diff --git a/CHANGES.md b/CHANGES.md
index 68a59e26d..0fdd75d24 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -31,6 +31,7 @@ application model is added.
 Applications have a new Attribute to set the IPv4 ToS field.
 * (core) Deprecated enum `TestDuration` in `TestCase` class. It has been replaced by enum class `Duration`.
 * (core) In `TestSuite` class, deprecated `ALL`, `UNIT`, `SYSTEM`, `EXAMPLE` and `PERFORMANCE`. They have been replaced by `Type::ALL`, `Type::UNIT`, `Type::SYSTEM`, `Type::EXAMPLE` and `Type::PERFORMANCE`, respectively.
+* (core) Deprecated `EventId::IsRunning()`. It has been replaced with `EventId::IsPending()`.
 * (wifi) Deprecated `WIFI_TID_TO_LINK_MAPPING_{NOT_SUPPORTED,SAME_LINK_SET,ANY_LINK_SET}`. They have been replaced by `WifiTidToLinkMappingNegSupport::{NOT_SUPPORTED,SAME_LINK_SET,ANY_LINK_SET}`, respectively.
 * (wifi) Deprecated `{IDLE, CCA_BUSY, TX, RX, SWITCHING, SLEEP, OFF}`. They have been replaced by `WifiPhyState::{IDLE, CCA_BUSY, TX, RX, SWITCHING, SLEEP, OFF}`, respectively.
 * (lr-wpan) `MacPibAttributeIdentifier` attribute ids are now standard compliant.
diff --git a/doc/tutorial/source/tracing.rst b/doc/tutorial/source/tracing.rst
index fe6ffb6ca..8ba188d48 100644
--- a/doc/tutorial/source/tracing.rst
+++ b/doc/tutorial/source/tracing.rst
@@ -1763,7 +1763,7 @@ creating simulation events.
   {
       m_running = false;
 
-      if (m_sendEvent.IsRunning())
+      if (m_sendEvent.IsPending())
       {
           Simulator::Cancel(m_sendEvent);
       }
@@ -1776,7 +1776,7 @@ creating simulation events.
 
 Every time a simulation event is scheduled, an ``Event`` is created.
 If the ``Event`` is pending execution or executing, its method
-``IsRunning`` will return ``true``.  In this code, if ``IsRunning()``
+``IsPending`` will return ``true``.  In this code, if ``IsPending()``
 returns true, we ``Cancel`` the event which removes it from the
 simulator event queue.  By doing this, we break the chain of events
 that the ``Application`` is using to keep sending its ``Packets`` and
diff --git a/examples/tutorial/tutorial-app.cc b/examples/tutorial/tutorial-app.cc
index 821cc0e9c..70568dec7 100644
--- a/examples/tutorial/tutorial-app.cc
+++ b/examples/tutorial/tutorial-app.cc
@@ -76,7 +76,7 @@ TutorialApp::StopApplication()
 {
     m_running = false;
 
-    if (m_sendEvent.IsRunning())
+    if (m_sendEvent.IsPending())
     {
         Simulator::Cancel(m_sendEvent);
     }
diff --git a/src/applications/model/onoff-application.cc b/src/applications/model/onoff-application.cc
index 7b1ad9064..a5f32c37f 100644
--- a/src/applications/model/onoff-application.cc
+++ b/src/applications/model/onoff-application.cc
@@ -268,7 +268,7 @@ OnOffApplication::CancelEvents()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_sendEvent.IsRunning() && m_cbrRateFailSafe == m_cbrRate)
+    if (m_sendEvent.IsPending() && m_cbrRateFailSafe == m_cbrRate)
     { // Cancel the pending send packet event
         // Calculate residual bits since last packet sent
         Time delta(Simulator::Now() - m_lastStartTime);
diff --git a/src/core/model/event-id.cc b/src/core/model/event-id.cc
index ef2dd46cd..174e01429 100644
--- a/src/core/model/event-id.cc
+++ b/src/core/model/event-id.cc
@@ -73,12 +73,18 @@ EventId::IsExpired() const
 }
 
 bool
-EventId::IsRunning() const
+EventId::IsPending() const
 {
     NS_LOG_FUNCTION(this);
     return !IsExpired();
 }
 
+bool
+EventId::IsRunning() const
+{
+    return IsPending();
+}
+
 EventImpl*
 EventId::PeekEventImpl() const
 {
diff --git a/src/core/model/event-id.h b/src/core/model/event-id.h
index 8361c6ec1..5f042d4d8 100644
--- a/src/core/model/event-id.h
+++ b/src/core/model/event-id.h
@@ -19,6 +19,7 @@
 #ifndef EVENT_ID_H
 #define EVENT_ID_H
 
+#include "deprecated.h"
 #include "event-impl.h"
 #include "ptr.h"
 
@@ -47,7 +48,7 @@ class EventImpl;
  * The important thing to remember about this class is that
  * every variable of this type is _always_ in a valid state,
  * even when it has not been assigned an EventId coming from a
- * Simulator::Schedule() method:  calling Simulator::Cancel(), IsRunning(),
+ * Simulator::Schedule() method:  calling Simulator::Cancel(), IsPending(),
  * IsExpired() or passing around instances of this object
  * will not result in crashes or memory leaks.
  */
@@ -101,6 +102,14 @@ class EventId
      *
      * \returns \c true if the event has not expired, \c false otherwise.
      */
+    bool IsPending() const;
+
+    /**
+     * This method is syntactic sugar for !IsExpired().
+     *
+     * \returns \c true if the event has not expired, \c false otherwise.
+     */
+    NS_DEPRECATED_3_42("Use IsPending instead")
     bool IsRunning() const;
 
   public:
diff --git a/src/core/model/simulator.h b/src/core/model/simulator.h
index 1e31d605a..326678304 100644
--- a/src/core/model/simulator.h
+++ b/src/core/model/simulator.h
@@ -426,7 +426,7 @@ class Simulator
      * Note that it is not possible to test for the expiration of
      * events which were scheduled for the "destroy" time. Doing so
      * will result in a program error (crash).
-     * An event is said to "expire" when it starts being scheduled
+     * An event is said to "expire" when it starts being executed,
      * which means that if the code executed by the event calls
      * this function, it will get true.
      *
diff --git a/src/core/model/timer.cc b/src/core/model/timer.cc
index 1fcba54c3..214125469 100644
--- a/src/core/model/timer.cc
+++ b/src/core/model/timer.cc
@@ -56,7 +56,7 @@ Timer::~Timer()
     NS_LOG_FUNCTION(this);
     if (m_flags & CHECK_ON_DESTROY)
     {
-        if (m_event.IsRunning())
+        if (m_event.IsPending())
         {
             NS_FATAL_ERROR("Event is still running while destroying.");
         }
@@ -129,7 +129,7 @@ bool
 Timer::IsRunning() const
 {
     NS_LOG_FUNCTION(this);
-    return !IsSuspended() && m_event.IsRunning();
+    return !IsSuspended() && m_event.IsPending();
 }
 
 bool
@@ -170,7 +170,7 @@ Timer::Schedule(Time delay)
 {
     NS_LOG_FUNCTION(this << delay);
     NS_ASSERT(m_impl != nullptr);
-    if (m_event.IsRunning())
+    if (m_event.IsPending())
     {
         NS_FATAL_ERROR("Event is still running while re-scheduling.");
     }
diff --git a/src/core/model/trickle-timer.cc b/src/core/model/trickle-timer.cc
index b9f8ec38e..524d1ac3c 100644
--- a/src/core/model/trickle-timer.cc
+++ b/src/core/model/trickle-timer.cc
@@ -132,7 +132,7 @@ TrickleTimer::GetDelayLeft() const
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_timerExpiration.IsRunning())
+    if (m_timerExpiration.IsPending())
     {
         return Simulator::GetDelayLeft(m_timerExpiration);
     }
@@ -145,7 +145,7 @@ TrickleTimer::GetIntervalLeft() const
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_intervalExpiration.IsRunning())
+    if (m_intervalExpiration.IsPending())
     {
         return Simulator::GetDelayLeft(m_intervalExpiration);
     }
diff --git a/src/core/model/unix-fd-reader.cc b/src/core/model/unix-fd-reader.cc
index 89dd3801c..f73dc356b 100644
--- a/src/core/model/unix-fd-reader.cc
+++ b/src/core/model/unix-fd-reader.cc
@@ -93,7 +93,7 @@ FdReader::Start(int fd, Callback<void, uint8_t*, ssize_t> readCallback)
     // scheduling a "destroy time" method to make sure the thread exits before
     // proceeding.
     //
-    if (!m_destroyEvent.IsRunning())
+    if (!m_destroyEvent.IsPending())
     {
         // hold a reference to ensure that this object is not
         // deallocated before the destroy-time event fires
diff --git a/src/core/model/watchdog.cc b/src/core/model/watchdog.cc
index 18255e929..d98f101e0 100644
--- a/src/core/model/watchdog.cc
+++ b/src/core/model/watchdog.cc
@@ -52,7 +52,7 @@ Watchdog::Ping(Time delay)
     NS_LOG_FUNCTION(this << delay);
     Time end = Simulator::Now() + delay;
     m_end = std::max(m_end, end);
-    if (m_event.IsRunning())
+    if (m_event.IsPending())
     {
         return;
     }
diff --git a/src/core/model/win32-fd-reader.cc b/src/core/model/win32-fd-reader.cc
index c376bdaa7..06ab1f2e2 100644
--- a/src/core/model/win32-fd-reader.cc
+++ b/src/core/model/win32-fd-reader.cc
@@ -104,7 +104,7 @@ FdReader::Start(int fd, Callback<void, uint8_t*, ssize_t> readCallback)
     // scheduling a "destroy time" method to make sure the thread exits before
     // proceeding.
     //
-    if (!m_destroyEvent.IsRunning())
+    if (!m_destroyEvent.IsPending())
     {
         // hold a reference to ensure that this object is not
         // deallocated before the destroy-time event fires
diff --git a/src/dsdv/model/dsdv-rtable.cc b/src/dsdv/model/dsdv-rtable.cc
index 7f1f392a7..5e1a58e64 100644
--- a/src/dsdv/model/dsdv-rtable.cc
+++ b/src/dsdv/model/dsdv-rtable.cc
@@ -312,7 +312,7 @@ RoutingTable::AnyRunningEvent(Ipv4Address address)
         return false;
     }
     event = i->second;
-    return event.IsRunning();
+    return event.IsPending();
 }
 
 bool
@@ -340,7 +340,7 @@ RoutingTable::DeleteIpv4Event(Ipv4Address address)
         return false;
     }
     event = i->second;
-    if (event.IsRunning())
+    if (event.IsPending())
     {
         return false;
     }
diff --git a/src/internet-apps/model/ping.cc b/src/internet-apps/model/ping.cc
index d7a9dbdbd..23a3c50c8 100644
--- a/src/internet-apps/model/ping.cc
+++ b/src/internet-apps/model/ping.cc
@@ -626,11 +626,11 @@ void
 Ping::StopApplication()
 {
     NS_LOG_FUNCTION(this);
-    if (m_stopEvent.IsRunning())
+    if (m_stopEvent.IsPending())
     {
         m_stopEvent.Cancel();
     }
-    if (m_next.IsRunning())
+    if (m_next.IsPending())
     {
         m_next.Cancel();
     }
diff --git a/src/internet-apps/model/radvd.cc b/src/internet-apps/model/radvd.cc
index b450ad8ab..2e62bdfac 100644
--- a/src/internet-apps/model/radvd.cc
+++ b/src/internet-apps/model/radvd.cc
@@ -369,7 +369,7 @@ Radvd::HandleRead(Ptr<Socket> socket)
                         if (m_solicitedEventIds.find((*it)->GetInterface()) !=
                             m_solicitedEventIds.end())
                         {
-                            if (m_solicitedEventIds[(*it)->GetInterface()].IsRunning())
+                            if (m_solicitedEventIds[(*it)->GetInterface()].IsPending())
                             {
                                 scheduleSingle = false;
                             }
diff --git a/src/internet-apps/model/v4traceroute.cc b/src/internet-apps/model/v4traceroute.cc
index b5d55c8bb..6cefc2194 100644
--- a/src/internet-apps/model/v4traceroute.cc
+++ b/src/internet-apps/model/v4traceroute.cc
@@ -162,12 +162,12 @@ V4TraceRoute::StopApplication()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_next.IsRunning())
+    if (m_next.IsPending())
     {
         m_next.Cancel();
     }
 
