wifi-emlsr-basic-exchanges-test.cc

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/*
 * Copyright (c) 2023 Universita' degli Studi di Napoli Federico II
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Stefano Avallone <stavallo@unina.it>
 */
 
#include "wifi-emlsr-basic-exchanges-test.h"
 
#include "ns3/advanced-emlsr-manager.h"
#include "ns3/boolean.h"
#include "ns3/config.h"
#include "ns3/eht-configuration.h"
#include "ns3/eht-frame-exchange-manager.h"
#include "ns3/log.h"
#include "ns3/mgt-action-headers.h"
#include "ns3/qos-txop.h"
#include "ns3/rr-multi-user-scheduler.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/wifi-net-device.h"
 
#include <algorithm>
#include <functional>
#include <iomanip>
 
using namespace ns3;
 
NS_LOG_COMPONENT_DEFINE("WifiEmlsrBasicExchangesTest");
 
EmlsrDlTxopTest::EmlsrDlTxopTest(const Params& params)
    : EmlsrOperationsTestBase("Check EML DL TXOP transmissions (" +
                              std::to_string(params.nEmlsrStations) + "," +
                              std::to_string(params.nNonEmlsrStations) + ")"),
      m_emlsrLinks(params.linksToEnableEmlsrOn),
      m_emlsrEnabledTime(0),
      m_fe2to3delay(MilliSeconds(20)),
      m_countQoSframes(0),
      m_countBlockAck(0)
{
    m_nEmlsrStations = params.nEmlsrStations;
    m_nNonEmlsrStations = params.nNonEmlsrStations;
    m_linksToEnableEmlsrOn = {}; // do not enable EMLSR right after association
    m_mainPhyId = 1;
    m_paddingDelay = params.paddingDelay;
    m_transitionDelay = params.transitionDelay;
    m_transitionTimeout = params.transitionTimeout;
    m_establishBaDl = {0};
    m_putAuxPhyToSleep = params.putAuxPhyToSleep;
    m_duration = Seconds(1.5);
 
    NS_ABORT_MSG_IF(params.linksToEnableEmlsrOn.size() < 2,
                    "This test requires at least two links to be configured as EMLSR links");
}
 
void
EmlsrDlTxopTest::Transmit(Ptr<WifiMac> mac,
                          uint8_t phyId,
                          WifiConstPsduMap psduMap,
                          WifiTxVector txVector,
                          double txPowerW)
{
    EmlsrOperationsTestBase::Transmit(mac, phyId, psduMap, txVector, txPowerW);
    auto linkId = m_txPsdus.back().linkId;
 
    auto psdu = psduMap.begin()->second;
    auto nodeId = mac->GetDevice()->GetNode()->GetId();
 
    switch (psdu->GetHeader(0).GetType())
    {
    case WIFI_MAC_MGT_ASSOCIATION_REQUEST:
        NS_ASSERT_MSG(nodeId > 0, "APs do not send AssocReq frames");
        if (nodeId <= m_nEmlsrStations)
        {
            NS_TEST_EXPECT_MSG_EQ(+linkId, +m_mainPhyId, "AssocReq not sent by the main PHY");
            // this AssocReq is being sent by an EMLSR client. The other EMLSR links should be
            // in powersave mode after association; we let the non-EMLSR links transition to
            // active mode (by sending data null frames) after association
            for (const auto id : m_staMacs.at(nodeId - 1)->GetLinkIds())
            {
                if (id != linkId && m_emlsrLinks.count(id) == 1)
                {
                    m_staMacs[nodeId - 1]->SetPowerSaveMode({true, id});
                }
            }
        }
        break;
 
    case WIFI_MAC_MGT_ACTION: {
        auto [category, action] = WifiActionHeader::Peek(psdu->GetPayload(0));
 
        if ((category == WifiActionHeader::PROTECTED_EHT) &&
            (action.protectedEhtAction ==
             WifiActionHeader::PROTECTED_EHT_EML_OPERATING_MODE_NOTIFICATION))
        {
            nodeId == 0 ? CheckApEmlNotificationFrame(*psdu->begin(), txVector, linkId)
                        : CheckStaEmlNotificationFrame(*psdu->begin(), txVector, linkId);
        }
        else if (category == WifiActionHeader::BLOCK_ACK &&
                 action.blockAck == WifiActionHeader::BLOCK_ACK_ADDBA_REQUEST)
        {
            CheckPmModeAfterAssociation(psdu->GetAddr1());
        }
    }
    break;
 
    case WIFI_MAC_CTL_TRIGGER:
        CheckInitialControlFrame(*psdu->begin(), txVector, linkId);
        break;
 
    case WIFI_MAC_QOSDATA:
        CheckQosFrames(psduMap, txVector, linkId);
        break;
 
    case WIFI_MAC_CTL_BACKRESP:
        CheckBlockAck(psduMap, txVector, phyId);
        break;
 
    case WIFI_MAC_CTL_END:
        if (auto apMac = DynamicCast<ApWifiMac>(mac))
        {
            const auto txDuration =
                WifiPhy::CalculateTxDuration(psduMap,
                                             txVector,
                                             apMac->GetDevice()->GetPhy(phyId)->GetPhyBand());
            for (std::size_t i = 0; i < m_nEmlsrStations; ++i)
            {
                if (m_staMacs[i]->IsEmlsrLink(linkId) &&
                    m_staMacs[i]->GetWifiPhy(linkId) ==
                        m_staMacs[i]->GetDevice()->GetPhy(m_mainPhyId))
                {
                    // AP is terminating a TXOP on an EMLSR link on which the main PHY is operating,
                    // aux PHYs should resume from sleep
                    Simulator::Schedule(txDuration + TimeStep(1),
                                        &EmlsrDlTxopTest::CheckAuxPhysSleepMode,
                                        this,
                                        m_staMacs[i],
                                        false);
                }
            }
        }
        break;
 
    default:;
    }
}
 
void
EmlsrDlTxopTest::DoSetup()
{
    // Channel switch delay should be less than the ICF padding duration, otherwise
    // DL TXOPs cannot be initiated on auxiliary links
    Config::SetDefault("ns3::WifiPhy::ChannelSwitchDelay", TimeValue(MicroSeconds(75)));
 
    EmlsrOperationsTestBase::DoSetup();
 
    m_errorModel = CreateObject<ListErrorModel>();
    for (std::size_t linkId = 0; linkId < m_apMac->GetNLinks(); linkId++)
    {
        m_apMac->GetWifiPhy(linkId)->SetPostReceptionErrorModel(m_errorModel);
    }
 
    m_apMac->GetQosTxop(AC_BE)->SetTxopLimits(
        {MicroSeconds(3200), MicroSeconds(3200), MicroSeconds(3200)});
 
    if (m_nEmlsrStations + m_nNonEmlsrStations > 1)
    {
        auto muScheduler =
            CreateObjectWithAttributes<RrMultiUserScheduler>("EnableUlOfdma", BooleanValue(false));
        m_apMac->AggregateObject(muScheduler);
        for (uint8_t linkId = 0; linkId < m_apMac->GetNLinks(); linkId++)
        {
            m_apMac->GetFrameExchangeManager(linkId)->GetAckManager()->SetAttribute(
                "DlMuAckSequenceType",
                EnumValue(WifiAcknowledgment::DL_MU_AGGREGATE_TF));
        }
    }
}
 
void
EmlsrDlTxopTest::StartTraffic()
{
    if (m_emlsrEnabledTime.IsZero())
    {
        // we are done with association and Block Ack agreement; we can now enable EMLSR mode
        m_lastAid = 0;
        EnableEmlsrMode();
        return;
    }
 
    // we are done with sending EML Operating Mode Notification frames. We can now generate
    // packets for all non-AP MLDs
    for (std::size_t i = 0; i < m_nEmlsrStations + m_nNonEmlsrStations; i++)
    {
        // when multiple non-AP MLDs are present, MU transmission are used. Given that the
        // available bandwidth decreases as the number of non-AP MLDs increases, compute the
        // number of packets to generate so that we always have two A-MPDUs per non-AP MLD
        std::size_t count = 8 / (m_nEmlsrStations + m_nNonEmlsrStations);
        m_apMac->GetDevice()->GetNode()->AddApplication(GetApplication(DOWNLINK, i, count, 450));
    }
 
    // in case of 2 EMLSR clients using no non-EMLSR link, generate one additional short
    // packet to each EMLSR client to test transition delay
    if (m_nEmlsrStations == 2 && m_apMac->GetNLinks() == m_emlsrLinks.size())
    {
        Simulator::Schedule(m_fe2to3delay, [&]() {
            m_apMac->GetDevice()->GetNode()->AddApplication(GetApplication(DOWNLINK, 0, 1, 40));
            m_apMac->GetDevice()->GetNode()->AddApplication(GetApplication(DOWNLINK, 1, 1, 40));
        });
    }
 
    // schedule the transmission of EML Operating Mode Notification frames to disable EMLSR mode
    // and the generation of other packets destined to the EMLSR clients
    for (std::size_t id = 0; id < m_nEmlsrStations; id++)
    {
        Simulator::Schedule(m_fe2to3delay + MilliSeconds(5 * (id + 1)), [=, this]() {
            m_staMacs.at(id)->GetEmlsrManager()->SetAttribute(
                "EmlsrLinkSet",
                AttributeContainerValue<UintegerValue>({}));
        });
 
        Simulator::Schedule(m_fe2to3delay + MilliSeconds(5 * (m_nEmlsrStations + 1)), [=, this]() {
            m_apMac->GetDevice()->GetNode()->AddApplication(
                GetApplication(DOWNLINK, id, 8 / m_nEmlsrStations, 650));
        });
    }
}
 
void
EmlsrDlTxopTest::EnableEmlsrMode()
{
    m_staMacs.at(m_lastAid)->GetEmlsrManager()->SetAttribute(
        "EmlsrLinkSet",
        AttributeContainerValue<UintegerValue>(m_emlsrLinks));
    m_lastAid++;
    Simulator::Schedule(MilliSeconds(5), [=, this]() {
        if (m_lastAid < m_nEmlsrStations)
        {
            // make the next STA send EML Notification frame
            EnableEmlsrMode();
            return;
        }
        // all stations enabled EMLSR mode; start traffic
        m_emlsrEnabledTime = Simulator::Now();
        StartTraffic();
    });
}
 
void
EmlsrDlTxopTest::CheckResults()
{
    auto psduIt = m_txPsdus.cbegin();
 
    // lambda to jump to the next QoS data frame or MU-RTS Trigger Frame transmitted
    // to an EMLSR client
    auto jumpToQosDataOrMuRts = [&]() {
        while (psduIt != m_txPsdus.cend() &&
               !psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData())
        {
            auto psdu = psduIt->psduMap.cbegin()->second;
            if (psdu->GetHeader(0).IsTrigger())
            {
                CtrlTriggerHeader trigger;
                psdu->GetPayload(0)->PeekHeader(trigger);
                if (trigger.IsMuRts())
                {
                    break;
                }
            }
            psduIt++;
        }
    };
 
    /**
     * Before enabling EMLSR mode, no MU-RTS TF should be sent. Four packets are generated
     * after association to trigger the establishment of a Block Ack agreement. The TXOP Limit
     * and the MCS are set such that two packets can be transmitted in a TXOP, hence we expect
     * that the AP MLD sends two A-MPDUs to each non-AP MLD.
     *
     * EMLSR client with EMLSR mode to be enabled on all links: after ML setup, all other links
     * stay in power save mode, hence BA establishment occurs on the same link.
     *
     *  [link 0]
     *  ───────────────────────────────────────────────────────────────────────────
     *                              | power save mode
     *
     *                   ┌─────┐      ┌─────┐                   ┌───┬───┐     ┌───┬───┐
     *            ┌───┐  │Assoc│      │ADDBA│             ┌───┐ │QoS│QoS│     │QoS│QoS│
     *  [link 1]  │ACK│  │Resp │      │ Req │             │ACK│ │ 0 │ 1 │     │ 2 │ 3 │
     *  ───┬─────┬┴───┴──┴─────┴┬───┬─┴─────┴┬───┬─┬─────┬┴───┴─┴───┴───┴┬──┬─┴───┴───┴┬──┬───
     *     │Assoc│              │ACK│        │ACK│ │ADDBA│               │BA│          │BA│
     *     │ Req │              └───┘        └───┘ │Resp │               └──┘          └──┘
     *     └─────┘                                 └─────┘
     *
     *  [link 2]
     *  ───────────────────────────────────────────────────────────────────────────
     *                              | power save mode
     *
     *
     * EMLSR client with EMLSR mode to be enabled on not all the links: after ML setup,
     * the other EMLSR links stay in power save mode, the non-EMLSR link (link 1) transitions
     * to active mode.
     *
     *                                             ┌─────┐                   ┌───┬───┐
     *                                      ┌───┐  │ADDBA│             ┌───┐ │QoS│QoS│
     *  [link 0 - non EMLSR]                │ACK│  │ Req │             │ACK│ │ 2 │ 3 │
     *  ──────────────────────────────┬────┬┴───┴──┴─────┴┬───┬─┬─────┬┴───┴─┴───┴───┴┬──┬─
     *                                │Data│              │ACK│ │ADDBA│               │BA│
     *                                │Null│              └───┘ │Resp │               └──┘
     *                                └────┘                    └─────┘
     *                   ┌─────┐                                       ┌───┬───┐
     *            ┌───┐  │Assoc│                                       │QoS│QoS│
     *  [link 1]  │ACK│  │Resp │                                       │ 0 │ 1 │
     *  ───┬─────┬┴───┴──┴─────┴┬───┬──────────────────────────────────┴───┴───┴┬──┬───────
     *     │Assoc│              │ACK│                                           │BA│
     *     │ Req │              └───┘                                           └──┘
     *     └─────┘
     *
     *  [link 2]
     *  ───────────────────────────────────────────────────────────────────────────
     *                              | power save mode
     *
     * Non-EMLSR client (not shown): after ML setup, all other links transition to active mode
     * by sending a Data Null frame; QoS data frame exchanges occur on two links simultaneously.
     */
    for (std::size_t i = 0; i < m_nEmlsrStations + m_nNonEmlsrStations; i++)
    {
        std::set<uint8_t> linkIds;
 
        jumpToQosDataOrMuRts();
        NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend() &&
                               psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData()),
                              true,
                              "Expected at least one QoS data frame before enabling EMLSR mode");
        linkIds.insert(psduIt->linkId);
        const auto firstAmpduTxEnd =
            psduIt->startTx +
            WifiPhy::CalculateTxDuration(psduIt->psduMap,
                                         psduIt->txVector,
                                         m_staMacs[i]->GetWifiPhy(psduIt->linkId)->GetPhyBand());
        auto firstQos = psduIt++;
 
        jumpToQosDataOrMuRts();
        NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend() &&
                               psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData()),
                              true,
                              "Expected at least two QoS data frames before enabling EMLSR mode");
        linkIds.insert(psduIt->linkId);
        const auto secondAmpduTxStart = psduIt->startTx;
 
        auto beaconInBetween{false};
        while (++firstQos != psduIt)
        {
            if (firstQos->psduMap.cbegin()->second->GetHeader(0).IsBeacon())
            {
                beaconInBetween = true;
                break;
            }
        }
 
        psduIt++;
 
