feat(802.11n): add configurable HT Greenfield mode

WHATSNEW

@@ -119,6 +119,13 @@ Notable backward incompatible changes are the following:
    These changes are backward incompatible for C++ code that directly references
    the old combined ICMP error indication or tag types.
 
+7. 802.11n control-response rate selection
+
+   Ordinary ACK and Basic BlockAck responses in the n(mixed-2.4Ghz) profile now
+   use the mandatory non-HT fallback because BSSBasicRateSet is not modelled.
+   This can change airtime, timeout trajectories, throughput, and fingerprints
+   in existing simulations. An HT RTS continues to receive an HT-mixed CTS.
+
 Notable backward compatible changes are the following:
 
 1. IPv6 network configurator

examples/wireless/lan80211/omnetpp-ht-greenfield.ini

@@ -0,0 +1,37 @@
+[General]
+network = Lan80211
+abstract = true
+cmdenv-express-mode = true
+
+**.constraintAreaMinX = 0m
+**.constraintAreaMinY = 0m
+**.constraintAreaMinZ = 0m
+**.constraintAreaMaxX = 600m
+**.constraintAreaMaxY = 400m
+**.constraintAreaMaxZ = 0m
+
+**.arp.typename = "GlobalArp"
+**.opMode = "n(greenfield-2.4Ghz)"
+**.wlan[*].bitrate = 13Mbps
+
+*.ap.wlan[*].address = "10:00:00:00:00:00"
+*.host[*].**.mgmt.accessPointAddress = "10:00:00:00:00:00"
+
+*.ap.mobility.typename = "StationaryMobility"
+*.ap.mobility.initialX = 250m
+*.ap.mobility.initialY = 200m
+*.host[*].mobility.typename = "StationaryMobility"
+*.host[*].mobility.initialY = 200m
+*.host[0].mobility.initialX = 260m
+*.host[1].mobility.initialX = 270m
+
+[Config HtGreenfield]
+description = "HT Greenfield mode exchanging ping traffic through an access point"
+sim-time-limit = 2s
+*.numHosts = 2
+*.host[0].numApps = 0
+*.host[1].numApps = 1
+*.host[1].app[0].typename = "PingApp"
+*.host[1].app[0].destAddr = "host[0]"
+*.host[1].app[0].sendInterval = 100ms
+*.host[1].app[0].printPing = true

src/inet/emulation/linklayer/ieee80211/ExtUpperIeee80211Interface.ned

@@ -27,7 +27,7 @@ module ExtUpperIeee80211Interface extends ExtInterface like IWirelessInterface
 {
     parameters:
         string energySourceModule = default("");
-        string opMode @enum("a","b","g(erp)","g(mixed)","n(mixed-2.4Ghz)","p","ac") = default("g(mixed)");
+        string opMode @enum("a","b","g(erp)","g(mixed)","n(mixed-2.4Ghz)","n(greenfield-2.4Ghz)","p","ac") = default("g(mixed)");
         double bitrate @unit(bps) = default(-1bps);
         **.opMode = this.opMode;
         **.bitrate = this.bitrate;
@@ -92,4 +92,3 @@ module ExtUpperIeee80211Interface extends ExtInterface like IWirelessInterface
 
         classifier.in <-- { @display("m=n"); } <-- tap.lowerLayerOut;
 }
-

src/inet/linklayer/ieee80211/Ieee80211Interface.ned

@@ -63,7 +63,7 @@ module Ieee80211Interface extends NetworkInterface like IWirelessInterface
     parameters:
         string interfaceTableModule;
         string energySourceModule = default("");
-        string opMode @enum("a","b","g(erp)","g(mixed)","n(mixed-2.4Ghz)","p","ac") = default("g(mixed)");
+        string opMode @enum("a","b","g(erp)","g(mixed)","n(mixed-2.4Ghz)","n(greenfield-2.4Ghz)","p","ac") = default("g(mixed)");
         string address @mutable = default("auto"); // MAC address as hex string (12 hex digits), or
                                                    // "auto". "auto" values will be replaced by
                                                    // a generated MAC address in init stage 0.
@@ -129,4 +129,3 @@ module Ieee80211Interface extends NetworkInterface like IWirelessInterface
 
         classifier.in <-- { @display("m=n"); } <-- upperLayerIn;
 }
-

src/inet/linklayer/ieee80211/mac/Ieee80211Mac.ned

@@ -78,7 +78,7 @@ module Ieee80211Mac extends MacProtocolBase like IIeee80211Mac
 {
     parameters:
         string mibModule;
-        string modeSet @enum("a","b","g(erp)","g(mixed)","n(mixed-2.4Ghz)","p","ac") = default("g(mixed)");
+        string modeSet @enum("a","b","g(erp)","g(mixed)","n(mixed-2.4Ghz)","n(greenfield-2.4Ghz)","p","ac") = default("g(mixed)");
         string fcsMode @enum("declared","computed") = default("declared");
         string initialRadioMode @enum("off","sleep","receiver","transmitter","transceiver") = default("receiver");
 