-    if (m_waitIcmpReplyTimer.IsRunning())
+    if (m_waitIcmpReplyTimer.IsPending())
     {
         m_waitIcmpReplyTimer.Cancel();
     }
@@ -193,7 +193,7 @@ V4TraceRoute::DoDispose()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_next.IsRunning() || m_waitIcmpReplyTimer.IsRunning())
+    if (m_next.IsPending() || m_waitIcmpReplyTimer.IsPending())
     {
         StopApplication();
     }
@@ -422,7 +422,7 @@ void
 V4TraceRoute::StartWaitReplyTimer()
 {
     NS_LOG_FUNCTION(this);
-    if (!m_waitIcmpReplyTimer.IsRunning())
+    if (!m_waitIcmpReplyTimer.IsPending())
     {
         NS_LOG_LOGIC("Starting WaitIcmpReplyTimer at " << Simulator::Now() << " for "
                                                        << m_waitIcmpReplyTimeout);
diff --git a/src/internet/doc/tcp.rst b/src/internet/doc/tcp.rst
index aabd67ff3..1de27d188 100644
--- a/src/internet/doc/tcp.rst
+++ b/src/internet/doc/tcp.rst
@@ -1986,7 +1986,7 @@ processing of the SYN-ACK:
          if (h.GetFlags() & TcpHeader::SYN)
            {
              EventId persistentEvent = GetPersistentEvent(SENDER);
-             NS_TEST_ASSERT_MSG_EQ(persistentEvent.IsRunning(), true,
+             NS_TEST_ASSERT_MSG_EQ(persistentEvent.IsPending(), true,
                                    "Persistent event not started");
            }
        }
diff --git a/src/internet/model/arp-cache.cc b/src/internet/model/arp-cache.cc
index 1e2c7157b..4d48a8716 100644
--- a/src/internet/model/arp-cache.cc
+++ b/src/internet/model/arp-cache.cc
@@ -102,7 +102,7 @@ ArpCache::DoDispose()
     Flush();
     m_device = nullptr;
     m_interface = nullptr;
-    if (!m_waitReplyTimer.IsRunning())
+    if (!m_waitReplyTimer.IsPending())
     {
         m_waitReplyTimer.Cancel();
     }
@@ -184,7 +184,7 @@ void
 ArpCache::StartWaitReplyTimer()
 {
     NS_LOG_FUNCTION(this);
-    if (!m_waitReplyTimer.IsRunning())
+    if (!m_waitReplyTimer.IsPending())
     {
         NS_LOG_LOGIC("Starting WaitReplyTimer at " << Simulator::Now() << " for "
                                                    << m_waitReplyTimeout);
@@ -250,7 +250,7 @@ ArpCache::Flush()
         delete (*i).second;
     }
     m_arpCache.erase(m_arpCache.begin(), m_arpCache.end());
-    if (m_waitReplyTimer.IsRunning())
+    if (m_waitReplyTimer.IsPending())
     {
         NS_LOG_LOGIC("Stopping WaitReplyTimer at " << Simulator::Now().GetSeconds()
                                                    << " due to ArpCache flush");
diff --git a/src/internet/model/icmpv6-l4-protocol.cc b/src/internet/model/icmpv6-l4-protocol.cc
index 4f37f8c08..6d02650ed 100644
--- a/src/internet/model/icmpv6-l4-protocol.cc
+++ b/src/internet/model/icmpv6-l4-protocol.cc
@@ -421,7 +421,7 @@ Icmpv6L4Protocol::HandleRA(Ptr<Packet> packet,
 {
     NS_LOG_FUNCTION(this << packet << src << dst << interface);
 
-    if (m_handleRsTimeoutEvent.IsRunning())
+    if (m_handleRsTimeoutEvent.IsPending())
     {
         m_handleRsTimeoutEvent.Cancel();
         // We need to update this in case we need to restart RS retransmissions.
diff --git a/src/internet/model/ipv4-l3-protocol.cc b/src/internet/model/ipv4-l3-protocol.cc
index b113dd0d6..469086b17 100644
--- a/src/internet/model/ipv4-l3-protocol.cc
+++ b/src/internet/model/ipv4-l3-protocol.cc
@@ -333,12 +333,12 @@ Ipv4L3Protocol::DoDispose()
 
     m_fragments.clear();
     m_timeoutEventList.clear();
-    if (m_timeoutEvent.IsRunning())
+    if (m_timeoutEvent.IsPending())
     {
         m_timeoutEvent.Cancel();
     }
 
-    if (m_cleanDpd.IsRunning())
+    if (m_cleanDpd.IsPending())
     {
         m_cleanDpd.Cancel();
     }
@@ -1800,7 +1800,7 @@ Ipv4L3Protocol::UpdateDuplicate(Ptr<const Packet> p, const Ipv4Header& header)
     }
 
     // set cleanup job for new duplicate entries
-    if (!m_cleanDpd.IsRunning() && m_purge.IsStrictlyPositive())
+    if (!m_cleanDpd.IsPending() && m_purge.IsStrictlyPositive())
     {
         m_cleanDpd = Simulator::Schedule(m_expire, &Ipv4L3Protocol::RemoveDuplicates, this);
     }
diff --git a/src/internet/model/ipv6-extension.cc b/src/internet/model/ipv6-extension.cc
index 9103f6773..8f66e5978 100644
--- a/src/internet/model/ipv6-extension.cc
+++ b/src/internet/model/ipv6-extension.cc
@@ -361,7 +361,7 @@ Ipv6ExtensionFragment::DoDispose()
 
     m_fragments.clear();
     m_timeoutEventList.clear();
-    if (m_timeoutEvent.IsRunning())
+    if (m_timeoutEvent.IsPending())
     {
         m_timeoutEvent.Cancel();
     }
diff --git a/src/internet/model/rip.cc b/src/internet/model/rip.cc
index 9b6478024..acba6fdf6 100644
--- a/src/internet/model/rip.cc
+++ b/src/internet/model/rip.cc
@@ -741,7 +741,7 @@ Rip::InvalidateRoute(RipRoutingTableEntry* route)
             route->SetRouteStatus(RipRoutingTableEntry::RIP_INVALID);
             route->SetRouteMetric(m_linkDown);
             route->SetRouteChanged(true);
-            if (it->second.IsRunning())
+            if (it->second.IsPending())
             {
                 it->second.Cancel();
             }
@@ -1275,7 +1275,7 @@ Rip::SendTriggeredRouteUpdate()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_nextTriggeredUpdate.IsRunning())
+    if (m_nextTriggeredUpdate.IsPending())
     {
         NS_LOG_LOGIC("Skipping Triggered Update due to cooldown");
         return;
@@ -1307,7 +1307,7 @@ Rip::SendUnsolicitedRouteUpdate()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_nextTriggeredUpdate.IsRunning())
+    if (m_nextTriggeredUpdate.IsPending())
     {
         m_nextTriggeredUpdate.Cancel();
     }
diff --git a/src/internet/model/ripng.cc b/src/internet/model/ripng.cc
index 85304550d..45b10ef87 100644
--- a/src/internet/model/ripng.cc
+++ b/src/internet/model/ripng.cc
@@ -740,7 +740,7 @@ RipNg::InvalidateRoute(RipNgRoutingTableEntry* route)
             route->SetRouteStatus(RipNgRoutingTableEntry::RIPNG_INVALID);
             route->SetRouteMetric(m_linkDown);
             route->SetRouteChanged(true);
-            if (it->second.IsRunning())
+            if (it->second.IsPending())
             {
                 it->second.Cancel();
             }
@@ -1276,7 +1276,7 @@ RipNg::SendTriggeredRouteUpdate()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_nextTriggeredUpdate.IsRunning())
+    if (m_nextTriggeredUpdate.IsPending())
     {
         NS_LOG_LOGIC("Skipping Triggered Update due to cooldown");
         return;
@@ -1308,7 +1308,7 @@ RipNg::SendUnsolicitedRouteUpdate()
 {
     NS_LOG_FUNCTION(this);
 
-    if (m_nextTriggeredUpdate.IsRunning())
+    if (m_nextTriggeredUpdate.IsPending())
     {
         m_nextTriggeredUpdate.Cancel();
     }
diff --git a/src/internet/model/tcp-socket-base.cc b/src/internet/model/tcp-socket-base.cc
index b681c1204..11eb8742e 100644
--- a/src/internet/model/tcp-socket-base.cc
+++ b/src/internet/model/tcp-socket-base.cc
@@ -869,7 +869,7 @@ TcpSocketBase::Send(Ptr<Packet> p, uint32_t flags)
         if ((m_state == ESTABLISHED || m_state == CLOSE_WAIT) && AvailableWindow() > 0)
         { // Try to send the data out: Add a little step to allow the application
             // to fill the buffer
-            if (!m_sendPendingDataEvent.IsRunning())
+            if (!m_sendPendingDataEvent.IsPending())
             {
                 m_sendPendingDataEvent = Simulator::Schedule(TimeStep(1),
                                                              &TcpSocketBase::SendPendingData,
@@ -1136,7 +1136,7 @@ TcpSocketBase::CloseAndNotify()
         NotifyNormalClose();
         m_closeNotified = true;
     }
-    if (m_lastAckEvent.IsRunning())
+    if (m_lastAckEvent.IsPending())
     {
         m_lastAckEvent.Cancel();
     }
@@ -1473,7 +1473,7 @@ TcpSocketBase::DoForwardUp(Ptr<Packet> packet, const Address& fromAddress, const
         break;
     }
 
