wifi: Reset current MU PPDU UID when payload reception ends

Improves the fix applied with bdfa4111. Basically, a non-AP STA could
receive a DL MU PPDU including a MU-BAR TF, store the MU PPDU UID when
processing SIG-B, do not respond to the MU-BAR TF (this may happen in
some cases with EMLSR clients) and used the stored MU PPDU UID to schedule
the reception of the OFDMA payload of the TB PPDU sent by other non-AP STAs.

src/wifi/model/he/he-phy.cc

@@ -740,18 +740,9 @@ HePhy::ProcessSigB(Ptr<Event> event, PhyFieldRxStatus status)
             return PhyFieldRxStatus(false, FILTERED, DROP);
         }
     }
-    if (event->GetTxVector().IsDlMu())
-    {
-        // When including a Trigger Frame, a DL MU PPDU solicits a TB PPDU.
-        // NOTE that the 'if' condition above is not needed for HE because SIG-B is only
-        // included in HE MU PPDUs, but it is necessary for EHT to avoid that a non-AP
-        // STA receiving a Trigger Frame sent as an EHT SU transmission (which carries
-        // the EHT-SIG field) stores the PPDU UID and uses it later to schedule the
-        // reception of the payload of the TB PPDU (see HePhy::StartReceivePreamble())
-        // despite it lacks the TRIGVECTOR.
-        m_currentMuPpduUid =
-            event->GetPpdu()->GetUid(); // to be able to correctly schedule start of MU payload
-    }
+    m_currentMuPpduUid =
+        event->GetPpdu()->GetUid(); // to be able to correctly schedule start of MU payload
+
     return status;
 }
 
@@ -934,6 +925,8 @@ HePhy::DoEndReceivePayload(Ptr<const WifiPpdu> ppdu)
         NS_ASSERT(m_wifiPhy->GetLastRxEndTime() == Simulator::Now());
         PhyEntity::DoEndReceivePayload(ppdu);
     }
+    // we are done receiving the payload, we can reset the current MU PPDU UID
+    m_currentMuPpduUid = UINT64_MAX;
 }
 
 void