        /**
         * If this is an EMLSR client and there is no setup link other than the one used to
         * establish association that is not an EMLSR link, then the two A-MPDUs are sent one
         * after another on the link used to establish association.
         */
        auto setupLinks = m_staMacs[i]->GetSetupLinkIds();
 
        bool areAllSetupLinksEmlsr =
            std::all_of(setupLinks.begin(), setupLinks.end(), [&](auto&& linkId) {
                return linkId == m_mainPhyId || m_emlsrLinks.contains(linkId);
            });
 
        if (i < m_nEmlsrStations && areAllSetupLinksEmlsr)
        {
            NS_TEST_EXPECT_MSG_EQ(linkIds.size(),
                                  1,
                                  "Expected both A-MPDUs to be sent on the same link");
            NS_TEST_EXPECT_MSG_EQ(*linkIds.begin(), +m_mainPhyId, "A-MPDUs sent on incorrect link");
            NS_TEST_EXPECT_MSG_LT(firstAmpduTxEnd,
                                  secondAmpduTxStart,
                                  "A-MPDUs are not sent one after another");
        }
        /**
         * Otherwise, the two A-MPDUs can be sent concurrently on two distinct links (may be
         * the link used to establish association and a non-EMLSR link).
         */
        else if (!beaconInBetween)
        {
            NS_TEST_EXPECT_MSG_EQ(linkIds.size(),
                                  2,
                                  "Expected A-MPDUs to be sent on distinct links");
            NS_TEST_EXPECT_MSG_GT(firstAmpduTxEnd,
                                  secondAmpduTxStart,
                                  "A-MPDUs are not sent concurrently");
        }
    }
 
    /**
     * After enabling EMLSR mode, MU-RTS TF should only be sent on EMLSR links. After the exchange
     * of EML Operating Mode Notification frames, a number of packets are generated at the AP MLD
     * to prepare two A-MPDUs for each non-AP MLD.
     *
     * EMLSR client with EMLSR mode to be enabled on all links (A is the EMLSR client, B is the
     * non-EMLSR client):
     *                                      ┌─────┬─────┐
     *                                      │QoS 4│QoS 5│
     *                                      │ to A│ to A│
     *                            ┌───┐     ├─────┼─────┤
     *                            │MU │     │QoS 4│QoS 5│
     *  [link 0]                  │RTS│     │ to B│ to B│
     *  ──────────────────────────┴───┴┬───┬┴─────┴─────┴┬──┬────────────
     *                                 │CTS│             │BA│
     *                                 ├───┤             ├──┤
     *                                 │CTS│             │BA│
     *                                 └───┘             └──┘
     *                  ┌───┐      ┌─────┬─────┐
     *           ┌───┐  │EML│      │QoS 6│QoS 7│
     *  [link 1] │ACK│  │OM │      │ to B│ to B│
     *  ────┬───┬┴───┴──┴───┴┬───┬─┴─────┴─────┴┬──┬────────────────────────────────────
     *      │EML│            │ACK│              │BA│
     *      │OM │            └───┘              └──┘
     *      └───┘
     *                                                           ┌───┐     ┌─────┬─────┐
     *                                                           │MU │     │QoS 6│QoS 7│
     *  [link 2]                                                 │RTS│     │ to A│ to A│
     *  ─────────────────────────────────────────────────────────┴───┴┬───┬┴─────┴─────┴┬──┬─
     *                                                                │CTS│             │BA│
     *                                                                └───┘             └──┘
     *
     * EMLSR client with EMLSR mode to be enabled on not all the links (A is the EMLSR client,
     * B is the non-EMLSR client):
     *                             ┌─────┬─────┐
     *                             │QoS 4│QoS 5│
     *                             │ to A│ to A│
     *                             ├─────┼─────┤
     *                             │QoS 4│QoS 5│
     *  [link 0 - non EMLSR]       │ to B│ to B│
     *  ───────────────────────────┴─────┴─────┴┬──┬───────────────────────────
     *                                          │BA│
     *                                          ├──┤
     *                                          │BA│
     *                                          └──┘
     *                                       ┌─────┬─────┐
     *                                       │QoS 6│QoS 7│
     *                                       │ to A│ to A│
     *                  ┌───┐      ┌───┐     ├─────┼─────┤
     *           ┌───┐  │EML│      │MU │     │QoS 6│QoS 7│
     *  [link 1] │ACK│  │OM │      │RTS│     │ to B│ to B│
     *  ────┬───┬┴───┴──┴───┴┬───┬─┴───┴┬───┬┴─────┴─────┴┬──┬────────────
     *      │EML│            │ACK│      │CTS│             │BA│
     *      │OM │            └───┘      ├───┤             ├──┤
     *      └───┘                       │CTS│             │BA│
     *                                  └───┘             └──┘
     *
     *  [link 2]
     *  ────────────────────────────────────────────────────────────────────────────────
     */
 
    /// Store a QoS data frame or an MU-RTS TF followed by a QoS data frame
    using FrameExchange = std::list<decltype(psduIt)>;
 
    std::vector<std::list<FrameExchange>> frameExchanges(m_nEmlsrStations);
 
    // compute all frame exchanges involving EMLSR clients
    while (psduIt != m_txPsdus.cend())
    {
        jumpToQosDataOrMuRts();
        if (psduIt == m_txPsdus.cend())
        {
            break;
        }
 
        if (IsTrigger(psduIt->psduMap))
        {
            CtrlTriggerHeader trigger;
            psduIt->psduMap.cbegin()->second->GetPayload(0)->PeekHeader(trigger);
            // this is an MU-RTS TF starting a new frame exchange sequence; add it to all
            // the addressed EMLSR clients
            NS_TEST_ASSERT_MSG_EQ(trigger.IsMuRts(),
                                  true,
                                  "jumpToQosDataOrMuRts does not return TFs other than MU-RTS");
            for (const auto& userInfo : trigger)
            {
                for (std::size_t i = 0; i < m_nEmlsrStations; i++)
                {
                    if (m_staMacs.at(i)->GetAssociationId() == userInfo.GetAid12())
                    {
                        frameExchanges.at(i).emplace_back(FrameExchange{psduIt});
                        break;
                    }
                }
            }
            psduIt++;
            continue;
        }
 
        // we get here if psduIt points to a psduMap containing QoS data frame(s); find (if any)
        // the QoS data frame(s) addressed to EMLSR clients and add them to the appropriate
        // frame exchange sequence
        for (const auto& staIdPsduPair : psduIt->psduMap)
        {
            std::for_each_n(m_staMacs.cbegin(), m_nEmlsrStations, [&](auto&& staMac) {
                if (!staMac->GetLinkIdByAddress(staIdPsduPair.second->GetAddr1()))
                {
                    // not addressed to this non-AP MLD
                    return;
                }
                // a QoS data frame starts a new frame exchange sequence if there is no previous
                // MU-RTS TF that has been sent on the same link and is not already followed by
                // a QoS data frame
                std::size_t id = staMac->GetDevice()->GetNode()->GetId() - 1;
                for (auto& frameExchange : frameExchanges.at(id))
                {
                    if (IsTrigger(frameExchange.front()->psduMap) &&
                        frameExchange.front()->linkId == psduIt->linkId &&
                        frameExchange.size() == 1)
                    {
                        auto it = std::next(frameExchange.front());
                        while (it != m_txPsdus.end())
                        {
                            // stop at the first frame other than CTS sent on this link
                            if (it->linkId == psduIt->linkId &&
                                !it->psduMap.begin()->second->GetHeader(0).IsCts())
                            {
                                break;
                            }
                            ++it;
                        }
                        if (it == psduIt)
                        {
                            // the QoS data frame actually followed the MU-RTS TF
                            frameExchange.emplace_back(psduIt);
                            return;
                        }
                    }
                }
                frameExchanges.at(id).emplace_back(FrameExchange{psduIt});
            });
        }
        psduIt++;
    }
 
    /**
     * Let's focus on the first two frame exchanges for each EMLSR clients. If all setup links are
     * EMLSR links, both frame exchanges are protected by MU-RTS TF and occur one after another.
     * Otherwise, one frame exchange occurs on the non-EMLSR link and is not protected by
     * MU-RTS TF; the other frame exchange occurs on an EMLSR link and is protected by MU-RTS TF.
     */
    for (std::size_t i = 0; i < m_nEmlsrStations; i++)
    {
        NS_TEST_EXPECT_MSG_GT_OR_EQ(frameExchanges.at(i).size(),
                                    2,
                                    "Expected at least 2 frame exchange sequences "
                                        << "involving EMLSR client " << i);
 
        auto firstExchangeIt = frameExchanges.at(i).begin();
        auto secondExchangeIt = std::next(firstExchangeIt);
 
        const auto firstAmpduTxEnd =
            firstExchangeIt->back()->startTx +
            WifiPhy::CalculateTxDuration(
                firstExchangeIt->back()->psduMap,
                firstExchangeIt->back()->txVector,
                m_staMacs[i]->GetWifiPhy(firstExchangeIt->back()->linkId)->GetPhyBand());
        const auto secondAmpduTxStart = secondExchangeIt->front()->startTx;
 
        if (m_staMacs[i]->GetNLinks() == m_emlsrLinks.size())
        {
            // all links are EMLSR links
            NS_TEST_EXPECT_MSG_EQ(IsTrigger(firstExchangeIt->front()->psduMap),
                                  true,
                                  "Expected an MU-RTS TF as ICF of first frame exchange sequence");
            NS_TEST_EXPECT_MSG_EQ(
                firstExchangeIt->back()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                true,
                "Expected a QoS data frame in the first frame exchange sequence");
 
            NS_TEST_EXPECT_MSG_EQ(IsTrigger(secondExchangeIt->front()->psduMap),
                                  true,
                                  "Expected an MU-RTS TF as ICF of second frame exchange sequence");
            NS_TEST_EXPECT_MSG_EQ(
                secondExchangeIt->back()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                true,
                "Expected a QoS data frame in the second frame exchange sequence");
 
            NS_TEST_EXPECT_MSG_LT(firstAmpduTxEnd,
                                  secondAmpduTxStart,
                                  "A-MPDUs are not sent one after another");
        }
        else
        {
            std::vector<uint8_t> nonEmlsrIds;
            auto setupLinks = m_staMacs[i]->GetSetupLinkIds();
            std::set_difference(setupLinks.begin(),
                                setupLinks.end(),
                                m_emlsrLinks.begin(),
                                m_emlsrLinks.end(),
                                std::back_inserter(nonEmlsrIds));
            NS_TEST_ASSERT_MSG_EQ(nonEmlsrIds.size(), 1, "Unexpected number of non-EMLSR links");
 
            auto nonEmlsrLinkExchangeIt = firstExchangeIt->front()->linkId == nonEmlsrIds[0]
                                              ? firstExchangeIt
                                              : secondExchangeIt;
            NS_TEST_EXPECT_MSG_EQ(IsTrigger(nonEmlsrLinkExchangeIt->front()->psduMap),
                                  false,
                                  "Did not expect an MU-RTS TF as ICF on non-EMLSR link");
            NS_TEST_EXPECT_MSG_EQ(
                nonEmlsrLinkExchangeIt->front()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                true,
                "Expected a QoS data frame on the non-EMLSR link");
 
            auto emlsrLinkExchangeIt =
                nonEmlsrLinkExchangeIt == firstExchangeIt ? secondExchangeIt : firstExchangeIt;
            NS_TEST_EXPECT_MSG_NE(+emlsrLinkExchangeIt->front()->linkId,
                                  +nonEmlsrIds[0],
                                  "Expected this exchange not to occur on non-EMLSR link");
            NS_TEST_EXPECT_MSG_EQ(IsTrigger(emlsrLinkExchangeIt->front()->psduMap),
                                  true,
                                  "Expected an MU-RTS TF as ICF on the EMLSR link");
            NS_TEST_EXPECT_MSG_EQ(
                emlsrLinkExchangeIt->back()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                true,
                "Expected a QoS data frame on the EMLSR link");
 
            NS_TEST_EXPECT_MSG_GT(firstAmpduTxEnd,
                                  secondAmpduTxStart,
                                  "A-MPDUs are not sent concurrently");
        }
 
        // we are done with processing the first two frame exchanges, remove them
        frameExchanges.at(i).erase(firstExchangeIt);
        frameExchanges.at(i).erase(secondExchangeIt);
    }
 
    /**
     * A and B are two EMLSR clients. No ICF before the second QoS data frame because B
     * has not switched to listening mode. ICF is sent before the third QoS data frame because
     * A has switched to listening mode. C is a non-EMLSR client.
     *
     *                        ┌─────┐          A switches to listening
     *                        │QoS x│          after transition delay
     *                        │ to A│          |
     *              ┌───┐     ├─────┤    ┌─────┐
     *              │MU │     │QoS x│    │QoS y│
     *  [link 0]    │RTS│     │ to B│    │ to B│
     *  ────────────┴───┴┬───┬┴─────┴┬──┬┴─────┴┬──┬────────────
     *                   │CTS│       │BA│       │BA│
     *                   ├───┤       ├──┤       └──┘
     *                   │CTS│       │BA│
     *                   └───┘       └──┘        AP continues the TXOP     A switches to listening
     *                                             after PIFS recovery      after transition delay
     *                                                                │                       │
     *                                 ┌─────┐    ┌───┐     ┌─────┐   │┌───┐              ┌───┐
     *                                 │QoS z│    │MU │     │QoS x│   ││MU │     ┌───┐    │CF-│
     *  [link 1]                       │ to C│    │RTS│     │ to A│   ││RTS│     │BAR│    │End│
     *  ───────────────────────────────┴─────┴┬──┬┴───┴┬───┬┴─────┴┬──┬┴───┴┬───┬┴───┴┬──┬┴───┴─
     *                                        │BA│     │CTS│       │BA│     │CTS│     │BA│
     *                                        └──┘     └───┘       └──x     └───┘     └──┘
     */
    if (m_nEmlsrStations == 2 && m_apMac->GetNLinks() == m_emlsrLinks.size())
    {
        // the following checks are only done with 2 EMLSR clients having no non-EMLSR link
        for (std::size_t i = 0; i < m_nEmlsrStations; i++)
        {
            NS_TEST_EXPECT_MSG_GT_OR_EQ(frameExchanges.at(i).size(),
                                        2,
                                        "Expected at least 2 frame exchange sequences "
                                            << "involving EMLSR client " << i);
            // the first frame exchange must start with an ICF
            auto firstExchangeIt = frameExchanges.at(i).begin();
 
            NS_TEST_EXPECT_MSG_EQ(IsTrigger(firstExchangeIt->front()->psduMap),
                                  true,
                                  "Expected an MU-RTS TF as ICF of first frame exchange sequence");
            NS_TEST_EXPECT_MSG_EQ(
                firstExchangeIt->back()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                true,
                "Expected a QoS data frame in the first frame exchange sequence");
        }
 
        // the second frame exchange is the one that starts first
        auto secondExchangeIt = std::next(frameExchanges.at(0).begin())->front()->startTx <
                                        std::next(frameExchanges.at(1).begin())->front()->startTx
                                    ? std::next(frameExchanges.at(0).begin())
                                    : std::next(frameExchanges.at(1).begin());
        decltype(secondExchangeIt) thirdExchangeIt;
        std::size_t thirdExchangeStaId;
 
        if (secondExchangeIt == std::next(frameExchanges.at(0).begin()))
        {
            thirdExchangeIt = std::next(frameExchanges.at(1).begin());
            thirdExchangeStaId = 1;
        }
        else
        {
            thirdExchangeIt = std::next(frameExchanges.at(0).begin());
            thirdExchangeStaId = 0;
        }
 
        // the second frame exchange is not protected by the ICF and starts a SIFS after the end
        // of the previous one
        NS_TEST_EXPECT_MSG_EQ(IsTrigger(secondExchangeIt->front()->psduMap),
                              false,
                              "Expected no ICF for the second frame exchange sequence");
        NS_TEST_EXPECT_MSG_EQ(
            secondExchangeIt->front()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
            true,
            "Expected a QoS data frame in the second frame exchange sequence");
 
        // the first two frame exchanges occur on the same link
        NS_TEST_EXPECT_MSG_EQ(+secondExchangeIt->front()->linkId,
                              +frameExchanges.at(0).begin()->front()->linkId,
                              "Expected the first two frame exchanges to occur on the same link");
 
        auto bAckRespIt = std::prev(secondExchangeIt->front());
        NS_TEST_EXPECT_MSG_EQ(bAckRespIt->psduMap.cbegin()->second->GetHeader(0).IsBlockAck(),
                              true,
                              "Expected a BlockAck response before the second frame exchange");
        auto bAckRespTxEnd =
            bAckRespIt->startTx +
            WifiPhy::CalculateTxDuration(bAckRespIt->psduMap,
                                         bAckRespIt->txVector,
                                         m_apMac->GetWifiPhy(bAckRespIt->linkId)->GetPhyBand());
 
