spectrum: ThreeGppChannelModel is adapted so it can be inherited and GetNewChannel virtual

src/spectrum/model/three-gpp-channel-model.cc

@@ -275,7 +275,6 @@ TypeId
 ThreeGppChannelModel::GetTypeId (void)
 {
   static TypeId tid = TypeId ("ns3::ThreeGppChannelModel")
-    .SetParent<Object> ()
     .SetGroupName ("Spectrum")
     .SetParent<MatrixBasedChannelModel> ()
     .AddConstructor<ThreeGppChannelModel> ()

src/spectrum/model/three-gpp-channel-model.h

@@ -138,8 +138,8 @@ public:
    * \return the number of stream indices assigned by this model
    */
   int64_t AssignStreams (int64_t stream);
-
-private:
+  
+protected:
   /**
    * Wrap an (azimuth, inclination) angle pair in a valid range.
    * Specifically, inclination must be in [0, M_PI] and azimuth in [0, 2*M_PI).
@@ -277,7 +277,7 @@ private:
    * \return the channel realization
    */
 
-  Ptr<ChannelMatrix> GetNewChannel (Ptr<const ThreeGppChannelParams> channelParams,
+  virtual Ptr<ChannelMatrix> GetNewChannel (Ptr<const ThreeGppChannelParams> channelParams,
                                     Ptr<const ParamsTable> table3gpp,
                                     const Ptr<const MobilityModel> sMob,
                                     const Ptr<const MobilityModel> uMob,

src/spectrum/model/three-gpp-spectrum-propagation-loss-model.cc

@@ -25,7 +25,6 @@
 #include "three-gpp-spectrum-propagation-loss-model.h"
 #include "ns3/net-device.h"
 #include "ns3/node.h"
-#include "ns3/channel-condition-model.h"
 #include "ns3/double.h"
 #include "ns3/string.h"
 #include "ns3/simulator.h"

src/spectrum/model/three-gpp-spectrum-propagation-loss-model.h

@@ -32,8 +32,6 @@
 namespace ns3 {
 
 class NetDevice;
-class ChannelConditionModel;
-class ChannelCondition;
 
 /**
  * \ingroup spectrum