From b227e1614d39be1bb7231061b53c6a7580acaa53 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Deronne?= <sebastien.deronne@gmail.com>
Date: Sat, 22 Feb 2025 09:27:17 +0100
Subject: [PATCH] wifi: Add PHY function to retrieve time until preamble
 detection period has elapsed

---
 src/wifi/model/phy-entity.cc | 27 +++++++++++++++++++++------
 src/wifi/model/phy-entity.h  | 15 ++++-----------
 src/wifi/model/wifi-phy.cc   | 32 +++++++++++++++++---------------
 src/wifi/model/wifi-phy.h    | 13 +++++++++++--
 4 files changed, 53 insertions(+), 34 deletions(-)

diff --git a/src/wifi/model/phy-entity.cc b/src/wifi/model/phy-entity.cc
index 715a6f8bc..97fab508f 100644
--- a/src/wifi/model/phy-entity.cc
+++ b/src/wifi/model/phy-entity.cc
@@ -844,6 +844,27 @@ PhyEntity::GetReceptionStatus(Ptr<WifiMpdu> mpdu,
     }
 }
 
+std::optional<Time>
+PhyEntity::GetTimeToPreambleDetectionEnd() const
+{
+    if (m_endPreambleDetectionEvents.empty())
+    {
+        return {};
+    }
+
+    std::optional<Time> delayUntilPreambleDetectionEnd;
+    for (const auto& endPreambleDetectionEvent : m_endPreambleDetectionEvents)
+    {
+        if (endPreambleDetectionEvent.IsPending())
+        {
+            delayUntilPreambleDetectionEnd =
+                std::max(delayUntilPreambleDetectionEnd.value_or(Time{0}),
+                         Simulator::GetDelayLeft(endPreambleDetectionEvent));
+        }
+    }
+    return delayUntilPreambleDetectionEnd;
+}
+
 std::optional<Time>
 PhyEntity::GetTimeToMacHdrEnd(uint16_t staId) const
 {
@@ -1181,12 +1202,6 @@ PhyEntity::CancelAllEvents()
     m_endOfMacHdrEvents.clear();
 }
 
-bool
-PhyEntity::NoEndPreambleDetectionEvents() const
-{
-    return m_endPreambleDetectionEvents.empty();
-}
-
 void
 PhyEntity::CancelRunningEndPreambleDetectionEvents()
 {
diff --git a/src/wifi/model/phy-entity.h b/src/wifi/model/phy-entity.h
index ee25e992c..1b903cd70 100644
--- a/src/wifi/model/phy-entity.h
+++ b/src/wifi/model/phy-entity.h
@@ -400,22 +400,15 @@ class PhyEntity : public SimpleRefCount<PhyEntity>
      * Cancel and clear all running events.
      */
     virtual void CancelAllEvents();
-    /**
-     * @return \c true if there is no end preamble detection event running, \c false otherwise
-     */
-    bool NoEndPreambleDetectionEvents() const;
     /**
      * Cancel all end preamble detection events.
      */
     void CancelRunningEndPreambleDetectionEvents();
 
-    /**
-     * Get the remaining time to the end of the MAC header reception of the next MPDU being
-     * received from the given STA, if any.
-     *
-     * @param staId the STA-ID of the transmitter; equals SU_STA_ID for SU PPDUs
-     * @return the remaining time to the end of the MAC header reception of the next MPDU, if any
-     */
+    /// @copydoc WifiPhy::GetTimeToPreambleDetectionEnd
+    virtual std::optional<Time> GetTimeToPreambleDetectionEnd() const;
+
+    /// @copydoc WifiPhy::GetTimeToMacHdrEnd
     virtual std::optional<Time> GetTimeToMacHdrEnd(uint16_t staId) const;
 
     /**
diff --git a/src/wifi/model/wifi-phy.cc b/src/wifi/model/wifi-phy.cc
index 5f278fd39..237ff4208 100644
--- a/src/wifi/model/wifi-phy.cc
+++ b/src/wifi/model/wifi-phy.cc
@@ -1773,6 +1773,19 @@ WifiPhy::NotifyMonitorSniffTx(Ptr<const WifiPsdu> psdu,
     }
 }
 