        // the second frame exchange starts a SIFS after the previous one
        NS_TEST_EXPECT_MSG_EQ(
            bAckRespTxEnd + m_apMac->GetWifiPhy(bAckRespIt->linkId)->GetSifs(),
            secondExchangeIt->front()->startTx,
            "Expected the second frame exchange to start a SIFS after the first one");
 
        // the third frame exchange is protected by MU-RTS and occurs on a different link
        NS_TEST_EXPECT_MSG_EQ(IsTrigger(thirdExchangeIt->front()->psduMap),
                              true,
                              "Expected an MU-RTS as ICF for the third frame exchange sequence");
        NS_TEST_EXPECT_MSG_EQ(
            thirdExchangeIt->back()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
            true,
            "Expected a QoS data frame in the third frame exchange sequence");
 
        NS_TEST_EXPECT_MSG_NE(
            +secondExchangeIt->front()->linkId,
            +thirdExchangeIt->front()->linkId,
            "Expected the second and third frame exchanges to occur on distinct links");
 
        auto secondQosIt = secondExchangeIt->front();
        auto secondQosTxEnd =
            secondQosIt->startTx +
            WifiPhy::CalculateTxDuration(secondQosIt->psduMap,
                                         secondQosIt->txVector,
                                         m_apMac->GetWifiPhy(secondQosIt->linkId)->GetPhyBand());
 
        NS_TEST_EXPECT_MSG_GT_OR_EQ(thirdExchangeIt->front()->startTx,
                                    secondQosTxEnd + m_transitionDelay.at(thirdExchangeStaId),
                                    "Transmission started before transition delay");
 
        // the BlockAck of the third frame exchange is not received correctly, so there should be
        // another frame exchange
        NS_TEST_EXPECT_MSG_EQ((thirdExchangeIt != frameExchanges.at(thirdExchangeStaId).end()),
                              true,
                              "Expected a fourth frame exchange");
        auto fourthExchangeIt = std::next(thirdExchangeIt);
 
        // the fourth frame exchange is protected by MU-RTS
        NS_TEST_EXPECT_MSG_EQ(IsTrigger(fourthExchangeIt->front()->psduMap),
                              true,
                              "Expected an MU-RTS as ICF for the fourth frame exchange sequence");
 
        bAckRespIt = std::prev(fourthExchangeIt->front());
        NS_TEST_EXPECT_MSG_EQ(bAckRespIt->psduMap.cbegin()->second->GetHeader(0).IsBlockAck(),
                              true,
                              "Expected a BlockAck response before the fourth frame exchange");
        auto phy = m_apMac->GetWifiPhy(bAckRespIt->linkId);
        bAckRespTxEnd = bAckRespIt->startTx + WifiPhy::CalculateTxDuration(bAckRespIt->psduMap,
                                                                           bAckRespIt->txVector,
                                                                           phy->GetPhyBand());
 
        // the fourth frame exchange starts a PIFS after the previous one because the AP
        // performs PIFS recovery (the initial frame in the TXOP was successfully received by
        // a non-EMLSR client)
        NS_TEST_EXPECT_MSG_GT_OR_EQ(fourthExchangeIt->front()->startTx,
                                    bAckRespTxEnd + phy->GetPifs(),
                                    "Transmission started less than a PIFS after BlockAck");
        NS_TEST_EXPECT_MSG_LT(fourthExchangeIt->front()->startTx,
                              bAckRespTxEnd + phy->GetPifs() +
                                  MicroSeconds(1) /* propagation delay upper bound */,
                              "Transmission started too much time after BlockAck");
 
        auto bAckReqIt = std::next(fourthExchangeIt->front(), 2);
        NS_TEST_EXPECT_MSG_EQ(bAckReqIt->psduMap.cbegin()->second->GetHeader(0).IsBlockAckReq(),
                              true,
                              "Expected a BlockAck request in the fourth frame exchange");
 
        // we are done with processing the frame exchanges, remove them (two frame exchanges
        // per EMLSR client, plus the last one)
        frameExchanges.at(0).pop_front();
        frameExchanges.at(0).pop_front();
        frameExchanges.at(1).pop_front();
        frameExchanges.at(1).pop_front();
        frameExchanges.at(thirdExchangeStaId).pop_front();
    }
 
    /**
     * After disabling EMLSR mode, no MU-RTS TF should be sent. After the exchange of
     * EML Operating Mode Notification frames, a number of packets are generated at the AP MLD
     * to prepare two A-MPDUs for each EMLSR client.
     *
     * EMLSR client with EMLSR mode to be enabled on all links (A is the EMLSR client, B is the
     * non-EMLSR client):
     *
     *  [link 0]                            | power save mode
     *  ────────────────────────────────────────────────────────
     *                                        ┌─────┬─────┐        ┌──────┬──────┐
     *                                        │QoS 8│QoS 9│        │QoS 10│QoS 11│
     *                                        │ to A│ to A│        │ to A │ to A │
     *                  ┌───┐     ┌───┐       ├─────┼─────┤        ├──────┼──────┤
     *           ┌───┐  │MU │     │EML│       │QoS 8│QoS 9│        │QoS 10│QoS 11│
     *  [link 1] │ACK│  │RTS│     │OM │       │ to B│ to B│        │ to B │ to B │
     *  ────┬───┬┴───┴──┴───┴┬───┬┴───┴┬───┬──┴─────┴─────┴┬──┬────┴──────┴──────┴┬──┬─────
     *      │EML│            │CTS│     │ACK│               │BA│                   │BA│
     *      │OM │            └───┘     └───┘               ├──┤                   ├──┤
     *      └───┘                                          │BA│                   │BA│
     *                                                     └──┘                   └──┘
     *
     *  [link 2]                            | power save mode
     *  ────────────────────────────────────────────────────────────────────────────
     *
     *
     * EMLSR client with EMLSR mode to be enabled on not all the links (A is the EMLSR client,
     * B is the non-EMLSR client):
     *                                           ┌─────┬─────┐
     *                                           │QoS 8│QoS 9│
     *                                           │ to A│ to A│
     *                                           ├─────┼─────┤
     *                                           │QoS 8│QoS 9│
     *  [link 0 - non EMLSR]                     │ to B│ to B│
     *  ─────────────────────────────────────────┴─────┴─────┴┬──┬─────────────
     *                                                        │BA│
     *                                                        ├──┤
     *                                                        │BA│
     *                                                        └──┘
     *                                        ┌──────┬──────┐
     *                                        │QoS 10│QoS 11│
     *                                        │ to A │ to A │
     *                  ┌───┐     ┌───┐       ├──────┼──────┤
     *           ┌───┐  │MU │     │EML│       │QoS 10│QoS 11│
     *  [link 1] │ACK│  │RTS│     │OM │       │ to B │ to B │
     *  ────┬───┬┴───┴──┴───┴┬───┬┴───┴┬───┬──┴──────┴──────┴┬──┬─────
     *      │EML│            │CTS│     │ACK│                 │BA│
     *      │OM │            └───┘     └───┘                 ├──┤
     *      └───┘                                            │BA│
     *                                                       └──┘
     *
     *  [link 2]                            | power save mode
     *  ────────────────────────────────────────────────────────────────────────────
     *
     */
 
    // for each EMLSR client, there should be a frame exchange with ICF and no data frame
    // (ICF protects the EML Notification response) if the EML Notification response is sent
    // while EMLSR mode is still enabled and two frame exchanges with data frames
    for (std::size_t i = 0; i < m_nEmlsrStations; i++)
    {
        // the default EMLSR Manager requests to send EML Notification frames on the link where
        // the main PHY is operating; if EMLSR mode is still enabled on this link when the AP MLD
        // sends the EML Notification response, the latter is protected by an ICF
        auto exchangeIt = frameExchanges.at(i).cbegin();
 
        auto linkIdOpt = m_staMacs[i]->GetLinkForPhy(m_mainPhyId);
        NS_TEST_ASSERT_MSG_EQ(linkIdOpt.has_value(),
                              true,
                              "Didn't find a link on which the main PHY is operating");
 
        if (IsTrigger(exchangeIt->front()->psduMap))
        {
            NS_TEST_EXPECT_MSG_EQ(+exchangeIt->front()->linkId,
                                  +linkIdOpt.value(),
                                  "ICF was not sent on the expected link");
            NS_TEST_EXPECT_MSG_EQ(exchangeIt->size(),
                                  1,
                                  "Expected no data frame in the first frame exchange sequence");
            frameExchanges.at(i).pop_front();
        }
 
        NS_TEST_EXPECT_MSG_GT_OR_EQ(frameExchanges.at(i).size(),
                                    2,
                                    "Expected at least 2 frame exchange sequences "
                                        << "involving EMLSR client " << i);
 
        auto firstExchangeIt = frameExchanges.at(i).cbegin();
        auto secondExchangeIt = std::next(firstExchangeIt);
 
        const auto firstAmpduTxEnd =
            firstExchangeIt->back()->startTx +
            WifiPhy::CalculateTxDuration(
                firstExchangeIt->back()->psduMap,
                firstExchangeIt->back()->txVector,
                m_staMacs[i]->GetWifiPhy(firstExchangeIt->back()->linkId)->GetPhyBand());
        const auto secondAmpduTxStart = secondExchangeIt->front()->startTx;
 
        NS_TEST_EXPECT_MSG_EQ(
            firstExchangeIt->front()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
            true,
            "Expected a QoS data frame in the first frame exchange sequence");
        NS_TEST_EXPECT_MSG_EQ(firstExchangeIt->size(),
                              1,
                              "Expected one frame only in the first frame exchange sequence");
 
        NS_TEST_EXPECT_MSG_EQ(
            secondExchangeIt->front()->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
            true,
            "Expected a QoS data frame in the second frame exchange sequence");
        NS_TEST_EXPECT_MSG_EQ(secondExchangeIt->size(),
                              1,
                              "Expected one frame only in the second frame exchange sequence");
 
        if (m_staMacs[i]->GetNLinks() == m_emlsrLinks.size())
        {
            // all links are EMLSR links: the two QoS data frames are sent one after another on
            // the link used for sending EML OMN
            NS_TEST_EXPECT_MSG_EQ(
                +firstExchangeIt->front()->linkId,
                +linkIdOpt.value(),
                "First frame exchange expected to occur on link used to send EML OMN");
 
            NS_TEST_EXPECT_MSG_EQ(
                +secondExchangeIt->front()->linkId,
                +linkIdOpt.value(),
                "Second frame exchange expected to occur on link used to send EML OMN");
 
            NS_TEST_EXPECT_MSG_LT(firstAmpduTxEnd,
                                  secondAmpduTxStart,
                                  "A-MPDUs are not sent one after another");
        }
        else
        {
            // the two QoS data frames are sent concurrently on distinct links
            NS_TEST_EXPECT_MSG_NE(+firstExchangeIt->front()->linkId,
                                  +secondExchangeIt->front()->linkId,
                                  "Frame exchanges expected to occur on distinct links");
 
            NS_TEST_EXPECT_MSG_GT(firstAmpduTxEnd,
                                  secondAmpduTxStart,
                                  "A-MPDUs are not sent concurrently");
        }
    }
}
 
void
EmlsrDlTxopTest::CheckPmModeAfterAssociation(const Mac48Address& address)
{
    std::optional<std::size_t> staId;
    for (std::size_t id = 0; id < m_nEmlsrStations + m_nNonEmlsrStations; id++)
    {
        if (m_staMacs.at(id)->GetLinkIdByAddress(address))
        {
            staId = id;
            break;
        }
    }
    NS_TEST_ASSERT_MSG_EQ(staId.has_value(), true, "Not an address of a non-AP MLD " << address);
 
    // check that all EMLSR links (but the link used for ML setup) of the EMLSR clients
    // are considered to be in power save mode by the AP MLD; all the other links have
    // transitioned to active mode instead
    for (uint8_t linkId = 0; linkId < m_apMac->GetNLinks(); linkId++)
    {
        bool psModeExpected =
            *staId < m_nEmlsrStations && linkId != m_mainPhyId && m_emlsrLinks.count(linkId) == 1;
        auto addr = m_staMacs.at(*staId)->GetAddress();
        auto psMode = m_apMac->GetWifiRemoteStationManager(linkId)->IsInPsMode(addr);
        NS_TEST_EXPECT_MSG_EQ(psMode,
                              psModeExpected,
                              "EMLSR link " << +linkId << " of EMLSR client " << *staId
                                            << " not in " << (psModeExpected ? "PS" : "active")
                                            << " mode");
        // check that AP is blocking transmission of QoS data frames on this link
        CheckBlockedLink(m_apMac,
                         addr,
                         linkId,
                         WifiQueueBlockedReason::POWER_SAVE_MODE,
                         psModeExpected,
                         "Checking PM mode after association on AP MLD for EMLSR client " +
                             std::to_string(*staId),
                         false);
    }
}
 
void
EmlsrDlTxopTest::CheckApEmlNotificationFrame(Ptr<const WifiMpdu> mpdu,
                                             const WifiTxVector& txVector,
                                             uint8_t linkId)
{
    // the AP is replying to a received EMLSR Notification frame
    auto pkt = mpdu->GetPacket()->Copy();
    const auto& hdr = mpdu->GetHeader();
    WifiActionHeader::Remove(pkt);
    MgtEmlOmn frame;
    pkt->RemoveHeader(frame);
 
    std::optional<std::size_t> staId;
    for (std::size_t id = 0; id < m_nEmlsrStations; id++)
    {
        if (m_staMacs.at(id)->GetFrameExchangeManager(linkId)->GetAddress() == hdr.GetAddr1())
        {
            staId = id;
            break;
        }
    }
    NS_TEST_ASSERT_MSG_EQ(staId.has_value(),
                          true,
                          "Not an address of an EMLSR client " << hdr.GetAddr1());
 
    // The EMLSR mode change occurs a Transition Timeout after the end of the PPDU carrying the Ack
    auto phy = m_apMac->GetWifiPhy(linkId);
    auto txDuration =
        WifiPhy::CalculateTxDuration(mpdu->GetSize() + 4, // A-MPDU Subframe header size
                                     txVector,
                                     phy->GetPhyBand());
    WifiTxVector ackTxVector =
        m_staMacs.at(*staId)->GetWifiRemoteStationManager(linkId)->GetAckTxVector(hdr.GetAddr2(),
                                                                                  txVector);
    auto ackDuration = WifiPhy::CalculateTxDuration(GetAckSize() + 4, // A-MPDU Subframe header
                                                    ackTxVector,
                                                    phy->GetPhyBand());
 
