wifi: Block transmissions on other EMLSR links as soon as DL TXOP start is detected

RELEASE_NOTES.md

@@ -39,6 +39,7 @@ ns-3 has switched to the C++23 standard by default.
 ### Bugs fixed
 
 - (internet) #1251 - Added check for longest prefix match in GlobalRouting
+- (wifi) Block transmission on other EMLSR links as soon as it is detected that the main PHY is receiving an A-MPDU, to prevent that the EMLSR client starts an UL TXOP before the end of the A-MPDU
 
 ## Release 3.45
 

src/wifi/model/eht/advanced-emlsr-manager.cc

@@ -329,6 +329,7 @@ AdvancedEmlsrManager::ReceivedMacHdr(Ptr<WifiPhy> phy,
     NS_LOG_FUNCTION(this << *linkId << macHdr << txVector << psduDuration.As(Time::MS));
 
     auto& ongoingTxopEnd = GetEhtFem(*linkId)->GetOngoingTxopEndEvent();
+    const auto isMainPhy = (phy->GetPhyId() == GetMainPhyId());
 
     if (ongoingTxopEnd.IsPending() && macHdr.GetAddr1() != GetEhtFem(*linkId)->GetAddress() &&
         !macHdr.GetAddr1().IsBroadcast() &&
@@ -346,13 +347,30 @@ AdvancedEmlsrManager::ReceivedMacHdr(Ptr<WifiPhy> phy,
         Simulator::ScheduleNow(&AdvancedEmlsrManager::NotifyTxopEnd, this, *linkId, nullptr);
     }
 
+    if (!ongoingTxopEnd.IsPending() && GetStaMac()->IsEmlsrLink(*linkId) && isMainPhy &&
+        !GetEhtFem(*linkId)->UsingOtherEmlsrLink() &&
+        (macHdr.IsRts() || macHdr.IsBlockAckReq() || macHdr.IsData()) &&
+        (macHdr.GetAddr1() == GetEhtFem(*linkId)->GetAddress()))
+    {
+        // a frame that is starting a DL TXOP is being received by the main PHY; start blocking
+        // transmission on other links (which is normally done later on by PostProcessFrame()) to
+        // avoid starting an UL TXOP before the end of the MPDU
+        for (auto id : GetStaMac()->GetLinkIds())
+        {
+            if (id != *linkId && GetStaMac()->IsEmlsrLink(id))
+            {
+                GetStaMac()->BlockTxOnLink(id, WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK);
+            }
+        }
+        return;
+    }
+
     // if the MAC header has been received on the link on which the main PHY is operating (or on
     // the link the main PHY is switching to), the switch main PHY back timer is running and channel
     // access is not expected to be gained by the main PHY before the switch main PHY back timer
     // expires (plus a channel switch delay), try to switch the main PHY back to the preferred link
     const auto mainPhyInvolved =
-        (phy->GetPhyId() == GetMainPhyId()) ||
-        (m_mainPhySwitchInfo.disconnected && m_mainPhySwitchInfo.to == *linkId);
+        isMainPhy || (m_mainPhySwitchInfo.disconnected && m_mainPhySwitchInfo.to == *linkId);
     const auto delay =
         Simulator::GetDelayLeft(m_switchMainPhyBackEvent) + phy->GetChannelSwitchDelay();
 

src/wifi/model/eht/eht-frame-exchange-manager.cc

@@ -1526,10 +1526,29 @@ EhtFrameExchangeManager::ReceiveMpdu(Ptr<const WifiMpdu> mpdu,
     }
     else if (m_staMac && m_staMac->IsEmlsrLink(m_linkId) && !m_ongoingTxopEnd.IsPending() &&
              m_phy->GetPhyId() == m_staMac->GetEmlsrManager()->GetMainPhyId() &&
-             (hdr.IsRts() || hdr.IsBlockAckReq() || (hdr.IsData() && hdr.GetAddr1() == m_self)))
+             (hdr.IsRts() || hdr.IsBlockAckReq() || hdr.IsData()) && hdr.GetAddr1() == m_self)
     {
-        // a frame that is starting a DL TXOP has been received by the main PHY
+        // a frame that is starting a DL TXOP has been received by the main PHY, check if the frame
+        // shall be dropped
+        if (DropReceivedIcf(mpdu))
+        {
+            return;
+        }
+
         m_dlTxopStart = true;
+
+        if (inAmpdu)
+        {
+            // start blocking transmission on other links (which is normally done later on by
+            // PostProcessFrame()) to avoid starting an UL TXOP before end of A-MPDU
+            for (auto id : m_staMac->GetLinkIds())
+            {
+                if (id != m_linkId && m_staMac->IsEmlsrLink(id))
+                {
+                    m_staMac->BlockTxOnLink(id, WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK);
+                }
+            }
+        }
     }
 
     if (!m_dlTxopStart && ShallDropReceivedMpdu(mpdu))
@@ -1555,33 +1574,6 @@ EhtFrameExchangeManager::ReceiveMpdu(Ptr<const WifiMpdu> mpdu,
     }
 }
 
-void
-EhtFrameExchangeManager::EndReceiveAmpdu(Ptr<const WifiPsdu> psdu,
-                                         const RxSignalInfo& rxSignalInfo,
-                                         const WifiTxVector& txVector,
-                                         const std::vector<bool>& perMpduStatus)
-{
-    NS_LOG_FUNCTION(
-        this << *psdu << rxSignalInfo << txVector << perMpduStatus.size()
-             << std::all_of(perMpduStatus.begin(), perMpduStatus.end(), [](bool v) { return v; }));
-
-    const auto& hdr = psdu->GetHeader(0);
-    if (m_staMac && m_staMac->IsEmlsrLink(m_linkId) && !m_ongoingTxopEnd.IsPending() &&
-        m_phy->GetPhyId() == m_staMac->GetEmlsrManager()->GetMainPhyId() &&
-        (hdr.IsData() && hdr.GetAddr1() == m_self))
-    {
-        // a frame that is starting a DL TXOP has been received by the main PHY
-        m_dlTxopStart = true;
-    }
-
-    if (!m_dlTxopStart && ShallDropReceivedMpdu(*psdu->begin()))
-    {
-        return;
-    }
-
-    HeFrameExchangeManager::EndReceiveAmpdu(psdu, rxSignalInfo, txVector, perMpduStatus);
-}
-
 bool
 EhtFrameExchangeManager::ShallDropReceivedMpdu(Ptr<const WifiMpdu> mpdu) const
 {

src/wifi/model/eht/eht-frame-exchange-manager.h

@@ -189,10 +189,6 @@ class EhtFrameExchangeManager : public HeFrameExchangeManager
                      RxSignalInfo rxSignalInfo,
                      const WifiTxVector& txVector,
                      bool inAmpdu) override;
-    void EndReceiveAmpdu(Ptr<const WifiPsdu> psdu,
-                         const RxSignalInfo& rxSignalInfo,
-                         const WifiTxVector& txVector,
-                         const std::vector<bool>& perMpduStatus) override;
     void NavResetTimeout() override;
     void IntraBssNavResetTimeout() override;
     void SendCtsAfterRts(const WifiMacHeader& rtsHdr,