->GetPosition ();
+  Vector childPosition (position.x - parentPosition.x,
 			  position.y - parentPosition.y,
 			  position.z - parentPosition.z);
   m_child->SetPosition (childPosition);
 }
-Speed 
+Vector
 HierarchicalMobilityModel::DoGetSpeed (void) const
 {
-  Speed parentSpeed = m_parent->GetSpeed ();
-  Speed childSpeed = m_child->GetSpeed ();
-  Speed speed (parentSpeed.dx + childSpeed.dx,
-               parentSpeed.dy + childSpeed.dy,
-               parentSpeed.dz + childSpeed.dz);
+  Vector parentSpeed = m_parent->GetSpeed ();
+  Vector childSpeed = m_child->GetSpeed ();
+  Vector speed (parentSpeed.x + childSpeed.x,
+               parentSpeed.y + childSpeed.y,
+               parentSpeed.z + childSpeed.z);
   return speed;
 }
 
diff --git a/src/mobility/hierarchical-mobility-model.h b/src/mobility/hierarchical-mobility-model.h
index d15c173c0..c454e043c 100644
--- a/src/mobility/hierarchical-mobility-model.h
+++ b/src/mobility/hierarchical-mobility-model.h
@@ -58,9 +58,9 @@ public:
   Ptr<MobilityModel> GetParent (void) const;
   
 private:
-  virtual Position DoGetPosition (void) const;
-  virtual void DoSetPosition (const Position &position);
-  virtual Speed DoGetSpeed (void) const;
+  virtual Vector DoGetPosition (void) const;
+  virtual void DoSetPosition (const Vector &position);
+  virtual Vector DoGetSpeed (void) const;
 
   void ParentChanged (const TraceContext &context, Ptr<const MobilityModel> model);
   void ChildChanged (const TraceContext &context, Ptr<const MobilityModel> model);
diff --git a/src/mobility/mobility-model.cc b/src/mobility/mobility-model.cc
index ffc4fdc70..0e4ef568f 100644
--- a/src/mobility/mobility-model.cc
+++ b/src/mobility/mobility-model.cc
@@ -33,19 +33,19 @@ MobilityModel::MobilityModel ()
 MobilityModel::~MobilityModel ()
 {}
 
-Position
+Vector
 MobilityModel::GetPosition (void) const
 {
   return DoGetPosition ();
 }
-Speed 
+Vector
 MobilityModel::GetSpeed (void) const
 {
   return DoGetSpeed ();
 }
 
 void 
-MobilityModel::SetPosition (const Position &position)
+MobilityModel::SetPosition (const Vector &position)
 {
   DoSetPosition (position);
 }
@@ -53,8 +53,8 @@ MobilityModel::SetPosition (const Position &position)
 double 
 MobilityModel::GetDistanceFrom (Ptr<const MobilityModel> other) const
 {
-  Position oPosition = other->DoGetPosition ();
-  Position position = DoGetPosition ();
+  Vector oPosition = other->DoGetPosition ();
+  Vector position = DoGetPosition ();
   return CalculateDistance (position, oPosition);
 }
 
diff --git a/src/mobility/mobility-model.h b/src/mobility/mobility-model.h
index 774f293b6..6702e10c5 100644
--- a/src/mobility/mobility-model.h
+++ b/src/mobility/mobility-model.h
@@ -21,8 +21,7 @@
 #define MOBILITY_MODEL_H
 
 #include "ns3/object.h"
-#include "position.h"
-#include "speed.h"
+#include "vector.h"
 
 namespace ns3 {
 
@@ -43,15 +42,15 @@ public:
   /**
    * \returns the current position
    */
-  Position GetPosition (void) const;
+  Vector GetPosition (void) const;
   /**
    * \param position the position to set.
    */
-  void SetPosition (const Position &position);
+  void SetPosition (const Vector &position);
   /**
    * \returns the current position.
    */
-  Speed GetSpeed (void) const;
+  Vector GetSpeed (void) const;
   /**
    * \param position a reference to another mobility model
    * \returns the distance between the two objects. Unit is meters.
@@ -70,21 +69,21 @@ private:
    * Concrete subclasses of this base class must 
    * implement this method.
    */
-  virtual Position DoGetPosition (void) const = 0;
+  virtual Vector DoGetPosition (void) const = 0;
   /**
    * \param position the position to set.
    *
    * Concrete subclasses of this base class must 
    * implement this method.
    */
-  virtual void DoSetPosition (const Position &position) = 0;
+  virtual void DoSetPosition (const Vector &position) = 0;
   /**
    * \returns the current speed.
    *
    * Concrete subclasses of this base class must 
    * implement this method.
    */
-  virtual Speed DoGetSpeed (void) const = 0;
+  virtual Vector DoGetSpeed (void) const = 0;
 };
 