@@ -130,4 +130,3 @@ module Ieee80211Mac extends MacProtocolBase like IIeee80211Mac
                 @display("p=250,200");
         }
 }
-

src/inet/linklayer/ieee80211/mac/rateselection/QosRateSelection.cc

@@ -16,30 +16,65 @@ namespace ieee80211 {
 
 using namespace inet::physicallayer;
 
+static const IIeee80211Mode *resolveConfiguredResponseCtsFrameMode(const Ieee80211ModeSet *modeSet, double bitrate, const char *modulePath)
+{
+    if (bitrate == -1)
+        return nullptr;
+    try {
+        return modeSet->getMode(bps(bitrate));
+    }
+    catch (const cRuntimeError& error) {
+        throw cRuntimeError("%s has invalid responseCtsFrameBitrate=%g bps for operation mode '%s'; "
+                "the configured CTS rate must resolve to a selectable mode (HT RTS responses require an HT mode): %s",
+                modulePath, bitrate, modeSet->getName(), error.getFormattedMessage().c_str());
+    }
+}
+
 Define_Module(QosRateSelection);
 
 void QosRateSelection::initialize(int stage)
 {
     ModeSetListener::initialize(stage);
     if (stage == INITSTAGE_LINK_LAYER) {
         dataOrMgmtRateControl = dynamic_cast<IRateControl *>(findModuleByPath(par("rateControlModule")));
-        double multicastFrameBitrate = par("multicastFrameBitrate");
-        multicastFrameMode = (multicastFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(multicastFrameBitrate));
-        double dataFrameBitrate = par("dataFrameBitrate");
-        dataFrameMode = (dataFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(dataFrameBitrate), Hz(par("dataFrameBandwidth")), par("dataFrameNumSpatialStreams"));
-        double mgmtFrameBitrate = par("mgmtFrameBitrate");
-        mgmtFrameMode = (mgmtFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(mgmtFrameBitrate));
-        double controlFrameBitrate = par("controlFrameBitrate");
-        controlFrameMode = (controlFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(controlFrameBitrate));
-        double responseAckFrameBitrate = par("responseAckFrameBitrate");
-        responseAckFrameMode = (responseAckFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(responseAckFrameBitrate));
-        double responseBlockAckFrameBitrate = par("responseBlockAckFrameBitrate");
-        responseBlockAckFrameMode = (responseBlockAckFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(responseBlockAckFrameBitrate));
-        double responseCtsFrameBitrate = par("responseCtsFrameBitrate");
-        responseCtsFrameMode = (responseCtsFrameBitrate == -1) ? nullptr : modeSet->getMode(bps(responseCtsFrameBitrate));
+        if (modeSet == nullptr)
+            throw cRuntimeError("QosRateSelection module %s has no mode set at link-layer initialization", getFullPath().c_str());
+        resolveConfiguredModes(modeSet);
     }
 }
 
