wifi: Block Ack Manager schedules BARs received as MPDUs

src/wifi/model/block-ack-manager.cc

@@ -587,7 +587,20 @@ BlockAckManager::NotifyDiscardedMpdu (Ptr<const WifiMacQueueItem> mpdu)
 
   // schedule a block ack request
   NS_LOG_DEBUG ("Schedule a Block Ack Request for agreement (" << recipient << ", " << +tid << ")");
-  ScheduleBlockAckReq (recipient, tid);
+  Ptr<Packet> bar = Create<Packet> ();
+  bar->AddHeader (GetBlockAckReqHeader (recipient, tid));
+
+  WifiMacHeader hdr;
+  hdr.SetType (WIFI_MAC_CTL_BACKREQ);
+  hdr.SetAddr1 (recipient);
+  hdr.SetAddr2 (mpdu->GetHeader ().GetAddr2 ());
+  hdr.SetAddr3 (mpdu->GetHeader ().GetAddr3 ());
+  hdr.SetDsNotTo ();
+  hdr.SetDsNotFrom ();
+  hdr.SetNoRetry ();
+  hdr.SetNoMoreFragments ();
+
+  ScheduleBar (Create<const WifiMacQueueItem> (bar, hdr));
 }
 
 CtrlBAckRequestHeader
@@ -605,28 +618,35 @@ BlockAckManager::GetBlockAckReqHeader (Mac48Address recipient, uint8_t tid) cons
 }
 
 void
-BlockAckManager::ScheduleBlockAckReq (Mac48Address recipient, uint8_t tid)
+BlockAckManager::ScheduleBar (Ptr<const WifiMacQueueItem> bar)
 {
-  NS_LOG_FUNCTION (this << recipient << +tid);
+  NS_LOG_FUNCTION (this << *bar);
+  NS_ASSERT (bar->GetHeader ().IsBlockAckReq ());
 
-  Ptr<Packet> bar = Create<Packet> ();
-  bar->AddHeader (GetBlockAckReqHeader (recipient, tid));
-  WifiMacHeader hdr;
-  hdr.SetAddr1 (recipient);
-  hdr.SetType (WIFI_MAC_CTL_BACKREQ);
-  Bar request (Create<const WifiMacQueueItem> (bar, hdr), tid);
+  CtrlBAckRequestHeader reqHdr;
+  bar->GetPacket ()->PeekHeader (reqHdr);
+  uint8_t tid = reqHdr.GetTidInfo ();
+  Bar request (bar, tid);
 
   // if a BAR for the given agreement is present, replace it with the new one
   for (std::list<Bar>::const_iterator i = m_bars.begin (); i != m_bars.end (); i++)
     {
-      if (i->bar->GetHeader ().GetAddr1 () == recipient && i->tid == tid)
+      if (i->bar->GetHeader ().GetAddr1 () == bar->GetHeader ().GetAddr1 () && i->tid == tid)
         {
           i = m_bars.erase (i);
           m_bars.insert (i, request);
           return;
         }
     }
-  m_bars.push_back (request);
+
+  if (bar->GetHeader ().IsRetry ())
+    {
+      m_bars.push_front (request);
+    }
+  else
+    {
+      m_bars.push_back (request);
+    }
 }
 
 void

src/wifi/model/block-ack-manager.h

@@ -393,22 +393,20 @@ public:
    * \param recipient the recipient
    * \param tid the TID
    *
-   * Get the block ack request header for the established BA agreement
+   * Get the Block Ack Request header for the established BA agreement
    * (<i>recipient</i>,<i>tid</i>).
    */
   CtrlBAckRequestHeader GetBlockAckReqHeader (Mac48Address recipient, uint8_t tid) const;
 