-    if (m_rWnd.Get() != 0 && m_persistEvent.IsRunning())
+    if (m_rWnd.Get() != 0 && m_persistEvent.IsPending())
     { // persist probes end, the other end has increased the window
         NS_ASSERT(m_connected);
         NS_LOG_LOGIC(this << " Leaving zerowindow persist state");
diff --git a/src/internet/test/tcp-cong-avoid-test.cc b/src/internet/test/tcp-cong-avoid-test.cc
index e938f4c1f..3d2843ed9 100644
--- a/src/internet/test/tcp-cong-avoid-test.cc
+++ b/src/internet/test/tcp-cong-avoid-test.cc
@@ -132,7 +132,7 @@ TcpNewRenoCongAvoidNormalTest::CWndTrace(uint32_t oldValue, uint32_t newValue)
         return;
     }
 
-    if (!m_event.IsRunning())
+    if (!m_event.IsPending())
     {
         m_event = Simulator::Schedule(Seconds(1.0), &TcpNewRenoCongAvoidNormalTest::Check, this);
     }
diff --git a/src/internet/test/tcp-zero-window-test.cc b/src/internet/test/tcp-zero-window-test.cc
index 4b6ebf629..25a703a1a 100644
--- a/src/internet/test/tcp-zero-window-test.cc
+++ b/src/internet/test/tcp-zero-window-test.cc
@@ -236,7 +236,7 @@ TcpZeroWindowTest::ProcessedAck(const Ptr<const TcpSocketState> tcb,
         if (h.GetFlags() & TcpHeader::SYN)
         {
             EventId persistentEvent = GetPersistentEvent(SENDER);
-            NS_TEST_ASSERT_MSG_EQ(persistentEvent.IsRunning(),
+            NS_TEST_ASSERT_MSG_EQ(persistentEvent.IsPending(),
                                   true,
                                   "Persistent event not started");
         }
diff --git a/src/lr-wpan/model/lr-wpan-mac.cc b/src/lr-wpan/model/lr-wpan-mac.cc
index 1ba5b025c..f5d6ff9f6 100644
--- a/src/lr-wpan/model/lr-wpan-mac.cc
+++ b/src/lr-wpan/model/lr-wpan-mac.cc
@@ -630,7 +630,7 @@ LrWpanMac::MlmeScanRequest(MlmeScanRequestParams params)
     confirmParams.m_scanType = params.m_scanType;
     confirmParams.m_chPage = params.m_chPage;
 
-    if ((m_scanEvent.IsRunning() || m_scanEnergyEvent.IsRunning()) || m_scanOrphanEvent.IsRunning())
+    if ((m_scanEvent.IsPending() || m_scanEnergyEvent.IsPending()) || m_scanOrphanEvent.IsPending())
     {
         if (!m_mlmeScanConfirmCallback.IsNull())
         {
@@ -879,7 +879,7 @@ LrWpanMac::MlmeSyncRequest(MlmeSyncRequestParams params)
     uint64_t searchSymbols;
     Time searchBeaconTime;
 
-    if (m_trackingEvent.IsRunning())
+    if (m_trackingEvent.IsPending())
     {
         m_trackingEvent.Cancel();
     }
@@ -1718,13 +1718,13 @@ LrWpanMac::CheckQueue()
 {
     NS_LOG_FUNCTION(this);
     // Pull a packet from the queue and start sending if we are not already sending.
-    if (m_macState == MAC_IDLE && !m_txQueue.empty() && !m_setMacState.IsRunning())
+    if (m_macState == MAC_IDLE && !m_txQueue.empty() && !m_setMacState.IsPending())
     {
         if (m_csmaCa->IsUnSlottedCsmaCa() || (m_outSuperframeStatus == CAP && m_coor) ||
             m_incSuperframeStatus == CAP)
         {
             // check MAC is not in a IFS
-            if (!m_ifsEvent.IsRunning())
+            if (!m_ifsEvent.IsPending())
             {
                 Ptr<TxQueueElement> txQElement = m_txQueue.front();
                 m_txPkt = txQElement->txQPkt;
@@ -1946,21 +1946,21 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                 acceptFrame = (receivedMacHdr.GetExtDstAddr() == m_macExtendedAddress);
             }
 
-            if (acceptFrame && m_scanEvent.IsRunning())
+            if (acceptFrame && m_scanEvent.IsPending())
             {
                 if (!receivedMacHdr.IsBeacon())
                 {
                     acceptFrame = false;
                 }
             }
-            else if (acceptFrame && m_scanOrphanEvent.IsRunning())
+            else if (acceptFrame && m_scanOrphanEvent.IsPending())
             {
                 if (!receivedMacHdr.IsCommand())
                 {
                     acceptFrame = false;
                 }
             }
-            else if (m_scanEnergyEvent.IsRunning())
+            else if (m_scanEnergyEvent.IsPending())
             {
                 // Reject any frames if energy scan is running
                 acceptFrame = false;
@@ -1985,7 +1985,7 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                 // Although ACKs do not use CSMA to to be transmitted, we need to make sure
                 // that the transmitted ACK will not collide with the transmission of a beacon
                 // when beacon-enabled mode is running in the coordinator.
-                if (acceptFrame && (m_csmaCa->IsSlottedCsmaCa() && m_capEvent.IsRunning()))
+                if (acceptFrame && (m_csmaCa->IsSlottedCsmaCa() && m_capEvent.IsPending()))
                 {
                     Time timeLeftInCap = Simulator::GetDelayLeft(m_capEvent);
                     uint64_t ackSymbols = lrwpan::aTurnaroundTime + m_phy->GetPhySHRDuration() +
@@ -2123,7 +2123,7 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                     panDescriptor.m_timeStamp = m_macBeaconRxTime;
 
                     // Process beacon when device belongs to a PAN (associated device)
-                    if (!m_scanEvent.IsRunning() && m_macPanId == receivedMacHdr.GetDstPanId())
+                    if (!m_scanEvent.IsPending() && m_macPanId == receivedMacHdr.GetDstPanId())
                     {
                         // We need to make sure to cancel any possible ongoing unslotted CSMA/CA
                         // operations when receiving a beacon (e.g. Those taking place at the
@@ -2178,7 +2178,7 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                         m_setMacState =
                             Simulator::ScheduleNow(&LrWpanMac::SetLrWpanMacState, this, MAC_IDLE);
                     }
-                    else if (!m_scanEvent.IsRunning() && m_macPanId == 0xFFFF)
+                    else if (!m_scanEvent.IsPending() && m_macPanId == 0xFFFF)
                     {
                         NS_LOG_DEBUG(this << " Device not associated, cannot process beacon");
                     }
@@ -2199,7 +2199,7 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                             }
                         }
 
-                        if (m_scanEvent.IsRunning())
+                        if (m_scanEvent.IsPending())
                         {
                             // Channel scanning is taking place, save only unique PAN descriptors
                             bool descriptorExists = false;
@@ -2236,7 +2236,7 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                             }
                             return;
                         }
-                        else if (m_trackingEvent.IsRunning())
+                        else if (m_trackingEvent.IsPending())
                         {
                             // check if MLME-SYNC.request was previously issued and running
                             // Sync. is necessary to handle pending messages (indirect
@@ -2318,7 +2318,7 @@ LrWpanMac::PdDataIndication(uint32_t psduLength, Ptr<Packet> p, uint8_t lqi)
                         }
                         break;
                     case CommandPayloadHeader::COOR_REALIGN:
-                        if (m_scanOrphanEvent.IsRunning())
+                        if (m_scanOrphanEvent.IsPending())
                         {
                             // Coordinator located, no need to keep scanning other channels
                             m_scanOrphanEvent.Cancel();
@@ -3298,7 +3298,7 @@ LrWpanMac::PlmeSetTRXStateConfirm(PhyEnumeration status)
         NS_ASSERT(status == IEEE_802_15_4_PHY_RX_ON || status == IEEE_802_15_4_PHY_SUCCESS ||
                   status == IEEE_802_15_4_PHY_TRX_OFF);
 
-        if (status == IEEE_802_15_4_PHY_RX_ON && m_scanEnergyEvent.IsRunning())
+        if (status == IEEE_802_15_4_PHY_RX_ON && m_scanEnergyEvent.IsPending())
         {
             // Kick start Energy Detection Scan
             m_phy->PlmeEdRequest();
@@ -3651,7 +3651,7 @@ LrWpanMac::SetLrWpanMacState(MacState macState)
                 break;
             }
             case CommandPayloadHeader::ORPHAN_NOTIF: {
-                if (m_scanOrphanEvent.IsRunning())
+                if (m_scanOrphanEvent.IsPending())
                 {
                     m_unscannedChannels.emplace_back(m_phy->GetCurrentChannelNum());
                 }
@@ -3660,7 +3660,7 @@ LrWpanMac::SetLrWpanMacState(MacState macState)
                 break;
             }
             case CommandPayloadHeader::BEACON_REQ: {
-                if (m_scanEvent.IsRunning())
+                if (m_scanEvent.IsPending())
                 {
                     m_unscannedChannels.emplace_back(m_phy->GetCurrentChannelNum());
                 }
diff --git a/src/lr-wpan/model/lr-wpan-phy.cc b/src/lr-wpan/model/lr-wpan-phy.cc
index 782263514..058c4fa2e 100644
--- a/src/lr-wpan/model/lr-wpan-phy.cc
+++ b/src/lr-wpan/model/lr-wpan-phy.cc
@@ -403,7 +403,7 @@ LrWpanPhy::StartRx(Ptr<SpectrumSignalParameters> spectrumRxParams)
     NS_ASSERT(p);
 
     // Prevent PHY from receiving another packet while switching the transceiver state.
-    if (m_trxState == IEEE_802_15_4_PHY_RX_ON && !m_setTRXState.IsRunning())
+    if (m_trxState == IEEE_802_15_4_PHY_RX_ON && !m_setTRXState.IsPending())
     {
         // The specification doesn't seem to refer to BUSY_RX, but vendor
         // data sheets suggest that this is a substate of the RX_ON state
@@ -646,7 +646,7 @@ LrWpanPhy::PdDataRequest(const uint32_t psduLength, Ptr<Packet> p)
     }
 
     // Prevent PHY from sending a packet while switching the transceiver state.
-    if (!m_setTRXState.IsRunning())
+    if (!m_setTRXState.IsPending())
     {
         if (m_trxState == IEEE_802_15_4_PHY_TX_ON)
         {
@@ -1547,7 +1547,7 @@ LrWpanPhy::EndTx()
     {
         // Only change the state immediately, if the transceiver is not already
         // switching the state.
-        if (!m_setTRXState.IsRunning())
+        if (!m_setTRXState.IsPending())
         {
             NS_LOG_LOGIC("Apply pending state change to " << m_trxStatePending);
             ChangeTrxState(m_trxStatePending);
diff --git a/src/lte/model/lte-rlc-am.cc b/src/lte/model/lte-rlc-am.cc
index 03c190e7a..bfa0ad6bd 100644
--- a/src/lte/model/lte-rlc-am.cc
+++ b/src/lte/model/lte-rlc-am.cc
@@ -212,7 +212,7 @@ LteRlcAm::DoNotifyTxOpportunity(LteMacSapUser::TxOpportunityParameters txOpParam
         return;
     }
 
