--- a/src/devices/wifi/propagation-delay-model.cc	Thu Oct 11 13:27:39 2007 +0200
+++ b/src/devices/wifi/propagation-delay-model.cc	Thu Oct 11 15:43:47 2007 +0200
@@ -1,10 +1,55 @@
 #include "propagation-delay-model.h"
 #include "ns3/random-variable.h"
+#include "ns3/default-value.h"
+#include "ns3/random-variable-default-value.h"
 
 namespace ns3 {
 
+enum ModelType
+{
+  RANDOM,
+  CONSTANT_SPEED
+};
+
+static EnumDefaultValue<enum ModelType> g_modelType
+("PropagationDelayModelType",
+ "The type of propagation delay model to use.",
+ CONSTANT_SPEED, "ConstantSpeed",
+ RANDOM, "Random");
+
+static NumericDefaultValue<double> g_speed
+("PropagationDelayConstantSpeed",
+ "The speed (m/s) of propagation if a ConstantSpeed propagation delay model is used.",
+ 300000000.0);
+
+static RandomVariableDefaultValue g_random
+("PropagationDelayRandomDistribution", 
+ "The delay distribution to use if a Random propagation delay model is used.",
+ "Uniform:0:1.0");
+
+
 PropagationDelayModel::~PropagationDelayModel ()
 {}
+Ptr<PropagationDelayModel> 
+PropagationDelayModel::CreateDefault (void)
+{
+  switch (g_modelType.GetValue ()) {
+  case CONSTANT_SPEED:
+    return Create<ConstantSpeedPropagationDelayModel> (g_speed.GetValue ());
+    break;
+  case RANDOM:
+    return Create<RandomPropagationDelayModel> ();
+    break;
+  default:
+    NS_ASSERT (false);
+    return 0;
+    break;
+  }
+}
+
+RandomPropagationDelayModel::RandomPropagationDelayModel ()
+  : m_variable (g_random.GetCopy ())
+{}
 
 RandomPropagationDelayModel::RandomPropagationDelayModel (const RandomVariable &variable)
   : m_variable (variable.Copy ())
@@ -19,9 +64,6 @@
   return Seconds (m_variable->GetValue ());
 }
 
-ConstantSpeedPropagationDelayModel::ConstantSpeedPropagationDelayModel ()
-  : m_speed (300000000.0)
-{}
 ConstantSpeedPropagationDelayModel::ConstantSpeedPropagationDelayModel (double speed)
   : m_speed (speed)
 {}