diff -r 2c4e9171497e src/devices/wifi/dcf-manager.cc
--- a/src/devices/wifi/dcf-manager.cc	Sat Feb 27 12:26:36 2010 +0300
+++ b/src/devices/wifi/dcf-manager.cc	Sat Feb 27 17:14:13 2010 +0300
@@ -228,20 +228,20 @@
  ****************************************************************/
 
 DcfManager::DcfManager ()
-  : m_lastAckTimeoutEnd (MicroSeconds (0)),
-    m_lastCtsTimeoutEnd (MicroSeconds (0)),
-    m_lastNavStart (MicroSeconds (0)),
-    m_lastNavDuration (MicroSeconds (0)),
-    m_lastRxStart (MicroSeconds (0)),
-    m_lastRxDuration (MicroSeconds (0)),
+  : m_lastAckTimeoutEnd (0),
+    m_lastCtsTimeoutEnd (0),
+    m_lastNavStart (0),
+    m_lastNavDuration (0),
+    m_lastRxStart (0),
+    m_lastRxDuration (0),
     m_lastRxReceivedOk (true),
-    m_lastRxEnd (MicroSeconds (0)),
-    m_lastTxStart (MicroSeconds (0)),
-    m_lastTxDuration (MicroSeconds (0)),
-    m_lastBusyStart (MicroSeconds (0)),
-    m_lastBusyDuration (MicroSeconds (0)),
-    m_lastSwitchingStart (MicroSeconds (0)), 
-    m_lastSwitchingDuration (MicroSeconds (0)), 
+    m_lastRxEnd (0),
+    m_lastTxStart (0),
+    m_lastTxDuration (0),
+    m_lastBusyStart (0),
+    m_lastBusyDuration (0),
+    m_lastSwitchingStart (0), 
+    m_lastSwitchingDuration (0), 
     m_rxing (false),
     m_slotTimeUs (0),
     m_sifs (Seconds (0.0)),
@@ -340,23 +340,34 @@
   Time retval = Max (k, l);
   return retval;
 }
+uint64_t
+DcfManager::Maximum (uint64_t a, uint64_t b, uint64_t c, uint64_t d, uint64_t e, uint64_t f, uint64_t g) const
+{
+  uint64_t h = a > b ? a : b;
+  uint64_t i = c > d ? c: d;
+  uint64_t j = e > f ? e : f;
+  uint64_t k = h > i ? h : i;
+  uint64_t l = j > g ? j : g;
+  return (k > l ? k : l);
+}
 