-    if (m_statusPduRequested && !m_statusProhibitTimer.IsRunning())
+    if (m_statusPduRequested && !m_statusProhibitTimer.IsPending())
     {
         if (txOpParams.bytes < m_statusPduBufferSize)
         {
@@ -340,7 +340,7 @@ LteRlcAm::DoNotifyTxOpportunity(LteMacSapUser::TxOpportunityParameters txOpParam
                         m_pollSn = m_vtS - 1;
                         NS_LOG_LOGIC("New POLL_SN = " << m_pollSn);
 
-                        if (!m_pollRetransmitTimer.IsRunning())
+                        if (!m_pollRetransmitTimer.IsPending())
                         {
                             NS_LOG_LOGIC("Start PollRetransmit timer");
 
@@ -728,7 +728,7 @@ LteRlcAm::DoNotifyTxOpportunity(LteMacSapUser::TxOpportunityParameters txOpParam
         m_pollSn = m_vtS - 1;
         NS_LOG_LOGIC("New POLL_SN = " << m_pollSn);
 
-        if (!m_pollRetransmitTimer.IsRunning())
+        if (!m_pollRetransmitTimer.IsPending())
         {
             NS_LOG_LOGIC("Start PollRetransmit timer");
 
@@ -884,7 +884,7 @@ LteRlcAm::DoReceivePdu(LteMacSapUser::ReceivePduParameters rxPduParams)
             m_statusPduRequested = true;
             m_statusPduBufferSize = 4;
 
-            if (!m_statusProhibitTimer.IsRunning())
+            if (!m_statusProhibitTimer.IsPending())
             {
                 DoReportBufferStatus();
             }
@@ -1018,7 +1018,7 @@ LteRlcAm::DoReceivePdu(LteMacSapUser::ReceivePduParameters rxPduParams)
         //     - if VR(X) falls outside of the receiving window and VR(X) is not equal to VR(MR):
         //         - stop and reset t-Reordering;
 
-        if (m_reorderingTimer.IsRunning())
+        if (m_reorderingTimer.IsPending())
         {
             NS_LOG_LOGIC("Reordering timer is running");
             if ((m_vrX == m_vrR) || ((!IsInsideReceivingWindow(m_vrX)) && (m_vrX != m_vrMr)))
@@ -1035,7 +1035,7 @@ LteRlcAm::DoReceivePdu(LteMacSapUser::ReceivePduParameters rxPduParams)
         //         - start t-Reordering;
         //         - set VR(X) to VR(H).
 
-        if (!m_reorderingTimer.IsRunning())
+        if (!m_reorderingTimer.IsPending())
         {
             NS_LOG_LOGIC("Reordering timer is not running");
             if (m_vrH > m_vrR)
@@ -1076,7 +1076,7 @@ LteRlcAm::DoReceivePdu(LteMacSapUser::ReceivePduParameters rxPduParams)
 
             uint16_t seqNumberValue = sn.GetValue();
 
-            if (m_pollRetransmitTimer.IsRunning() && (seqNumberValue == m_pollSn.GetValue()))
+            if (m_pollRetransmitTimer.IsPending() && (seqNumberValue == m_pollSn.GetValue()))
             {
                 m_pollRetransmitTimer.Cancel();
             }
@@ -1665,7 +1665,7 @@ LteRlcAm::DoReportBufferStatus()
     r.retxQueueSize = m_retxBufferSize + m_txedBufferSize;
     r.retxQueueHolDelay = retxQueueHolDelay.GetMilliSeconds();
 
-    if (m_statusPduRequested && !m_statusProhibitTimer.IsRunning())
+    if (m_statusPduRequested && !m_statusProhibitTimer.IsPending())
     {
         r.statusPduSize = m_statusPduBufferSize;
     }
diff --git a/src/lte/model/lte-rlc-um.cc b/src/lte/model/lte-rlc-um.cc
index 9e02a8628..c49dc0a3c 100644
--- a/src/lte/model/lte-rlc-um.cc
+++ b/src/lte/model/lte-rlc-um.cc
@@ -584,7 +584,7 @@ LteRlcUm::DoReceivePdu(LteMacSapUser::ReceivePduParameters rxPduParams)
     //    - if VR(UX) <= VR(UR); or
     //    - if VR(UX) falls outside of the reordering window and VR(UX) is not equal to VR(UH)::
     //        - stop and reset t-Reordering;
-    if (m_reorderingTimer.IsRunning())
+    if (m_reorderingTimer.IsPending())
     {
         NS_LOG_LOGIC("Reordering timer is running");
 
@@ -600,7 +600,7 @@ LteRlcUm::DoReceivePdu(LteMacSapUser::ReceivePduParameters rxPduParams)
     //    - if VR(UH) > VR(UR):
     //        - start t-Reordering;
     //        - set VR(UX) to VR(UH).
-    if (!m_reorderingTimer.IsRunning())
+    if (!m_reorderingTimer.IsPending())
     {
         NS_LOG_LOGIC("Reordering timer is not running");
 
diff --git a/src/lte/model/lte-ue-rrc.cc b/src/lte/model/lte-ue-rrc.cc
index e61290721..d8759b07e 100644
--- a/src/lte/model/lte-ue-rrc.cc
+++ b/src/lte/model/lte-ue-rrc.cc
@@ -1061,7 +1061,7 @@ LteUeRrc::DoRecvRrcConnectionReconfiguration(LteRrcSap::RrcConnectionReconfigura
         {
             NS_LOG_INFO("haveMobilityControlInfo == true");
             SwitchToState(CONNECTED_HANDOVER);
-            if (m_radioLinkFailureDetected.IsRunning())
+            if (m_radioLinkFailureDetected.IsPending())
             {
                 ResetRlfParams();
             }
@@ -2814,7 +2814,7 @@ LteUeRrc::VarMeasReportListAdd(uint8_t measId, ConcernedCells_t enteringCells)
     NS_ASSERT(!measReportIt->second.cellsTriggeredList.empty());
 
     // #issue 224, schedule only when there is no periodic event scheduled already
-    if (!measReportIt->second.periodicReportTimer.IsRunning())
+    if (!measReportIt->second.periodicReportTimer.IsPending())
     {
         measReportIt->second.numberOfReportsSent = 0;
         measReportIt->second.periodicReportTimer =
@@ -3312,7 +3312,7 @@ LteUeRrc::DoNotifyOutOfSync()
     {
         m_radioLinkFailureDetected =
             Simulator::Schedule(m_t310, &LteUeRrc::RadioLinkFailureDetected, this);
-        if (m_radioLinkFailureDetected.IsRunning())
+        if (m_radioLinkFailureDetected.IsPending())
         {
             NS_LOG_INFO("t310 started");
         }
diff --git a/src/mesh/model/dot11s/hwmp-protocol-mac.cc b/src/mesh/model/dot11s/hwmp-protocol-mac.cc
index 3234e3085..b72a5e4cf 100644
--- a/src/mesh/model/dot11s/hwmp-protocol-mac.cc
+++ b/src/mesh/model/dot11s/hwmp-protocol-mac.cc
@@ -321,7 +321,7 @@ void
 HwmpProtocolMac::SendMyPreq()
 {
     NS_LOG_FUNCTION(this);
-    if (m_preqTimer.IsRunning())
+    if (m_preqTimer.IsPending())
     {
         return;
     }
@@ -330,7 +330,7 @@ HwmpProtocolMac::SendMyPreq()
         return;
     }
     // reschedule sending PREQ
-    NS_ASSERT(!m_preqTimer.IsRunning());
+    NS_ASSERT(!m_preqTimer.IsPending());
     m_preqTimer =
         Simulator::Schedule(m_protocol->GetPreqMinInterval(), &HwmpProtocolMac::SendMyPreq, this);
     SendPreqVector(m_myPreq);
@@ -466,7 +466,7 @@ void
 HwmpProtocolMac::SendMyPerr()
 {
     NS_LOG_FUNCTION(this);
-    if (m_perrTimer.IsRunning())
+    if (m_perrTimer.IsPending())
     {
         return;
     }
diff --git a/src/mesh/model/mesh-wifi-interface-mac.cc b/src/mesh/model/mesh-wifi-interface-mac.cc
index 1d4049c8f..1ff9e94e3 100644
--- a/src/mesh/model/mesh-wifi-interface-mac.cc
+++ b/src/mesh/model/mesh-wifi-interface-mac.cc
@@ -149,7 +149,7 @@ MeshWifiInterfaceMac::DoInitialize()
     {
         Time randomStart = Seconds(m_coefficient->GetValue());
         // Now start sending beacons after some random delay (to avoid collisions)
-        NS_ASSERT(!m_beaconSendEvent.IsRunning());
+        NS_ASSERT(!m_beaconSendEvent.IsPending());
         m_beaconSendEvent =
             Simulator::Schedule(randomStart, &MeshWifiInterfaceMac::SendBeacon, this);
         m_tbtt = Simulator::Now() + randomStart;
@@ -387,7 +387,7 @@ MeshWifiInterfaceMac::SetBeaconGeneration(bool enable)
 bool
 MeshWifiInterfaceMac::GetBeaconGeneration() const
 {
-    return m_beaconSendEvent.IsRunning();
+    return m_beaconSendEvent.IsPending();
 }
 
 Time
@@ -423,7 +423,7 @@ MeshWifiInterfaceMac::SendBeacon()
     NS_LOG_FUNCTION(this);
     NS_LOG_DEBUG(GetAddress() << " is sending beacon");
 
-    NS_ASSERT(!m_beaconSendEvent.IsRunning());
+    NS_ASSERT(!m_beaconSendEvent.IsPending());
 