    Simulator::Schedule(txDuration + phy->GetSifs() + ackDuration, [=, this]() {
        if (frame.m_emlControl.emlsrMode == 1)
        {
            // EMLSR mode enabled. Check that all EMLSR links of the EMLSR clients are considered
            // to be in active mode by the AP MLD
            for (const auto linkId : m_emlsrLinks)
            {
                auto addr = m_staMacs.at(*staId)->GetAddress();
                auto psMode = m_apMac->GetWifiRemoteStationManager(linkId)->IsInPsMode(addr);
                NS_TEST_EXPECT_MSG_EQ(psMode,
                                      false,
                                      "EMLSR link " << +linkId << " of EMLSR client " << *staId
                                                    << " not in active mode");
                // check that AP is not blocking transmission of QoS data frames on this link
                CheckBlockedLink(
                    m_apMac,
                    addr,
                    linkId,
                    WifiQueueBlockedReason::POWER_SAVE_MODE,
                    false,
                    "Checking EMLSR links on AP MLD after EMLSR mode is enabled on EMLSR client " +
                        std::to_string(*staId),
                    false);
            }
        }
        else
        {
            // EMLSR mode disabled. Check that all EMLSR links (but the link used to send the
            // EML Notification frame) of the EMLSR clients are considered to be in power save
            // mode by the AP MLD; the other links are in active mode
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                bool psModeExpected = id != linkId && m_emlsrLinks.count(id) == 1;
                auto addr = m_staMacs.at(*staId)->GetAddress();
                auto psMode = m_apMac->GetWifiRemoteStationManager(id)->IsInPsMode(addr);
                NS_TEST_EXPECT_MSG_EQ(psMode,
                                      psModeExpected,
                                      "EMLSR link "
                                          << +id << " of EMLSR client " << *staId << " not in "
                                          << (psModeExpected ? "PS" : "active") << " mode");
                // check that AP is blocking transmission of QoS data frames on this link
                CheckBlockedLink(
                    m_apMac,
                    addr,
                    id,
                    WifiQueueBlockedReason::POWER_SAVE_MODE,
                    psModeExpected,
                    "Checking links on AP MLD after EMLSR mode is disabled on EMLSR client " +
                        std::to_string(*staId),
                    false);
            }
        }
    });
}
 
void
EmlsrDlTxopTest::CheckStaEmlNotificationFrame(Ptr<const WifiMpdu> mpdu,
                                              const WifiTxVector& txVector,
                                              uint8_t linkId)
{
    // an EMLSR client is sending an EMLSR Notification frame
    auto pkt = mpdu->GetPacket()->Copy();
    const auto& hdr = mpdu->GetHeader();
    WifiActionHeader::Remove(pkt);
    MgtEmlOmn frame;
    pkt->RemoveHeader(frame);
 
    std::optional<std::size_t> staId;
    for (std::size_t id = 0; id < m_nEmlsrStations; id++)
    {
        if (m_staMacs.at(id)->GetFrameExchangeManager(linkId)->GetAddress() == hdr.GetAddr2())
        {
            staId = id;
            break;
        }
    }
    NS_TEST_ASSERT_MSG_EQ(staId.has_value(),
                          true,
                          "Not an address of an EMLSR client " << hdr.GetAddr1());
 
    auto phy = m_staMacs.at(*staId)->GetWifiPhy(linkId);
    auto txDuration = WifiPhy::CalculateTxDuration(mpdu->GetSize(), txVector, phy->GetPhyBand());
    auto ackTxVector =
        m_apMac->GetWifiRemoteStationManager(linkId)->GetAckTxVector(hdr.GetAddr2(), txVector);
    auto ackDuration = WifiPhy::CalculateTxDuration(GetAckSize(), ackTxVector, phy->GetPhyBand());
    auto cfEndDuration = WifiPhy::CalculateTxDuration(
        Create<WifiPsdu>(Create<Packet>(), WifiMacHeader(WIFI_MAC_CTL_END)),
        m_staMacs.at(*staId)->GetWifiRemoteStationManager(linkId)->GetRtsTxVector(
            Mac48Address::GetBroadcast(),
            txVector.GetChannelWidth()),
        phy->GetPhyBand());
 
    if (frame.m_emlControl.emlsrMode != 0)
    {
        return;
    }
 
    // EMLSR mode disabled
    auto timeToCfEnd = txDuration + phy->GetSifs() + ackDuration + phy->GetSifs() + cfEndDuration;
 
    // before the end of the CF-End frame, this link only is not blocked on both the
    // EMLSR client and the AP MLD
    Simulator::Schedule(timeToCfEnd - MicroSeconds(1), [=, this]() {
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            CheckBlockedLink(m_staMacs.at(*staId),
                             m_apMac->GetAddress(),
                             id,
                             WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                             id != linkId && m_staMacs.at(*staId)->IsEmlsrLink(id),
                             "Checking links on EMLSR client " + std::to_string(*staId) +
                                 " before the end of CF-End frame");
            CheckBlockedLink(m_apMac,
                             m_staMacs.at(*staId)->GetAddress(),
                             id,
                             WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                             id != linkId && m_staMacs.at(*staId)->IsEmlsrLink(id),
                             "Checking links of EMLSR client " + std::to_string(*staId) +
                                 " on the AP MLD before the end of CF-End frame");
        }
    });
    // after the end of the CF-End frame, all links for the EMLSR client are blocked on the
    // AP MLD
    Simulator::Schedule(timeToCfEnd + MicroSeconds(1), [=, this]() {
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            if (m_staMacs.at(*staId)->IsEmlsrLink(id))
            {
                CheckBlockedLink(
                    m_apMac,
                    m_staMacs.at(*staId)->GetAddress(),
                    id && m_staMacs.at(*staId)->IsEmlsrLink(id),
                    WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                    true,
                    "Checking links of EMLSR client " + std::to_string(*staId) +
                        " are all blocked on the AP MLD right after the end of CF-End");
            }
        }
    });
    // before the end of the transition delay, all links for the EMLSR client are still
    // blocked on the AP MLD
    Simulator::Schedule(timeToCfEnd + m_transitionDelay.at(*staId) - MicroSeconds(1), [=, this]() {
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            if (m_staMacs.at(*staId)->IsEmlsrLink(id))
            {
                CheckBlockedLink(m_apMac,
                                 m_staMacs.at(*staId)->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                                 true,
                                 "Checking links of EMLSR client " + std::to_string(*staId) +
                                     " are all blocked on the AP MLD before the end of "
                                     "transition delay");
            }
        }
    });
    // immediately after the transition delay, all links for the EMLSR client are unblocked
    Simulator::Schedule(timeToCfEnd + m_transitionDelay.at(*staId) + MicroSeconds(1), [=, this]() {
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            if (m_staMacs.at(*staId)->IsEmlsrLink(id))
            {
                CheckBlockedLink(m_apMac,
                                 m_staMacs.at(*staId)->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                                 false,
                                 "Checking links of EMLSR client " + std::to_string(*staId) +
                                     " are all unblocked on the AP MLD after the transition delay");
            }
        }
    });
}
 
void
EmlsrDlTxopTest::CheckInitialControlFrame(Ptr<const WifiMpdu> mpdu,
                                          const WifiTxVector& txVector,
                                          uint8_t linkId)
{
    CtrlTriggerHeader trigger;
    mpdu->GetPacket()->PeekHeader(trigger);
    if (!trigger.IsMuRts())
    {
        return;
    }
 
    NS_TEST_EXPECT_MSG_EQ(m_emlsrEnabledTime.IsStrictlyPositive(),
                          true,
                          "Did not expect an ICF before enabling EMLSR mode");
 
    NS_TEST_EXPECT_MSG_LT(txVector.GetPreambleType(),
                          WIFI_PREAMBLE_HT_MF,
                          "Unexpected preamble type for the Initial Control frame");
    auto rate = txVector.GetMode().GetDataRate(txVector);
    NS_TEST_EXPECT_MSG_EQ((rate == 6e6 || rate == 12e6 || rate == 24e6),
                          true,
                          "Unexpected rate for the Initial Control frame: " << rate);
 
    bool found = false;
    Time maxPaddingDelay{};
 
    for (const auto& userInfo : trigger)
    {
        auto addr = m_apMac->GetMldOrLinkAddressByAid(userInfo.GetAid12());
        NS_TEST_ASSERT_MSG_EQ(addr.has_value(),
                              true,
                              "AID " << userInfo.GetAid12() << " not found");
 
        if (m_apMac->GetWifiRemoteStationManager(linkId)->GetEmlsrEnabled(*addr))
        {
            found = true;
 
            for (std::size_t i = 0; i < m_nEmlsrStations; i++)
            {
                if (m_staMacs.at(i)->GetAddress() == *addr)
                {
                    maxPaddingDelay = Max(maxPaddingDelay, m_paddingDelay.at(i));
                    break;
                }
            }
 
            // check that the AP has blocked transmission on all other EMLSR links
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                if (!m_apMac->GetWifiRemoteStationManager(id)->GetEmlsrEnabled(*addr))
                {
                    continue;
                }
 
                CheckBlockedLink(m_apMac,
                                 *addr,
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking that AP blocked transmissions on all other EMLSR "
                                 "links after sending ICF to client with AID=" +
                                     std::to_string(userInfo.GetAid12()),
                                 false);
            }
        }
    }
 
    NS_TEST_EXPECT_MSG_EQ(found, true, "Expected ICF to be addressed to at least an EMLSR client");
 
    auto txDuration = WifiPhy::CalculateTxDuration(mpdu->GetSize(),
                                                   txVector,
                                                   m_apMac->GetWifiPhy(linkId)->GetPhyBand());
 
    if (maxPaddingDelay.IsStrictlyPositive())
    {
        // compare the TX duration of this Trigger Frame to that of the Trigger Frame with no
        // padding added
        trigger.SetPaddingSize(0);
        auto pkt = Create<Packet>();
        pkt->AddHeader(trigger);
        auto txDurationWithout =
            WifiPhy::CalculateTxDuration(Create<WifiPsdu>(pkt, mpdu->GetHeader()),
                                         txVector,
                                         m_apMac->GetWifiPhy(linkId)->GetPhyBand());
 
        NS_TEST_EXPECT_MSG_EQ(txDuration,
                              txDurationWithout + maxPaddingDelay,
                              "Unexpected TX duration of the MU-RTS TF with padding "
                                  << maxPaddingDelay.As(Time::US));
    }
 
    // check that the EMLSR clients have blocked transmissions on other links, switched their main
    // PHY (if needed) and have put aux PHYs to sleep after receiving this ICF
    for (const auto& userInfo : trigger)
    {
        for (std::size_t i = 0; i < m_nEmlsrStations; i++)
        {
            if (m_staMacs[i]->GetAssociationId() != userInfo.GetAid12())
            {
                continue;
            }
 
            const auto mainPhyLinkId = m_staMacs[i]->GetLinkForPhy(m_mainPhyId);
 
            Simulator::Schedule(txDuration + NanoSeconds(5), [=, this]() {
                for (uint8_t id = 0; id < m_staMacs[i]->GetNLinks(); id++)
                {
                    // non-EMLSR links or links on which ICF is received are not blocked
                    CheckBlockedLink(m_staMacs[i],
                                     m_apMac->GetAddress(),
                                     id,
                                     WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                     id != linkId && m_staMacs[i]->IsEmlsrLink(id),
                                     "Checking EMLSR links on EMLSR client " + std::to_string(i) +
                                         " after receiving ICF");
                }
 
                if (mainPhyLinkId != linkId)
                {
                    CheckMainPhyTraceInfo(i, "DlTxopIcfReceivedByAuxPhy", mainPhyLinkId, linkId);
                }
 
                CheckAuxPhysSleepMode(m_staMacs[i], true);
            });
 
            break;
        }
    }
}
 
void
EmlsrDlTxopTest::CheckQosFrames(const WifiConstPsduMap& psduMap,
                                const WifiTxVector& txVector,
                                uint8_t linkId)
{
    if (m_nEmlsrStations != 2 || m_apMac->GetNLinks() != m_emlsrLinks.size() ||
        m_emlsrEnabledTime.IsZero() || Simulator::Now() < m_emlsrEnabledTime + m_fe2to3delay)
 
    {
        // we are interested in frames sent to test transition delay
        return;
    }
 
    std::size_t firstClientId = 0;
    std::size_t secondClientId = 1;
    auto addr = m_staMacs[secondClientId]->GetAddress();
    auto txDuration =
        WifiPhy::CalculateTxDuration(psduMap, txVector, m_apMac->GetWifiPhy(linkId)->GetPhyBand());
 
    m_countQoSframes++;
 
    switch (m_countQoSframes)
    {
    case 1:
        // generate another small packet addressed to the first EMLSR client only
        m_apMac->GetDevice()->GetNode()->AddApplication(
            GetApplication(DOWNLINK, firstClientId, 1, 40));
        // both EMLSR clients are about to receive a QoS data frame
        for (std::size_t clientId : {firstClientId, secondClientId})
        {
            Simulator::Schedule(txDuration, [=, this]() {
                for (uint8_t id = 0; id < m_staMacs[clientId]->GetNLinks(); id++)
                {
                    // link on which QoS data is received is not blocked
                    CheckBlockedLink(m_staMacs[clientId],
                                     m_apMac->GetAddress(),
                                     id,
                                     WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                     id != linkId,
                                     "Checking EMLSR links on EMLSR client " +
                                         std::to_string(clientId) +
                                         " after receiving the first QoS data frame");
                }
            });
        }
        break;
    case 2:
        // generate another small packet addressed to the second EMLSR client
        m_apMac->GetDevice()->GetNode()->AddApplication(
            GetApplication(DOWNLINK, secondClientId, 1, 40));
 
        // when the transmission of the second QoS data frame starts, both EMLSR clients are
        // still blocking all the links but the one used to receive the QoS data frame
        for (std::size_t clientId : {firstClientId, secondClientId})
        {
            for (uint8_t id = 0; id < m_staMacs[clientId]->GetNLinks(); id++)
            {
                // link on which QoS data is received is not blocked
                CheckBlockedLink(m_staMacs[clientId],
                                 m_apMac->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking EMLSR links on EMLSR client " +
                                     std::to_string(clientId) +
                                     " when starting the reception of the second QoS frame");
            }
        }
 
        // the EMLSR client that is not the recipient of the QoS frame being transmitted will
        // switch back to listening mode after a transition delay starting from the end of
        // the PPDU carrying this QoS data frame
 
        // immediately before the end of the PPDU, this link only is not blocked for the EMLSR
        // client on the AP MLD
        Simulator::Schedule(txDuration - NanoSeconds(1), [=, this]() {
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                CheckBlockedLink(m_apMac,
                                 addr,
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking that links of EMLSR client " +
                                     std::to_string(secondClientId) +
                                     " are blocked on the AP MLD before the end of the PPDU");
            }
        });
        // immediately before the end of the PPDU, all the links on the EMLSR client that is not
        // the recipient of the second QoS frame are unblocked (they are unblocked when the
        // PHY-RXSTART.indication is not received)
        Simulator::Schedule(txDuration - NanoSeconds(1), [=, this]() {
            for (uint8_t id = 0; id < m_staMacs[secondClientId]->GetNLinks(); id++)
            {
                CheckBlockedLink(m_staMacs[secondClientId],
                                 m_apMac->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 false,
                                 "Checking that links of EMLSR client " +
                                     std::to_string(secondClientId) +
                                     " are unblocked before the end of the second QoS frame");
            }
        });
        // immediately after the end of the PPDU, all links are blocked for the EMLSR client
        Simulator::Schedule(txDuration + NanoSeconds(1), [=, this]() {
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                CheckBlockedLink(m_apMac,
                                 addr,
                                 id,
                                 WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                                 true,
                                 "Checking links of EMLSR client " +
                                     std::to_string(secondClientId) +
                                     " are all blocked on the AP MLD after the end of the PPDU");
            }
        });
        // immediately before the transition delay, all links are still blocked for the EMLSR client
        Simulator::Schedule(
            txDuration + m_transitionDelay.at(secondClientId) - NanoSeconds(1),
            [=, this]() {
                for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
                {
                    CheckBlockedLink(
                        m_apMac,
                        addr,
                        id,
                        WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                        true,
                        "Checking links of EMLSR client " + std::to_string(secondClientId) +
                            " are all blocked on the AP MLD before the transition delay",
                        false);
                }
            });
 
        // 100 us before the transition delay expires, generate another small packet addressed
        // to a non-EMLSR client. The AP will start a TXOP to transmit this frame, while the
        // frame addressed to the EMLSR client is still queued because the transition delay has
        // not yet elapsed. The transition delay will expire while the AP is transmitting the
        // frame to the non-EMLSR client, so that the AP continues the TXOP to transmit the frame
        // to the EMLSR client and we can check that the AP performs PIFS recovery after missing
        // the BlockAck from the EMLSR client
        Simulator::Schedule(txDuration + m_transitionDelay.at(secondClientId) - MicroSeconds(100),
                            [=, this]() {
                                m_apMac->GetDevice()->GetNode()->AddApplication(
                                    GetApplication(DOWNLINK, m_nEmlsrStations, 1, 40));
                            });
 
        break;
    case 3:
        // this is the frame addressed to a non-EMLSR client, which is transmitted before the
        // frame addressed to the EMLSR client, because the links of the latter are still blocked
        // at the AP because the transition delay has not yet elapsed
        NS_TEST_EXPECT_MSG_EQ(
            psduMap.cbegin()->second->GetAddr1(),
            m_staMacs[m_nEmlsrStations]->GetFrameExchangeManager(linkId)->GetAddress(),
            "QoS frame not addressed to a non-EMLSR client");
 