 bool 
 DcfManager::IsBusy (void) const
 {
   // PHY busy
+  uint64_t now = Simulator::Now ().GetNanoSeconds ();
   if (m_rxing) 
     {
       return true;
     }
-  Time lastTxEnd = m_lastTxStart + m_lastTxDuration;
-  if (lastTxEnd > Simulator::Now ()) 
+  uint64_t lastTxEnd = m_lastTxStart + m_lastTxDuration;
+  if (lastTxEnd > now) 
     {
       return true;
     }
   // NAV busy
-  Time lastNavEnd = m_lastNavStart + m_lastNavDuration;
-  if (lastNavEnd > Simulator::Now ())
+  uint64_t lastNavEnd = m_lastNavStart + m_lastNavDuration;
+  if (lastNavEnd > now)
     {
       return true;
     }
@@ -454,39 +465,40 @@
 Time
 DcfManager::GetAccessGrantStart (void) const
 {
-  Time rxAccessStart;
+  uint64_t rxAccessStart;
+  uint64_t sifsNanoSeconds = m_sifs.GetNanoSeconds ();
   if (!m_rxing) 
     {
-      rxAccessStart = m_lastRxEnd + m_sifs;
+      rxAccessStart = m_lastRxEnd + sifsNanoSeconds;
       if (!m_lastRxReceivedOk)
         {
-          rxAccessStart += m_eifsNoDifs;
+          rxAccessStart += m_eifsNoDifs.GetNanoSeconds ();
         }
     } 
   else 
     {
-      rxAccessStart = m_lastRxStart + m_lastRxDuration + m_sifs;
+      rxAccessStart = m_lastRxStart + m_lastRxDuration + m_sifs.GetNanoSeconds ();
     }
-  Time busyAccessStart = m_lastBusyStart + m_lastBusyDuration + m_sifs;
-  Time txAccessStart = m_lastTxStart + m_lastTxDuration + m_sifs;
-  Time navAccessStart = m_lastNavStart + m_lastNavDuration + m_sifs;
-  Time ackTimeoutAccessStart = m_lastAckTimeoutEnd + m_sifs;
-  Time ctsTimeoutAccessStart = m_lastCtsTimeoutEnd + m_sifs;
-  Time switchingAccessStart = m_lastSwitchingStart + m_lastSwitchingDuration + m_sifs; 
-  Time accessGrantedStart = MostRecent (rxAccessStart, 
-                                        busyAccessStart,
-                                        txAccessStart, 
-                                        navAccessStart,
-                                        ackTimeoutAccessStart,
-                                        ctsTimeoutAccessStart,
-                                        switchingAccessStart 
-                                        );
+  uint64_t busyAccessStart = m_lastBusyStart + m_lastBusyDuration + sifsNanoSeconds;
+  uint64_t txAccessStart = m_lastTxStart + m_lastTxDuration + sifsNanoSeconds;
+  uint64_t navAccessStart = m_lastNavStart + m_lastNavDuration + sifsNanoSeconds;
+  uint64_t ackTimeoutAccessStart = m_lastAckTimeoutEnd + sifsNanoSeconds;
+  uint64_t ctsTimeoutAccessStart = m_lastCtsTimeoutEnd + sifsNanoSeconds;
+  uint64_t switchingAccessStart = m_lastSwitchingStart + m_lastSwitchingDuration + sifsNanoSeconds; 
+  uint64_t accessGrantedStart = Maximum (rxAccessStart, 
+                                          busyAccessStart,
+                                          txAccessStart, 
+                                          navAccessStart,
+                                          ackTimeoutAccessStart,
+                                          ctsTimeoutAccessStart,
+                                          switchingAccessStart 
+                                          );
   NS_LOG_INFO ("access grant start=" << accessGrantedStart <<
                ", rx access start=" << rxAccessStart <<
                ", busy access start=" << busyAccessStart <<
                ", tx access start=" << txAccessStart <<
                ", nav access start=" << navAccessStart);
-  return accessGrantedStart;
+  return NanoSeconds (accessGrantedStart);
 }
 
 Time
@@ -569,15 +581,15 @@
 {
   MY_DEBUG ("rx start for="<<duration);
   UpdateBackoff ();
-  m_lastRxStart = Simulator::Now ();
-  m_lastRxDuration = duration;
+  m_lastRxStart = Simulator::Now ().GetNanoSeconds ();
+  m_lastRxDuration = duration.GetNanoSeconds ();
   m_rxing = true;
 }
 void 
 DcfManager::NotifyRxEndOkNow (void)
 {
   MY_DEBUG ("rx end ok");
-  m_lastRxEnd = Simulator::Now ();
+  m_lastRxEnd = Simulator::Now ().GetNanoSeconds ();
   m_lastRxReceivedOk = true;
   m_rxing = false;
 }
@@ -585,7 +597,7 @@
 DcfManager::NotifyRxEndErrorNow (void)
 {
   MY_DEBUG ("rx end error");
-  m_lastRxEnd = Simulator::Now ();
+  m_lastRxEnd = Simulator::Now ().GetNanoSeconds ();
   m_lastRxReceivedOk = false;
   m_rxing = false;
 }
@@ -597,38 +609,38 @@
       //this may be caused only if PHY has started to receive a packet
       //inside SIFS, so, we check that lastRxStart was maximum a SIFS
       //ago
-      NS_ASSERT (Simulator::Now () - m_lastRxStart <= m_sifs);
-      m_lastRxEnd = Simulator::Now ();
+      NS_ASSERT (Simulator::Now () - NanoSeconds (m_lastRxStart) <= m_sifs);
+      m_lastRxEnd = Simulator::Now ().GetNanoSeconds ();
       m_lastRxDuration = m_lastRxEnd - m_lastRxStart;
       m_lastRxReceivedOk = true;
       m_rxing = false;
     }
   MY_DEBUG ("tx start for "<<duration);
   UpdateBackoff ();
-  m_lastTxStart = Simulator::Now ();
-  m_lastTxDuration = duration;
+  m_lastTxStart = Simulator::Now ().GetNanoSeconds ();
+  m_lastTxDuration = duration.GetNanoSeconds ();
 }
 void 
 DcfManager::NotifyMaybeCcaBusyStartNow (Time duration)
 {
   MY_DEBUG ("busy start for "<<duration);
   UpdateBackoff ();
-  m_lastBusyStart = Simulator::Now ();
-  m_lastBusyDuration = duration;
+  m_lastBusyStart = Simulator::Now ().GetNanoSeconds ();
+  m_lastBusyDuration = duration.GetNanoSeconds ();
 }
 