     // Form & send beacon
     MeshWifiBeacon beacon(GetSsid(), GetSupportedRates(), m_beaconInterval.GetMicroSeconds());
diff --git a/src/mobility/model/steady-state-random-waypoint-mobility-model.cc b/src/mobility/model/steady-state-random-waypoint-mobility-model.cc
index 0af855134..668e3396c 100644
--- a/src/mobility/model/steady-state-random-waypoint-mobility-model.cc
+++ b/src/mobility/model/steady-state-random-waypoint-mobility-model.cc
@@ -183,7 +183,7 @@ SteadyStateRandomWaypointMobilityModel::DoInitializePrivate()
         {
             pause = Seconds(u * expectedPauseTime);
         }
-        NS_ASSERT(!m_event.IsRunning());
+        NS_ASSERT(!m_event.IsPending());
         m_event =
             Simulator::Schedule(pause, &SteadyStateRandomWaypointMobilityModel::BeginWalk, this);
     }
@@ -209,7 +209,7 @@ SteadyStateRandomWaypointMobilityModel::DoInitializePrivate()
         double u2 = m_u_r->GetValue(0, 1);
         m_helper.SetPosition(
             Vector(m_minX + u2 * x1 + (1 - u2) * x2, m_minY + u2 * y1 + (1 - u2) * y2, m_z));
-        NS_ASSERT(!m_event.IsRunning());
+        NS_ASSERT(!m_event.IsPending());
         m_event =
             Simulator::ScheduleNow(&SteadyStateRandomWaypointMobilityModel::SteadyStateBeginWalk,
                                    this,
diff --git a/src/network/utils/simple-net-device.cc b/src/network/utils/simple-net-device.cc
index 8394b062f..af6b75b49 100644
--- a/src/network/utils/simple-net-device.cc
+++ b/src/network/utils/simple-net-device.cc
@@ -450,7 +450,7 @@ SimpleNetDevice::SendFrom(Ptr<Packet> p,
 
     if (m_queue->Enqueue(p))
     {
-        if (m_queue->GetNPackets() == 1 && !FinishTransmissionEvent.IsRunning())
+        if (m_queue->GetNPackets() == 1 && !FinishTransmissionEvent.IsPending())
         {
             StartTransmission();
         }
@@ -467,7 +467,7 @@ SimpleNetDevice::StartTransmission()
     {
         return;
     }
-    NS_ASSERT_MSG(!FinishTransmissionEvent.IsRunning(),
+    NS_ASSERT_MSG(!FinishTransmissionEvent.IsPending(),
                   "Tried to transmit a packet while another transmission was in progress");
     Ptr<Packet> packet = m_queue->Dequeue();
 
@@ -544,7 +544,7 @@ SimpleNetDevice::DoDispose()
     m_node = nullptr;
     m_receiveErrorModel = nullptr;
     m_queue->Dispose();
-    if (FinishTransmissionEvent.IsRunning())
+    if (FinishTransmissionEvent.IsPending())
     {
         FinishTransmissionEvent.Cancel();
     }
diff --git a/src/sixlowpan/model/sixlowpan-net-device.cc b/src/sixlowpan/model/sixlowpan-net-device.cc
index a9eef7a79..056809d63 100644
--- a/src/sixlowpan/model/sixlowpan-net-device.cc
+++ b/src/sixlowpan/model/sixlowpan-net-device.cc
@@ -180,7 +180,7 @@ SixLowPanNetDevice::DoDispose()
     m_node = nullptr;
 
     m_timeoutEventList.clear();
-    if (m_timeoutEvent.IsRunning())
+    if (m_timeoutEvent.IsPending())
     {
         m_timeoutEvent.Cancel();
     }
diff --git a/src/spectrum/model/waveform-generator.cc b/src/spectrum/model/waveform-generator.cc
index 0d9825e00..47a4b48d1 100644
--- a/src/spectrum/model/waveform-generator.cc
+++ b/src/spectrum/model/waveform-generator.cc
@@ -53,7 +53,7 @@ WaveformGenerator::DoDispose()
     m_channel = nullptr;
     m_netDevice = nullptr;
     m_mobility = nullptr;
-    if (m_nextWave.IsRunning())
+    if (m_nextWave.IsPending())
     {
         m_nextWave.Cancel();
     }
@@ -202,7 +202,7 @@ void
 WaveformGenerator::Start()
 {
     NS_LOG_FUNCTION(this);
-    if (!m_nextWave.IsRunning())
+    if (!m_nextWave.IsPending())
     {
         NS_LOG_LOGIC("generator was not active, now starting");
         m_startTime = Now();
@@ -214,7 +214,7 @@ void
 WaveformGenerator::Stop()
 {
     NS_LOG_FUNCTION(this);
-    if (m_nextWave.IsRunning())
+    if (m_nextWave.IsPending())
     {
         m_nextWave.Cancel();
     }
diff --git a/src/uan/model/uan-mac-rc.cc b/src/uan/model/uan-mac-rc.cc
index 5714d0026..58160b5b7 100644
--- a/src/uan/model/uan-mac-rc.cc
+++ b/src/uan/model/uan-mac-rc.cc
@@ -294,7 +294,7 @@ UanMacRc::Enqueue(Ptr<Packet> packet, uint16_t protocolNumber, const Address& de
         Associate();
         return true;
     case IDLE:
-        if (!m_rtsEvent.IsRunning())
+        if (!m_rtsEvent.IsPending())
         {
             SendRts();
         }
@@ -489,7 +489,7 @@ UanMacRc::ScheduleData(const UanHeaderRcCts& ctsh,
     m_state = IDLE;
     if (!m_pktQueue.empty())
     {
-        if (m_rtsEvent.IsRunning())
+        if (m_rtsEvent.IsPending())
         {
             m_rtsEvent.Cancel();
         }
@@ -625,7 +625,7 @@ UanMacRc::Associate()
         SendPacket(pkt, m_currentRate + m_numRates);
     }
     m_state = GWPSENT;
-    NS_ASSERT(!m_rtsEvent.IsRunning());
+    NS_ASSERT(!m_rtsEvent.IsPending());
     m_ev->SetAttribute("Mean", DoubleValue(1 / m_retryRate));
     double timeout = m_ev->GetValue();
     m_rtsEvent = Simulator::Schedule(Seconds(timeout), &UanMacRc::AssociateTimeout, this);
@@ -659,7 +659,7 @@ UanMacRc::AssociateTimeout()
         SendPacket(pkt, m_currentRate + m_numRates);
         m_resList.push_back(res);
     }
-    NS_ASSERT(!m_rtsEvent.IsRunning());
+    NS_ASSERT(!m_rtsEvent.IsPending());
     m_ev->SetAttribute("Mean", DoubleValue(1 / m_retryRate));
     double timeout = m_ev->GetValue();
     m_rtsEvent = Simulator::Schedule(Seconds(timeout), &UanMacRc::AssociateTimeout, this);
@@ -693,7 +693,7 @@ UanMacRc::SendRts()
         SendPacket(pkt, m_currentRate + m_numRates);
     }
     m_state = RTSSENT;
-    NS_ASSERT(!m_rtsEvent.IsRunning());
+    NS_ASSERT(!m_rtsEvent.IsPending());
     m_ev->SetAttribute("Mean", DoubleValue(1 / m_retryRate));
     double timeout = m_ev->GetValue();
     m_rtsEvent = Simulator::Schedule(Seconds(timeout), &UanMacRc::RtsTimeout, this);
@@ -755,7 +755,7 @@ UanMacRc::RtsTimeout()
         SendPacket(pkt, m_currentRate + m_numRates);
     }
     m_state = RTSSENT;
-    NS_ASSERT(!m_rtsEvent.IsRunning());
+    NS_ASSERT(!m_rtsEvent.IsPending());
     m_ev->SetAttribute("Mean", DoubleValue(1 / m_retryRate));
     double timeout = m_ev->GetValue();
     m_rtsEvent = Simulator::Schedule(Seconds(timeout), &UanMacRc::RtsTimeout, this);
diff --git a/src/uan/model/uan-phy-gen.cc b/src/uan/model/uan-phy-gen.cc
index 257a4f5a2..8a26806fe 100644
--- a/src/uan/model/uan-phy-gen.cc
+++ b/src/uan/model/uan-phy-gen.cc
@@ -656,13 +656,13 @@ UanPhyGen::EnergyDepletionHandler()
                                             << ", stopping rx/tx activities");
 
     m_state = DISABLED;
-    if (m_txEndEvent.IsRunning())
+    if (m_txEndEvent.IsPending())
     {
         Simulator::Cancel(m_txEndEvent);
         NotifyTxDrop(m_pktTx);
         m_pktTx = nullptr;
     }
-    if (m_rxEndEvent.IsRunning())
+    if (m_rxEndEvent.IsPending())
     {
         Simulator::Cancel(m_rxEndEvent);
         NotifyRxDrop(m_pktRx);
diff --git a/src/wifi/model/ap-wifi-mac.cc b/src/wifi/model/ap-wifi-mac.cc
index e57a69f65..5954a5cbb 100644
--- a/src/wifi/model/ap-wifi-mac.cc
+++ b/src/wifi/model/ap-wifi-mac.cc
@@ -1749,7 +1749,7 @@ ApWifiMac::TxOk(Ptr<const WifiMpdu> mpdu)
             // we can stop the timer and enforce the configuration deriving from the
             // EML Notification frame sent by the EMLSR client
             if (auto eventIt = m_transitionTimeoutEvents.find(hdr.GetAddr1());
-                eventIt != m_transitionTimeoutEvents.cend() && eventIt->second.IsRunning())
+                eventIt != m_transitionTimeoutEvents.cend() && eventIt->second.IsPending())
             {
                 // no need to wait until the expiration of the transition timeout
                 eventIt->second.PeekEventImpl()->Invoke();
diff --git a/src/wifi/model/block-ack-manager.cc b/src/wifi/model/block-ack-manager.cc
index 49cb83918..bc02ffb9b 100644
--- a/src/wifi/model/block-ack-manager.cc
+++ b/src/wifi/model/block-ack-manager.cc
@@ -450,7 +450,7 @@ BlockAckManager::NotifyGotBlockAck(uint8_t linkId,
     uint16_t nSuccessfulMpdus = 0;
     uint16_t nFailedMpdus = 0;
 
-    if (it->second.first.m_inactivityEvent.IsRunning())
+    if (it->second.first.m_inactivityEvent.IsPending())
     {
         /* Upon reception of a BlockAck frame, the inactivity timer at the
             originator must be reset.
diff --git a/src/wifi/model/channel-access-manager.cc b/src/wifi/model/channel-access-manager.cc
index 5a2716fdc..73967797f 100644
--- a/src/wifi/model/channel-access-manager.cc
+++ b/src/wifi/model/channel-access-manager.cc
@@ -733,7 +733,7 @@ ChannelAccessManager::DoRestartAccessTimeoutIfNeeded()
     {
         NS_LOG_DEBUG("expected backoff end=" << expectedBackoffEnd);
         Time expectedBackoffDelay = expectedBackoffEnd - Simulator::Now();
-        if (m_accessTimeout.IsRunning() &&
+        if (m_accessTimeout.IsPending() &&
             Simulator::GetDelayLeft(m_accessTimeout) > expectedBackoffDelay)
         {
             m_accessTimeout.Cancel();
@@ -976,7 +976,7 @@ ChannelAccessManager::ResetState()
     InitLastBusyStructs();
 
