wifi: EMLSR clients honor the limit on max number of TXOP attempts

nsnam · Oct 12, 2023 · edf72af · edf72af
1 parent 74c9b84
commit edf72af
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Showing 4 changed files with 111 additions and 1 deletion.
diff --git a/src/wifi/model/eht/eht-frame-exchange-manager.cc b/src/wifi/model/eht/eht-frame-exchange-manager.cc
@@ -154,6 +154,24 @@ EhtFrameExchangeManager::StartTransmission(Ptr<Txop> edca, uint16_t allowedWidth
         NS_ASSERT_MSG(mask && !mask->test(static_cast<std::size_t>(
                                   WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK)),
                       "StartTransmission called while EMLSR link is being used");
+
+        auto emlsrManager = m_staMac->GetEmlsrManager();
+
+        if (auto elapsed = emlsrManager->GetElapsedMediumSyncDelayTimer(m_linkId);
+            elapsed && emlsrManager->MediumSyncDelayNTxopsExceeded(m_linkId))
+        {
+            edca->NotifyChannelReleased(m_linkId);
+            NS_LOG_DEBUG("No new TXOP attempts allowed while MediumSyncDelay is running");
+            // request channel access if needed when the MediumSyncDelay timer expires
+            Simulator::Schedule(emlsrManager->GetMediumSyncDuration() - *elapsed, [=]() {
+                if (edca->GetAccessStatus(m_linkId) == Txop::NOT_REQUESTED &&
+                    edca->HasFramesToTransmit(m_linkId))
+                {
+                    m_staMac->GetChannelAccessManager(m_linkId)->RequestAccess(edca);
+                }
+            });
+            return false;
+        }
     }
 
     auto started = HeFrameExchangeManager::StartTransmission(edca, allowedWidth);
@@ -489,11 +507,35 @@ EhtFrameExchangeManager::GetEmlsrSwitchToListening(Ptr<const WifiPsdu> psdu,
     return true;
 }
 
+void
+EhtFrameExchangeManager::TransmissionSucceeded()
+{
+    NS_LOG_FUNCTION(this);
+
+    if (m_staMac && m_staMac->IsEmlsrLink(m_linkId) &&
+        m_staMac->GetEmlsrManager()->GetElapsedMediumSyncDelayTimer(m_linkId))
+    {
+        NS_LOG_DEBUG("Reset the counter of TXOP attempts allowed while "
+                     "MediumSyncDelay is running");
+        m_staMac->GetEmlsrManager()->ResetMediumSyncDelayNTxops(m_linkId);
+    }
+
+    HeFrameExchangeManager::TransmissionSucceeded();
+}
+
 void
 EhtFrameExchangeManager::TransmissionFailed()
 {
     NS_LOG_FUNCTION(this);
 
+    if (m_staMac && m_staMac->IsEmlsrLink(m_linkId) &&
+        m_staMac->GetEmlsrManager()->GetElapsedMediumSyncDelayTimer(m_linkId))
+    {
+        NS_LOG_DEBUG("Decrement the remaining number of TXOP attempts allowed while "
+                     "MediumSyncDelay is running");
+        m_staMac->GetEmlsrManager()->DecrementMediumSyncDelayNTxops(m_linkId);
+    }
+
     for (const auto& address : m_txTimer.GetStasExpectedToRespond())
     {
         if (GetWifiRemoteStationManager()->GetEmlsrEnabled(address))
@@ -509,7 +551,7 @@ EhtFrameExchangeManager::TransmissionFailed()
             // protected stations, hence next transmission to this client in this TXOP will be
             // protected by ICF
             NS_LOG_DEBUG("EMLSR client " << address << " did not respond, continue TXOP");
-            TransmissionSucceeded();
+            HeFrameExchangeManager::TransmissionSucceeded();
             return;
         }
     }