 }; // namespace ns3
diff --git a/src/mobility/ns2-mobility-file-topology.cc b/src/mobility/ns2-mobility-file-topology.cc
index 73add3c2c..44a31d8a3 100644
--- a/src/mobility/ns2-mobility-file-topology.cc
+++ b/src/mobility/ns2-mobility-file-topology.cc
@@ -97,7 +97,7 @@ Ns2MobilityFileTopology::LayoutObjectStore (const ObjectStore &store) const
 	    {
 	      double value = ReadDouble (line.substr (endNodeId + 9, std::string::npos));
 	      std::string coordinate = line.substr (endNodeId + 6, 1);
-              Position position = model->GetPosition ();
+              Vector position = model->GetPosition ();
 	      if (coordinate == "X")
 		{
                   position.x = value;
@@ -129,7 +129,7 @@ Ns2MobilityFileTopology::LayoutObjectStore (const ObjectStore &store) const
 	      double zSpeed = ReadDouble (line.substr (ySpeedEnd + 1, std::string::npos));
 	      NS_LOG_DEBUG ("at=" << at << "xSpeed=" << xSpeed << ", ySpeed=" << ySpeed << ", zSpeed=" << zSpeed);
 	      Simulator::Schedule (Seconds (at), &StaticSpeedMobilityModel::SetSpeed, model,
-				   Speed (xSpeed, ySpeed, zSpeed));
+				   Vector (xSpeed, ySpeed, zSpeed));
 	    }
 	}
       file.close();
diff --git a/src/mobility/position.cc b/src/mobility/position.cc
deleted file mode 100644
index 2418cb61e..000000000
--- a/src/mobility/position.cc
+++ /dev/null
@@ -1,48 +0,0 @@
-/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2007 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>
- */
-#include "position.h"
-#include <cmath>
-
-namespace ns3 {
-
-
-Position::Position (double _x, double _y, double _z)
-  : x (_x),
-    y (_y),
-    z (_z)
-{}
-
-Position::Position ()
-  : x (0.0),
-    y (0.0),
-    z (0.0)
-{}
-
-double 
-CalculateDistance (const Position &a, const Position &b)
-{
-  double dx = b.x - a.x;
-  double dy = b.y - a.y;
-  double dz = b.z - a.z;
-  double distance = std::sqrt (dx * dx + dy * dy + dz * dz);
-  return distance;
-}
-
-} // namespace ns3
diff --git a/src/mobility/position.h b/src/mobility/position.h
deleted file mode 100644
index 08ab9a134..000000000
--- a/src/mobility/position.h
+++ /dev/null
@@ -1,63 +0,0 @@
-/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2007 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 POSITION_H
-#define POSITION_H
-
-namespace ns3 {
-
-/**
- * \brief a 3d cartesian position vector
- *
- * Unit is meters.
- */
-class Position
-{
-public:
-  /**
-   * \param _x x coordinate of position vector
-   * \param _y y coordinate of position vector
-   * \param _z z coordinate of position vector
-   *
-   * Create position vector (_x, _y, _z)
-   */
-  Position (double _x, double _y, double _z);
-  /**
-   * Create position vector (0.0, 0.0, 0.0)
-   */
-  Position ();
-  /**
-   * x coordinate of position vector
-   */
-  double x;
-  /**
-   * y coordinate of position vector
-   */
-  double y;
-  /**
-   * z coordinate of position vector
-   */
-  double z;
-};
-
-double CalculateDistance (const Position &a, const Position &b);
-
-} // namespace ns3
-
-#endif /* POSITION_H */
diff --git a/src/mobility/random-direction-2d-mobility-model.cc b/src/mobility/random-direction-2d-mobility-model.cc
index 508478d18..8163aee53 100644
--- a/src/mobility/random-direction-2d-mobility-model.cc
+++ b/src/mobility/random-direction-2d-mobility-model.cc
@@ -153,12 +153,12 @@ RandomDirection2dMobilityModel::SetDirectionAndSpeed (double direction)
 {
   NS_LOG_FUNCTION;
   double speed = m_parameters->m_speedVariable->GetValue ();
-  const Speed vector (std::cos (direction) * speed,
-                      std::sin (direction) * speed,
-                      0.0);
-  Position position = m_helper.GetCurrentPosition (m_parameters->m_bounds);
+  const Vector vector (std::cos (direction) * speed,
+                       std::sin (direction) * speed,
+                       0.0);
+  Vector position = m_helper.GetCurrentPosition (m_parameters->m_bounds);
   m_helper.Reset (vector);
-  Position next = m_parameters->m_bounds.CalculateIntersection (position, vector);
+  Vector next = m_parameters->m_bounds.CalculateIntersection (position, vector);
   Time delay = Seconds (CalculateDistance (position, next) / speed);
   m_event = Simulator::Schedule (delay,
 				 &RandomDirection2dMobilityModel::BeginPause, this);
@@ -169,7 +169,7 @@ RandomDirection2dMobilityModel::ResetDirectionAndSpeed (void)
 {
   double direction = UniformVariable::GetSingleValue (0, PI);
   
