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wifi: Use aux PHY CCA (if possible) also when nSlotsAlert > 0

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This commit is contained in:
Stefano Avallone
2024-10-04 15:39:18 +02:00
parent 4516f1347e
commit 860059d597
2 changed files with 63 additions and 16 deletions
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2
examples/wireless/examples-to-run.py
View File

@@ -210,7 +210,7 @@ cpp_examples = [
"True",
),
(
"wifi-eht-network --simulationTime=0.2s --frequency=2.4 --frequency2=5 --guardInterval=1600 --udp=0 --downlink=0 --useRts=0 --mpduBufferSize=512 --emlsrLinks=0,1 --emlsrPaddingDelay=0 --emlsrTransitionDelay=0 --channelSwitchDelay=1ns --emlsrMgrTypeId=ns3::AdvancedEmlsrManager --emlsrAuxSwitch=False --emlsrAuxTxCapable=False --minExpectedThroughput=5 --maxExpectedThroughput=40 --RngRun=2",
"wifi-eht-network --simulationTime=0.2s --frequency=2.4 --frequency2=5 --guardInterval=1600 --udp=0 --downlink=0 --useRts=0 --mpduBufferSize=512 --emlsrLinks=0,1 --emlsrPaddingDelay=0 --emlsrTransitionDelay=0 --channelSwitchDelay=1ns --emlsrMgrTypeId=ns3::AdvancedEmlsrManager --emlsrAuxSwitch=False --emlsrAuxTxCapable=False --minExpectedThroughput=5 --maxExpectedThroughput=40 --RngRun=7",
"True",
"True",
),