diff --git a/src/wifi/model/eht/eht-frame-exchange-manager.h b/src/wifi/model/eht/eht-frame-exchange-manager.h
@@ -93,6 +93,7 @@ class EhtFrameExchangeManager : public HeFrameExchangeManager
     void ForwardPsduDown(Ptr<const WifiPsdu> psdu, WifiTxVector& txVector) override;
     void ForwardPsduMapDown(WifiConstPsduMap psduMap, WifiTxVector& txVector) override;
     void SendMuRts(const WifiTxParameters& txParams) override;
+    void TransmissionSucceeded() override;
     void TransmissionFailed() override;
     void NotifyChannelReleased(Ptr<Txop> txop) override;
     void PreProcessFrame(Ptr<const WifiPsdu> psdu, const WifiTxVector& txVector) override;

diff --git a/src/wifi/model/eht/emlsr-manager.cc b/src/wifi/model/eht/emlsr-manager.cc
@@ -621,6 +621,44 @@ EmlsrManager::MediumSyncDelayTimerExpired(uint8_t linkId)
     m_prevCcaEdThreshold.erase(threshIt);
 }
 
+void
+EmlsrManager::DecrementMediumSyncDelayNTxops(uint8_t linkId)
+{
+    NS_LOG_FUNCTION(this << linkId);
+
+    const auto timerIt = m_mediumSyncDelayStatus.find(linkId);
+
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    NS_ASSERT(timerIt->second.msdNTxopsLeft != 0);
+
+    if (timerIt->second.msdNTxopsLeft)
+    {
+        --timerIt->second.msdNTxopsLeft.value();
+    }
+}
+
+void
+EmlsrManager::ResetMediumSyncDelayNTxops(uint8_t linkId)
+{
+    NS_LOG_FUNCTION(this << linkId);
+
+    auto timerIt = m_mediumSyncDelayStatus.find(linkId);
+
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    timerIt->second.msdNTxopsLeft.reset();
+}
+
+bool
+EmlsrManager::MediumSyncDelayNTxopsExceeded(uint8_t linkId)
+{
+    NS_LOG_FUNCTION(this << linkId);
+
+    auto timerIt = m_mediumSyncDelayStatus.find(linkId);
+
+    NS_ASSERT(timerIt != m_mediumSyncDelayStatus.cend() && timerIt->second.timer.IsRunning());
+    return timerIt->second.msdNTxopsLeft == 0;
+}
+
 MgtEmlOmn
 EmlsrManager::GetEmlOmn()
 {

diff --git a/src/wifi/model/eht/emlsr-manager.h b/src/wifi/model/eht/emlsr-manager.h
@@ -195,6 +195,35 @@ class EmlsrManager : public Object
      */
     void CancelMediumSyncDelayTimer(uint8_t linkId);
 
+    /**
+     * Decrement the counter indicating the number of TXOP attempts left while the MediumSyncDelay
+     * timer is running. This function must not be called when the MediumSyncDelay timer is not
+     * running on the given link.
+     *
+     * \param linkId the ID of the link on which a new TXOP attempt may be carried out
+     */
+    void DecrementMediumSyncDelayNTxops(uint8_t linkId);
+
+    /**
+     * Reset the counter indicating the number of TXOP attempts left while the MediumSyncDelay
+     * timer is running, so as to remove the limit on the number of attempts that can be made
+     * while the MediumSyncDelay timer is running. This function is normally called when a TXOP
+     * attempt is successful. This function must not be called when the MediumSyncDelay timer is
+     * not running on the given link.
+     *
+     * \param linkId the ID of the link for which the counter of the TXOP attempts is reset
+     */
+    void ResetMediumSyncDelayNTxops(uint8_t linkId);
+
+    /**
+     * Return whether no more TXOP attempt is allowed on the given link. This function must not
+     * be called when the MediumSyncDelay timer is not running on the given link.
+     *
+     * \param linkId the ID of the link on which a new TXOP attempt may be carried out
+     * \return whether no more TXOP attempt on the given link is allowed
+     */
+    bool MediumSyncDelayNTxopsExceeded(uint8_t linkId);
+
   protected:
     void DoDispose() override;