-  Position position = m_helper.GetCurrentPosition (m_parameters->m_bounds);
+  Vector position = m_helper.GetCurrentPosition (m_parameters->m_bounds);
   switch (m_parameters->m_bounds.GetClosestSide (position))
     {
     case Rectangle::RIGHT:
@@ -187,19 +187,19 @@ RandomDirection2dMobilityModel::ResetDirectionAndSpeed (void)
     }
   SetDirectionAndSpeed (direction);
 }
-Position
+Vector
 RandomDirection2dMobilityModel::DoGetPosition (void) const
 {
   return m_helper.GetCurrentPosition (m_parameters->m_bounds);
 }
 void
-RandomDirection2dMobilityModel::DoSetPosition (const Position &position)
+RandomDirection2dMobilityModel::DoSetPosition (const Vector &position)
 {
   m_helper.InitializePosition (position);
   Simulator::Remove (m_event);
   m_event = Simulator::ScheduleNow (&RandomDirection2dMobilityModel::Start, this);
 }
-Speed 
+Vector
 RandomDirection2dMobilityModel::DoGetSpeed (void) const
 {
   return m_helper.GetSpeed ();
diff --git a/src/mobility/random-direction-2d-mobility-model.h b/src/mobility/random-direction-2d-mobility-model.h
index 7c5520a35..8ebc21100 100644
--- a/src/mobility/random-direction-2d-mobility-model.h
+++ b/src/mobility/random-direction-2d-mobility-model.h
@@ -106,9 +106,9 @@ class RandomDirection2dMobilityModel : public MobilityModel
   void SetDirectionAndSpeed (double direction);
   void InitializeDirectionAndSpeed (void);
   virtual void DoDispose (void);
-  virtual Position DoGetPosition (void) const;
-  virtual void DoSetPosition (const Position &position);
-  virtual Speed DoGetSpeed (void) const;
+  virtual Vector DoGetPosition (void) const;
+  virtual void DoSetPosition (const Vector &position);
+  virtual Vector DoGetSpeed (void) const;
 
   static const double PI;
   Ptr<RandomDirection2dMobilityModelParameters> m_parameters;
diff --git a/src/mobility/random-position.cc b/src/mobility/random-position.cc
index 4e2a79f69..2dab23144 100644
--- a/src/mobility/random-position.cc
+++ b/src/mobility/random-position.cc
@@ -91,12 +91,12 @@ RandomRectanglePosition::~RandomRectanglePosition ()
   m_x = 0;
   m_y = 0;
 }
-Position
+Vector
 RandomRectanglePosition::Get (void) const
 {
   double x = m_x->GetValue ();
   double y = m_y->GetValue ();
-  return Position (x, y, 0.0);
+  return Vector (x, y, 0.0);
 }
 
 RandomDiscPosition::RandomDiscPosition ()
@@ -120,7 +120,7 @@ RandomDiscPosition::~RandomDiscPosition ()
   m_theta = 0;
   m_rho = 0;
 }
-Position
+Vector
 RandomDiscPosition::Get (void) const
 {
   double theta = m_theta->GetValue ();
@@ -128,7 +128,7 @@ RandomDiscPosition::Get (void) const
   double x = m_x + std::cos (theta) * rho;
   double y = m_y + std::sin (theta) * rho;
   NS_LOG_DEBUG ("Disc position x=" << x << ", y=" << y);
-  return Position (x, y, 0.0);
+  return Vector (x, y, 0.0);
 }
 
 
diff --git a/src/mobility/random-position.h b/src/mobility/random-position.h
index 04a5b6890..aa4b5a14b 100644
--- a/src/mobility/random-position.h
+++ b/src/mobility/random-position.h
@@ -22,7 +22,7 @@
 
 #include "ns3/object.h"
 #include "ns3/component-manager.h"
-#include "position.h"
+#include "vector.h"
 
 namespace ns3 {
 
@@ -42,7 +42,7 @@ public:
   /**
    * \returns the next randomly-choosen position.
    */
-  virtual Position Get (void) const = 0;
+  virtual Vector Get (void) const = 0;
 };
 
 /**
@@ -67,7 +67,7 @@ public:
   RandomRectanglePosition (const RandomVariable &x,
 			   const RandomVariable &y);
   virtual ~RandomRectanglePosition ();
-  virtual Position Get (void) const;
+  virtual Vector Get (void) const;
 private:
   RandomVariable *m_x;
   RandomVariable *m_y;
@@ -102,7 +102,7 @@ public:
 		      const RandomVariable &rho,
 		      double x, double y);
   virtual ~RandomDiscPosition ();
-  virtual Position Get (void) const;
+  virtual Vector Get (void) const;
 private:
   RandomVariable *m_theta;
   RandomVariable *m_rho;
diff --git a/src/mobility/random-topology.cc b/src/mobility/random-topology.cc
index 2e044cce9..64469053b 100644
--- a/src/mobility/random-topology.cc
+++ b/src/mobility/random-topology.cc
@@ -70,7 +70,7 @@ RandomTopology::LayoutOne (Ptr<Object> object)
   Ptr<MobilityModel> mobility = ComponentManager::Create<MobilityModel> (m_mobilityModel, 
                                                                          MobilityModel::iid);
   object->AddInterface (mobility);
-  Position position = m_positionModel->Get ();
+  Vector position = m_positionModel->Get ();
   mobility->SetPosition (position);
 }
 
diff --git a/src/mobility/random-walk-2d-mobility-model.cc b/src/mobility/random-walk-2d-mobility-model.cc
index 0c2304c62..6f1e93aee 100644
--- a/src/mobility/random-walk-2d-mobility-model.cc
+++ b/src/mobility/random-walk-2d-mobility-model.cc
@@ -143,9 +143,9 @@ RandomWalk2dMobilityModel::Start (void)
 {
   double speed = m_parameters->m_speed->GetValue ();
   double direction = m_parameters->m_direction->GetValue ();
-  Speed vector (std::cos (direction) * speed,
-                std::sin (direction) * speed,
-                0.0);
+  Vector vector (std::cos (direction) * speed,
+                 std::sin (direction) * speed,
+                 0.0);
   m_helper.Reset (vector);
 
