--- a/src/devices/wifi/edca-txop-n.cc	Thu Feb 25 22:45:40 2010 +0300
+++ b/src/devices/wifi/edca-txop-n.cc	Fri Feb 26 12:11:11 2010 +0300
@@ -1080,5 +1080,11 @@
 
   PushFront (packet, hdr);
 }
-
+void
+EdcaTxopN::DoStart ()
+{
+  m_dcf->ResetCw ();
+  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));
+  ns3::Dcf::DoStart ();
+}
 } //namespace ns3