From 2df30d6838e4fefa173052f00aeb8a9795f693c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Deronne?= <sebastien.deronne@gmail.com>
Date: Sun, 5 Feb 2023 14:12:22 +0100
Subject: [PATCH] wifi: Only update bands tracked by interference helper if
 needed

---
 src/wifi/model/interference-helper.cc |  7 +++++++
 src/wifi/model/interference-helper.h  |  9 +++++++++
 src/wifi/model/spectrum-wifi-phy.cc   | 23 ++++++++++++++++++-----
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/wifi/model/interference-helper.cc b/src/wifi/model/interference-helper.cc
index 83a0637c2..6d22d8829 100644
--- a/src/wifi/model/interference-helper.cc
+++ b/src/wifi/model/interference-helper.cc
@@ -274,6 +274,13 @@ InterferenceHelper::RemoveBands(FrequencyRange range)
     m_firstPowers.erase(range);
 }
 
+bool
+InterferenceHelper::HasBand(WifiSpectrumBand band, const FrequencyRange& range) const
+{
+    NS_LOG_FUNCTION(this << band.first << band.second << range);
+    return (m_niChanges.count(range) > 0 && m_niChanges.at(range).count(band) > 0);
+}
+
 void
 InterferenceHelper::AddBand(WifiSpectrumBand band, const FrequencyRange& range)
 {
diff --git a/src/wifi/model/interference-helper.h b/src/wifi/model/interference-helper.h
index b4c6d806f..145b17b9b 100644
--- a/src/wifi/model/interference-helper.h
+++ b/src/wifi/model/interference-helper.h
@@ -159,6 +159,15 @@ class InterferenceHelper : public Object
      */
     void RemoveBands(FrequencyRange range);
 
+    /**
+     * Check whether a given band is tracked by this interference helper.
+     *
+     * \param band the band to be checked
+     * \param range the frequency range the band to check belongs to
+     * \return true if the band is already tracked by this interference helper, false otherwise
+     */
+    bool HasBand(WifiSpectrumBand band, const FrequencyRange& range) const;
+
     /**
      * Set the noise figure.
      *
diff --git a/src/wifi/model/spectrum-wifi-phy.cc b/src/wifi/model/spectrum-wifi-phy.cc
index 871dfe1fd..a85fb9409 100644
--- a/src/wifi/model/spectrum-wifi-phy.cc
+++ b/src/wifi/model/spectrum-wifi-phy.cc
@@ -38,6 +38,8 @@
 #include "ns3/spectrum-channel.h"
 #include "ns3/wifi-net-device.h"
 
+#include <algorithm>
+
 namespace ns3
 {
 
@@ -119,11 +121,10 @@ SpectrumWifiPhy::UpdateInterferenceHelperBands()
     NS_LOG_FUNCTION(this);
     NS_ASSERT(!m_spectrumPhyInterfaces.empty());
     uint16_t channelWidth = GetChannelWidth();
-    m_interference->RemoveBands(WHOLE_WIFI_SPECTRUM);
+    std::vector<WifiSpectrumBand> bands;
     if (channelWidth < 20)
     {
-        WifiSpectrumBand band = GetBand(channelWidth);
-        m_interference->AddBand(band, WHOLE_WIFI_SPECTRUM);
+        bands.push_back(GetBand(channelWidth));
     }
     else
     {
@@ -131,7 +132,7 @@ SpectrumWifiPhy::UpdateInterferenceHelperBands()
         {
             for (uint32_t i = 0; i < (channelWidth / bw); ++i)
             {
-                m_interference->AddBand(GetBand(bw, i), WHOLE_WIFI_SPECTRUM);
+                bands.push_back(GetBand(bw, i));
             }
         }
     }
@@ -183,9 +184,21 @@ SpectrumWifiPhy::UpdateInterferenceHelperBands()
         }
         for (const auto& bandRuPair : m_ruBands[channelWidth])
         {
-            m_interference->AddBand(bandRuPair.first, WHOLE_WIFI_SPECTRUM);
+            bands.push_back(bandRuPair.first);
         }
     }
+    const auto bandsChanged = std::any_of(bands.cbegin(), bands.cend(), [&](const auto& band) {
+        return !m_interference->HasBand(band, WHOLE_WIFI_SPECTRUM);
+    });
+    if (!bandsChanged)
+    {
+        return;
+    }
+    m_interference->RemoveBands(WHOLE_WIFI_SPECTRUM);
+    for (const auto& band : bands)
+    {
+        m_interference->AddBand(band, WHOLE_WIFI_SPECTRUM);
+    }
 }
 
 Ptr<Channel>