   Time delayLeft;
@@ -163,11 +163,11 @@ RandomWalk2dMobilityModel::Start (void)
 void
 RandomWalk2dMobilityModel::DoWalk (Time delayLeft)
 {
-  Position position = m_helper.GetCurrentPosition ();
-  Speed speed = m_helper.GetSpeed ();
-  Position nextPosition = position;
-  nextPosition.x += speed.dx * delayLeft.GetSeconds ();
-  nextPosition.y += speed.dy * delayLeft.GetSeconds ();
+  Vector position = m_helper.GetCurrentPosition ();
+  Vector speed = m_helper.GetSpeed ();
+  Vector nextPosition = position;
+  nextPosition.x += speed.x * delayLeft.GetSeconds ();
+  nextPosition.y += speed.y * delayLeft.GetSeconds ();
   if (m_parameters->m_bounds.IsInside (nextPosition))
     {
       m_event = Simulator::Schedule (delayLeft, &RandomWalk2dMobilityModel::Start, this);
@@ -175,7 +175,7 @@ RandomWalk2dMobilityModel::DoWalk (Time delayLeft)
   else
     {
       nextPosition = m_parameters->m_bounds.CalculateIntersection (position, speed);
-      Time delay = Seconds ((nextPosition.x - position.x) / speed.dx);
+      Time delay = Seconds ((nextPosition.x - position.x) / speed.x);
       m_event = Simulator::Schedule (delay, &RandomWalk2dMobilityModel::Rebound, this,
                                      delayLeft - delay);      
     }  
@@ -185,17 +185,17 @@ RandomWalk2dMobilityModel::DoWalk (Time delayLeft)
 void
 RandomWalk2dMobilityModel::Rebound (Time delayLeft)
 {
-  Position position = m_helper.GetCurrentPosition (m_parameters->m_bounds);
-  Speed speed = m_helper.GetSpeed ();
+  Vector position = m_helper.GetCurrentPosition (m_parameters->m_bounds);
+  Vector speed = m_helper.GetSpeed ();
   switch (m_parameters->m_bounds.GetClosestSide (position))
     {
     case Rectangle::RIGHT:
     case Rectangle::LEFT:
-      speed.dx = - speed.dx;
+      speed.x = - speed.x;
       break;
     case Rectangle::TOP:
     case Rectangle::BOTTOM:
-      speed.dy = - speed.dy;
+      speed.y = - speed.y;
       break;
     }
   m_helper.Reset (speed);
@@ -209,20 +209,20 @@ RandomWalk2dMobilityModel::DoDispose (void)
   // chain up
   MobilityModel::DoDispose ();
 }
-Position
+Vector
 RandomWalk2dMobilityModel::DoGetPosition (void) const
 {
   return m_helper.GetCurrentPosition (m_parameters->m_bounds);
 }
 void
-RandomWalk2dMobilityModel::DoSetPosition (const Position &position)
+RandomWalk2dMobilityModel::DoSetPosition (const Vector &position)
 {
   NS_ASSERT (m_parameters->m_bounds.IsInside (position));
   m_helper.InitializePosition (position);
   Simulator::Remove (m_event);
   m_event = Simulator::ScheduleNow (&RandomWalk2dMobilityModel::Start, this);
 }
-Speed 
+Vector
 RandomWalk2dMobilityModel::DoGetSpeed (void) const
 {
   return m_helper.GetSpeed ();
diff --git a/src/mobility/random-walk-2d-mobility-model.h b/src/mobility/random-walk-2d-mobility-model.h
index aeaa6625c..f018d8b13 100644
--- a/src/mobility/random-walk-2d-mobility-model.h
+++ b/src/mobility/random-walk-2d-mobility-model.h
@@ -132,9 +132,9 @@ class RandomWalk2dMobilityModel : public MobilityModel
   void Rebound (Time timeLeft);
   void DoWalk (Time timeLeft);
   virtual void DoDispose (void);
-  virtual Position DoGetPosition (void) const;
-  virtual void DoSetPosition (const Position &position);
-  virtual Speed DoGetSpeed (void) const;
+  virtual Vector DoGetPosition (void) const;
+  virtual void DoSetPosition (const Vector &position);
+  virtual Vector DoGetSpeed (void) const;
 
   StaticSpeedHelper m_helper;
   EventId m_event;
diff --git a/src/mobility/random-waypoint-mobility-model.cc b/src/mobility/random-waypoint-mobility-model.cc
index 420903123..1807f5227 100644
--- a/src/mobility/random-waypoint-mobility-model.cc
+++ b/src/mobility/random-waypoint-mobility-model.cc
@@ -117,15 +117,15 @@ RandomWaypointMobilityModel::RandomWaypointMobilityModel (Ptr<RandomWaypointMobi
 void
 RandomWaypointMobilityModel::BeginWalk (void)
 {
-  Position m_current = m_helper.GetCurrentPosition ();
-  Position destination = m_parameters->m_position->Get ();
+  Vector m_current = m_helper.GetCurrentPosition ();
+  Vector destination = m_parameters->m_position->Get ();
   double speed = m_parameters->m_speed->GetValue ();
   double dx = (destination.x - m_current.x);
   double dy = (destination.y - m_current.y);
   double dz = (destination.z - m_current.z);
   double k = speed / std::sqrt (dx*dx + dy*dy + dz*dz);
 