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            CheckBlockedLink(m_apMac,
                             addr,
                             id,
                             WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                             true,
                             "Checking links of EMLSR client " + std::to_string(secondClientId) +
                                 " are all blocked on the AP MLD before the transition delay");
        }
        // Block transmissions to the EMLSR client on all the links but the one on which this
        // frame is sent, so that the AP will continue this TXOP to send the queued frame to the
        // EMLSR client once the transition delay elapses
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            if (id != linkId)
            {
                m_apMac->BlockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED, addr, {id});
            }
        }
        break;
    case 4:
        // the AP is continuing the TXOP, no need to block transmissions anymore
        for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
        {
            m_apMac->UnblockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED, addr, {id});
        }
        // at the end of the fourth QoS frame, this link only is not blocked on the EMLSR
        // client receiving the frame
        Simulator::Schedule(txDuration, [=, this]() {
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                CheckBlockedLink(m_staMacs[secondClientId],
                                 m_apMac->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking EMLSR links on EMLSR client " +
                                     std::to_string(secondClientId) +
                                     " after receiving the fourth QoS data frame");
            }
        });
        break;
    }
}
 
void
EmlsrDlTxopTest::CheckBlockAck(const WifiConstPsduMap& psduMap,
                               const WifiTxVector& txVector,
                               uint8_t phyId)
{
    if (m_nEmlsrStations != 2 || m_apMac->GetNLinks() != m_emlsrLinks.size() ||
        m_emlsrEnabledTime.IsZero() || Simulator::Now() < m_emlsrEnabledTime + m_fe2to3delay)
    {
        // we are interested in frames sent to test transition delay
        return;
    }
 
    if (++m_countBlockAck == 4)
    {
        // fourth BlockAck is sent by a non-EMLSR client
        return;
    }
 
    auto taddr = psduMap.cbegin()->second->GetAddr2();
    std::size_t clientId;
    if (m_staMacs[0]->GetLinkIdByAddress(taddr))
    {
        clientId = 0;
    }
    else
    {
        NS_TEST_ASSERT_MSG_EQ(m_staMacs[1]->GetLinkIdByAddress(taddr).has_value(),
                              true,
                              "Unexpected TA for BlockAck: " << taddr);
        clientId = 1;
    }
 
    // find the link on which the main PHY is operating
    auto currMainPhyLinkId = m_staMacs[clientId]->GetLinkForPhy(phyId);
    NS_TEST_ASSERT_MSG_EQ(
        currMainPhyLinkId.has_value(),
        true,
        "Didn't find the link on which the PHY sending the BlockAck is operating");
    auto linkId = *currMainPhyLinkId;
 
    // we need the MLD address to check the status of the container queues
    auto addr = m_apMac->GetWifiRemoteStationManager(linkId)->GetMldAddress(taddr);
    NS_TEST_ASSERT_MSG_EQ(addr.has_value(), true, "MLD address not found for " << taddr);
 
    auto apPhy = m_apMac->GetWifiPhy(linkId);
    auto txDuration = WifiPhy::CalculateTxDuration(psduMap, txVector, apPhy->GetPhyBand());
    auto cfEndTxDuration = WifiPhy::CalculateTxDuration(
        Create<WifiPsdu>(Create<Packet>(), WifiMacHeader(WIFI_MAC_CTL_END)),
        m_apMac->GetWifiRemoteStationManager(linkId)->GetRtsTxVector(Mac48Address::GetBroadcast(),
                                                                     txVector.GetChannelWidth()),
        apPhy->GetPhyBand());
 
    switch (m_countBlockAck)
    {
    case 5:
        // the PPDU carrying this BlockAck is corrupted, hence the AP MLD MAC receives the
        // PHY-RXSTART indication but it does not receive any frame from the PHY. Therefore,
        // at the end of the PPDU transmission, the AP MLD realizes that the EMLSR client has
        // not responded and makes an attempt at continuing the TXOP
 
        // at the end of the PPDU, this link only is not blocked on both the EMLSR client and
        // the AP MLD
        Simulator::Schedule(txDuration, [=, this]() {
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                CheckBlockedLink(m_staMacs[clientId],
                                 m_apMac->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking links on EMLSR client " + std::to_string(clientId) +
                                     " at the end of fourth BlockAck");
                CheckBlockedLink(m_apMac,
                                 *addr,
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking links of EMLSR client " + std::to_string(clientId) +
                                     " on the AP MLD at the end of fourth BlockAck");
            }
        });
        // a SIFS after the end of the PPDU, still this link only is not blocked on both the
        // EMLSR client and the AP MLD
        Simulator::Schedule(txDuration + apPhy->GetSifs(), [=, this]() {
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                CheckBlockedLink(m_staMacs[clientId],
                                 m_apMac->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking links on EMLSR client " + std::to_string(clientId) +
                                     " a SIFS after the end of fourth BlockAck");
                CheckBlockedLink(m_apMac,
                                 *addr,
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking links of EMLSR client " + std::to_string(clientId) +
                                     " a SIFS after the end of fourth BlockAck");
            }
        });
        // corrupt this BlockAck so that the AP MLD sends a BlockAckReq later on
        {
            auto uid = psduMap.cbegin()->second->GetPacket()->GetUid();
            m_errorModel->SetList({uid});
        }
        break;
    case 6:
        // at the end of the PPDU, this link only is not blocked on both the EMLSR client and
        // the AP MLD
        Simulator::Schedule(txDuration, [=, this]() {
            for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
            {
                CheckBlockedLink(m_staMacs[clientId],
                                 m_apMac->GetAddress(),
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking links on EMLSR client " + std::to_string(clientId) +
                                     " at the end of fifth BlockAck");
                CheckBlockedLink(m_apMac,
                                 *addr,
                                 id,
                                 WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                 id != linkId,
                                 "Checking links of EMLSR client " + std::to_string(clientId) +
                                     " on the AP MLD at the end of fifth BlockAck");
            }
        });
        // before the end of the CF-End frame, still this link only is not blocked on both the
        // EMLSR client and the AP MLD
        Simulator::Schedule(
            txDuration + apPhy->GetSifs() + cfEndTxDuration - MicroSeconds(1),
            [=, this]() {
                for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
                {
                    CheckBlockedLink(m_staMacs[clientId],
                                     m_apMac->GetAddress(),
                                     id,
                                     WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                     id != linkId,
                                     "Checking links on EMLSR client " + std::to_string(clientId) +
                                         " before the end of CF-End frame");
                    CheckBlockedLink(m_apMac,
                                     *addr,
                                     id,
                                     WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                     id != linkId,
                                     "Checking links of EMLSR client " + std::to_string(clientId) +
                                         " on the AP MLD before the end of CF-End frame");
                }
            });
        // after the end of the CF-End frame, all links for the EMLSR client are blocked on the
        // AP MLD
        Simulator::Schedule(
            txDuration + apPhy->GetSifs() + cfEndTxDuration + MicroSeconds(1),
            [=, this]() {
                for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
                {
                    CheckBlockedLink(
                        m_apMac,
                        *addr,
                        id,
                        WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                        true,
                        "Checking links of EMLSR client " + std::to_string(clientId) +
                            " are all blocked on the AP MLD right after the end of CF-End");
                }
            });
        // before the end of the transition delay, all links for the EMLSR client are still
        // blocked on the AP MLD
        Simulator::Schedule(
            txDuration + apPhy->GetSifs() + cfEndTxDuration + m_transitionDelay.at(clientId) -
                MicroSeconds(1),
            [=, this]() {
                for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
                {
                    CheckBlockedLink(
                        m_apMac,
                        *addr,
                        id,
                        WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                        true,
                        "Checking links of EMLSR client " + std::to_string(clientId) +
                            " are all blocked on the AP MLD before the end of transition delay");
                }
            });
        // immediately after the transition delay, all links for the EMLSR client are unblocked
        Simulator::Schedule(
            txDuration + apPhy->GetSifs() + cfEndTxDuration + m_transitionDelay.at(clientId) +
                MicroSeconds(1),
            [=, this]() {
                for (uint8_t id = 0; id < m_apMac->GetNLinks(); id++)
                {
                    CheckBlockedLink(
                        m_apMac,
                        *addr,
                        id,
                        WifiQueueBlockedReason::WAITING_EMLSR_TRANSITION_DELAY,
                        false,
                        "Checking links of EMLSR client " + std::to_string(clientId) +
                            " are all unblocked on the AP MLD after the transition delay");
                }
            });
        break;
    }
}
 
void
EmlsrDlTxopTest::DoRun()
{
    Simulator::Stop(m_duration);
    Simulator::Run();
 
    CheckResults();
 
    Simulator::Destroy();
}
 
EmlsrUlTxopTest::EmlsrUlTxopTest(const Params& params)
    : EmlsrOperationsTestBase("Check EML UL TXOP transmissions (genBackoffIfTxopWithoutTx=" +
                              std::to_string(params.genBackoffIfTxopWithoutTx)),
      m_emlsrLinks(params.linksToEnableEmlsrOn),
      m_channelWidth(params.channelWidth),
      m_auxPhyChannelWidth(params.auxPhyChannelWidth),
      m_mediumSyncDuration(params.mediumSyncDuration),
      m_msdMaxNTxops(params.msdMaxNTxops),
      m_emlsrEnabledTime(0),
      m_firstUlPktsGenTime(0),
      m_unblockMainPhyLinkDelay(MilliSeconds(20)),
      m_checkBackoffStarted(false),
      m_countQoSframes(0),
      m_countBlockAck(0),
      m_countRtsframes(0),
      m_genBackoffIfTxopWithoutTx(params.genBackoffIfTxopWithoutTx)
{
    m_nEmlsrStations = 1;
    m_nNonEmlsrStations = 0;
    m_linksToEnableEmlsrOn = params.linksToEnableEmlsrOn;
    m_mainPhyId = 1;
 
    // when aux PHYs do not switch link, the main PHY switches back to its previous link after
    // a TXOP, hence the transition delay must exceed the channel switch delay (default: 250us)
    m_transitionDelay = {MicroSeconds(256)};
    m_establishBaDl = {0};
    m_establishBaUl = {0};
    m_putAuxPhyToSleep = params.putAuxPhyToSleep;
    m_duration = Seconds(1);
 
    NS_ABORT_MSG_IF(params.linksToEnableEmlsrOn.size() < 2,
                    "This test requires at least two links to be configured as EMLSR links");
    for (uint8_t id = 0; id < 3; id++)
    {
        if (!m_emlsrLinks.contains(id))
        {
            // non-EMLSR link found
            m_nonEmlsrLink = id;
            break;
        }
    }
}
 
void
EmlsrUlTxopTest::DoSetup()
{
    Config::SetDefault("ns3::EmlsrManager::AuxPhyChannelWidth",
                       UintegerValue(m_auxPhyChannelWidth));
    Config::SetDefault("ns3::DefaultEmlsrManager::SwitchAuxPhy", BooleanValue(false));
    // switch main PHY back delay should be at least a PIFS for the switch to occur
    Config::SetDefault("ns3::EhtConfiguration::MediumSyncDuration",
                       TimeValue(m_mediumSyncDuration));
    Config::SetDefault("ns3::EhtConfiguration::MsdMaxNTxops", UintegerValue(m_msdMaxNTxops));
    Config::SetDefault("ns3::ChannelAccessManager::GenerateBackoffIfTxopWithoutTx",
                       BooleanValue(m_genBackoffIfTxopWithoutTx));
    // Channel switch delay should be less than RTS TX time + SIFS + CTS TX time, otherwise
    // UL TXOPs cannot be initiated by aux PHYs
    Config::SetDefault("ns3::WifiPhy::ChannelSwitchDelay", TimeValue(MicroSeconds(75)));
    Config::SetDefault("ns3::WifiPhy::NotifyMacHdrRxEnd", BooleanValue(true));
 
    EmlsrOperationsTestBase::DoSetup();
 
    m_staMacs[0]->GetQosTxop(AC_BE)->TraceConnectWithoutContext(
        "BackoffTrace",
        MakeCallback(&EmlsrUlTxopTest::BackoffGenerated, this));
 
    uint8_t linkId = 0;
    // configure channels of the given width
    for (auto band : {WIFI_PHY_BAND_2_4GHZ, WIFI_PHY_BAND_5GHZ, WIFI_PHY_BAND_6GHZ})
    {
        MHz_u bw{20};
        uint8_t number = band == WIFI_PHY_BAND_5GHZ ? 36 : 1;
 
        auto width =
            std::min(m_channelWidth, band == WIFI_PHY_BAND_2_4GHZ ? MHz_u{40} : MHz_u{160});
        while (bw < width)
        {
            bw *= 2;
            number += Count20MHzSubchannels(bw);
        }
 
        for (auto mac : std::initializer_list<Ptr<WifiMac>>{m_apMac, m_staMacs[0]})
        {
            mac->GetWifiPhy(linkId)->SetOperatingChannel(
                WifiPhy::ChannelTuple{number, width, band, 0});
        }
        linkId++;
    }
 
    // install post reception error model on the AP affiliated with the AP MLD and operating on
    // the same link as the main PHY of the EMLSR client
    m_errorModel = CreateObject<ListErrorModel>();
    m_apMac->GetWifiPhy(m_mainPhyId)->SetPostReceptionErrorModel(m_errorModel);
}
 
void
EmlsrUlTxopTest::BackoffGenerated(uint32_t backoff, uint8_t linkId)
{
    NS_LOG_INFO("Backoff value " << backoff << " generated by EMLSR client on link " << +linkId
                                 << "\n");
    if (linkId != m_mainPhyId)
    {
        return; // we are only interested in backoff on main PHY link
    }
 
    if (m_backoffEndTime)
    {
        if (m_checkBackoffStarted)
        {
            // another backoff value while checkBackoffStarted is true is generated only if
            // GenerateBackoffIfTxopWithoutTx is true
            NS_TEST_EXPECT_MSG_EQ(
                m_genBackoffIfTxopWithoutTx,
                true,
                "Another backoff value should not be generated while the main PHY link is blocked");
 
            NS_TEST_EXPECT_MSG_EQ(m_backoffEndTime.value(),
                                  Simulator::Now(),
                                  "Backoff generated at unexpected time");
        }
        else
        {
            // we are done checking the backoff
            m_backoffEndTime.reset();
        }
    }
 
    if (m_checkBackoffStarted)
    {
        if (!m_backoffEndTime.has_value())
        {
            // this is the first time we set m_backoffEndTime, which is done right after receiving
            // a BlockAck, thus we have to wait an AIFS before invoking backoff
            m_backoffEndTime = Simulator::Now() +
                               m_staMacs[0]->GetChannelAccessManager(linkId)->GetSifs() +
                               m_staMacs[0]->GetQosTxop(AC_BE)->GetAifsn(linkId) *
                                   m_staMacs[0]->GetChannelAccessManager(linkId)->GetSlot();
        }
        else
        {
            // we get here when the backoff expired but no transmission occurred, thus we have
            // generated a new backoff value and we will start decrementing the counter in a slot
            m_backoffEndTime =
                Simulator::Now() + m_staMacs[0]->GetChannelAccessManager(linkId)->GetSlot();
        }
        // add the time corresponding to the generated number of slots
        m_backoffEndTime.value() +=
            backoff * m_staMacs[0]->GetChannelAccessManager(linkId)->GetSlot();
        NS_LOG_DEBUG("Expected backoff end time = " << m_backoffEndTime->As(Time::US) << "\n");
    }
}
 
void
EmlsrUlTxopTest::Transmit(Ptr<WifiMac> mac,
                          uint8_t phyId,
                          WifiConstPsduMap psduMap,
                          WifiTxVector txVector,
                          double txPowerW)
{
    EmlsrOperationsTestBase::Transmit(mac, phyId, psduMap, txVector, txPowerW);
    auto linkId = m_txPsdus.back().linkId;
 
    auto psdu = psduMap.begin()->second;
    auto nodeId = mac->GetDevice()->GetNode()->GetId();
 
    switch (psdu->GetHeader(0).GetType())
    {
    case WIFI_MAC_MGT_ASSOCIATION_REQUEST:
        NS_ASSERT_MSG(nodeId > 0, "APs do not send AssocReq frames");
        NS_TEST_EXPECT_MSG_EQ(+linkId, +m_mainPhyId, "AssocReq not sent by the main PHY");
        break;
 
    case WIFI_MAC_CTL_RTS:
        CheckRtsFrames(*psdu->begin(), txVector, linkId);
        break;
 
    case WIFI_MAC_CTL_CTS:
        CheckCtsFrames(*psdu->begin(), txVector, linkId);
        break;
 
    case WIFI_MAC_QOSDATA:
        CheckQosFrames(psduMap, txVector, linkId);
        break;
 
    case WIFI_MAC_CTL_BACKRESP:
        CheckBlockAck(psduMap, txVector, linkId);
        break;
 
    default:;
    }
}
 
void
EmlsrUlTxopTest::StartTraffic()
{
    // initially, we prevent transmissions on aux PHY links
    auto auxPhyLinks = m_staMacs[0]->GetSetupLinkIds();
    auxPhyLinks.erase(m_mainPhyId);
    if (m_nonEmlsrLink)
    {
        auxPhyLinks.erase(*m_nonEmlsrLink);
    }
    m_staMacs[0]->BlockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                        m_apMac->GetAddress(),
                                        auxPhyLinks);
 
