Ieee80211: fix HT40 medium sensing during reception, band-aware secondary idle check, and rate reconfiguration

- Rx: require receptionState == IDLE in HT40 primaryPhysicallyIdle calculation to prevent transmitting during in-progress frame reception
- Hcf: apply DIFS in 2.4 GHz and PIFS in 5 GHz for secondary channel idle verification per IEEE Std 802.11-2024 clause 11.15.9 item b
- Ieee80211Radio: restrict publishModeSet so bitrate-only reconfigurations do not reset receiver state or emit spurious listening signals

Author: mgonzalezlopezudc

src/inet/linklayer/ieee80211/mac/Rx.cc

@@ -159,7 +159,7 @@ void Rx::recomputeMediumFree()
 {
     bool oldMediumFree = mediumFree;
     // note: the duration of mode switching (rx-to-tx or tx-to-rx) should also count as busy
-    bool primaryPhysicallyIdle = ht40Cca ? !primaryCcaBusy : receptionState == IRadio::RECEPTION_STATE_IDLE;
+    bool primaryPhysicallyIdle = (receptionState == IRadio::RECEPTION_STATE_IDLE) && (!ht40Cca || !primaryCcaBusy);
     mediumFree = primaryPhysicallyIdle && transmissionState == IRadio::TRANSMISSION_STATE_UNDEFINED && !endNavTimer->isScheduled();
     if (mediumFree != oldMediumFree) {
         for (auto contention : contentions)

src/inet/linklayer/ieee80211/mac/coordinationfunction/Hcf.cc

@@ -206,10 +206,12 @@ bool Hcf::shouldRestartHt40ChannelAccess(Edcaf *edcaf)
             mode->getDataMode()->getBandwidth() != MHz(40))
         return false;
     // IEEE Std 802.11-2024, 11.15.9 item b):
-    // If the secondary channel was busy during DIFS before channel access,
-    // invoke the backoff procedure with the current CW[AC].
-    simtime_t difs = modeSet->getSifsTime() + 2 * modeSet->getSlotTime();
-    return !rx->isSecondaryChannelIdleFor(difs);
+    // Secondary channel must be idle during an interval of DIFS for the 2.4 GHz band
+    // and PIFS for the 5 GHz band immediately preceding the expiration of the backoff counter.
+    // If the secondary channel was busy during this interval, invoke the backoff procedure with the current CW[AC].
+    bool is24GHz = modeSet != nullptr && strstr(modeSet->getName(), "2.4Ghz") != nullptr;
+    simtime_t requiredIdle = modeSet->getSifsTime() + (is24GHz ? 2 : 1) * modeSet->getSlotTime();
+    return !rx->isSecondaryChannelIdleFor(requiredIdle);
 }
 
 void Hcf::channelGranted(IChannelAccess *channelAccess)
@@ -226,7 +228,7 @@ void Hcf::channelGranted(IChannelAccess *channelAccess)
             emit(edcaCollisionDetectedSignal, (unsigned long)internallyCollidedEdcafs.size());
         }
         if (shouldRestartHt40ChannelAccess(edcaf)) {
-            EV_INFO << "Secondary channel was busy during DIFS before channel access for HT40 transmission, restarting backoff.\n";
+            EV_INFO << "Secondary channel was busy during required interval before channel access for HT40 transmission, restarting backoff.\n";
             edcaf->restartChannelAccess(this);
             return;
         }

src/inet/physicallayer/wireless/ieee80211/packetlevel/Ieee80211Radio.cc

@@ -169,7 +169,7 @@ void Ieee80211Radio::handleUpperCommand(cMessage *message)
                 throw cRuntimeError("HT 40 MHz operation requires a secondary channel offset of above or below");
 
             bool publishModeSet = targetModeSet != this->modeSet || targetBand != this->band ||
-                    !std::isnan(newBandwidth.get()) || !std::isnan(newBitrate.get()) || *requestedOpMode;
+                    *requestedOpMode;
 
             if (targetChannelNumber != -1 &&
                     (currentChannel == nullptr || targetBand != this->band || targetChannelNumber != currentChannel->getChannelNumber() ||