-  m_helper.Reset (Speed (k*dx, k*dy, k*dz));
+  m_helper.Reset (Vector (k*dx, k*dy, k*dz));
   Time travelDelay = Seconds (CalculateDistance (destination, m_current) / speed);
   m_event = Simulator::Schedule (travelDelay,
 				 &RandomWaypointMobilityModel::Start, this);
@@ -141,19 +141,19 @@ RandomWaypointMobilityModel::Start (void)
   m_event = Simulator::Schedule (pause, &RandomWaypointMobilityModel::BeginWalk, this);
 }
 
-Position 
+Vector
 RandomWaypointMobilityModel::DoGetPosition (void) const
 {
   return m_helper.GetCurrentPosition ();
 }
 void 
-RandomWaypointMobilityModel::DoSetPosition (const Position &position)
+RandomWaypointMobilityModel::DoSetPosition (const Vector &position)
 {
   m_helper.InitializePosition (position);
   Simulator::Remove (m_event);
   Simulator::ScheduleNow (&RandomWaypointMobilityModel::Start, this);
 }
-Speed 
+Vector
 RandomWaypointMobilityModel::DoGetSpeed (void) const
 {
   return m_helper.GetSpeed ();
diff --git a/src/mobility/random-waypoint-mobility-model.h b/src/mobility/random-waypoint-mobility-model.h
index a45061a25..922d0310b 100644
--- a/src/mobility/random-waypoint-mobility-model.h
+++ b/src/mobility/random-waypoint-mobility-model.h
@@ -98,9 +98,9 @@ public:
 private:
   void Start (void);
   void BeginWalk (void);
-  virtual Position DoGetPosition (void) const;
-  virtual void DoSetPosition (const Position &position);
-  virtual Speed DoGetSpeed (void) const;
+  virtual Vector DoGetPosition (void) const;
+  virtual void DoSetPosition (const Vector &position);
+  virtual Vector DoGetSpeed (void) const;
 
   StaticSpeedHelper m_helper;
   Ptr<RandomWaypointMobilityModelParameters> m_parameters;
diff --git a/src/mobility/rectangle.cc b/src/mobility/rectangle.cc
index 2f10a7d43..e39f8ae74 100644
--- a/src/mobility/rectangle.cc
+++ b/src/mobility/rectangle.cc
@@ -18,8 +18,7 @@
  * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
  */
 #include "rectangle.h"
-#include "position.h"
-#include "speed.h"
+#include "vector.h"
 #include "ns3/assert.h"
 #include <cmath>
 #include <algorithm>
@@ -42,7 +41,7 @@ Rectangle::Rectangle ()
 {}
 
 bool 
-Rectangle::IsInside (const Position &position) const
+Rectangle::IsInside (const Vector &position) const
 {
   return 
     position.x <= this->xMax && position.x >= this->xMin &&
@@ -50,7 +49,7 @@ Rectangle::IsInside (const Position &position) const
 }
 
 Rectangle::Side 
-Rectangle::GetClosestSide (const Position &position) const
+Rectangle::GetClosestSide (const Vector &position) const
 {
   double xMinDist = std::abs (position.x - this->xMin);
   double xMaxDist = std::abs (this->xMax - position.x);
@@ -82,38 +81,38 @@ Rectangle::GetClosestSide (const Position &position) const
     }
 }
 
-Position
-Rectangle::CalculateIntersection (const Position &current, const Speed &speed) const
+Vector
+Rectangle::CalculateIntersection (const Vector &current, const Vector &speed) const
 {
-  double xMaxY = current.y + (this->xMax - current.x) / speed.dx * speed.dy;
-  double xMinY = current.y + (this->xMin - current.x) / speed.dx * speed.dy;
-  double yMaxX = current.x + (this->yMax - current.y) / speed.dy * speed.dx;
-  double yMinX = current.x + (this->yMin - current.y) / speed.dy * speed.dx;
+  double xMaxY = current.y + (this->xMax - current.x) / speed.x * speed.y;
+  double xMinY = current.y + (this->xMin - current.x) / speed.x * speed.y;
+  double yMaxX = current.x + (this->yMax - current.y) / speed.y * speed.x;
+  double yMinX = current.x + (this->yMin - current.y) / speed.y * speed.x;
   bool xMaxYOk = (xMaxY <= this->yMax && xMaxY >= this->yMin);
   bool xMinYOk = (xMinY <= this->yMax && xMinY >= this->yMin);
   bool yMaxXOk = (yMaxX <= this->xMax && yMaxX >= this->xMin);
   bool yMinXOk = (yMinX <= this->xMax && yMinX >= this->xMin);
-  if (xMaxYOk && speed.dx >= 0)
+  if (xMaxYOk && speed.x >= 0)
     {
-      return Position (this->xMax, xMaxY, 0.0);
+      return Vector (this->xMax, xMaxY, 0.0);
     }
-  else if (xMinYOk && speed.dx <= 0)
+  else if (xMinYOk && speed.x <= 0)
     {
-      return Position (this->xMin, xMinY, 0.0);
+      return Vector (this->xMin, xMinY, 0.0);
     }
-  else if (yMaxXOk && speed.dy >= 0)
+  else if (yMaxXOk && speed.y >= 0)
     {
-      return Position (yMaxX, this->yMax, 0.0);
+      return Vector (yMaxX, this->yMax, 0.0);
     }
-  else if (yMinXOk && speed.dy <= 0)
+  else if (yMinXOk && speed.y <= 0)
     {
-      return Position (yMinX, this->yMin, 0.0);
+      return Vector (yMinX, this->yMin, 0.0);
     }
   else
     {
       NS_ASSERT (false);
       // quiet compiler
-      return Position (0.0, 0.0, 0.0);
+      return Vector (0.0, 0.0, 0.0);
     }
 