    // Association, Block Ack agreement establishment and enabling EMLSR mode have been done.
    // After 50ms, schedule:
    // - block of transmissions on the link where the main PHY is operating and on the non-EMLSR
    //   link (if any)
    // - the generation of two UL packets
    // - after m_unblockMainPhyLinkDelay, unblock transmissions on the link where the main PHY
    //   is operating, so that the first data frame is transmitted on that link
    Simulator::Schedule(MilliSeconds(50), [&]() {
        std::set<uint8_t> linkIds;
        linkIds.insert(*m_staMacs[0]->GetLinkForPhy(m_mainPhyId));
        if (m_nonEmlsrLink)
        {
            linkIds.insert(*m_nonEmlsrLink);
        }
        m_staMacs[0]->BlockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                            m_apMac->GetAddress(),
                                            linkIds);
 
        NS_LOG_INFO("Enqueuing two packets at the EMLSR client\n");
        m_staMacs[0]->GetDevice()->GetNode()->AddApplication(GetApplication(UPLINK, 0, 2, 1000));
        m_firstUlPktsGenTime = Simulator::Now();
 
        Simulator::Schedule(m_unblockMainPhyLinkDelay, [&]() {
            m_staMacs[0]->UnblockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                                  m_apMac->GetAddress(),
                                                  {*m_staMacs[0]->GetLinkForPhy(m_mainPhyId)});
        });
    });
}
 
void
EmlsrUlTxopTest::CheckQosFrames(const WifiConstPsduMap& psduMap,
                                const WifiTxVector& txVector,
                                uint8_t linkId)
{
    m_countQoSframes++;
 
    auto txDuration =
        WifiPhy::CalculateTxDuration(psduMap, txVector, m_apMac->GetWifiPhy(linkId)->GetPhyBand());
 
    switch (m_countQoSframes)
    {
    case 1:
    case 2:
        // do nothing, these are the QoS data frames sent to establish BA agreements in DL and UL
        // direction
        break;
    case 3:
        // first UL data frame (transmitted by the main PHY)
        if (m_nonEmlsrLink)
        {
            // generate data packets for another UL data frame, which will be sent on the
            // non-EMLSR link
            NS_LOG_INFO("Enqueuing two packets at the EMLSR client\n");
            m_staMacs[0]->GetDevice()->GetNode()->AddApplication(
                GetApplication(UPLINK, 0, 2, 1000));
 
            // unblock transmissions on the non-EMLSR link once the two packets are queued
            Simulator::ScheduleNow([=, this]() {
                m_staMacs[0]->UnblockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                                      m_apMac->GetAddress(),
                                                      {*m_nonEmlsrLink});
            });
        }
 
        // check that other EMLSR links are now blocked on the EMLSR client and on the AP MLD
        // after this QoS data frame is received
        Simulator::ScheduleNow([=, this]() {
            auto phyHdrTxTime = WifiPhy::CalculatePhyPreambleAndHeaderDuration(txVector);
            auto macHdrSize = (*psduMap.at(SU_STA_ID)->begin())->GetHeader().GetSerializedSize() +
                              4 /* A-MPDU subframe header size */;
            auto macHdrTxTime =
                DataRate(txVector.GetMode().GetDataRate(txVector)).CalculateBytesTxTime(macHdrSize);
 
            for (auto id : m_staMacs[0]->GetLinkIds())
            {
                CheckBlockedLink(
                    m_staMacs[0],
                    m_apMac->GetAddress(),
                    id,
                    WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                    id != m_staMacs[0]->GetLinkForPhy(m_mainPhyId) && m_staMacs[0]->IsEmlsrLink(id),
                    "Checking EMLSR links on EMLSR client while sending the first data frame",
                    false);
 
                Simulator::Schedule(phyHdrTxTime + macHdrTxTime + MicroSeconds(1), [=, this]() {
                    CheckBlockedLink(m_apMac,
                                     m_staMacs[0]->GetAddress(),
                                     id,
                                     WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                                     id != m_staMacs[0]->GetLinkForPhy(m_mainPhyId) &&
                                         m_staMacs[0]->IsEmlsrLink(id),
                                     "Checking EMLSR links on AP MLD right after receiving the MAC "
                                     "header of the first data frame");
                });
 
                Simulator::Schedule(txDuration + MAX_PROPAGATION_DELAY, [=, this]() {
                    CheckBlockedLink(
                        m_apMac,
                        m_staMacs[0]->GetAddress(),
                        id,
                        WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                        id != m_staMacs[0]->GetLinkForPhy(m_mainPhyId) &&
                            m_staMacs[0]->IsEmlsrLink(id),
                        "Checking EMLSR links on AP MLD after sending the first data frame");
                });
            }
        });
 
        if (m_nonEmlsrLink)
        {
            break;
        }
        m_countQoSframes++; // if all EMLSR links, next case is already executed now
        [[fallthrough]];
    case 4:
        // check that other EMLSR links are now blocked on the EMLSR client and on the AP MLD
        // after this QoS data frame is received
        Simulator::ScheduleNow([=, this]() {
            // make aux PHYs capable of transmitting frames
            auto auxPhyLinks = m_staMacs[0]->GetSetupLinkIds();
            auxPhyLinks.erase(m_mainPhyId);
            if (m_nonEmlsrLink)
            {
                auxPhyLinks.erase(*m_nonEmlsrLink);
            }
            m_staMacs[0]->UnblockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                                  m_apMac->GetAddress(),
                                                  auxPhyLinks);
 
            // block transmissions on the link where the main PHY is operating
            m_staMacs[0]->BlockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                                m_apMac->GetAddress(),
                                                {*m_staMacs[0]->GetLinkForPhy(m_mainPhyId)});
 
            // generate data packets for another UL data frame, which will be sent on a link on
            // which an aux PHY is operating
            NS_LOG_INFO("Enqueuing two packets at the EMLSR client\n");
            m_staMacs[0]->GetDevice()->GetNode()->AddApplication(
                GetApplication(UPLINK, 0, 2, 1000));
        });
        break;
    case 5:
        // check that other EMLSR links are now blocked on both the EMLSR client and the AP MLD
        Simulator::ScheduleNow([=, this]() {
            for (auto id : m_staMacs[0]->GetLinkIds())
            {
                CheckBlockedLink(
                    m_staMacs[0],
                    m_apMac->GetAddress(),
                    id,
                    WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                    id != linkId && m_staMacs[0]->IsEmlsrLink(id),
                    "Checking EMLSR links on EMLSR client while sending the second data frame",
                    false);
 
                CheckBlockedLink(
                    m_apMac,
                    m_staMacs[0]->GetAddress(),
                    id,
                    WifiQueueBlockedReason::USING_OTHER_EMLSR_LINK,
                    id != linkId && m_staMacs[0]->IsEmlsrLink(id),
                    "Checking EMLSR links on AP MLD while sending the second data frame",
                    false);
            }
 
            // unblock transmission on the link where the main PHY is operating
            m_staMacs[0]->GetMacQueueScheduler()->UnblockQueues(
                WifiQueueBlockedReason::TID_NOT_MAPPED,
                AC_BE,
                {WIFI_QOSDATA_QUEUE},
                m_apMac->GetAddress(),
                m_staMacs[0]->GetAddress(),
                {0},
                {m_mainPhyId});
        });
        break;
    }
}
 
void
EmlsrUlTxopTest::CheckBlockAck(const WifiConstPsduMap& psduMap,
                               const WifiTxVector& txVector,
                               uint8_t linkId)
{
    m_countBlockAck++;
 
    auto auxPhyLinks = m_staMacs[0]->GetSetupLinkIds();
    auxPhyLinks.erase(m_mainPhyId);
    if (m_nonEmlsrLink)
    {
        auxPhyLinks.erase(*m_nonEmlsrLink);
    }
 
    auto txDuration =
        WifiPhy::CalculateTxDuration(psduMap, txVector, m_apMac->GetWifiPhy(linkId)->GetPhyBand());
 
    // in this test, BlockAck frames terminates TXOP, thus aux PHYs shall be in sleep mode before
    // the end of BlockAck reception and awake right afterwards
    if (linkId != m_nonEmlsrLink)
    {
        Simulator::Schedule(txDuration - TimeStep(1),
                            &EmlsrUlTxopTest::CheckAuxPhysSleepMode,
                            this,
                            m_staMacs[0],
                            true);
        Simulator::Schedule(txDuration + TimeStep(1),
                            &EmlsrUlTxopTest::CheckAuxPhysSleepMode,
                            this,
                            m_staMacs[0],
                            false);
 
        // if the TXOP has been carried out on a link other than the preferred link, the main PHY
        // switches back to the preferred link when the TXOP ends
        if (m_staMacs[0]->GetLinkForPhy(m_mainPhyId) != linkId)
        {
            Simulator::Schedule(txDuration + TimeStep(1), [=, this]() {
                CheckMainPhyTraceInfo(0, "TxopEnded", linkId, m_mainPhyId);
            });
        }
    }
 
    switch (m_countBlockAck)
    {
    case 1:
    case 2:
        // do nothing, these are BlockAcks in response to the QoS data frames sent to establish
        // BA agreements in DL and UL direction
        break;
    case 3:
        if (linkId == m_nonEmlsrLink)
        {
            // this BlockAck has been sent on the non-EMLSR link, ignore it
            break;
        }
        m_checkBackoffStarted = true;
        if (!m_nonEmlsrLink)
        {
            m_countBlockAck++; // if all EMLSR links, next case is already executed now
        }
        [[fallthrough]];
    case 4:
        if (m_nonEmlsrLink && m_countBlockAck == 4)
        {
            // block transmissions on the non-EMLSR link
            Simulator::Schedule(txDuration + NanoSeconds(1), [=, this]() {
                m_staMacs[0]->BlockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                                    m_apMac->GetAddress(),
                                                    {*m_nonEmlsrLink});
            });
        }
        if (linkId == m_nonEmlsrLink)
        {
            // this BlockAck has been sent on the non-EMLSR link, ignore it
            break;
        }
        m_checkBackoffStarted = true;
        break;
    case 5:
        // Block Ack in response to the second data frame sent by the EMLSR client on EMLSR links.
        // Check that MediumSyncDelay timer starts running on the link where the main PHY switches
        // to when the channel switch is completed
        Simulator::Schedule(
            txDuration + m_staMacs[0]->GetDevice()->GetPhy(m_mainPhyId)->GetChannelSwitchDelay() +
                NanoSeconds(1),
            [=, this]() {
                auto elapsed =
                    m_staMacs[0]->GetEmlsrManager()->GetElapsedMediumSyncDelayTimer(m_mainPhyId);
                NS_TEST_EXPECT_MSG_EQ(
                    elapsed.has_value(),
                    true,
                    "MediumSyncDelay timer not running on link where main PHY is operating");
                m_lastMsdExpiryTime = Simulator::Now() +
                                      m_staMacs[0]->GetEmlsrManager()->GetMediumSyncDuration() -
                                      *elapsed;
            });
 
        // Check that the number of backoff slots is not changed since the beginning of the TXOP
        Simulator::Schedule(txDuration, [=, this]() {
            m_checkBackoffStarted = false;
            NS_TEST_ASSERT_MSG_EQ(m_backoffEndTime.has_value(),
                                  true,
                                  "Backoff end time should have been calculated");
            // when this BlockAck is received, the TXOP ends and the main PHY link is unblocked,
            // which causes a new backoff timer to be generated if the backoff timer is not
            // already running
            *m_backoffEndTime = Max(*m_backoffEndTime, Simulator::Now());
        });
 
        // make aux PHYs not capable of transmitting frames
        m_staMacs[0]->BlockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                            m_apMac->GetAddress(),
                                            auxPhyLinks);
 
        // generate data packets for another UL data frame, which will be sent on the link where
        // the main PHY is operating
        NS_LOG_INFO("Enqueuing two packets at the EMLSR client\n");
        m_staMacs[0]->GetDevice()->GetNode()->AddApplication(GetApplication(UPLINK, 0, 2, 1000));
        break;
    case 6: {
        // block transmission on the main PHY link and on the non-EMLSR link (if any), so that
        // the next QoS frames are sent on a link where an aux PHY is operating
        std::set<uint8_t> linkIds{m_mainPhyId};
        if (m_nonEmlsrLink)
        {
            linkIds.insert(*m_nonEmlsrLink);
        }
        m_staMacs[0]->GetMacQueueScheduler()->BlockQueues(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                                          AC_BE,
                                                          {WIFI_QOSDATA_QUEUE},
                                                          m_apMac->GetAddress(),
                                                          m_staMacs[0]->GetAddress(),
                                                          {0},
                                                          linkIds);
    }
        // make sure aux PHYs are capable of transmitting frames
        m_staMacs[0]->UnblockUnicastTxOnLinks(WifiQueueBlockedReason::TID_NOT_MAPPED,
                                              m_apMac->GetAddress(),
                                              auxPhyLinks);
 
        // generate data packets for another UL data frame
        NS_LOG_INFO("Enqueuing two packets at the EMLSR client\n");
        m_staMacs[0]->GetDevice()->GetNode()->AddApplication(GetApplication(UPLINK, 0, 2, 1000));
        break;
    }
}
 
void
EmlsrUlTxopTest::CheckRtsFrames(Ptr<const WifiMpdu> mpdu,
                                const WifiTxVector& txVector,
                                uint8_t linkId)
{
    if (m_firstUlPktsGenTime.IsZero())
    {
        // this function only considers RTS frames sent after the first QoS data frame
        return;
    }
 
    if (linkId != m_mainPhyId)
    {
        if (m_countRtsframes > 0 && !m_corruptCts.has_value())
        {
            // we get here for the frame exchange in which the CTS response must be corrupted.
            // Install post reception error model on the STA affiliated with the EMLSR client that
            // is transmitting this RTS frame
            m_errorModel = CreateObject<ListErrorModel>();
            m_staMacs[0]->GetWifiPhy(linkId)->SetPostReceptionErrorModel(m_errorModel);
            m_corruptCts = true;
        }
 
        return;
    }
 
    // we get here for RTS frames sent by the main PHY while the MediumSyncDelay timer is running
    m_countRtsframes++;
 
    NS_TEST_EXPECT_MSG_EQ(txVector.GetChannelWidth(),
                          m_staMacs[0]->GetDevice()->GetPhy(m_mainPhyId)->GetChannelWidth(),
                          "RTS sent by main PHY on an unexpected width");
 
