wifi: GCR manager indicates whether a group addressed frame should be transmitted to the GCR concealment address

src/wifi/model/gcr-manager.cc

@@ -143,6 +143,29 @@ GcrManager::GetGcrConcealmentAddress() const
     return m_gcrConcealmentAddress;
 }
 
+bool
+GcrManager::UseConcealment(const WifiMacHeader& header) const
+{
+    NS_ASSERT_MSG(header.IsQosData() && IsGroupcast(header.GetAddr1()),
+                  "GCR service is only for QoS groupcast data frames");
+    NS_ASSERT_MSG(m_retransmissionPolicy != GroupAddressRetransmissionPolicy::NO_ACK_NO_RETRY,
+                  "GCR service is not enabled");
+    NS_ASSERT_MSG(!m_staMembers.empty(), "GCR service should not be used");
+
+    // Only GCR capable STAs, hence concealment is always used
+    if (m_nonGcrStas.empty())
+    {
+        return true;
+    }
+    // If A-MSDU is used, that means previous transmission was already concealed
+    if (header.IsQosAmsdu())
+    {
+        return true;
+    }
+    // Otherwise, use concealment except for the first transmission (hence when it is a retry)
+    return header.IsRetry();
+}
+
 bool
 GcrManager::KeepGroupcastQueued(Ptr<WifiMpdu> mpdu)
 {

src/wifi/model/gcr-manager.h

@@ -92,6 +92,15 @@ class GcrManager : public Object
      */
     const Mac48Address& GetGcrConcealmentAddress() const;
 
+    /**
+     * Indicate whether a group addressed packet should be transmitted to the GCR concealment
+     * address.
+     *
+     * @param header the header of the groupcast packet
+     * @return whether GCR concealment should be used
+     */
+    bool UseConcealment(const WifiMacHeader& header) const;
+
     /**
      * This function indicates whether a groupcast MPDU should be kept for next retransmission.
      *