   /**
-   * \param recipient the recipient
-   * \param tid the TID
+   * \param bar the Block Ack Request to enqueue
    *
-   * Enqueue a block ack request for the established BA agreement
-   * (<i>recipient</i>,<i>tid</i>) into the queue storing the next
-   * BAR frames to transmit. If a BAR for the given agreement is
-   * already present in the queue, it is replaced by the new one.
+   * Enqueue the given Block Ack Request into the queue storing the next BAR
+   * frames to transmit. If a BAR for the same recipient and TID is already present
+   * in the queue, it is replaced by the new one. If the given BAR is retransmitted,
+   * it is placed at the head of the queue, otherwise at the tail.
    */
-  void ScheduleBlockAckReq (Mac48Address recipient, uint8_t tid);
-
+  void ScheduleBar (Ptr<const WifiMacQueueItem> bar);
 
 private:
   /**

src/wifi/model/mac-low.cc

@@ -1973,7 +1973,8 @@ MacLow::SendDataPacket (void)
     {
       Ptr<QosTxop> qosTxop = DynamicCast<QosTxop> (m_currentTxop);
       NS_ASSERT (qosTxop != 0);
-      qosTxop->ScheduleBlockAckReq (m_currentPacket->GetAddr1 (), *m_currentPacket->GetTids ().begin ());
+      auto bar = qosTxop->PrepareBlockAckRequest (m_currentPacket->GetAddr1 (), *m_currentPacket->GetTids ().begin ());
+      qosTxop->ScheduleBar (bar);
     }
   ForwardDown (m_currentPacket, m_currentTxVector);
 }
@@ -2089,7 +2090,8 @@ MacLow::SendDataAfterCts (Time duration)
     {
       Ptr<QosTxop> qosTxop = DynamicCast<QosTxop> (m_currentTxop);
       NS_ASSERT (qosTxop != 0);
-      qosTxop->ScheduleBlockAckReq (m_currentPacket->GetAddr1 (), *m_currentPacket->GetTids ().begin ());
+      auto bar = qosTxop->PrepareBlockAckRequest (m_currentPacket->GetAddr1 (), *m_currentPacket->GetTids ().begin ());
+      qosTxop->ScheduleBar (bar);
     }
   ForwardDown (m_currentPacket, m_currentTxVector);
 }

src/wifi/model/qos-txop.cc

@@ -164,9 +164,9 @@ QosTxop::PrepareBlockAckRequest (Mac48Address recipient, uint8_t tid) const
 }
 
 void
-QosTxop::ScheduleBlockAckReq (Mac48Address address, uint8_t tid)
+QosTxop::ScheduleBar (Ptr<const WifiMacQueueItem> bar)
 {
-  m_baManager->ScheduleBlockAckReq (address, tid);
+  m_baManager->ScheduleBar (bar);
 }
 
 void
@@ -900,7 +900,8 @@ QosTxop::MissedBlockAck (uint8_t nMpdus)
             }
           else // missed block ack after data frame with Implicit BAR Ack policy
             {
-              m_baManager->ScheduleBlockAckReq (m_currentHdr.GetAddr1 (), tid);
+              Ptr<const WifiMacQueueItem> bar = PrepareBlockAckRequest (m_currentHdr.GetAddr1 (), tid);
+              ScheduleBar (bar);
               m_currentPacket = 0;
             }
         }

src/wifi/model/qos-txop.h

@@ -196,13 +196,12 @@ public:
    */
   Ptr<const WifiMacQueueItem> PrepareBlockAckRequest (Mac48Address recipient, uint8_t tid) const;
   /**
-   * \param address recipient address
-   * \param tid traffic ID
+   * \param bar the Block Ack Request to schedule
    *
-   * Request the Block Ack manager to schedule the transmission of a
-   * block ack request for the established BA agreement (<i>address</i>,<i>tid</i>).
+   * Request the Block Ack manager to schedule the transmission of the given
+   * Block Ack Request.
    */
-  void ScheduleBlockAckReq (Mac48Address address, uint8_t tid);
+  void ScheduleBar (Ptr<const WifiMacQueueItem> bar);
 
   /* dcf notifications forwarded here */
   /**