diff -r 24667d1f463f src/uan/model/uan-mac-cw.cc
--- a/src/uan/model/uan-mac-cw.cc	Fri Mar 09 14:18:54 2018 +0100
+++ b/src/uan/model/uan-mac-cw.cc	Fri Mar 09 15:47:24 2018 +0100
@@ -35,10 +35,11 @@
 
 UanMacCw::UanMacCw ()
   : UanMac (),
-    m_phy (0),
-    m_pktTx (0),
-    m_state (IDLE),
-    m_cleared (false)
+  m_phy (0),
+  m_pktTx (0),
+  m_state (IDLE),
+  m_txNotified (false),
+  m_cleared (false)
 
 {
   m_rv = CreateObject<UniformRandomVariable> ();
@@ -63,7 +64,7 @@
       m_phy = 0;
     }
   m_sendEvent.Cancel ();
-  m_txEndEvent.Cancel ();
+  m_txNotified = false;
 }
 
 void
@@ -115,7 +116,7 @@
     {
     case CCABUSY:
       NS_LOG_DEBUG ("Time " << Simulator::Now ().GetSeconds () << " MAC " << GetAddress () << " Starting enqueue CCABUSY");
-      if (m_txEndEvent.IsRunning ())
+      if (m_txNotified == true)
         {
           NS_LOG_DEBUG ("State is TX");
         }
@@ -253,14 +254,10 @@
 void
 UanMacCw::NotifyTxStart (Time duration)
 {
+  m_txNotified = true;
 
-  if (m_txEndEvent.IsRunning ())
-    {
-      Simulator::Cancel (m_txEndEvent);
-    }
+  NS_LOG_DEBUG ("Time " << Simulator::Now ().GetSeconds () << " Tx Start Notified");
 
-  m_txEndEvent = Simulator::Schedule (duration, &UanMacCw::EndTx, this);
-  NS_LOG_DEBUG ("Time " << Simulator::Now ().GetSeconds () << " scheduling TxEndEvent with delay " << duration.GetSeconds ());
   if (m_state == RUNNING)
     {
       NS_ASSERT (0);
@@ -271,6 +268,14 @@
 
 }
 
+void
+UanMacCw::NotifyTxEnd (void)
+{
+  EndTx ();
+
+  m_txNotified = false;
+}
+
 int64_t
 UanMacCw::AssignStreams (int64_t stream)
 {
diff -r 24667d1f463f src/uan/model/uan-mac-cw.h
--- a/src/uan/model/uan-mac-cw.h	Fri Mar 09 14:18:54 2018 +0100
+++ b/src/uan/model/uan-mac-cw.h	Fri Mar 09 15:47:24 2018 +0100
@@ -59,7 +59,7 @@
 
   /**
    * Set the contention window size.
-   *   
+   *
    * \param cw Contention window size.
    */
   virtual void SetCw (uint32_t cw);
@@ -96,6 +96,7 @@
   virtual void NotifyCcaStart (void);
   virtual void NotifyCcaEnd (void);
   virtual void NotifyTxStart (Time duration);
+  virtual void NotifyTxEnd (void);
 
   /**
    *  TracedCallback signature for enqueue/dequeue of a packet.
@@ -103,12 +104,12 @@
    * \param [in] packet The Packet being received.
    * \param [in] proto The protocol number.
    */
-  typedef void (* QueueTracedCallback)
-    (Ptr<const Packet> packet, uint16_t proto);
+  typedef void (* QueueTracedCallback)(Ptr<const Packet> packet, uint16_t proto);
 
 private:
   /** Enum defining possible Phy states. */
-  typedef enum {
+  typedef enum
+  {
     IDLE,     //!< Idle state.
     CCABUSY,  //!< Channel busy.
     RUNNING,  //!< Delay timer running.
@@ -143,8 +144,8 @@
   uint16_t m_pktTxProt;
   /** Scheduled SendPacket event. */
   EventId m_sendEvent;
-  /** Scheduled EndTx event. */
-  EventId m_txEndEvent;
+  /** Tx has been notified from Phy. */
+  bool m_txNotified;
   /** Current state. */
   State m_state;
 