+std::optional<Time>
+WifiPhy::GetTimeToPreambleDetectionEnd() const
+{
+    for (const auto& [modClass, phyEntity] : m_phyEntities)
+    {
+        if (auto remTime = phyEntity->GetTimeToPreambleDetectionEnd())
+        {
+            return remTime;
+        }
+    }
+    return std::nullopt;
+}
+
 std::optional<Time>
 WifiPhy::GetTimeToMacHdrEnd(uint16_t staId) const
 {
@@ -1852,20 +1865,15 @@ WifiPhy::Send(const WifiConstPsduMap& psdus, const WifiTxVector& txVector)
 
     const auto txDuration = CalculateTxDuration(psdus, txVector, GetPhyBand());
 
-    auto noEndPreambleDetectionEvent = true;
-    for (const auto& [mc, entity] : m_phyEntities)
-    {
-        noEndPreambleDetectionEvent =
-            noEndPreambleDetectionEvent && entity->NoEndPreambleDetectionEvents();
-    }
-    if (!noEndPreambleDetectionEvent && !m_currentEvent)
+    if (const auto timeToPreambleDetectionEnd = GetTimeToPreambleDetectionEnd();
+        timeToPreambleDetectionEnd && !m_currentEvent)
     {
         // PHY is in the initial few microseconds during which the
         // start of RX has occurred but the preamble detection period
         // has not elapsed
         AbortCurrentReception(SIGNAL_DETECTION_ABORTED_BY_TX);
     }
-    else if (!noEndPreambleDetectionEvent || m_currentEvent)
+    else if (timeToPreambleDetectionEnd || m_currentEvent)
     {
         AbortCurrentReception(RECEPTION_ABORTED_BY_TX);
     }
@@ -1944,13 +1952,7 @@ WifiPhy::Reset()
 {
     NS_LOG_FUNCTION(this);
     m_currentPreambleEvents.clear();
-    bool noEndPreambleDetectionEvent = true;
-    for (const auto& [mc, entity] : m_phyEntities)
-    {
-        noEndPreambleDetectionEvent =
-            noEndPreambleDetectionEvent && entity->NoEndPreambleDetectionEvents();
-    }
-    if (m_interference && (m_currentEvent || !noEndPreambleDetectionEvent))
+    if (m_interference && (m_currentEvent || GetTimeToPreambleDetectionEnd()))
     {
         m_interference->NotifyRxEnd(Simulator::Now(), GetCurrentFrequencyRange());
     }
diff --git a/src/wifi/model/wifi-phy.h b/src/wifi/model/wifi-phy.h
index 565ad55dd..baccaae15 100644
--- a/src/wifi/model/wifi-phy.h
+++ b/src/wifi/model/wifi-phy.h
@@ -117,7 +117,8 @@ class WifiPhy : public Object
      * @return if the PHY is busy decoding the PHY header fields of a PPDU, return the TXVECTOR
      *         used to transmit the PPDU; otherwise, return a null optional value
      */
-    std::optional<std::reference_wrapper<const WifiTxVector>> GetInfoIfRxingPhyHeader() const;
+    virtual std::optional<std::reference_wrapper<const WifiTxVector>> GetInfoIfRxingPhyHeader()
+        const;
 
     /**
      * For HE receptions only, check and possibly modify the transmit power restriction state at
@@ -882,6 +883,14 @@ class WifiPhy : public Object
      */
     dB_u GetRxGain() const;
 
+    /**
+     * Get the remaining time to preamble detection period to elapse, if preamble detection is
+     * ongoing.
+     *
+     * @return the remaining time to the end of the preamble detection detection period, if ongoing
+     */
+    virtual std::optional<Time> GetTimeToPreambleDetectionEnd() const;
+
     /**
      * Get the remaining time to the end of the MAC header reception of the next MPDU being
      * received from the given STA, if any.
@@ -889,7 +898,7 @@ class WifiPhy : public Object
      * @param staId the STA-ID of the transmitter; equals SU_STA_ID for SU PPDUs
      * @return the remaining time to the end of the MAC header reception of the next MPDU, if any
      */
-    std::optional<Time> GetTimeToMacHdrEnd(uint16_t staId) const;
+    virtual std::optional<Time> GetTimeToMacHdrEnd(uint16_t staId) const;
 
     /**
      * Sets the device this PHY is associated with.