 }
diff --git a/src/mobility/rectangle.h b/src/mobility/rectangle.h
index df519b545..d61620960 100644
--- a/src/mobility/rectangle.h
+++ b/src/mobility/rectangle.h
@@ -22,8 +22,7 @@
 
 namespace ns3 {
 
-class Position;
-class Speed;
+class Vector;
 
 /**
  * \brief a 2d rectangle
@@ -51,9 +50,9 @@ public:
    * Create a zero-sized rectangle located at coordinates (0.0,0.0)
    */
   Rectangle ();
-  bool IsInside (const Position &position) const;
-  Side GetClosestSide (const Position &position) const;
-  Position CalculateIntersection (const Position &current, const Speed &speed) const;
+  bool IsInside (const Vector &position) const;
+  Side GetClosestSide (const Vector &position) const;
+  Vector CalculateIntersection (const Vector &current, const Vector &speed) const;
 
   double xMin;
   double xMax;
diff --git a/src/mobility/speed.cc b/src/mobility/speed.cc
deleted file mode 100644
index c6abd0c1d..000000000
--- a/src/mobility/speed.cc
+++ /dev/null
@@ -1,36 +0,0 @@
-/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2007 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>
- */
-#include "speed.h"
-
-namespace ns3 {
-
-Speed::Speed (double _dx, double _dy, double _dz)
-  : dx (_dx),
-    dy (_dy),
-    dz (_dz)
-{}
-
-Speed::Speed ()
-  : dx (0.0),
-    dy (0.0),
-    dz (0.0)
-{}
-
-} // namespace ns3
diff --git a/src/mobility/speed.h b/src/mobility/speed.h
deleted file mode 100644
index d64b1e63b..000000000
--- a/src/mobility/speed.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2007 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 SPEED_H
-#define SPEED_H
-
-namespace ns3 {
-
-/**
- * \brief keep track of 3d cartesian speed vectors
- *
- * Unit is meters/s.
- */
-class Speed 
-{
-public:
-  /**
-   * \param _dx x coordinate of speed vector
-   * \param _dy y coordinate of speed vector
-   * \param _dz z coordinate of speed vector
-   *
-   * Create speed vector (_dx, _dy, _dz)
-   */
-  Speed (double _dx, double _dy, double _dz);
-  /**
-   * Create speed vector (0.0, 0.0, 0.0)
-   */
-  Speed ();
-  /**
-   * x coordinate of speed vector
-   */
-  double dx;
-  /**
-   * y coordinate of speed vector
-   */
-  double dy;
-  /**
-   * z coordinate of speed vector
-   */
-  double dz;
-};
-
-} // namespace ns3
-
-#endif /* SPEED_H */
diff --git a/src/mobility/static-mobility-model.cc b/src/mobility/static-mobility-model.cc
index 7297640c8..4729e2c3f 100644
--- a/src/mobility/static-mobility-model.cc
+++ b/src/mobility/static-mobility-model.cc
@@ -28,7 +28,7 @@ StaticMobilityModel::StaticMobilityModel ()
 {
   SetInterfaceId (StaticMobilityModel::iid);
 }
-StaticMobilityModel::StaticMobilityModel (const Position &position)
+StaticMobilityModel::StaticMobilityModel (const Vector &position)
   : m_position (position)
 {
   SetInterfaceId (StaticMobilityModel::iid);
@@ -36,21 +36,21 @@ StaticMobilityModel::StaticMobilityModel (const Position &position)
 StaticMobilityModel::~StaticMobilityModel ()
 {}
 
-Position
+Vector
 StaticMobilityModel::DoGetPosition (void) const
 {
   return m_position;
 }
 void 
-StaticMobilityModel::DoSetPosition (const Position &position)
+StaticMobilityModel::DoSetPosition (const Vector &position)
 {
   m_position = position;
   NotifyCourseChange ();
 }
-Speed 
+Vector
 StaticMobilityModel::DoGetSpeed (void) const
 {
-  return Speed ();
+  return Vector (0.0, 0.0, 0.0);
 }
 
 }; // namespace ns3
diff --git a/src/mobility/static-mobility-model.h b/src/mobility/static-mobility-model.h
index 6caba0367..3143097ba 100644
--- a/src/mobility/static-mobility-model.h
+++ b/src/mobility/static-mobility-model.h
@@ -44,15 +44,15 @@ public:
    * Create a position located at coordinates (x,y,z).
    * Unit is meters
    */
-  StaticMobilityModel (const Position &position);
+  StaticMobilityModel (const Vector &position);
   virtual ~StaticMobilityModel ();
 
 private:
-  virtual Position DoGetPosition (void) const;
-  virtual void DoSetPosition (const Position &position);
-  virtual Speed DoGetSpeed (void) const;
+  virtual Vector DoGetPosition (void) const;
+  virtual void DoSetPosition (const Vector &position);
+  virtual Vector DoGetSpeed (void) const;
 
-  Position m_position;
+  Vector m_position;
 };
 