diff -r 24667d1f463f src/uan/model/uan-phy-gen.cc
--- a/src/uan/model/uan-phy-gen.cc	Fri Mar 09 14:18:54 2018 +0100
+++ b/src/uan/model/uan-phy-gen.cc	Fri Mar 09 15:47:24 2018 +0100
@@ -149,17 +149,17 @@
       if (std::abs (pit->GetAmp ()) > maxAmp)
         {
           maxAmp = std::abs (pit->GetAmp ());
-          // Modified in order to subtract delay of first tap (maxTapDelay appears to be used later in code 
+          // Modified in order to subtract delay of first tap (maxTapDelay appears to be used later in code
           // as delay from first reception, not from TX time)
-          maxTapDelay = pit->GetDelay ().GetSeconds () - pdp.GetTap(0).GetDelay().GetSeconds();
+          maxTapDelay = pit->GetDelay ().GetSeconds () - pdp.GetTap (0).GetDelay ().GetSeconds ();
         }
     }
 
 
   double effRxPowerDb = rxPowerDb + KpToDb (csp);
-  //It appears to be just the first elements of the sum in Parrish paper, 
+  //It appears to be just the first elements of the sum in Parrish paper,
   // "System Design Considerations for Undersea Networks: Link and Multiple Access Protocols", eq. 14
-  double isiUpa = DbToKp(rxPowerDb) * pdp.SumTapsFromMaxNc (Seconds (ts + clearingTime), Seconds (ts)); // added DpToKp()
+  double isiUpa = DbToKp (rxPowerDb) * pdp.SumTapsFromMaxNc (Seconds (ts + clearingTime), Seconds (ts)); // added DpToKp()
   UanTransducer::ArrivalList::const_iterator it = arrivalList.begin ();
   double intKp = -DbToKp (effRxPowerDb);
   for (; it != arrivalList.end (); it++)
@@ -493,17 +493,17 @@
 /*************** UanPhyGen definition *****************/
 UanPhyGen::UanPhyGen ()
   : UanPhy (),
-    m_state (IDLE),
-    m_channel (0),
-    m_transducer (0),
-    m_device (0),
-    m_mac (0),
-    m_txPwrDb (0),
-    m_rxThreshDb (0),
-    m_ccaThreshDb (0),
-    m_pktRx (0),
-    m_pktTx (0),
-    m_cleared (false)
+  m_state (IDLE),
+  m_channel (0),
+  m_transducer (0),
+  m_device (0),
+  m_mac (0),
+  m_txPwrDb (0),
+  m_rxThreshDb (0),
+  m_ccaThreshDb (0),
+  m_pktRx (0),
+  m_pktTx (0),
+  m_cleared (false)
 {
   m_pg = CreateObject<UniformRandomVariable> ();
 
@@ -741,6 +741,8 @@
       m_state = IDLE;
     }
   UpdatePowerConsumption (IDLE);
+
+  NotifyListenersTxEnd ();
 }
 
 void
@@ -1004,13 +1006,13 @@
 UanPhyGen::SetSleepMode (bool sleep )
 {
   if (sleep )
-  {
-    m_state = SLEEP;
-    if (!m_energyCallback.IsNull ())
-      {
-        m_energyCallback (SLEEP);
-      }
-  }
+    {
+      m_state = SLEEP;
+      if (!m_energyCallback.IsNull ())
+        {
+          m_energyCallback (SLEEP);
+        }
+    }
   else if (m_state == SLEEP)
     {
       if (GetInterferenceDb ((Ptr<Packet>) 0) > m_ccaThreshDb)
@@ -1155,6 +1157,16 @@
     }
 }
 