+void QosRateSelection::resolveConfiguredModes(const Ieee80211ModeSet *newModeSet)
+{
+    if (newModeSet == nullptr)
+        return;
+    double multicastFrameBitrate = par("multicastFrameBitrate");
+    auto newMulticastFrameMode = multicastFrameBitrate == -1 ? nullptr : newModeSet->getMode(bps(multicastFrameBitrate));
+    double dataFrameBitrate = par("dataFrameBitrate");
+    auto newDataFrameMode = dataFrameBitrate == -1 ? nullptr : newModeSet->getMode(bps(dataFrameBitrate), Hz(par("dataFrameBandwidth")), par("dataFrameNumSpatialStreams"));
+    double mgmtFrameBitrate = par("mgmtFrameBitrate");
+    auto newMgmtFrameMode = mgmtFrameBitrate == -1 ? nullptr : newModeSet->getMode(bps(mgmtFrameBitrate));
+    double controlFrameBitrate = par("controlFrameBitrate");
+    auto newControlFrameMode = controlFrameBitrate == -1 ? nullptr : newModeSet->getMode(bps(controlFrameBitrate));
+    double responseAckFrameBitrate = par("responseAckFrameBitrate");
+    auto newResponseAckFrameMode = responseAckFrameBitrate == -1 ? nullptr : newModeSet->getMode(bps(responseAckFrameBitrate));
+    double responseBlockAckFrameBitrate = par("responseBlockAckFrameBitrate");
+    auto newResponseBlockAckFrameMode = responseBlockAckFrameBitrate == -1 ? nullptr : newModeSet->getMode(bps(responseBlockAckFrameBitrate));
+    double responseCtsFrameBitrate = par("responseCtsFrameBitrate");
+    auto newResponseCtsFrameMode = resolveConfiguredResponseCtsFrameMode(newModeSet, responseCtsFrameBitrate, getFullPath().c_str());
+    auto newFastestMandatoryMode = newModeSet->getFastestMandatoryMode();
+
+    modeSet = newModeSet;
+    multicastFrameMode = newMulticastFrameMode;
+    dataFrameMode = newDataFrameMode;
+    mgmtFrameMode = newMgmtFrameMode;
+    controlFrameMode = newControlFrameMode;
+    responseAckFrameMode = newResponseAckFrameMode;
+    responseBlockAckFrameMode = newResponseBlockAckFrameMode;
+    responseCtsFrameMode = newResponseCtsFrameMode;
+    fastestMandatoryMode = newFastestMandatoryMode;
+    lastTransmittedFrameMode.clear();
+}
+
 const IIeee80211Mode *QosRateSelection::getMode(Packet *packet, const Ptr<const Ieee80211MacHeader>& header)
 {
     const auto& modeReqTag = packet->findTag<Ieee80211ModeReq>();
@@ -71,36 +106,22 @@ bool QosRateSelection::isControlResponseFrame(const Ptr<const Ieee80211MacHeader
 //
 const IIeee80211Mode *QosRateSelection::computeResponseAckFrameMode(Packet *packet, const Ptr<const Ieee80211DataOrMgmtHeader>& dataOrMgmtHeader)
 {
-    // TODO BSSBasicRateSet, alternate rate
+    if (responseAckFrameMode)
+        return modeSet->getNonHtControlResponseMode(responseAckFrameMode, false);
     auto mode = getMode(packet, dataOrMgmtHeader);
-    ASSERT(modeSet->containsMode(mode));
-    if (!responseAckFrameMode) {
-        if (modeSet->getIsMandatory(mode))
-            return mode;
-        else if (auto slowerMode = modeSet->getSlowerMandatoryMode(mode))
-            return slowerMode;
-        else
-            throw cRuntimeError("Mandatory mode not found");
-    }
-    else
-        return responseAckFrameMode;
+    ASSERT(modeSet->supportsMode(mode));
+    // IEEE 802.11-2024 10.6.6.1/10.6.6.5.2: this bounded model uses a
+    // mandatory non-HT rate for ordinary ACK responses; BSSBasicRateSet is not modelled.
+    return modeSet->getMandatoryControlResponseMode(mode);
 }
 
 const IIeee80211Mode *QosRateSelection::computeResponseCtsFrameMode(Packet *packet, const Ptr<const Ieee80211RtsFrame>& rtsFrame)
 {
-    // TODO BSSBasicRateSet, alternate rate
     auto mode = getMode(packet, rtsFrame);
-    ASSERT(modeSet->containsMode(mode));
-    if (!responseCtsFrameMode) {
-        if (modeSet->getIsMandatory(mode))
-            return mode;
-        else if (auto slowerMode = modeSet->getSlowerMandatoryMode(mode))
-            return slowerMode;
-        else
-            throw cRuntimeError("Mandatory mode not found");
-    }
-    else
-        return responseCtsFrameMode;
+    ASSERT(modeSet->supportsMode(mode));
+    // The eliciting mode is required even when a CTS rate is configured because
+    // the response format and CandidateMCSSet depend on the received PPDU.
+    return modeSet->getControlResponseMode(mode, responseCtsFrameMode);
 }
 
