wifi: OriginatorBlockAckAgreement uses a Block Ack window

src/wifi/model/originator-block-ack-agreement.cc

@@ -19,10 +19,15 @@
  *          Tommaso Pecorella <tommaso.pecorella@unifi.it>
  */
 
+#include "ns3/log.h"
 #include "originator-block-ack-agreement.h"
+#include "wifi-mac-queue-item.h"
+#include "wifi-utils.h"
 
 namespace ns3 {
 
+NS_LOG_COMPONENT_DEFINE ("OriginatorBlockAckAgreement");
+
 OriginatorBlockAckAgreement::OriginatorBlockAckAgreement (Mac48Address recipient, uint8_t tid)
   : BlockAckAgreement (recipient, tid),
     m_state (PENDING)
@@ -69,4 +74,104 @@ OriginatorBlockAckAgreement::IsReset (void) const
   return (m_state == RESET) ? true : false;
 }
 
+uint16_t
+OriginatorBlockAckAgreement::GetStartingSequence (void) const
+{
+  if (m_txWindow.GetWinSize () == 0)
+    {
+      // the TX window has not been initialized yet
+      return m_startingSeq;
+    }
+  return m_txWindow.GetWinStart ();
+}
+
+std::size_t
+OriginatorBlockAckAgreement::GetDistance (uint16_t seqNumber) const
+{
+  NS_ASSERT (seqNumber < SEQNO_SPACE_SIZE);
+  return (seqNumber - GetStartingSequence () + SEQNO_SPACE_SIZE) % SEQNO_SPACE_SIZE;
+}
+
+void
+OriginatorBlockAckAgreement::InitTxWindow (void)
+{
+  m_txWindow.Init (m_startingSeq, m_bufferSize);
+}
+
+void
+OriginatorBlockAckAgreement::AdvanceTxWindow (void)
+{
+  while (m_txWindow.At (0))
+    {
+      m_txWindow.Advance (1); // reset the current head -- ensures loop termination
+    }
+}
+
+void
+OriginatorBlockAckAgreement::NotifyTransmittedMpdu (Ptr<const WifiMacQueueItem> mpdu)
+{
+  uint16_t mpduSeqNumber = mpdu->GetHeader ().GetSequenceNumber ();
+  uint16_t distance = GetDistance (mpduSeqNumber);
+
+  if (distance >= SEQNO_SPACE_HALF_SIZE)
+    {
+      NS_LOG_DEBUG ("Transmitted an old MPDU, do nothing.");
+      return;
+    }
+
+  // advance the transmit window if an MPDU beyond the current transmit window
+  // is transmitted (see Section 10.24.7.7 of 802.11-2016)
+  if (distance >= m_txWindow.GetWinSize ())
+    {
+      std::size_t count = distance - m_txWindow.GetWinSize () + 1;
+      m_txWindow.Advance (count);
+      // transmit window may advance further
+      AdvanceTxWindow ();
+      NS_LOG_DEBUG ("Transmitted MPDU beyond current transmit window. New starting sequence number: "
+                    << m_txWindow.GetWinStart ());
+    }
+}
+
+void
+OriginatorBlockAckAgreement::NotifyAckedMpdu (Ptr<const WifiMacQueueItem> mpdu)
+{
+  uint16_t mpduSeqNumber = mpdu->GetHeader ().GetSequenceNumber ();
+  uint16_t distance = GetDistance (mpduSeqNumber);
+
+  if (distance >= SEQNO_SPACE_HALF_SIZE)
+    {
+      NS_LOG_DEBUG ("Acked an old MPDU, do nothing.");
+      return;
+    }
+
+  // when an MPDU is transmitted, the transmit window is updated such that the
+  // transmitted MPDU is in the window, hence we cannot be notified of the
+  // acknowledgment of an MPDU which is beyond the transmit window
+  m_txWindow.At (distance) = true;
+
+  // the starting sequence number can be advanced to the sequence number of
+  // the nearest unacknowledged MPDU
+  AdvanceTxWindow ();
+  NS_LOG_DEBUG ("Starting sequence number: " << m_txWindow.GetWinStart ());
+}
+
+void
+OriginatorBlockAckAgreement::NotifyDiscardedMpdu (Ptr<const WifiMacQueueItem> mpdu)
+{
+  uint16_t mpduSeqNumber = mpdu->GetHeader ().GetSequenceNumber ();
+  uint16_t distance = GetDistance (mpduSeqNumber);
+
+  if (distance >= SEQNO_SPACE_HALF_SIZE)
+    {
+      NS_LOG_DEBUG ("Discarded an old MPDU, do nothing.");
+      return;
+    }
+
+  m_txWindow.Advance (distance + 1);
+  // transmit window may advance further
+  AdvanceTxWindow ();
+  NS_LOG_DEBUG ("Discarded MPDU within current transmit window. New starting sequence number: "
+                << m_txWindow.GetWinStart ());
+}
+
 } //namespace ns3

src/wifi/model/originator-block-ack-agreement.h

@@ -22,9 +22,12 @@
 #define ORIGINATOR_BLOCK_ACK_AGREEMENT_H
 
 #include "block-ack-agreement.h"
+#include "block-ack-window.h"
 
 namespace ns3 {
 
+class WifiMacQueueItem;
+
 /**
  * \ingroup wifi
  * Maintains the state and information about transmitted MPDUs with ack policy block ack
@@ -141,8 +144,64 @@ public:
    */
   bool IsRejected (void) const;
 
+  /**
+   * Return the starting sequence number of the transmit window, if a transmit
+   * window has been initialized. Otherwise, return the starting sequence number
+   * stored by the BlockAckAgreement base class.
+   *
+   * \return the starting sequence number.
+   */
+  uint16_t GetStartingSequence (void) const;
+
+  /**
+   * Get the distance between the current starting sequence number and the
+   * given sequence number.
+   *
+   * \param seqNumber the given sequence number
+   * \return the distance of the given sequence number from the current winstart
+   */
+  std::size_t GetDistance (uint16_t seqNumber) const;
+
+  /**
+   * Initialize the originator's transmit window by setting its size and starting
+   * sequence number equal to the values stored by the BlockAckAgreement base class.
+   */
+  void InitTxWindow (void);
+
+  /**
+   * Advance the transmit window so as to include the transmitted MPDU, if the
+   * latter is not an old packet and is beyond the current transmit window.
+   *
+   * \param mpdu the transmitted MPDU
+   */
+  void NotifyTransmittedMpdu (Ptr<const WifiMacQueueItem> mpdu);
+  /**
+   * Record that the given MPDU has been acknowledged and advance the transmit
+   * window if possible.
+   *
+   * \param mpdu the acknowledged MPDU
+   */
+  void NotifyAckedMpdu (Ptr<const WifiMacQueueItem> mpdu);
+  /**
+   * Advance the transmit window beyond the MPDU that has been reported to
+   * be discarded.
+   *
+   * \param mpdu the discarded MPDU
+   */
+  void NotifyDiscardedMpdu (Ptr<const WifiMacQueueItem> mpdu);
+
+
 private:
-  State m_state; ///< state
+  /**
+   * Advance the transmit window so that the starting sequence number is the
+   * nearest unacknowledged MPDU.
+   *
+   * \param newStartingSeq the new starting sequence number
+   */
+  void AdvanceTxWindow (void);
+
+  State m_state;                 ///< state
+  BlockAckWindow m_txWindow;     ///< originator's transmit window
 };
 
 } //namespace ns3