From a4626d178a8a26e96b80bb2996672f8086a96b42 Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@unina.it>
Date: Sat, 18 Dec 2021 18:36:27 +0100
Subject: [PATCH] wifi: Set TXOP holder when receiving a Trigger Frame

---
 .../model/he/he-frame-exchange-manager.cc     | 19 ++++++++++++++++++-
 src/wifi/model/he/he-frame-exchange-manager.h |  1 +
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/wifi/model/he/he-frame-exchange-manager.cc b/src/wifi/model/he/he-frame-exchange-manager.cc
index ca2cdcbde..464333543 100644
--- a/src/wifi/model/he/he-frame-exchange-manager.cc
+++ b/src/wifi/model/he/he-frame-exchange-manager.cc
@@ -1234,7 +1234,9 @@ HeFrameExchangeManager::SendQosNullFramesInTbPpdu (const CtrlTriggerHeader& trig
 
   if (trigger.GetCsRequired () && hdr.GetAddr2 () != m_txopHolder && m_navEnd > Simulator::Now ())
     {
-      NS_LOG_DEBUG ("Carrier Sensing required and channel busy, do nothing");
+      NS_LOG_DEBUG ("Carrier Sensing required and channel busy (TA=" << hdr.GetAddr2 ()
+                    << ", TxopHolder=" << m_txopHolder << ", NAV end=" << m_navEnd.As (Time::S)
+                    << "), do nothing");
       return;
     }
 
@@ -1296,6 +1298,21 @@ HeFrameExchangeManager::SendQosNullFramesInTbPpdu (const CtrlTriggerHeader& trig
   SendPsduMapWithProtection (WifiPsduMap {{staId, psdu}}, txParams);
 }
 
+void
+HeFrameExchangeManager::SetTxopHolder (Ptr<const WifiPsdu> psdu, const WifiTxVector& txVector)
+{
+  NS_LOG_FUNCTION (this << psdu << txVector);
+
+  if (psdu->GetHeader (0).IsTrigger ())
+    {
+      m_txopHolder = psdu->GetAddr2 ();
+    }
+  else if (!txVector.IsUlMu ())  // the sender of a TB PPDU is not the TXOP holder
+    {
+      VhtFrameExchangeManager::SetTxopHolder (psdu, txVector);
+    }
+}
+
 void
 HeFrameExchangeManager::ReceiveMpdu (Ptr<WifiMacQueueItem> mpdu, RxSignalInfo rxSignalInfo,
                                      const WifiTxVector& txVector, bool inAmpdu)
diff --git a/src/wifi/model/he/he-frame-exchange-manager.h b/src/wifi/model/he/he-frame-exchange-manager.h
index 63ccf6757..8c7b12276 100644
--- a/src/wifi/model/he/he-frame-exchange-manager.h
+++ b/src/wifi/model/he/he-frame-exchange-manager.h
@@ -63,6 +63,7 @@ public:
   bool StartFrameExchange (Ptr<QosTxop> edca, Time availableTime, bool initialFrame) override;
   void SetWifiMac (const Ptr<RegularWifiMac> mac) override;
   void CalculateAcknowledgmentTime (WifiAcknowledgment* acknowledgment) const override;
+  void SetTxopHolder (Ptr<const WifiPsdu> psdu, const WifiTxVector& txVector) override;
 
   /**
    * Set the Multi-user Scheduler associated with this Frame Exchange Manager.