+void
+UanPhyGen::NotifyListenersTxEnd (void)
+{
+  ListenerList::const_iterator it = m_listeners.begin ();
+  for (; it != m_listeners.end (); it++)
+    {
+      (*it)->NotifyTxEnd ();
+    }
+}
+
 uint32_t
 UanPhyGen::GetNModes (void)
 {
diff -r 24667d1f463f src/uan/model/uan-phy-gen.h
--- a/src/uan/model/uan-phy-gen.h	Fri Mar 09 14:18:54 2018 +0100
+++ b/src/uan/model/uan-phy-gen.h	Fri Mar 09 15:47:24 2018 +0100
@@ -215,10 +215,10 @@
  * clearing time between symbols transmitted on the same frequency.
  * This clearing time combats ISI from channel delay spread and also has
  * a byproduct of possibly reducing interference from other transmitted packets.
- * 
- * Thanks to Randall Plate for the latest model revision based on the following 
+ *
+ * Thanks to Randall Plate for the latest model revision based on the following
  * papers:
- * <ul> 
+ * <ul>
  * <li>Parrish, "System Design Considerations for Undersea Networks: Link and Multiple Access Protocols"
  * <li>Siderius, "Effects of Ocean Thermocline Variability on Noncoherent Underwater Acoustic Communications"
  * <li>Rao, "Channel Coding Techniques for Wireless Communications", ch 2
@@ -442,6 +442,10 @@
    * \param duration Duration of transmission.
    */
   void NotifyListenersTxStart (Time duration);
+  /**
+   * Call UanListener::NotifyTxEnd on all listeners.
+   */
+  void NotifyListenersTxEnd (void);
 
 protected:
   virtual void DoDispose ();
diff -r 24667d1f463f src/uan/model/uan-phy.h
--- a/src/uan/model/uan-phy.h	Fri Mar 09 14:18:54 2018 +0100
+++ b/src/uan/model/uan-phy.h	Fri Mar 09 15:47:24 2018 +0100
@@ -96,7 +96,7 @@
 
 protected:
   virtual void DoDispose (void);
-  
+
 };  // class UanPhyCalcSinr
 
 /**
@@ -147,7 +147,9 @@
 {
 public:
   /** Default destructor */
-  virtual ~UanPhyListener () { }
+  virtual ~UanPhyListener ()
+  {
+  }
   /** Called when UanPhy begins receiving packet. */
   virtual void NotifyRxStart (void) = 0;
   /** Called when UanPhy finishes receiving packet without error. */
@@ -164,7 +166,8 @@
    * \param duration Duration of transmission.
    */
   virtual void NotifyTxStart (Time duration) = 0;
-
+  /** Function called when Phy object finishes transmitting packet */
+  virtual void NotifyTxEnd (void) = 0;
 };  // class UanPhyListener
 
 /**
@@ -210,13 +213,12 @@
    * \param [in] sinr The SINR.
    * \param [in] mode The channel mode.
    */
-  typedef void (* TracedCallback)
-    (Ptr<const Packet> pkt, double sinr, UanTxMode mode);
+  typedef void (* TracedCallback)(Ptr<const Packet> pkt, double sinr, UanTxMode mode);
+
 
-  
   /**
-   * Set the DeviceEnergyModel callback for UanPhy device. 
-   * 
+   * Set the DeviceEnergyModel callback for UanPhy device.
+   *
    * \param callback The DeviceEnergyModel change state callback.
    */
   virtual void SetEnergyModelCallback (DeviceEnergyModel::ChangeStateCallback callback) = 0;
@@ -487,14 +489,14 @@
    */
   void NotifyRxDrop (Ptr<const Packet> packet);
 
- /**
-  * Assign a fixed random variable stream number to the random variables
-  * used by this model.  Return the number of streams (possibly zero) that
-  * have been assigned.
-  *
-  * \param stream First stream index to use.
-  * \return The number of stream indices assigned by this model.
-  */
+  /**
+   * Assign a fixed random variable stream number to the random variables
+   * used by this model.  Return the number of streams (possibly zero) that
+   * have been assigned.
+   *
+   * \param stream First stream index to use.
+   * \return The number of stream indices assigned by this model.
+   */
   virtual int64_t AssignStreams (int64_t stream) = 0;
 
   /**