--- a/src/lte/model/lte-ue-phy.cc	Sun Jul 29 20:32:28 2012 +0200
+++ b/src/lte/model/lte-ue-phy.cc	Tue Jul 31 12:57:55 2012 +0200
@@ -154,6 +154,8 @@
   std::vector <int> ulRb;
   m_subChannelsForTransmissionQueue.resize (m_macChTtiDelay, ulRb);
 
+  NS_ASSERT_MSG (Simulator::Now ().GetNanoSeconds () == 0,
+                 "Cannot create UE devices after simulation started");
   Simulator::ScheduleNow (&LteUePhy::SubframeIndication, this, 1, 1);
 }