     // Cancel timeout
-    if (m_accessTimeout.IsRunning())
+    if (m_accessTimeout.IsPending())
     {
         m_accessTimeout.Cancel();
     }
@@ -1015,7 +1015,7 @@ ChannelAccessManager::NotifySleepNow()
     NS_LOG_FUNCTION(this);
     m_sleeping = true;
     // Cancel timeout
-    if (m_accessTimeout.IsRunning())
+    if (m_accessTimeout.IsPending())
     {
         m_accessTimeout.Cancel();
     }
@@ -1033,7 +1033,7 @@ ChannelAccessManager::NotifyOffNow()
     NS_LOG_FUNCTION(this);
     m_off = true;
     // Cancel timeout
-    if (m_accessTimeout.IsRunning())
+    if (m_accessTimeout.IsPending())
     {
         m_accessTimeout.Cancel();
     }
diff --git a/src/wifi/model/eht/eht-frame-exchange-manager.cc b/src/wifi/model/eht/eht-frame-exchange-manager.cc
index 5ffe3f790..abce2538a 100644
--- a/src/wifi/model/eht/eht-frame-exchange-manager.cc
+++ b/src/wifi/model/eht/eht-frame-exchange-manager.cc
@@ -192,7 +192,7 @@ EhtFrameExchangeManager::StartTransmission(Ptr<Txop> edca, uint16_t allowedWidth
             // check if an EMLSR client is the holder of an UL TXOP on the other link
             if (auto ehtFem =
                     StaticCast<EhtFrameExchangeManager>(m_mac->GetFrameExchangeManager(linkId));
-                ehtFem->m_ongoingTxopEnd.IsRunning() && ehtFem->m_txopHolder &&
+                ehtFem->m_ongoingTxopEnd.IsPending() && ehtFem->m_txopHolder &&
                 m_mac->GetWifiRemoteStationManager(linkId)->GetEmlsrEnabled(
                     ehtFem->m_txopHolder.value()))
             {
@@ -473,7 +473,7 @@ EhtFrameExchangeManager::EmlsrSwitchToListening(const Mac48Address& address, con
     {
         if (auto ehtFem =
                 StaticCast<EhtFrameExchangeManager>(m_mac->GetFrameExchangeManager(linkId));
-            ehtFem->m_ongoingTxopEnd.IsRunning() && ehtFem->m_txopHolder &&
+            ehtFem->m_ongoingTxopEnd.IsPending() && ehtFem->m_txopHolder &&
             m_mac->GetWifiRemoteStationManager(linkId)->GetMldAddress(*ehtFem->m_txopHolder) ==
                 mldAddress)
         {
@@ -705,7 +705,7 @@ EhtFrameExchangeManager::CtsAfterMuRtsTimeout(Ptr<WifiMpdu> muRts, const WifiTxV
         auto mldAddress = GetWifiRemoteStationManager()->GetMldAddress(address);
         NS_ASSERT(mldAddress);
 
-        if (m_ongoingTxopEnd.IsRunning() && m_txopHolder &&
+        if (m_ongoingTxopEnd.IsPending() && m_txopHolder &&
             m_mac->GetMldAddress(*m_txopHolder) == mldAddress)
         {
             continue;
@@ -897,7 +897,7 @@ EhtFrameExchangeManager::NotifyChannelReleased(Ptr<Txop> txop)
         NS_ASSERT(m_staMac->GetEmlsrManager());
         m_staMac->GetEmlsrManager()->NotifyTxopEnd(m_linkId,
                                                    (!txopStart || *txopStart == Simulator::Now()),
-                                                   m_ongoingTxopEnd.IsRunning());
+                                                   m_ongoingTxopEnd.IsPending());
     }
 
     HeFrameExchangeManager::NotifyChannelReleased(txop);
@@ -962,7 +962,7 @@ EhtFrameExchangeManager::PostProcessFrame(Ptr<const WifiPsdu> psdu, const WifiTx
     if (m_apMac && m_txopHolder == psdu->GetAddr2() &&
         GetWifiRemoteStationManager()->GetEmlsrEnabled(*m_txopHolder))
     {
-        if (!m_ongoingTxopEnd.IsRunning())
+        if (!m_ongoingTxopEnd.IsPending())
         {
             // an EMLSR client has started an UL TXOP. Start the ongoingTxopEnd timer so that
             // the next call to UpdateTxopEndOnRxEnd does its job
@@ -973,7 +973,7 @@ EhtFrameExchangeManager::PostProcessFrame(Ptr<const WifiPsdu> psdu, const WifiTx
         UpdateTxopEndOnRxEnd(psdu->GetDuration());
     }
 
-    if (m_staMac && m_ongoingTxopEnd.IsRunning())
+    if (m_staMac && m_ongoingTxopEnd.IsPending())
     {
         if (GetEmlsrSwitchToListening(psdu, m_staMac->GetAssociationId(), m_self))
         {
@@ -996,7 +996,7 @@ EhtFrameExchangeManager::CheckEmlsrClientStartingTxop(const WifiMacHeader& hdr,
 
     auto sender = hdr.GetAddr2();
 
-    if (m_ongoingTxopEnd.IsRunning())
+    if (m_ongoingTxopEnd.IsPending())
     {
         NS_LOG_DEBUG("A TXOP is already ongoing");
         return false;
@@ -1041,7 +1041,7 @@ EhtFrameExchangeManager::CheckEmlsrClientStartingTxop(const WifiMacHeader& hdr,
 
     // Stop the transition delay timer for this EMLSR client, if any is running
     if (auto it = m_transDelayTimer.find(*mldAddress);
-        it != m_transDelayTimer.end() && it->second.IsRunning())
+        it != m_transDelayTimer.end() && it->second.IsPending())
     {
         it->second.PeekEventImpl()->Invoke();
         it->second.Cancel();
@@ -1209,7 +1209,7 @@ EhtFrameExchangeManager::UpdateTxopEndOnTxStart(Time txDuration, Time durationId
 {
     NS_LOG_FUNCTION(this << txDuration.As(Time::MS) << durationId.As(Time::US));
 
-    if (!m_ongoingTxopEnd.IsRunning())
+    if (!m_ongoingTxopEnd.IsPending())
     {
         // nothing to do
         return;
@@ -1252,7 +1252,7 @@ EhtFrameExchangeManager::UpdateTxopEndOnRxStartIndication(Time psduDuration)
 {
     NS_LOG_FUNCTION(this << psduDuration.As(Time::MS));
 
-    if (!m_ongoingTxopEnd.IsRunning() || !psduDuration.IsStrictlyPositive())
+    if (!m_ongoingTxopEnd.IsPending() || !psduDuration.IsStrictlyPositive())
     {
         // nothing to do
         return;
@@ -1273,7 +1273,7 @@ EhtFrameExchangeManager::UpdateTxopEndOnRxEnd(Time durationId)
 {
     NS_LOG_FUNCTION(this << durationId.As(Time::US));
 
-    if (!m_ongoingTxopEnd.IsRunning())
+    if (!m_ongoingTxopEnd.IsPending())
     {
         // nothing to do
         return;
diff --git a/src/wifi/model/eht/emlsr-manager.cc b/src/wifi/model/eht/emlsr-manager.cc
index efb16cee1..08d1005be 100644
--- a/src/wifi/model/eht/emlsr-manager.cc
+++ b/src/wifi/model/eht/emlsr-manager.cc
@@ -231,7 +231,7 @@ std::optional<Time>
 EmlsrManager::GetElapsedMediumSyncDelayTimer(uint8_t linkId) const
 {
     if (const auto statusIt = m_mediumSyncDelayStatus.find(linkId);
-        statusIt != m_mediumSyncDelayStatus.cend() && statusIt->second.timer.IsRunning())
+        statusIt != m_mediumSyncDelayStatus.cend() && statusIt->second.timer.IsPending())
     {
         return m_mediumSyncDuration - Simulator::GetDelayLeft(statusIt->second.timer);
     }
@@ -343,7 +343,7 @@ EmlsrManager::NotifyMgtFrameReceived(Ptr<const WifiMpdu> mpdu, uint8_t linkId)
             action.protectedEhtAction ==
                 WifiActionHeader::PROTECTED_EHT_EML_OPERATING_MODE_NOTIFICATION)
         {
-            if (m_transitionTimeoutEvent.IsRunning())
+            if (m_transitionTimeoutEvent.IsPending())
             {
                 // no need to wait until the expiration of the transition timeout
                 m_transitionTimeoutEvent.PeekEventImpl()->Invoke();
@@ -462,7 +462,7 @@ EmlsrManager::NotifyTxopEnd(uint8_t linkId, bool ulTxopNotStarted, bool ongoingD
     // receive a CTS response.
     if (auto it = m_ulMainPhySwitch.find(linkId); it != m_ulMainPhySwitch.end())
     {
-        if (it->second.IsRunning())
+        if (it->second.IsPending())
         {
             NS_LOG_DEBUG("Cancelling main PHY channel switch event on link " << +linkId);
             it->second.Cancel();
@@ -515,7 +515,7 @@ EmlsrManager::SetCcaEdThresholdOnLinkSwitch(Ptr<WifiPhy> phy, uint8_t linkId)
     // if a MediumSyncDelay timer is running for the link on which the main PHY is going to
     // operate, set the CCA ED threshold to the MediumSyncDelay OFDM ED threshold
     if (auto statusIt = m_mediumSyncDelayStatus.find(linkId);
-        statusIt != m_mediumSyncDelayStatus.cend() && statusIt->second.timer.IsRunning())
+        statusIt != m_mediumSyncDelayStatus.cend() && statusIt->second.timer.IsPending())
     {
         NS_LOG_DEBUG("Setting CCA ED threshold of PHY " << phy << " to " << +m_msdOfdmEdThreshold
                                                         << " on link " << +linkId);
@@ -679,7 +679,7 @@ EmlsrManager::StartMediumSyncDelayTimer(uint8_t linkId)
             // switching to a link on which an aux PHY gained a TXOP and sent an RTS, but the CTS
             // is not received and the UL TXOP ends before the main PHY channel switch is
             // completed. The MSD timer is started on the link left "uncovered" by the main PHY
-            if (auto phy = m_staMac->GetWifiPhy(id); phy && !it->second.timer.IsRunning())
+            if (auto phy = m_staMac->GetWifiPhy(id); phy && !it->second.timer.IsPending())
             {
                 NS_LOG_DEBUG("Setting CCA ED threshold on link "
                              << +id << " to " << +m_msdOfdmEdThreshold << " PHY " << phy);
@@ -704,7 +704,7 @@ EmlsrManager::CancelMediumSyncDelayTimer(uint8_t linkId)
 
     auto timerIt = m_mediumSyncDelayStatus.find(linkId);
 
-    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsPending());
 
     timerIt->second.timer.Cancel();
     MediumSyncDelayTimerExpired(linkId);
@@ -717,7 +717,7 @@ EmlsrManager::MediumSyncDelayTimerExpired(uint8_t linkId)
 
     auto timerIt = m_mediumSyncDelayStatus.find(linkId);
 
-    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && !timerIt->second.timer.IsRunning());
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && !timerIt->second.timer.IsPending());
 