    // corrupt reception at AP MLD
    NS_LOG_INFO("CORRUPTED");
    m_errorModel->SetList({mpdu->GetPacket()->GetUid()});
}
 
void
EmlsrUlTxopTest::CheckCtsFrames(Ptr<const WifiMpdu> mpdu,
                                const WifiTxVector& txVector,
                                uint8_t linkId)
{
    if (m_firstUlPktsGenTime.IsZero())
    {
        // this function only considers CTS frames sent after the first QoS data frame
        return;
    }
 
    auto txDuration = WifiPhy::CalculateTxDuration(mpdu->GetSize(),
                                                   txVector,
                                                   m_apMac->GetWifiPhy(linkId)->GetPhyBand());
    const auto doCorruptCts = m_corruptCts.has_value() && *m_corruptCts;
 
    if (linkId != m_staMacs[0]->GetLinkForPhy(m_mainPhyId) && linkId != m_nonEmlsrLink &&
        mpdu->GetHeader().GetAddr1() == m_staMacs[0]->GetFrameExchangeManager(linkId)->GetAddress())
    {
        // this is a CTS sent to an aux PHY starting an UL TXOP. Given that aux PHYs do not
        // switch channel, they are put in sleep mode when the main PHY starts operating on their
        // link, which coincides with the end of CTS plus two propagation delays
        const auto auxPhy = m_staMacs[0]->GetWifiPhy(linkId);
        const auto mainPhy = m_staMacs[0]->GetDevice()->GetPhy(m_mainPhyId);
        Simulator::Schedule(txDuration, [=, this]() {
            // when CTS ends, the main PHY is still switching and the aux PHY is not yet sleeping
            NS_TEST_EXPECT_MSG_EQ(mainPhy->IsStateSwitching(),
                                  true,
                                  "Expecting the main PHY to be switching link");
            NS_TEST_EXPECT_MSG_EQ(auxPhy->IsStateSleep(),
                                  false,
                                  "Aux PHY on link " << +linkId << " already in sleep mode");
            // when CTS is sent, the main PHY may have already started switching, thus we may not
            // know which link the main PHY is moving from
            CheckMainPhyTraceInfo(0, "UlTxopRtsSentByAuxPhy", std::nullopt, linkId, false);
        });
        Simulator::Schedule(txDuration + (2 * MAX_PROPAGATION_DELAY) + TimeStep(1), [=, this]() {
            // aux PHYs are put to sleep if and only if CTS is not corrupted
            // (causing the end of the TXOP)
            CheckAuxPhysSleepMode(m_staMacs[0], !doCorruptCts);
            // if CTS is corrupted, TXOP ends and the main PHY switches back to the preferred
            // link, unless channel access is obtained on another link before the main PHY
            // completes the switch to the link on which CTS timeout occurred
            if (auto ehtFem = StaticCast<EhtFrameExchangeManager>(
                    m_staMacs[0]->GetFrameExchangeManager(linkId));
                doCorruptCts && !ehtFem->UsingOtherEmlsrLink())
            {
                // check the traced elapsed time since CTS timeout before calling
                // CheckMainPhyTraceInfo
                if (const auto traceInfoIt = m_traceInfo.find(0);
                    traceInfoIt != m_traceInfo.cend() &&
                    traceInfoIt->second->GetName() == "CtsAfterRtsTimeout")
                {
                    const auto& traceInfo =
                        static_cast<const EmlsrCtsAfterRtsTimeoutTrace&>(*traceInfoIt->second);
                    NS_TEST_EXPECT_MSG_GT(traceInfo.sinceCtsTimeout,
                                          Time{0},
                                          "Expected non-zero remaining time because main PHY "
                                          "was switching when CTS timeout occurred");
                }
 
                CheckMainPhyTraceInfo(0, "CtsAfterRtsTimeout", linkId, m_mainPhyId);
            }
        });
    }
 
    if (doCorruptCts)
    {
        // corrupt reception at EMLSR client
        NS_LOG_INFO("CORRUPTED");
        m_errorModel->SetList({mpdu->GetPacket()->GetUid()});
        m_corruptCts = false;
    }
}
 
void
EmlsrUlTxopTest::DoRun()
{
    Simulator::Stop(m_duration);
    Simulator::Run();
 
    CheckResults();
 
    Simulator::Destroy();
}
 
void
EmlsrUlTxopTest::CheckResults()
{
    if (m_msdMaxNTxops > 0)
    {
        NS_TEST_EXPECT_MSG_LT_OR_EQ(
            m_countRtsframes,
            +m_msdMaxNTxops,
            "Unexpected number of RTS frames sent while the MediumSyncDelay timer is running");
    }
 
    auto psduIt = m_txPsdus.cbegin();
 
    // lambda to jump to the next QoS data frame or MU-RTS Trigger Frame or RTS transmitted
    // to/by an EMLSR client
    auto jumpToQosDataOrMuRts = [&]() {
        while (psduIt != m_txPsdus.cend() &&
               !psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData() &&
               !psduIt->psduMap.cbegin()->second->GetHeader(0).IsRts())
        {
            auto psdu = psduIt->psduMap.cbegin()->second;
            if (psdu->GetHeader(0).IsTrigger())
            {
                CtrlTriggerHeader trigger;
                psdu->GetPayload(0)->PeekHeader(trigger);
                if (trigger.IsMuRts())
                {
                    break;
                }
            }
            psduIt++;
        }
    };
 
    /**
     * EMLSR client with EMLSR mode enabled on all links (main PHY ID = 1).
     *
     *  main PHY│
     *  blocked,│
     *  aux PHYs││main PHY blocked│
     *  cannot  │
     *  transmit│
     *          │                    ┌───┐         ┌──┐
     *  [link 0]                     │CTS│         │BA│
     *  ────────────────────────┬───┬┴───┴┬───┬───┬┴──┴─────────────────────────────────────────
     *                          │RTS│     │QoS│QoS│
     *                          └───┘     │ 6 │ 7 │
     *                                    └───┴───┘
     *                             gen backoff      gen backoff if     MediumSyncDelay
     *                    ┌──┐    (also many times)  not running       timer expired ┌──┐
     *  [link 1]          │BA│  │   if allowed        │                   │          │BA│
     *  ─────────┬───┬───┬┴──┴───────────────────────────┬───┬─────┬───┬────┬───┬───┬┴──┴───────
     *           │QoS│QoS│                               │RTS│ ... │RTS│    │QoS│QoS│
     *           │ 4 │ 5 │                               └───┘     └───┘    │ 8 │ 9 │
     *           └───┴───┘                                                  └───┴───┘
     *
     *  [link 2]
     *  ───────────────────────────────────────────────────────────────────────────
     *
     *
     *
     * EMLSR client with EMLSR mode enabled on links 0 and 1 (main PHY ID = 1).
     *
     * main PHY │
     *   and    │
     * non-EMLSR│
     *   link   │
     *  blocked,│
     *  aux PHYs││main PHY blocked│
     *  cannot  │
     *  transmit│
     *          │                    ┌───┐         ┌──┐
     *  [link 0]                     │CTS│         │BA│
     *  ────────────────────────┬───┬┴───┴┬───┬───┬┴──┴─────────────────────────────────────────
     *                          │RTS│     │QoS│QoS│
     *                          └───┘     │ 8 │ 9 │
     *                                    └───┴───┘
     *                             gen backoff      gen backoff if     MediumSyncDelay
     *                    ┌──┐    (also many times)  not running       timer expired ┌──┐
     *  [link 1]          │BA│  │   if allowed        │                   │          │BA│
     *  ─────────┬───┬───┬┴──┴───────────────────────────┬───┬─────┬───┬────┬───┬───┬┴──┴───────
     *           │QoS│QoS│                               │RTS│ ... │RTS│    │QoS│QoS│
     *           │ 4 │ 5 │                               └───┘     └───┘    │ 10│ 11│
     *           └───┴───┘                                                  └───┴───┘
     *                     ┌──┐
     *  [link 2]           │BA│
     *  ──────────┬───┬───┬┴──┴────────────────────────────────────────────────────────────
     *            │QoS│QoS│
     *            │ 6 │ 7 │
     *            └───┴───┘
     *
     * For both scenarios, after the last frame exchange on the main PHY link, we have the
     * following frame exchanges on an EMLSR link where an aux PHY is operating on.
     *
     *
     *  [ link ]   ┌───┐         ┌───┐         ┌──┐
     *  [0 or 2]   │CTS│         │CTS│         │BA│
     *  ──────┬───┬┴───X────┬───┬┴───┴┬───┬───┬┴──┴─────────────────────────────────────────
     *        │RTS│         │RTS│     │QoS│QoS│
     *        └───┘         └───┘     │ X │ Y │
     *                                └───┴───┘
     * For all EMLSR links scenario, X=10, Y=11
     * For the scenario with a non-EMLSR link, X=12, Y=13
     */
 
    // jump to the first (non-Beacon) frame transmitted after establishing BA agreements and
    // enabling EMLSR mode
    while (psduIt != m_txPsdus.cend() &&
           (psduIt->startTx < m_firstUlPktsGenTime ||
            psduIt->psduMap.cbegin()->second->GetHeader(0).IsBeacon()))
    {
        ++psduIt;
    }
 
    // the first QoS data frame is transmitted by the main PHY without RTS protection as soon
    // as transmissions on the link where the main PHY is operating are unblocked (at this
    // moment, aux PHYs cannot transmit)
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "First QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                          true,
                          "First QoS data frame should be transmitted without protection");
    NS_TEST_EXPECT_MSG_EQ(+psduIt->phyId,
                          +m_mainPhyId,
                          "First QoS data frame should be transmitted by the main PHY");
    NS_TEST_EXPECT_MSG_GT_OR_EQ(psduIt->startTx,
                                m_firstUlPktsGenTime + m_unblockMainPhyLinkDelay,
                                "First QoS data frame sent too early");
 
    auto prevPsduIt = psduIt++;
    jumpToQosDataOrMuRts();
 
    if (m_nonEmlsrLink)
    {
        // an additional data frame is sent concurrently on the non-EMLSR link
        NS_TEST_ASSERT_MSG_EQ(
            (psduIt != m_txPsdus.cend()),
            true,
            "Expected another QoS data frame sent concurrently with the first frame");
        NS_TEST_EXPECT_MSG_EQ(
            psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
            true,
            "First data frame on non-EMLSR link should be transmitted without protection");
        NS_TEST_EXPECT_MSG_EQ(+psduIt->linkId,
                              +m_nonEmlsrLink.value(),
                              "First data frame expected to be transmitted on the non-EMLSR link");
        const auto txDuration =
            WifiPhy::CalculateTxDuration(prevPsduIt->psduMap,
                                         prevPsduIt->txVector,
                                         m_staMacs[0]->GetWifiPhy(prevPsduIt->phyId)->GetPhyBand());
        NS_TEST_EXPECT_MSG_LT(psduIt->startTx,
                              prevPsduIt->startTx + txDuration,
                              "First data frame on the non-EMLSR link not sent concurrently");
        psduIt++;
        jumpToQosDataOrMuRts();
    }
 
    // the second QoS data frame is transmitted by the main PHY after that the aux PHY has
    // obtained a TXOP and sent an RTS
    // RTS
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "RTS before second QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsRts(),
                          true,
                          "Second QoS data frame should be transmitted with protection");
    NS_TEST_EXPECT_MSG_NE(
        +psduIt->phyId,
        +m_mainPhyId,
        "RTS before second QoS data frame should not be transmitted by the main PHY");
    NS_TEST_EXPECT_MSG_EQ(psduIt->txVector.GetChannelWidth(),
                          m_auxPhyChannelWidth,
                          "RTS before second data frame transmitted on an unexpected width");
    psduIt++;
    // CTS
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "CTS before second QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsCts(),
                          true,
                          "CTS before second QoS data frame has not been transmitted");
    psduIt++;
    // QoS Data
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "Second QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                          true,
                          "Second QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(+psduIt->phyId,
                          +m_mainPhyId,
                          "Second QoS data frame should be transmitted by the main PHY");
    NS_TEST_EXPECT_MSG_EQ(psduIt->txVector.GetChannelWidth(),
                          m_auxPhyChannelWidth,
                          "Second data frame not transmitted on the same width as RTS");
 
    bool moreQosDataFound = false;
 
    while (++psduIt != m_txPsdus.cend())
    {
        jumpToQosDataOrMuRts();
        if (psduIt != m_txPsdus.cend() &&
            psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData())
        {
            moreQosDataFound = true;
 
            NS_TEST_EXPECT_MSG_EQ(+psduIt->phyId,
                                  +m_mainPhyId,
                                  "Third QoS data frame should be transmitted by the main PHY");
            NS_TEST_EXPECT_MSG_EQ(psduIt->txVector.GetChannelWidth(),
                                  m_staMacs[0]->GetDevice()->GetPhy(m_mainPhyId)->GetChannelWidth(),
                                  "Expecting TX width of third data frame to equal the channel "
                                  "width used by the main PHY");
            NS_TEST_EXPECT_MSG_GT_OR_EQ(
                psduIt->startTx,
                m_lastMsdExpiryTime,
                "Third QoS data frame sent before MediumSyncDelay timer expired");
 
            break;
        }
    }
 
    NS_TEST_EXPECT_MSG_EQ(moreQosDataFound,
                          true,
                          "Third QoS data frame transmitted by the main PHY not found");
 
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()), true, "Expected more frames");
    ++psduIt;
    jumpToQosDataOrMuRts();
 
    // the first attempt at transmitting the fourth QoS data frame fails because CTS is corrupted
    // RTS
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "RTS before fourth QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsRts(),
                          true,
                          "Fourth QoS data frame should be transmitted with protection");
    NS_TEST_EXPECT_MSG_NE(
        +psduIt->phyId,
        +m_mainPhyId,
        "RTS before fourth QoS data frame should not be transmitted by the main PHY");
    NS_TEST_EXPECT_MSG_EQ(psduIt->txVector.GetChannelWidth(),
                          m_auxPhyChannelWidth,
                          "RTS before fourth data frame transmitted on an unexpected width");
    psduIt++;
    // CTS
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "CTS before fourth QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsCts(),
                          true,
                          "CTS before fourth QoS data frame has not been transmitted");
    psduIt++;
    jumpToQosDataOrMuRts();
 
    // the fourth QoS data frame is transmitted by an aux PHY after that the aux PHY has
    // obtained a TXOP and sent an RTS
    // RTS
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "RTS before fourth QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsRts(),
                          true,
                          "Fourth QoS data frame should be transmitted with protection");
    NS_TEST_EXPECT_MSG_NE(
        +psduIt->phyId,
        +m_mainPhyId,
        "RTS before fourth QoS data frame should not be transmitted by the main PHY");
    NS_TEST_EXPECT_MSG_EQ(psduIt->txVector.GetChannelWidth(),
                          m_auxPhyChannelWidth,
                          "RTS before fourth data frame transmitted on an unexpected width");
    psduIt++;
    // CTS
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "CTS before fourth QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsCts(),
                          true,
                          "CTS before fourth QoS data frame has not been transmitted");
    psduIt++;
    // QoS Data
    NS_TEST_ASSERT_MSG_EQ((psduIt != m_txPsdus.cend()),
                          true,
                          "Fourth QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(psduIt->psduMap.cbegin()->second->GetHeader(0).IsQosData(),
                          true,
                          "Fourth QoS data frame has not been transmitted");
    NS_TEST_EXPECT_MSG_EQ(+psduIt->phyId,
                          +m_mainPhyId,
                          "Fourth QoS data frame should be transmitted by the main PHY");
    NS_TEST_EXPECT_MSG_EQ(psduIt->txVector.GetChannelWidth(),
                          m_auxPhyChannelWidth,
                          "Fourth data frame not transmitted on the same width as RTS");
}
 
