--- a/src/devices/wifi/edca-txop-n.cc	Wed Feb 03 20:34:51 2010 +0100
+++ b/src/devices/wifi/edca-txop-n.cc	Wed Feb 03 20:34:52 2010 +0100
@@ -87,6 +87,9 @@
   virtual void GotBlockAck (const CtrlBAckResponseHeader *blockAck, Mac48Address source) {
     m_txop->GotBlockAck (blockAck, source);
   }
+  virtual void MissedBlockAck (void) {
+    m_txop->MissedBlockAck ();
+  }
   virtual void StartNext (void) {
     m_txop->StartNext ();
   }
@@ -507,6 +510,20 @@
   RestartAccessIfNeeded ();
 }
 
+void
+EdcaTxopN::MissedBlockAck (void)
+{
+  NS_LOG_FUNCTION (this);
+  MY_DEBUG ("missed block ack");
+  
+  MY_DEBUG ("Retransmit block ack request");
+  m_currentHdr.SetRetry ();
+  m_dcf->UpdateFailedCw ();
+  
+  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));
+  RestartAccessIfNeeded ();
+}
+
 Ptr<MsduAggregator>
 EdcaTxopN::GetMsduAggregator (void) const
 {