     // reset the MSD OFDM ED threshold
     auto phy = m_staMac->GetWifiPhy(linkId);
@@ -747,7 +747,7 @@ EmlsrManager::DecrementMediumSyncDelayNTxops(uint8_t linkId)
 
     const auto timerIt = m_mediumSyncDelayStatus.find(linkId);
 
-    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsPending());
     NS_ASSERT(timerIt->second.msdNTxopsLeft != 0);
 
     if (timerIt->second.msdNTxopsLeft)
@@ -763,7 +763,7 @@ EmlsrManager::ResetMediumSyncDelayNTxops(uint8_t linkId)
 
     auto timerIt = m_mediumSyncDelayStatus.find(linkId);
 
-    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsPending());
     timerIt->second.msdNTxopsLeft.reset();
 }
 
@@ -774,7 +774,7 @@ EmlsrManager::MediumSyncDelayNTxopsExceeded(uint8_t linkId)
 
     auto timerIt = m_mediumSyncDelayStatus.find(linkId);
 
-    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsPending());
     return timerIt->second.msdNTxopsLeft == 0;
 }
 
diff --git a/src/wifi/model/frame-exchange-manager.cc b/src/wifi/model/frame-exchange-manager.cc
index d78231526..ff5a116d4 100644
--- a/src/wifi/model/frame-exchange-manager.cc
+++ b/src/wifi/model/frame-exchange-manager.cc
@@ -73,7 +73,7 @@ FrameExchangeManager::Reset()
 {
     NS_LOG_FUNCTION(this);
     m_txTimer.Cancel();
-    if (m_navResetEvent.IsRunning())
+    if (m_navResetEvent.IsPending())
     {
         m_navResetEvent.Cancel();
     }
@@ -273,7 +273,7 @@ FrameExchangeManager::RxStartIndication(WifiTxVector txVector, Time psduDuration
     NS_LOG_FUNCTION(this << "PSDU reception started for " << psduDuration.As(Time::US)
                          << " (txVector: " << txVector << ")");
 
-    NS_ASSERT_MSG(!m_txTimer.IsRunning() || !m_navResetEvent.IsRunning(),
+    NS_ASSERT_MSG(!m_txTimer.IsRunning() || !m_navResetEvent.IsPending(),
                   "The TX timer and the NAV reset event cannot be both running");
 
     // No need to reschedule timeouts if PSDU duration is null. In this case,
@@ -288,7 +288,7 @@ FrameExchangeManager::RxStartIndication(WifiTxVector txVector, Time psduDuration
         m_channelAccessManager->NotifyAckTimeoutResetNow();
     }
 
-    if (m_navResetEvent.IsRunning())
+    if (m_navResetEvent.IsPending())
     {
         m_navResetEvent.Cancel();
     }
diff --git a/src/wifi/model/he/he-frame-exchange-manager.cc b/src/wifi/model/he/he-frame-exchange-manager.cc
index 01fcbb03e..cc1442146 100644
--- a/src/wifi/model/he/he-frame-exchange-manager.cc
+++ b/src/wifi/model/he/he-frame-exchange-manager.cc
@@ -88,7 +88,7 @@ void
 HeFrameExchangeManager::Reset()
 {
     NS_LOG_FUNCTION(this);
-    if (m_intraBssNavResetEvent.IsRunning())
+    if (m_intraBssNavResetEvent.IsPending())
     {
         m_intraBssNavResetEvent.Cancel();
     }
@@ -1273,7 +1273,7 @@ HeFrameExchangeManager::TbPpduTimeout(WifiPsduMap* psduMap, std::size_t nSolicit
 
         TransmissionFailed();
     }
-    else if (!m_multiStaBaEvent.IsRunning())
+    else if (!m_multiStaBaEvent.IsPending())
     {
         m_edca->ResetCw(m_linkId);
         TransmissionSucceeded();
@@ -2238,7 +2238,7 @@ HeFrameExchangeManager::ReceiveMpdu(Ptr<const WifiMpdu> mpdu,
         }
 
         // Schedule the transmission of a Multi-STA BlockAck frame if needed
-        if (!acknowledgment->stationsReceivingMultiStaBa.empty() && !m_multiStaBaEvent.IsRunning())
+        if (!acknowledgment->stationsReceivingMultiStaBa.empty() && !m_multiStaBaEvent.IsPending())
         {
             m_multiStaBaEvent = Simulator::Schedule(m_phy->GetSifs(),
                                                     &HeFrameExchangeManager::SendMultiStaBlockAck,
@@ -2256,7 +2256,7 @@ HeFrameExchangeManager::ReceiveMpdu(Ptr<const WifiMpdu> mpdu,
             m_txTimer.Cancel();
             m_channelAccessManager->NotifyAckTimeoutResetNow();
 
-            if (!m_multiStaBaEvent.IsRunning())
+            if (!m_multiStaBaEvent.IsPending())
             {
                 // all of the stations that replied with a TB PPDU sent QoS Null frames.
                 NS_LOG_DEBUG("Continue the TXOP");
@@ -2696,7 +2696,7 @@ HeFrameExchangeManager::EndReceiveAmpdu(Ptr<const WifiPsdu> psdu,
         }
 
         // Schedule the transmission of a Multi-STA BlockAck frame if needed
-        if (!acknowledgment->stationsReceivingMultiStaBa.empty() && !m_multiStaBaEvent.IsRunning())
+        if (!acknowledgment->stationsReceivingMultiStaBa.empty() && !m_multiStaBaEvent.IsPending())
         {
             m_multiStaBaEvent = Simulator::Schedule(m_phy->GetSifs(),
                                                     &HeFrameExchangeManager::SendMultiStaBlockAck,
@@ -2714,7 +2714,7 @@ HeFrameExchangeManager::EndReceiveAmpdu(Ptr<const WifiPsdu> psdu,
             m_txTimer.Cancel();
             m_channelAccessManager->NotifyAckTimeoutResetNow();
 
-            if (!m_multiStaBaEvent.IsRunning())
+            if (!m_multiStaBaEvent.IsPending())
             {
                 // all of the stations that replied with a TB PPDU sent QoS Null frames.
                 NS_LOG_DEBUG("Continue the TXOP");
diff --git a/src/wifi/model/he/he-phy.cc b/src/wifi/model/he/he-phy.cc
index cd0da9254..cb64dd769 100644
--- a/src/wifi/model/he/he-phy.cc
+++ b/src/wifi/model/he/he-phy.cc
@@ -832,7 +832,7 @@ HePhy::DoStartReceivePayload(Ptr<Event> event)
             Simulator::Schedule(timeToEndRx, &HePhy::ResetReceive, this, event));
         // Cancel all scheduled events for MU payload reception
         NS_ASSERT(!m_beginMuPayloadRxEvents.empty() &&
-                  m_beginMuPayloadRxEvents.begin()->second.IsRunning());
+                  m_beginMuPayloadRxEvents.begin()->second.IsPending());
         for (auto& beginMuPayloadRxEvent : m_beginMuPayloadRxEvents)
         {
             beginMuPayloadRxEvent.second.Cancel();
@@ -850,7 +850,7 @@ HePhy::DoStartReceivePayload(Ptr<Event> event)
         NS_ASSERT(!m_beginMuPayloadRxEvents.empty());
         for (auto& beginMuPayloadRxEvent : m_beginMuPayloadRxEvents)
         {
-            NS_ASSERT(beginMuPayloadRxEvent.second.IsRunning());
+            NS_ASSERT(beginMuPayloadRxEvent.second.IsPending());
         }
     }
 
diff --git a/src/wifi/model/he/multi-user-scheduler.cc b/src/wifi/model/he/multi-user-scheduler.cc
index 3782ce3c3..f3746e6ac 100644
--- a/src/wifi/model/he/multi-user-scheduler.cc
+++ b/src/wifi/model/he/multi-user-scheduler.cc
@@ -210,7 +210,7 @@ MultiUserScheduler::NotifyAccessGranted(Ptr<QosTxop> edca,
     m_allowedWidth = allowedWidth;
     m_linkId = linkId;
 
-    if (m_accessReqTimer.IsRunning() && m_restartTimerUponAccess)
+    if (m_accessReqTimer.IsPending() && m_restartTimerUponAccess)
     {
         // restart access timer
         m_accessReqTimer.Cancel();
diff --git a/src/wifi/model/qos-frame-exchange-manager.cc b/src/wifi/model/qos-frame-exchange-manager.cc
index c0de28402..2450378eb 100644
--- a/src/wifi/model/qos-frame-exchange-manager.cc
+++ b/src/wifi/model/qos-frame-exchange-manager.cc
@@ -149,7 +149,7 @@ void
 QosFrameExchangeManager::CancelPifsRecovery()
 {
     NS_LOG_FUNCTION(this);
-    NS_ASSERT(m_pifsRecoveryEvent.IsRunning());
+    NS_ASSERT(m_pifsRecoveryEvent.IsPending());
     NS_ASSERT(m_edca);
 
     NS_LOG_DEBUG("Cancel PIFS recovery being attempted by EDCAF " << m_edca);
@@ -162,7 +162,7 @@ QosFrameExchangeManager::StartTransmission(Ptr<Txop> edca, uint16_t allowedWidth
 {
     NS_LOG_FUNCTION(this << edca << allowedWidth);
 
-    if (m_pifsRecoveryEvent.IsRunning())
+    if (m_pifsRecoveryEvent.IsPending())
     {
         // Another AC (having AIFS=1 or lower, if the user changed the default settings)
         // gained channel access while performing PIFS recovery. Abort PIFS recovery
@@ -186,7 +186,7 @@ QosFrameExchangeManager::StartTransmission(Ptr<QosTxop> edca, Time txopDuration)
 {
     NS_LOG_FUNCTION(this << edca << txopDuration);
 
-    if (m_pifsRecoveryEvent.IsRunning())
+    if (m_pifsRecoveryEvent.IsPending())
     {
         // Another AC (having AIFS=1 or lower, if the user changed the default settings)
         // gained channel access while performing PIFS recovery. Abort PIFS recovery
@@ -641,7 +641,7 @@ QosFrameExchangeManager::TransmissionFailed()
             // we can continue the TXOP if the carrier sense mechanism indicates that
             // the medium is idle in a PIFS
             NS_LOG_DEBUG("TX of a non-initial frame of a TXOP failed: perform PIFS recovery");
-            NS_ASSERT(!m_pifsRecoveryEvent.IsRunning());
+            NS_ASSERT(!m_pifsRecoveryEvent.IsPending());
             m_pifsRecoveryEvent =
                 Simulator::Schedule(m_phy->GetPifs(), &QosFrameExchangeManager::PifsRecovery, this);
         }
diff --git a/src/wifi/model/sta-wifi-mac.cc b/src/wifi/model/sta-wifi-mac.cc
index 462f8fc20..ffc054e40 100644
--- a/src/wifi/model/sta-wifi-mac.cc
+++ b/src/wifi/model/sta-wifi-mac.cc
@@ -702,7 +702,7 @@ StaWifiMac::SendAssociationRequest(bool isReassoc)
         GetVOQueue()->Queue(packet, hdr);
     }
 