 }; // namespace ns3
diff --git a/src/mobility/static-speed-helper.cc b/src/mobility/static-speed-helper.cc
index b2d806ab8..9f91b87e2 100644
--- a/src/mobility/static-speed-helper.cc
+++ b/src/mobility/static-speed-helper.cc
@@ -25,40 +25,40 @@ namespace ns3 {
 
 StaticSpeedHelper::StaticSpeedHelper ()
 {}
-StaticSpeedHelper::StaticSpeedHelper (const Position &position)
+StaticSpeedHelper::StaticSpeedHelper (const Vector &position)
   : m_position (position)
 {}
-StaticSpeedHelper::StaticSpeedHelper (const Position &position,
-				      const Speed &speed)
+StaticSpeedHelper::StaticSpeedHelper (const Vector &position,
+				      const Vector &speed)
   : m_position (position),
     m_speed (speed),
     m_paused (true)
 {}
 void 
-StaticSpeedHelper::InitializePosition (const Position &position)
+StaticSpeedHelper::InitializePosition (const Vector &position)
 {
   m_position = position;
-  m_speed.dx = 0.0;
-  m_speed.dy = 0.0;
-  m_speed.dz = 0.0;
+  m_speed.x = 0.0;
+  m_speed.y = 0.0;
+  m_speed.z = 0.0;
   m_lastUpdate = Simulator::Now ();
   m_paused = true;
 }
 
-Position 
+Vector
 StaticSpeedHelper::GetCurrentPosition (void) const
 {
   Update ();
   return m_position;
 }
 
-Speed 
+Vector 
 StaticSpeedHelper::GetSpeed (void) const
 {
-  return m_paused? Speed (0, 0, 0) : m_speed;
+  return m_paused? Vector (0.0, 0.0, 0.0) : m_speed;
 }
 void 
-StaticSpeedHelper::SetSpeed (const Speed &speed)
+StaticSpeedHelper::SetSpeed (const Vector &speed)
 {
   Update ();
   m_speed = speed;
@@ -76,13 +76,13 @@ StaticSpeedHelper::Update (void) const
   Time deltaTime = now - m_lastUpdate;
   m_lastUpdate = now;
   double deltaS = deltaTime.GetSeconds ();
-  m_position.x += m_speed.dx * deltaS;
-  m_position.y += m_speed.dy * deltaS;
-  m_position.z += m_speed.dz * deltaS;
+  m_position.x += m_speed.x * deltaS;
+  m_position.y += m_speed.y * deltaS;
+  m_position.z += m_speed.z * deltaS;
 }
 
 void 
-StaticSpeedHelper::Reset (const Speed &speed)
+StaticSpeedHelper::Reset (const Vector &speed)
 {
   Update ();
   m_speed = speed;
@@ -98,7 +98,7 @@ StaticSpeedHelper::UpdateFull (const Rectangle &bounds) const
   m_position.y = std::max (bounds.yMin, m_position.y);
 }
 
-Position 
+Vector 
 StaticSpeedHelper::GetCurrentPosition (const Rectangle &bounds) const
 {
   UpdateFull (bounds);
diff --git a/src/mobility/static-speed-helper.h b/src/mobility/static-speed-helper.h
index 343898f22..b641ed626 100644
--- a/src/mobility/static-speed-helper.h
+++ b/src/mobility/static-speed-helper.h
@@ -21,8 +21,7 @@
 #define STATIC_SPEED_HELPER_H
 
 #include "ns3/nstime.h"
-#include "position.h"
-#include "speed.h"
+#include "vector.h"
 
 namespace ns3 {
 
@@ -32,16 +31,16 @@ class StaticSpeedHelper
 {
  public:
   StaticSpeedHelper ();
-  StaticSpeedHelper (const Position &position);
-  StaticSpeedHelper (const Position &position,
-		     const Speed &speed);
-  void InitializePosition (const Position &position);
+  StaticSpeedHelper (const Vector &position);
+  StaticSpeedHelper (const Vector &position,
+		     const Vector &speed);
+  void InitializePosition (const Vector &position);
 
-  void Reset (const Speed &speed);
-  Position GetCurrentPosition (const Rectangle &bounds) const;
-  Position GetCurrentPosition (void) const;
-  Speed GetSpeed (void) const;
-  void SetSpeed (const Speed &speed);
+  void Reset (const Vector &speed);
+  Vector GetCurrentPosition (const Rectangle &bounds) const;
+  Vector GetCurrentPosition (void) const;
+  Vector GetSpeed (void) const;
+  void SetSpeed (const Vector &speed);
   void Pause (void);
   void Unpause (void);
 
@@ -49,8 +48,8 @@ class StaticSpeedHelper
   void Update (void) const;
   void UpdateFull (const Rectangle &rectangle) const;
   mutable Time m_lastUpdate;
-  mutable Position m_position;
-  Speed m_speed;
+  mutable Vector m_position;
+  Vector m_speed;
   bool m_paused;
 };
 
