diff --git a/RELEASE_NOTES b/RELEASE_NOTES
index e4e62d9773a..d32fd788520 100644
--- a/RELEASE_NOTES
+++ b/RELEASE_NOTES
@@ -29,6 +29,7 @@ New user-visible features
 Bugs fixed
 ----------
 - Bug 2505 - network:  Avoid asserts in Header/Trailer deserialization
+- Bug 2764 - wifi: WifiSpectrumModelId doesn't distinguish 11ax from legacy
 
 Known issues
 ------------
diff --git a/src/spectrum/model/wifi-spectrum-value-helper.cc b/src/spectrum/model/wifi-spectrum-value-helper.cc
index a8686558ceb..5e2d603b697 100644
--- a/src/spectrum/model/wifi-spectrum-value-helper.cc
+++ b/src/spectrum/model/wifi-spectrum-value-helper.cc
@@ -38,17 +38,20 @@ struct WifiSpectrumModelId
    * Constructor
    * \param f the frequency in Mhz
    * \param w the channel width in Mhz
+   * \param b the width of each band (Hz)
    */ 
-  WifiSpectrumModelId (uint32_t f, uint8_t w);
+  WifiSpectrumModelId (uint32_t f, uint8_t w, double b);
   uint32_t m_centerFrequency;  ///< center frequency
   uint8_t m_channelWidth; ///< channel width
+  double m_bandBandwidth; ///< width of each band (Hz)
 };
 
-WifiSpectrumModelId::WifiSpectrumModelId (uint32_t f, uint8_t w)
+WifiSpectrumModelId::WifiSpectrumModelId (uint32_t f, uint8_t w, double b)
   : m_centerFrequency (f),
-    m_channelWidth (w)
+    m_channelWidth (w),
+    m_bandBandwidth (b)
 {
-  NS_LOG_FUNCTION (this << f << (uint16_t)w);
+  NS_LOG_FUNCTION (this << f << (uint16_t)w << b);
 }
 
 /**
@@ -60,7 +63,12 @@ WifiSpectrumModelId::WifiSpectrumModelId (uint32_t f, uint8_t w)
 bool
 operator < (const WifiSpectrumModelId& a, const WifiSpectrumModelId& b)
 {
-  return ( (a.m_centerFrequency < b.m_centerFrequency) || ( (a.m_centerFrequency == b.m_centerFrequency) && (a.m_channelWidth < b.m_channelWidth)));
+  return ( (a.m_centerFrequency < b.m_centerFrequency)
+          || ((a.m_centerFrequency == b.m_centerFrequency) &&
+              (a.m_channelWidth < b.m_channelWidth))
+          || ((a.m_centerFrequency == b.m_centerFrequency) && //to cover coexistence of 11ax with legacy case
+              (a.m_channelWidth == b.m_channelWidth) &&
+              (a.m_bandBandwidth < b.m_bandBandwidth)));
 }
 
 static std::map<WifiSpectrumModelId, Ptr<SpectrumModel> > g_wifiSpectrumModelMap; ///< static initializer for the class
@@ -70,7 +78,7 @@ WifiSpectrumValueHelper::GetSpectrumModel (uint32_t centerFrequency, uint8_t cha
 {
   NS_LOG_FUNCTION (centerFrequency << (uint16_t)channelWidth << bandBandwidth << (uint16_t)guardBandwidth);
   Ptr<SpectrumModel> ret;
-  WifiSpectrumModelId key (centerFrequency, channelWidth);
+  WifiSpectrumModelId key (centerFrequency, channelWidth, bandBandwidth);
   std::map<WifiSpectrumModelId, Ptr<SpectrumModel> >::iterator it = g_wifiSpectrumModelMap.find (key);
   if (it != g_wifiSpectrumModelMap.end ())
     {