EmlsrUlOfdmaTest::EmlsrUlOfdmaTest(bool enableBsrp)
    : EmlsrOperationsTestBase("Check UL OFDMA operations with an EMLSR client"),
      m_enableBsrp(enableBsrp),
      m_txPsdusPos(0),
      m_startAccessReq(0)
{
    m_linksToEnableEmlsrOn = {0, 1, 2};
    m_nEmlsrStations = 1;
    m_nNonEmlsrStations = 1;
    m_establishBaDl = {};
    m_establishBaUl = {0};
    m_mainPhyId = 1;
    m_duration = Seconds(1.0);
}
 
void
EmlsrUlOfdmaTest::DoSetup()
{
    Config::SetDefault("ns3::WifiPhy::ChannelSwitchDelay", TimeValue(m_transitionDelay.at(0)));
 
    EmlsrOperationsTestBase::DoSetup();
 
    m_apMac->GetQosTxop(AC_BE)->SetTxopLimits(
        {MicroSeconds(3200), MicroSeconds(3200), MicroSeconds(3200)});
 
    auto muScheduler = CreateObjectWithAttributes<RrMultiUserScheduler>("EnableUlOfdma",
                                                                        BooleanValue(true),
                                                                        "EnableBsrp",
                                                                        BooleanValue(m_enableBsrp));
    m_apMac->AggregateObject(muScheduler);
}
 
void
EmlsrUlOfdmaTest::Transmit(Ptr<WifiMac> mac,
                           uint8_t phyId,
                           WifiConstPsduMap psduMap,
                           WifiTxVector txVector,
                           double txPowerW)
{
    EmlsrOperationsTestBase::Transmit(mac, phyId, psduMap, txVector, txPowerW);
    auto linkId = m_txPsdus.back().linkId;
 
    auto psdu = psduMap.begin()->second;
 
    switch (psdu->GetHeader(0).GetType())
    {
    case WIFI_MAC_CTL_TRIGGER:
        if (m_txPsdusPos == 0 && !m_startAccessReq.IsZero() && Simulator::Now() >= m_startAccessReq)
        {
            // this is the first Trigger Frame sent after the AP requested channel access
            // through the Multi-user scheduler and it is an ICF for the EMLSR client
            m_txPsdusPos = m_txPsdus.size() - 1;
            auto txDuration = WifiPhy::CalculateTxDuration(psduMap,
                                                           txVector,
                                                           mac->GetWifiPhy(linkId)->GetPhyBand());
            NS_LOG_INFO("This is the first Trigger Frame\n");
            // once the Trigger Frame is received by the EMLSR client, make the client application
            // on the EMLSR client generate two packets. These packets will be sent via UL OFDMA
            // because the EMLSR client has blocked transmissions on other links when receiving
            // this Trigger Frame, hence it will not try to get access on other links via EDCA
            Simulator::Schedule(
                txDuration + MicroSeconds(1), // to account for propagation delay
                [=, this]() {
                    for (const auto id : m_staMacs[0]->GetLinkIds())
                    {
                        auto ehtFem = StaticCast<EhtFrameExchangeManager>(
                            m_staMacs[0]->GetFrameExchangeManager(id));
                        NS_TEST_EXPECT_MSG_EQ(
                            ehtFem->UsingOtherEmlsrLink(),
                            (id != linkId),
                            "Link " << +id << " was" << (id == linkId ? " not" : "")
                                    << " expected to be blocked on EMLSR client at time "
                                    << Simulator::Now().As(Time::NS));
                    }
                    NS_LOG_INFO("Generate two packets\n");
                    m_staMacs[0]->GetDevice()->GetNode()->AddApplication(
                        GetApplication(UPLINK, 0, 2, 100));
                });
        }
        break;
 
    case WIFI_MAC_CTL_BACKRESP:
        if (!m_startAccessReq.IsZero() && Simulator::Now() >= m_startAccessReq)
        {
            CtrlBAckResponseHeader blockAck;
            psdu->GetPayload(0)->PeekHeader(blockAck);
            if (blockAck.IsMultiSta())
            {
                auto txDuration =
                    WifiPhy::CalculateTxDuration(psduMap,
                                                 txVector,
                                                 mac->GetWifiPhy(linkId)->GetPhyBand());
                Simulator::Stop(txDuration + MicroSeconds(1));
            }
        }
        break;
 
    default:;
    }
 
    if (psdu->GetHeader(0).IsCfEnd())
    {
        // we do not check CF-End frames
        m_txPsdus.pop_back();
    }
}
 
void
EmlsrUlOfdmaTest::DoRun()
{
    Simulator::Stop(m_duration);
    Simulator::Run();
 
    CheckResults();
 
    Simulator::Destroy();
}
 
void
EmlsrUlOfdmaTest::StartTraffic()
{
    auto muScheduler = m_apMac->GetObject<MultiUserScheduler>();
    NS_TEST_ASSERT_MSG_NE(muScheduler, nullptr, "No MU scheduler installed on AP MLD");
 
    NS_LOG_INFO("Setting Access Request interval");
 
    const auto interval = MilliSeconds(50);
    muScheduler->SetAccessReqInterval(interval);
    m_startAccessReq = Simulator::Now() + interval;
}
 
void
EmlsrUlOfdmaTest::CheckResults()
{
    /**
     * Sending BSRP TF disabled.
     *
     * The figure assumes that link 0 is used to send the first Trigger Frame after that the
     * AP MLD requests channel access through the Multi-user scheduler. The first Trigger Frame
     * is MU-RTS because EMLSR client needs an ICF; the other Trigger Frames are Basic TFs and
     * do not solicit the EMLSR client.
     *             ┌─────┐     ┌─────┐           ┌──────┐
     *             │ MU  │     │Basic│           │Multi-│
     *  [link 0]   │ RTS │     │  TF │           │STA BA│
     *  ───────────┴─────┴┬───┬┴─────┴┬────────┬─┴──────┴───────────────
     *                    │CTS│       │QoS Null│
     *                    ├───┤       ├────────┤
     *                    │CTS│       │QoS Data│
     *                    └───┘       └────────┘
     *
     *               ┌─────┐
     *               │Basic│
     *  [link 1]     │  TF │
     *  ─────────────┴─────┴┬────┬──────────────────────────────────────
     *                      │QoS │
     *                      │Null│
     *                      └────┘
     *
     *               ┌─────┐
     *               │Basic│
     *  [link 2]     │  TF │
     *  ─────────────┴─────┴┬────┬──────────────────────────────────────
     *                      │QoS │
     *                      │Null│
     *                      └────┘
     *
     * Sending BSRP TF enabled.
     *
     * The figure assumes that link 0 is used to send the first Trigger Frame after that the
     * AP MLD requests channel access through the Multi-user scheduler. The first Trigger Frames
     * are all BSRP Trigger Frames, but only the first one solicits the EMLSR client, too.
     *             ┌─────┐          ┌─────┐           ┌──────┐
     *             │BSRP │          │Basic│           │Multi-│
     *  [link 0]   │  TF │          │  TF │           │STA BA│
     *  ───────────┴─────┴┬────────┬┴─────┴┬────────┬─┴──────┴──────────
     *                    │QoS Null│       │QoS Data│
     *                    ├────────┤       └────────┘
     *                    │QoS Null│
     *                    └────────┘
     *
     *               ┌─────┐
     *               │BSRP │
     *  [link 1]     │  TF │
     *  ─────────────┴─────┴┬────┬──────────────────────────────────────
     *                      │QoS │
     *                      │Null│
     *                      └────┘
     *
     *               ┌─────┐
     *               │BSRP │
     *  [link 2]     │  TF │
     *  ─────────────┴─────┴┬────┬──────────────────────────────────────
     *                      │QoS │
     *                      │Null│
     *                      └────┘
     */
 
    NS_TEST_ASSERT_MSG_GT(m_txPsdusPos, 0, "First Trigger Frame not detected");
 
    // Check the Trigger Frames (one per link) after requesting channel access
    auto index = m_txPsdusPos;
    const auto firstLinkId = m_txPsdus[m_txPsdusPos].linkId;
    for (; index < m_txPsdusPos + 3; ++index)
    {
        NS_TEST_ASSERT_MSG_EQ(m_txPsdus[index].psduMap.cbegin()->second->GetHeader(0).IsTrigger(),
                              true,
                              "Expected a Trigger Frame");
        CtrlTriggerHeader trigger;
        m_txPsdus[index].psduMap.cbegin()->second->GetPayload(0)->PeekHeader(trigger);
 
        TriggerFrameType triggerType =
            m_enableBsrp ? TriggerFrameType::BSRP_TRIGGER
                         : (index == m_txPsdusPos ? TriggerFrameType::MU_RTS_TRIGGER
                                                  : TriggerFrameType::BASIC_TRIGGER);
        NS_TEST_EXPECT_MSG_EQ(+static_cast<uint8_t>(trigger.GetType()),
                              +static_cast<uint8_t>(triggerType),
                              "Unexpected Trigger Frame type on link " << +m_txPsdus[index].linkId);
 
        // only the first TF solicits the EMLSR client and the non-AP MLD
        NS_TEST_EXPECT_MSG_EQ(
            trigger.GetNUserInfoFields(),
            (index == m_txPsdusPos ? 2 : 1),
            "Unexpected number of User Info fields for Trigger Frame, index=" << index);
    }
 
    auto startIndex = index;
    std::size_t ctsCount = 0;
    std::size_t qosNullCount = 0;
    // Check responses to Trigger Frames
    for (; index < startIndex + 4; ++index)
    {
        const auto& hdr = m_txPsdus[index].psduMap.cbegin()->second->GetHeader(0);
 
        if (hdr.IsCts())
        {
            ++ctsCount;
            continue;
        }
 
        if (hdr.IsQosData() && !hdr.HasData())
        {
            ++qosNullCount;
            // if BSRP is enabled, the QoS Null frame sent by the EMLSR client in response to the
            // first BSRP TF reports a non-null buffer status
            if (m_enableBsrp &&
                hdr.GetAddr2() == m_staMacs[0]->GetFrameExchangeManager(firstLinkId)->GetAddress())
            {
                NS_TEST_EXPECT_MSG_GT(+hdr.GetQosQueueSize(), 0, "Unexpected buffer size");
            }
            else
            {
                NS_TEST_EXPECT_MSG_EQ(+hdr.GetQosQueueSize(), 0, "Unexpected buffer size");
            }
            continue;
        }
    }
    NS_TEST_EXPECT_MSG_EQ(ctsCount, (m_enableBsrp ? 0 : 2), "Unexpected number of CTS frames");
    NS_TEST_EXPECT_MSG_EQ(qosNullCount,
                          (m_enableBsrp ? 4 : 2),
                          "Unexpected number of QoS Null frames");
 
    // we expect only one Basic Trigger Frame (sent on the same link as the first Trigger Frame),
    // because the buffer status reported on the other links by the non-EMLSR client is zero
    NS_TEST_ASSERT_MSG_EQ(m_txPsdus[index].psduMap.cbegin()->second->GetHeader(0).IsTrigger(),
                          true,
                          "Expected a Trigger Frame");
    NS_TEST_EXPECT_MSG_EQ(+m_txPsdus[index].linkId,
                          +firstLinkId,
                          "Unexpected link ID for Basic TF");
    CtrlTriggerHeader trigger;
    m_txPsdus[index].psduMap.cbegin()->second->GetPayload(0)->PeekHeader(trigger);
 
    NS_TEST_EXPECT_MSG_EQ(+static_cast<uint8_t>(trigger.GetType()),
                          +static_cast<uint8_t>(TriggerFrameType::BASIC_TRIGGER),
                          "Unexpected Trigger Frame type");
 
    // when BSRP TF is enabled, the non-EMLSR client has already communicated a buffer status of
    // zero, so it is not solicited by the AP through the Basic Trigger Frame. Otherwise, it is
    // solicited because buffer status was not known when the BSRP TF was prepared (before sending
    // MU-RTS)
    NS_TEST_EXPECT_MSG_EQ(trigger.GetNUserInfoFields(),
                          (m_enableBsrp ? 1 : 2),
                          "Unexpected number of User Info fields for Basic Trigger Frame");
 
    // Response(s) to the Basic Trigger Frame
    startIndex = ++index;
    for (; index < startIndex + (m_enableBsrp ? 1 : 2); ++index)
    {
        const auto& hdr = m_txPsdus[index].psduMap.cbegin()->second->GetHeader(0);
 
        NS_TEST_EXPECT_MSG_EQ(hdr.IsQosData(), true, "Expected a QoS frame");
 
        // EMLSR client sends a QoS Data frame, non-EMLSR client sends a QoS Null frame
        NS_TEST_EXPECT_MSG_EQ(
            hdr.HasData(),
            (hdr.GetAddr2() == m_staMacs[0]->GetFrameExchangeManager(firstLinkId)->GetAddress()),
            "Unexpected type of QoS data frame");
 
        if (hdr.HasData())
        {
            NS_TEST_EXPECT_MSG_EQ(m_txPsdus[index].txVector.IsUlMu(),
                                  true,
                                  "QoS Data frame should be sent in a TB PPDU");
        }
    }
 
    // Finally, the AP MLD sends a Multi-STA BlockAck
    NS_TEST_EXPECT_MSG_EQ(m_txPsdus[index].psduMap.cbegin()->second->GetHeader(0).IsBlockAck(),
                          true,
                          "Expected a BlockAck frame");
    CtrlBAckResponseHeader blockAck;
    m_txPsdus[index].psduMap.cbegin()->second->GetPayload(0)->PeekHeader(blockAck);
    NS_TEST_EXPECT_MSG_EQ(blockAck.IsMultiSta(), true, "Expected a Multi-STA BlockAck");
}
 
WifiEmlsrBasicExchangesTestSuite::WifiEmlsrBasicExchangesTestSuite()
    : TestSuite("wifi-emlsr-basic-exchanges", Type::UNIT)
{
    for (const auto& emlsrLinks :
         {std::set<uint8_t>{0, 1, 2}, std::set<uint8_t>{1, 2}, std::set<uint8_t>{0, 1}})
    {
        AddTestCase(new EmlsrDlTxopTest({1,
                                         0,
                                         emlsrLinks,
                                         {MicroSeconds(32)},
                                         {MicroSeconds(32)},
                                         MicroSeconds(512),
                                         true /* putAuxPhyToSleep */}),
                    TestCase::Duration::QUICK);
        AddTestCase(new EmlsrDlTxopTest({1,
                                         1,
                                         emlsrLinks,
                                         {MicroSeconds(64)},
                                         {MicroSeconds(64)},
                                         MicroSeconds(512),
                                         false /* putAuxPhyToSleep */}),
                    TestCase::Duration::QUICK);
        AddTestCase(new EmlsrDlTxopTest({2,
                                         2,
                                         emlsrLinks,
                                         {MicroSeconds(128), MicroSeconds(256)},
                                         {MicroSeconds(128), MicroSeconds(256)},
                                         MicroSeconds(512),
                                         true /* putAuxPhyToSleep */}),
                    TestCase::Duration::QUICK);
    }
 
    for (auto genBackoffIfTxopWithoutTx : {true, false})
    {
        AddTestCase(new EmlsrUlTxopTest({{0, 1, 2},
                                         MHz_u{40},
                                         MHz_u{20},
                                         MicroSeconds(5504),
                                         3,
                                         genBackoffIfTxopWithoutTx,
                                         true, /* putAuxPhyToSleep */
                                         false /* switchMainPhyBackDelayTimeout */}),
                    TestCase::Duration::QUICK);
        AddTestCase(new EmlsrUlTxopTest({{0, 1},
                                         MHz_u{40},
                                         MHz_u{20},
                                         MicroSeconds(5504),
                                         1,
                                         genBackoffIfTxopWithoutTx,
                                         false, /* putAuxPhyToSleep */
                                         true /* switchMainPhyBackDelayTimeout */}),
                    TestCase::Duration::QUICK);
    }
 
    AddTestCase(new EmlsrUlOfdmaTest(false), TestCase::Duration::QUICK);
    AddTestCase(new EmlsrUlOfdmaTest(true), TestCase::Duration::QUICK);
}
 
static WifiEmlsrBasicExchangesTestSuite g_wifiEmlsrBasicExchangesTestSuite; ///< the test suite