diff --git a/src/mobility/static-speed-mobility-model.cc b/src/mobility/static-speed-mobility-model.cc
index c2c18ea2a..57e7e1e84 100644
--- a/src/mobility/static-speed-mobility-model.cc
+++ b/src/mobility/static-speed-mobility-model.cc
@@ -33,13 +33,13 @@ StaticSpeedMobilityModel::StaticSpeedMobilityModel ()
 {
   SetInterfaceId (StaticSpeedMobilityModel::iid);
 }
-StaticSpeedMobilityModel::StaticSpeedMobilityModel (const Position &position)
+StaticSpeedMobilityModel::StaticSpeedMobilityModel (const Vector &position)
   : m_helper (position)
 {
   SetInterfaceId (StaticSpeedMobilityModel::iid);
 }
-StaticSpeedMobilityModel::StaticSpeedMobilityModel (const Position &position,
-                                                    const Speed &speed)
+StaticSpeedMobilityModel::StaticSpeedMobilityModel (const Vector &position,
+                                                    const Vector &speed)
   : m_helper (position, speed)
 {
   SetInterfaceId (StaticSpeedMobilityModel::iid);
@@ -49,25 +49,25 @@ StaticSpeedMobilityModel::~StaticSpeedMobilityModel ()
 {}
 
 void 
-StaticSpeedMobilityModel::SetSpeed (const Speed speed)
+StaticSpeedMobilityModel::SetSpeed (const Vector &speed)
 {
   m_helper.SetSpeed (speed);
   NotifyCourseChange ();
 }
 
 
-Position
+Vector
 StaticSpeedMobilityModel::DoGetPosition (void) const
 {
   return m_helper.GetCurrentPosition ();
 }
 void 
-StaticSpeedMobilityModel::DoSetPosition (const Position &position)
+StaticSpeedMobilityModel::DoSetPosition (const Vector &position)
 {
   m_helper.InitializePosition (position);
   NotifyCourseChange ();
 }
-Speed 
+Vector
 StaticSpeedMobilityModel::DoGetSpeed (void) const
 {
   return m_helper.GetSpeed ();
diff --git a/src/mobility/static-speed-mobility-model.h b/src/mobility/static-speed-mobility-model.h
index d997d16f7..f6f1dbddb 100644
--- a/src/mobility/static-speed-mobility-model.h
+++ b/src/mobility/static-speed-mobility-model.h
@@ -25,7 +25,6 @@
 #include "ns3/nstime.h"
 #include "ns3/component-manager.h"
 #include "static-speed-helper.h"
-#include "speed.h"
 
 namespace ns3 {
 
@@ -48,15 +47,15 @@ public:
    * Create a position located at coordinates (x,y,z) with
    * speed (0,0,0).
    */
-  StaticSpeedMobilityModel (const Position &position);
+  StaticSpeedMobilityModel (const Vector &position);
   /**
    *
    * Create a position located at coordinates (x,y,z) with
    * speed (dx,dy,dz).
    * Unit is meters and meters/s
    */
-  StaticSpeedMobilityModel (const Position &position,
-                            const Speed &speed);
+  StaticSpeedMobilityModel (const Vector &position,
+                            const Vector &speed);
   virtual ~StaticSpeedMobilityModel ();
 
   /**
@@ -65,11 +64,11 @@ public:
    * Set the current speed now to (dx,dy,dz)
    * Unit is meters/s
    */
-  void SetSpeed (const Speed speed);
+  void SetSpeed (const Vector &speed);
 private:
-  virtual Position DoGetPosition (void) const;
-  virtual void DoSetPosition (const Position &position);
-  virtual Speed DoGetSpeed (void) const;
+  virtual Vector DoGetPosition (void) const;
+  virtual void DoSetPosition (const Vector &position);
+  virtual Vector DoGetSpeed (void) const;
   void Update (void) const;
   StaticSpeedHelper m_helper;
 };
diff --git a/src/mobility/wscript b/src/mobility/wscript
index 2833ce1e0..8b5256a77 100644
--- a/src/mobility/wscript
+++ b/src/mobility/wscript
@@ -8,12 +8,10 @@ def build(bld):
         'hierarchical-mobility-model.cc',
         'mobility-model.cc',
         'mobility-model-notifier.cc',
-        'position.cc',
         'random-position.cc',
         'random-topology.cc',
         'rectangle.cc',
         'rectangle-default-value.cc',
-        'speed.cc',
         'static-mobility-model.cc',
         'static-speed-helper.cc',
         'static-speed-mobility-model.cc',
@@ -30,12 +28,10 @@ def build(bld):
         'hierarchical-mobility-model.h',
         'mobility-model.h',
         'mobility-model-notifier.h',
-        'position.h',
         'random-position.h',
         'random-topology.h',
         'rectangle.h',
         'rectangle-default-value.h',
-        'speed.h',
         'static-mobility-model.h',
         'static-speed-helper.h',
         'static-speed-mobility-model.h',
diff --git a/utils/mobility-visualizer-model.cc b/utils/mobility-visualizer-model.cc
index 94f46538c..b3c7773d3 100644
--- a/utils/mobility-visualizer-model.cc
+++ b/utils/mobility-visualizer-model.cc
@@ -48,15 +48,15 @@ Sample ()
     {
       Ptr<Node> node = *nodeIter;
       Ptr<MobilityModel> mobility = node->QueryInterface<MobilityModel> (MobilityModel::iid);
-      Position pos = mobility->GetPosition ();
-      Speed vel = mobility->GetSpeed ();
+      Vector pos = mobility->GetPosition ();
+      Vector vel = mobility->GetSpeed ();
 
       NodeUpdate update;
       update.node = PeekPointer<Node> (node);
       update.x = pos.x;
       update.y = pos.y;
-      update.vx = vel.dx;
-      update.vy = vel.dy;
+      update.vx = vel.x;
+      update.vy = vel.y;
       data->updateList.push_back (update);
     }
   data->time = Simulator::Now ().GetSeconds ();