--- a/src/devices/wifi/edca-txop-n.cc	Fri Jan 08 18:04:01 2010 +0100
+++ b/src/devices/wifi/edca-txop-n.cc	Mon Jan 11 12:23:09 2010 +0300
@@ -686,5 +686,11 @@
 {
   m_aggregator = aggr;
 }
-
+void
+EdcaTxopN::DoStart ()
+{
+  m_dcf->ResetCw ();
+  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));
+  ns3::Dcf::DoStart ();
+}
 } //namespace ns3