77
src/wifi/model/eht/advanced-emlsr-manager.cc
View File

@@ -597,6 +597,24 @@ AdvancedEmlsrManager::RequestMainPhyToSwitch(uint8_t linkId, AcIndex aci, const
return false;
}
// delay until the earliest time the main PHY can access medium on the aux PHY link
auto minDelay = mainPhy->GetChannelSwitchDelay();
if (!m_useAuxPhyCca && (GetChannelForAuxPhy(linkId).GetTotalWidth() <
GetChannelForMainPhy(linkId).GetTotalWidth()))
{
// cannot use aux PHY CCA
minDelay += GetStaMac()->GetWifiPhy(linkId)->GetPifs();
}
minDelay = std::max(delay, minDelay);
if (const auto elapsed = GetElapsedMediumSyncDelayTimer(linkId);
elapsed && MediumSyncDelayNTxopsExceeded(linkId) &&
(GetMediumSyncDuration() - *elapsed > minDelay))
{
NS_LOG_DEBUG("No more TXOP attempts allowed on aux PHY link and MSD timer still running");
return false;
}
// DoGetDelayUntilAccessRequest has already checked if the main PHY is receiving an ICF
if (const auto state = mainPhy->GetState()->GetState();
state != WifiPhyState::IDLE && state != WifiPhyState::CCA_BUSY && state != WifiPhyState::RX)
@@ -609,7 +627,8 @@ AdvancedEmlsrManager::RequestMainPhyToSwitch(uint8_t linkId, AcIndex aci, const
// quickly, i.e., if ALL the ACs with queued frames (that can be transmitted on the link on
// which the main PHY is currently operating) and with priority higher than or equal to that of
// the AC for which Aux PHY gained TXOP have their backoff counter greater than the maximum
// between the expected delay in gaining channel access and the channel switch delay plus PIFS
// between the expected delay in gaining channel access and the channel switch delay (plus PIFS
// if we cannot use aux PHY CCA)
auto requestSwitch = false;
const auto now = Simulator::Now();
@@ -626,10 +645,7 @@ AdvancedEmlsrManager::RequestMainPhyToSwitch(uint8_t linkId, AcIndex aci, const
NS_LOG_DEBUG("Backoff end for " << acIndex
<< " on preferred link: " << backoffEnd.As(Time::US));
if (const auto minDelay = std::max(delay,
mainPhy->GetChannelSwitchDelay() +
GetStaMac()->GetWifiPhy(linkId)->GetPifs());
backoffEnd <= now + minDelay && edca->HasFramesToTransmit(*mainPhyLinkId))
if ((backoffEnd <= now + minDelay) && edca->HasFramesToTransmit(*mainPhyLinkId))
{
requestSwitch = false;
break;
@@ -814,11 +830,36 @@ AdvancedEmlsrManager::SwitchMainPhyIfTxopToBeGainedByAuxPhy(uint8_t linkId,
}
// switch main PHY
// use aux PHY CCA (if allowed) if the backoff has already counted down to zero on the aux PHY
// link when the main PHY completes the switch
const auto edca = GetStaMac()->GetQosTxop(aci);
const auto cam = GetStaMac()->GetChannelAccessManager(linkId);
const auto auxPhy = GetStaMac()->GetWifiPhy(linkId);
const auto switchDelay = mainPhy->GetChannelSwitchDelay();
const auto now = Simulator::Now();
const auto auxPhyCcaCanBeUsed =
m_useAuxPhyCca || (GetChannelForAuxPhy(linkId).GetTotalWidth() >=
GetChannelForMainPhy(linkId).GetTotalWidth());
const auto backoffEndBeforeSwitch = (cam->GetBackoffEndFor(edca) - now) <= switchDelay;
if (auxPhyCcaCanBeUsed && backoffEndBeforeSwitch)
{
NS_LOG_DEBUG("Schedule CCA check at the end of main PHY switch");
m_ccaLastPifs = Simulator::Schedule(switchDelay, [=, this]() {
// check NAV and CCA only if the backoff actually counted down to zero already
if (cam->GetBackoffEndFor(edca) <= Simulator::Now())
{
CheckNavAndCcaLastPifs(auxPhy, linkId, edca);
}
});
}
Time remNav{0};
if (const auto mainPhyLinkId = GetStaMac()->GetLinkForPhy(mainPhy))
{
auto mainPhyNavEnd = GetStaMac()->GetChannelAccessManager(*mainPhyLinkId)->GetNavEnd();
remNav = Max(remNav, mainPhyNavEnd - Simulator::Now());
remNav = Max(remNav, mainPhyNavEnd - now);
}
SwitchMainPhy(linkId,
@@ -828,15 +869,20 @@ AdvancedEmlsrManager::SwitchMainPhyIfTxopToBeGainedByAuxPhy(uint8_t linkId,
EmlsrUlTxopAuxPhyNotTxCapableTrace(aci, delay, remNav));
// check expected channel access delay when switch is completed
Simulator::Schedule(mainPhy->GetChannelSwitchDelay(), [=, this]() {
const auto edca = GetStaMac()->GetQosTxop(aci);
Simulator::Schedule(switchDelay, [=, this]() {
const auto accessDelay = cam->GetBackoffEndFor(edca) - Simulator::Now();
if (auxPhyCcaCanBeUsed && backoffEndBeforeSwitch && accessDelay.IsNegative())
{
// backoff already counted down to zero and we used aux PHY CCA
return;
}
const auto pifs = GetStaMac()->GetWifiPhy(linkId)->GetPifs();
// if the remaining backoff time is shorter than PIFS when the main PHY completes the
// switch, we need to schedule a CCA check a PIFS after the end of the main PHY switch
if (const auto accessDelay =
GetStaMac()->GetChannelAccessManager(linkId)->GetBackoffEndFor(edca) -
Simulator::Now();
accessDelay <= pifs)
if (accessDelay <= pifs)
{
// use main PHY CCA in the last PIFS interval after main PHY switch end
NS_LOG_DEBUG("Schedule CCA check a PIFS after the end of main PHY switch");
@@ -856,9 +902,10 @@ AdvancedEmlsrManager::SwitchMainPhyIfTxopToBeGainedByAuxPhy(uint8_t linkId,
}
else
{
// the main PHY must stay for some time on this link to check if it gets channel access.
// The timer is stopped if a DL or UL TXOP is started. When the timer expires, the main
// PHY switches back to the preferred link if SwitchAuxPhy is false
// the main PHY must stay for some time on this link to check if it gets channel
// access. The timer is stopped if a DL or UL TXOP is started. When the timer
// expires, the main PHY switches back to the preferred link if SwitchAuxPhy is
// false
m_switchMainPhyBackEvent.Cancel();
m_switchMainPhyBackEvent =
Simulator::Schedule(accessDelay + m_switchMainPhyBackDelay,