wifi: (fixes #862) Cancel AssocReq timer upon dissociation

RELEASE_NOTES.md

@@ -31,6 +31,7 @@ Release 3-dev
 - (lr-wpan) !1406 - Fixes issues during MAC scan
 - (wifi) #880 - Post-install change in WifiPhy::ChannelSettings does not completely reconfigure Wi-Fi
 - (energy) !1422 - Fix null harvester issue in EnergySource
+- (wifi) #862 - sta-wifi-mac.cc cond="!link.bssid.has_value()", High occurrence at higher numbers of STAs per AP in indoor deployment.
 
 Release 3.38
 ------------

src/wifi/model/sta-wifi-mac.cc

@@ -674,6 +674,8 @@ StaWifiMac::Disassociated(uint8_t linkId)
 
     NS_LOG_DEBUG("Set state to UNASSOCIATED and start scanning");
     SetState(UNASSOCIATED);
+    // cancel the association request timer (see issue #862)
+    m_assocRequestEvent.Cancel();
     auto mldAddress = GetWifiRemoteStationManager(linkId)->GetMldAddress(GetBssid(linkId));
     if (GetNLinks() > 1 && mldAddress.has_value())
     {