 
 void 
 DcfManager::NotifySwitchingStartNow (Time duration)
 {
-  Time now = Simulator::Now ();
+  uint64_t now = Simulator::Now ().GetNanoSeconds ();
   NS_ASSERT (m_lastTxStart + m_lastTxDuration <= now);
   NS_ASSERT (m_lastSwitchingStart + m_lastSwitchingDuration <= now);
 
   if (m_rxing)
     {
       // channel switching during packet reception
-      m_lastRxEnd = Simulator::Now ();
+      m_lastRxEnd = Simulator::Now ().GetNanoSeconds ();
       m_lastRxDuration = m_lastRxEnd - m_lastRxStart;
       m_lastRxReceivedOk = true;
       m_rxing = false;
@@ -663,7 +675,7 @@
       uint32_t remainingSlots = state->GetBackoffSlots ();
       if (remainingSlots > 0) 
         {
-          state->UpdateBackoffSlotsNow (remainingSlots, now);
+          state->UpdateBackoffSlotsNow (remainingSlots, NanoSeconds(now));
           NS_ASSERT(state->GetBackoffSlots()==0);
         }
       state->ResetCw();
@@ -672,8 +684,8 @@
     } 
  
   MY_DEBUG ("switching start for "<<duration);
-  m_lastSwitchingStart = Simulator::Now ();
-  m_lastSwitchingDuration = duration;
+  m_lastSwitchingStart = Simulator::Now ().GetNanoSeconds ();
+  m_lastSwitchingDuration = duration.GetNanoSeconds ();
 