-    if (m_assocRequestEvent.IsRunning())
+    if (m_assocRequestEvent.IsPending())
     {
         m_assocRequestEvent.Cancel();
     }
@@ -862,7 +862,7 @@ StaWifiMac::MissedBeacons()
 
     if (m_beaconWatchdogEnd > Simulator::Now())
     {
-        if (m_beaconWatchdog.IsRunning())
+        if (m_beaconWatchdog.IsPending())
         {
             m_beaconWatchdog.Cancel();
         }
@@ -1324,7 +1324,7 @@ StaWifiMac::ReceiveAssocResp(Ptr<const WifiMpdu> mpdu, uint8_t linkId)
     std::optional<Mac48Address> apMldAddress;
     MgtAssocResponseHeader assocResp;
     mpdu->GetPacket()->PeekHeader(assocResp);
-    if (m_assocRequestEvent.IsRunning())
+    if (m_assocRequestEvent.IsPending())
     {
         m_assocRequestEvent.Cancel();
     }
diff --git a/src/wifi/model/txop.cc b/src/wifi/model/txop.cc
index cfcee0237..58f02cf51 100644
--- a/src/wifi/model/txop.cc
+++ b/src/wifi/model/txop.cc
@@ -644,7 +644,7 @@ Txop::Queue(Ptr<WifiMpdu> mpdu)
     // ignore the links for which a channel access request event is already running
     for (auto it = linkIds.begin(); it != linkIds.end();)
     {
-        if (const auto& event = GetLink(*it).accessRequest.event; event.IsRunning())
+        if (const auto& event = GetLink(*it).accessRequest.event; event.IsPending())
         {
             it = linkIds.erase(it);
         }
diff --git a/src/wifi/model/wifi-default-assoc-manager.cc b/src/wifi/model/wifi-default-assoc-manager.cc
index ba6d8bb3a..b672ff3ab 100644
--- a/src/wifi/model/wifi-default-assoc-manager.cc
+++ b/src/wifi/model/wifi-default-assoc-manager.cc
@@ -240,7 +240,7 @@ WifiDefaultAssocManager::EndScanning()
     }
 
     if (std::none_of(m_channelSwitchInfo.begin(), m_channelSwitchInfo.end(), [](auto&& info) {
-            return info.timer.IsRunning();
+            return info.timer.IsPending();
         }))
     {
         // we are done
@@ -252,13 +252,13 @@ void
 WifiDefaultAssocManager::NotifyChannelSwitched(uint8_t linkId)
 {
     NS_LOG_FUNCTION(this << +linkId);
-    if (m_channelSwitchInfo.size() > linkId && m_channelSwitchInfo[linkId].timer.IsRunning())
+    if (m_channelSwitchInfo.size() > linkId && m_channelSwitchInfo[linkId].timer.IsPending())
     {
         // we were waiting for this notification
         m_channelSwitchInfo[linkId].timer.Cancel();
 
         if (std::none_of(m_channelSwitchInfo.begin(), m_channelSwitchInfo.end(), [](auto&& info) {
-                return info.timer.IsRunning();
+                return info.timer.IsPending();
             }))
         {
             // we are done
@@ -282,7 +282,7 @@ WifiDefaultAssocManager::ChannelSwitchTimeout(uint8_t linkId)
     setupLinks.erase(it);
 
     if (std::none_of(m_channelSwitchInfo.begin(), m_channelSwitchInfo.end(), [](auto&& info) {
-            return info.timer.IsRunning();
+            return info.timer.IsPending();
         }))
     {
         // we are done
@@ -293,7 +293,7 @@ WifiDefaultAssocManager::ChannelSwitchTimeout(uint8_t linkId)
 bool
 WifiDefaultAssocManager::CanBeInserted(const StaWifiMac::ApInfo& apInfo) const
 {
-    return (m_waitBeaconEvent.IsRunning() || m_probeRequestEvent.IsRunning());
+    return (m_waitBeaconEvent.IsPending() || m_probeRequestEvent.IsPending());
 }
 
 bool
diff --git a/src/wifi/model/wifi-phy.cc b/src/wifi/model/wifi-phy.cc
index 26e56b886..87b4e4eef 100644
--- a/src/wifi/model/wifi-phy.cc
+++ b/src/wifi/model/wifi-phy.cc
@@ -1930,7 +1930,7 @@ WifiPhy::StartReceivePreamble(Ptr<const WifiPpdu> ppdu,
 bool
 WifiPhy::IsReceivingPhyHeader() const
 {
-    return m_endPhyRxEvent.IsRunning();
+    return m_endPhyRxEvent.IsPending();
 }
 
 void
diff --git a/src/wifi/model/wifi-tx-timer.cc b/src/wifi/model/wifi-tx-timer.cc
index 7ee49e25a..761ec2e58 100644
--- a/src/wifi/model/wifi-tx-timer.cc
+++ b/src/wifi/model/wifi-tx-timer.cc
@@ -49,7 +49,7 @@ WifiTxTimer::Reschedule(const Time& delay)
 {
     NS_LOG_FUNCTION(this << delay);
 
-    if (m_timeoutEvent.IsRunning())
+    if (m_timeoutEvent.IsPending())
     {
         NS_LOG_DEBUG("Rescheduling " << GetReasonString(m_reason) << " timeout in "
                                      << delay.As(Time::US));
@@ -120,7 +120,7 @@ WifiTxTimer::GetReasonString(Reason reason) const
 bool
 WifiTxTimer::IsRunning() const
 {
-    return m_timeoutEvent.IsRunning();
+    return m_timeoutEvent.IsPending();
 }
 
 void
diff --git a/src/wimax/model/bs-service-flow-manager.cc b/src/wimax/model/bs-service-flow-manager.cc
index 229b6e7dc..f6aed0bf5 100644
--- a/src/wimax/model/bs-service-flow-manager.cc
+++ b/src/wimax/model/bs-service-flow-manager.cc
@@ -169,7 +169,7 @@ BsServiceFlowManager::ScheduleDsaRsp(ServiceFlow* serviceFlow, Cid cid)
     ssRecord->IncrementDsaRspRetries();
     p->AddHeader(ManagementMessageType(ManagementMessageType::MESSAGE_TYPE_DSA_RSP));
 
-    if (m_dsaAckTimeoutEvent.IsRunning())
+    if (m_dsaAckTimeoutEvent.IsPending())
     {
         Simulator::Cancel(m_dsaAckTimeoutEvent);
     }
diff --git a/src/wimax/model/ss-link-manager.cc b/src/wimax/model/ss-link-manager.cc
index f564ad0ec..b14b572ff 100644
--- a/src/wimax/model/ss-link-manager.cc
+++ b/src/wimax/model/ss-link-manager.cc
@@ -377,7 +377,7 @@ SSLinkManager::PerformRanging(Cid cid, RngRsp rngrsp)
     }
 
     m_nrRngRspsRecvd++;
-    if (m_waitForRngRspEvent.IsRunning())
+    if (m_waitForRngRspEvent.IsPending())
     {
         Simulator::Cancel(m_waitForRngRspEvent);
     }
diff --git a/src/wimax/model/ss-net-device.cc b/src/wimax/model/ss-net-device.cc
index ec45c6f85..58a9d16d2 100644
--- a/src/wimax/model/ss-net-device.cc
+++ b/src/wimax/model/ss-net-device.cc
@@ -854,7 +854,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
                     Simulator::Cancel(m_linkManager->GetDlMapSyncTimeoutEvent());
                 }
 
-                if (m_lostDlMapEvent.IsRunning())
+                if (m_lostDlMapEvent.IsPending())
                 {
                     Simulator::Cancel(m_lostDlMapEvent);
                 }
@@ -864,7 +864,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
                                                        false,
                                                        m_lostDlMapEvent);
 
-                if (m_dcdWaitTimeoutEvent.IsRunning())
+                if (m_dcdWaitTimeoutEvent.IsPending())
                 {
                     Simulator::Cancel(m_dcdWaitTimeoutEvent);
                 }
@@ -874,7 +874,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
                                                        false,
                                                        m_dcdWaitTimeoutEvent);
 
-                if (m_ucdWaitTimeoutEvent.IsRunning())
+                if (m_ucdWaitTimeoutEvent.IsPending())
                 {
                     Simulator::Cancel(m_ucdWaitTimeoutEvent);
                 }
@@ -890,7 +890,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
                 break;
             }
             case ManagementMessageType::MESSAGE_TYPE_UL_MAP: {
-                if (m_lostUlMapEvent.IsRunning())
+                if (m_lostUlMapEvent.IsPending())
                 {
                     Simulator::Cancel(m_lostUlMapEvent);
                     m_linkManager->ScheduleScanningRestart(m_lostUlMapInterval,
@@ -908,7 +908,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
                 {
                     if (m_linkManager->GetRangingIntervalFound())
                     {
-                        if (m_rangOppWaitTimeoutEvent.IsRunning())
+                        if (m_rangOppWaitTimeoutEvent.IsPending())
                         {
                             Simulator::Cancel(m_rangOppWaitTimeoutEvent);
                         }
@@ -923,7 +923,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
                     SetState(SS_STATE_ACQUIRING_PARAMETERS);
                 }
 
-                if (m_dcdWaitTimeoutEvent.IsRunning())
+                if (m_dcdWaitTimeoutEvent.IsPending())
                 {
                     Simulator::Cancel(m_dcdWaitTimeoutEvent);
                     m_linkManager->ScheduleScanningRestart(m_intervalT1,
@@ -950,7 +950,7 @@ SubscriberStationNetDevice::DoReceive(Ptr<Packet> packet)
 
                 ProcessUcd(ucd);
 
-                if (m_ucdWaitTimeoutEvent.IsRunning())
+                if (m_ucdWaitTimeoutEvent.IsPending())
                 {
                     Simulator::Cancel(m_ucdWaitTimeoutEvent);
                     m_linkManager->ScheduleScanningRestart(m_intervalT12,
diff --git a/src/wimax/model/ss-service-flow-manager.cc b/src/wimax/model/ss-service-flow-manager.cc
index 629b679a7..d7b6385ef 100644
--- a/src/wimax/model/ss-service-flow-manager.cc
+++ b/src/wimax/model/ss-service-flow-manager.cc
@@ -182,7 +182,7 @@ SsServiceFlowManager::ScheduleDsaReq(const ServiceFlow* serviceFlow)
     m_dsaReqRetries++;
     p->AddHeader(ManagementMessageType(ManagementMessageType::MESSAGE_TYPE_DSA_REQ));
 
-    if (m_dsaRspTimeoutEvent.IsRunning())
+    if (m_dsaRspTimeoutEvent.IsPending())
     {
         Simulator::Cancel(m_dsaRspTimeoutEvent);
     }