From 56511e5108e6d0857ab4edd944d1c4e695408f2a Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@unina.it>
Date: Fri, 8 Sep 2023 22:11:01 +0200
Subject: [PATCH] wifi: Do not reset NAV while using another EMLSR link

CTS may have been missed due to the main PHY switching
to another link to take over a TXOP while receiving the CTS.
---
 src/wifi/model/channel-access-manager.cc      |  8 +++++++
 .../model/eht/eht-frame-exchange-manager.cc   | 24 +++++++++++++++++++
 .../model/eht/eht-frame-exchange-manager.h    |  2 ++
 3 files changed, 34 insertions(+)

diff --git a/src/wifi/model/channel-access-manager.cc b/src/wifi/model/channel-access-manager.cc
index da9ad82ec..4664e3dee 100644
--- a/src/wifi/model/channel-access-manager.cc
+++ b/src/wifi/model/channel-access-manager.cc
@@ -1028,6 +1028,14 @@ void
 ChannelAccessManager::NotifyNavResetNow(Time duration)
 {
     NS_LOG_FUNCTION(this << duration);
+
+    if (!m_phy)
+    {
+        NS_LOG_DEBUG("Do not reset NAV, CTS may have been missed due to the main PHY switching "
+                     "to another link to take over a TXOP while receiving the CTS");
+        return;
+    }
+
     NS_LOG_DEBUG("nav reset for=" << duration);
     UpdateBackoff();
     m_lastNavEnd = Simulator::Now() + duration;
diff --git a/src/wifi/model/eht/eht-frame-exchange-manager.cc b/src/wifi/model/eht/eht-frame-exchange-manager.cc
index 9c493c8e3..5314f8df4 100644
--- a/src/wifi/model/eht/eht-frame-exchange-manager.cc
+++ b/src/wifi/model/eht/eht-frame-exchange-manager.cc
@@ -294,6 +294,30 @@ EhtFrameExchangeManager::ForwardPsduMapDown(WifiConstPsduMap psduMap, WifiTxVect
     }
 }
 
+void
+EhtFrameExchangeManager::NavResetTimeout()
+{
+    NS_LOG_FUNCTION(this);
+    if (UsingOtherEmlsrLink())
+    {
+        // the CTS may have been missed because another EMLSR link is being used; do not reset NAV
+        return;
+    }
+    HeFrameExchangeManager::NavResetTimeout();
+}
+
+void
+EhtFrameExchangeManager::IntraBssNavResetTimeout()
+{
+    NS_LOG_FUNCTION(this);
+    if (UsingOtherEmlsrLink())
+    {
+        // the CTS may have been missed because another EMLSR link is being used; do not reset NAV
+        return;
+    }
+    HeFrameExchangeManager::IntraBssNavResetTimeout();
+}
+
 void
 EhtFrameExchangeManager::EmlsrSwitchToListening(const Mac48Address& address, const Time& delay)
 {
diff --git a/src/wifi/model/eht/eht-frame-exchange-manager.h b/src/wifi/model/eht/eht-frame-exchange-manager.h
index 72071f7df..bfb953610 100644
--- a/src/wifi/model/eht/eht-frame-exchange-manager.h
+++ b/src/wifi/model/eht/eht-frame-exchange-manager.h
@@ -113,6 +113,8 @@ class EhtFrameExchangeManager : public HeFrameExchangeManager
                      RxSignalInfo rxSignalInfo,
                      const WifiTxVector& txVector,
                      bool inAmpdu) override;
+    void NavResetTimeout() override;
+    void IntraBssNavResetTimeout() override;
 
     /**
      * This method is intended to be called when an AP MLD detects that an EMLSR client previously