 //
@@ -111,10 +132,15 @@ const IIeee80211Mode *QosRateSelection::computeResponseCtsFrameMode(Packet *pack
 //
 const IIeee80211Mode *QosRateSelection::computeResponseBlockAckFrameMode(Packet *packet, const Ptr<const Ieee80211BlockAckReq>& blockAckReq)
 {
-    if (dynamicPtrCast<const Ieee80211BasicBlockAckReq>(blockAckReq))
-        return responseBlockAckFrameMode ? responseBlockAckFrameMode : getMode(packet, blockAckReq);
-    else
+    if (!dynamicPtrCast<const Ieee80211BasicBlockAckReq>(blockAckReq))
         throw cRuntimeError("Unknown BlockAckReq frame type");
+    if (responseBlockAckFrameMode)
+        return modeSet->getNonHtControlResponseMode(responseBlockAckFrameMode, false);
+    auto mode = getMode(packet, blockAckReq);
+    ASSERT(modeSet->supportsMode(mode));
+    // IEEE 802.11-2024 10.6.6.5.2 permits non-HT Basic BlockAck responses;
+    // this model has no BSSBasicRateSet/HT Control context to select another PPDU.
+    return modeSet->getNonHtControlResponseMode(mode, false);
 }
 
 const IIeee80211Mode *QosRateSelection::computeDataOrMgmtFrameMode(const Ptr<const Ieee80211DataOrMgmtHeader>& dataOrMgmtHeader)
@@ -235,8 +261,7 @@ void QosRateSelection::receiveSignal(cComponent *source, simsignal_t signalID, c
     Enter_Method("%s", cComponent::getSignalName(signalID));
 
     if (signalID == modesetChangedSignal) {
-        modeSet = check_and_cast<Ieee80211ModeSet *>(obj);
-        fastestMandatoryMode = modeSet->getFastestMandatoryMode();
+        resolveConfiguredModes(check_and_cast<Ieee80211ModeSet *>(obj));
     }
 }
 
@@ -248,4 +273,3 @@ void QosRateSelection::frameTransmitted(Packet *packet, const Ptr<const Ieee8021
 
 } /* namespace ieee80211 */
 } /* namespace inet */
-

src/inet/linklayer/ieee80211/mac/rateselection/QosRateSelection.h

@@ -52,6 +52,7 @@ class INET_API QosRateSelection : public IQosRateSelection, public ModeSetListen
     virtual int numInitStages() const override { return NUM_INIT_STAGES; }
     virtual void initialize(int stage) override;
     virtual void receiveSignal(cComponent *source, simsignal_t signalID, cObject *obj, cObject *details) override;
+    void resolveConfiguredModes(const physicallayer::Ieee80211ModeSet *newModeSet);
 
     virtual const physicallayer::IIeee80211Mode *getMode(Packet *packet, const Ptr<const Ieee80211MacHeader>& header);
     virtual const physicallayer::IIeee80211Mode *computeControlFrameMode(const Ptr<const Ieee80211MacHeader>& header, TxopProcedure *txopProcedure);
@@ -78,4 +79,3 @@ class INET_API QosRateSelection : public IQosRateSelection, public ModeSetListen
 } /* namespace inet */
 
 #endif
-

src/inet/linklayer/ieee80211/mac/rateselection/QosRateSelection.ned

@@ -26,8 +26,18 @@ simple QosRateSelection extends SimpleModule
 
         double multicastFrameBitrate @unit(bps) = default(-1bps);
 
+        // -1 selects the standard-derived automatic response. In a 2.4 GHz HT profile,
+        // a configured HT bitrate is an upper bound mapped to the highest mandatory
+        // non-HT rate at or below it; it does not select an exact HT ACK PPDU.
         double responseAckFrameBitrate @unit(bps) = default(-1bps);
+        // -1 selects the standard-derived automatic response. In a 2.4 GHz HT profile,
+        // a configured HT bitrate is an upper bound mapped to the highest mandatory
+        // non-HT rate at or below it; it does not select an exact HT BlockAck PPDU.
         double responseBlockAckFrameBitrate @unit(bps) = default(-1bps);
+        // -1 selects the standard-derived automatic response. A configured value must resolve to a
+        // selectable mode; for an HT RTS it must be HT and is translated to the corresponding HT-mixed
+        // CTS while preserving MCS, bandwidth, NSS, and GI. An explicitly configured HT value is a
+        // deliberate override and may bypass IEEE 802.11-2024 10.6.6.5.3/10.6.6.5.7 response constraints.
         double responseCtsFrameBitrate @unit(bps) = default(-1bps);
 
         double dataFrameBitrate @unit(bps) = default(-1bps); // Fastest
@@ -38,4 +48,3 @@ simple QosRateSelection extends SimpleModule
         double controlFrameBitrate @unit(bps) = default(-1bps);
         @display("i=block/cogwheel");
 }
-