 }
 
@@ -682,8 +694,8 @@
 {
   MY_DEBUG ("nav reset for="<<duration);
   UpdateBackoff ();
-  m_lastNavStart = Simulator::Now ();
-  m_lastNavDuration = duration;
+  m_lastNavStart = Simulator::Now ().GetNanoSeconds ();
+  m_lastNavDuration = duration.GetNanoSeconds ();
   UpdateBackoff ();
   /**
    * If the nav reset indicates an end-of-nav which is earlier
@@ -696,38 +708,38 @@
 void 
 DcfManager::NotifyNavStartNow (Time duration)
 {
-  NS_ASSERT (m_lastNavStart < Simulator::Now ());
+  NS_ASSERT (NanoSeconds (m_lastNavStart) < Simulator::Now ());
   MY_DEBUG ("nav start for="<<duration);
   UpdateBackoff ();
-  Time newNavEnd = Simulator::Now () + duration;
-  Time lastNavEnd = m_lastNavStart + m_lastNavDuration;
+  uint64_t newNavEnd = (Simulator::Now () + duration).GetNanoSeconds ();
+  uint64_t lastNavEnd = m_lastNavStart + m_lastNavDuration;
   if (newNavEnd > lastNavEnd)
     {
-      m_lastNavStart = Simulator::Now ();
-      m_lastNavDuration = duration;
+      m_lastNavStart = Simulator::Now ().GetNanoSeconds ();
+      m_lastNavDuration = duration.GetNanoSeconds ();
     }
 }
 void
 DcfManager::NotifyAckTimeoutStartNow (Time duration)
 {
-  NS_ASSERT(m_lastAckTimeoutEnd < Simulator::Now ());
-  m_lastAckTimeoutEnd = Simulator::Now () + duration;
+  NS_ASSERT(NanoSeconds(m_lastAckTimeoutEnd) < Simulator::Now ());
+  m_lastAckTimeoutEnd = (Simulator::Now () + duration).GetNanoSeconds ();
 }
 void
 DcfManager::NotifyAckTimeoutResetNow ()
 {
-  m_lastAckTimeoutEnd = Simulator::Now ();
+  m_lastAckTimeoutEnd = Simulator::Now ().GetNanoSeconds ();
   DoRestartAccessTimeoutIfNeeded ();
 }
 void
 DcfManager::NotifyCtsTimeoutStartNow (Time duration)
 {
-  m_lastCtsTimeoutEnd = Simulator::Now () + duration;
+  m_lastCtsTimeoutEnd = (Simulator::Now () + duration).GetNanoSeconds ();
 }
 void
 DcfManager::NotifyCtsTimeoutResetNow ()
 {
-  m_lastCtsTimeoutEnd = Simulator::Now ();
+  m_lastCtsTimeoutEnd = Simulator::Now ().GetNanoSeconds ();
   DoRestartAccessTimeoutIfNeeded ();
 }
 } // namespace ns3
diff -r 2c4e9171497e src/devices/wifi/dcf-manager.h
--- a/src/devices/wifi/dcf-manager.h	Sat Feb 27 12:26:36 2010 +0300
+++ b/src/devices/wifi/dcf-manager.h	Sat Feb 27 17:14:13 2010 +0300
@@ -287,6 +287,7 @@
   Time MostRecent (Time a, Time b, Time c, Time d) const;
   Time MostRecent (Time a, Time b, Time c, Time d, Time e, Time f) const;
   Time MostRecent (Time a, Time b, Time c, Time d, Time e, Time f, Time g) const; 
+  uint64_t Maximum (uint64_t a, uint64_t b, uint64_t c, uint64_t d, uint64_t e, uint64_t f, uint64_t g) const;
   /**
    * Access will never be granted to the medium _before_
    * the time returned by this method.
@@ -305,20 +306,20 @@
   typedef std::vector<DcfState *> States;
 
   States m_states;
-  Time m_lastAckTimeoutEnd;
-  Time m_lastCtsTimeoutEnd;
-  Time m_lastNavStart;
-  Time m_lastNavDuration;
-  Time m_lastRxStart;
-  Time m_lastRxDuration;
+  uint64_t m_lastAckTimeoutEnd;
+  uint64_t m_lastCtsTimeoutEnd;
+  uint64_t m_lastNavStart;
+  uint64_t m_lastNavDuration;
+  uint64_t m_lastRxStart;
+  uint64_t m_lastRxDuration;
   bool m_lastRxReceivedOk;
-  Time m_lastRxEnd;
-  Time m_lastTxStart;
-  Time m_lastTxDuration;
-  Time m_lastBusyStart;
-  Time m_lastBusyDuration;
-  Time m_lastSwitchingStart; 
-  Time m_lastSwitchingDuration; 
+  uint64_t m_lastRxEnd;
+  uint64_t m_lastTxStart;
+  uint64_t m_lastTxDuration;
+  uint64_t m_lastBusyStart;
+  uint64_t m_lastBusyDuration;
+  uint64_t m_lastSwitchingStart; 
+  uint64_t m_lastSwitchingDuration; 
   bool m_rxing;
   bool m_sleeping;
   Time m_eifsNoDifs;