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auto-mcs-wifi-manager.cc
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auto-mcs-wifi-manager.cc
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/*
* Copyright (c) 2006 INRIA
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation;
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Mathieu Lacage <[email protected]>
*/
#include "auto-mcs-wifi-manager.h"
#include "ns3/log.h"
#include "ns3/simulator.h"
#include "ns3/wifi-phy.h"
#include <algorithm>
namespace ns3
{
/**
* \brief hold per-remote-station state for Auto Mcs Wifi manager.
*
* This struct extends from WifiRemoteStation struct to hold additional
* information required by the Auto Mcs Wifi manager
*/
struct AutoMcsWifiRemoteStation : public WifiRemoteStation
{
double m_lastSnrObserved; //!< SNR of most recently reported packet sent to the remote station
uint16_t m_lastChannelWidthObserved; //!< Channel width (in MHz) of most recently reported
//!< packet sent to the remote station
uint16_t m_lastNssObserved; //!< Number of spatial streams of most recently reported packet
//!< sent to the remote station
double m_lastSnrCached; //!< SNR most recently used to select a rate
uint8_t m_lastNss; //!< Number of spatial streams most recently used to the remote station
WifiMode m_lastMode; //!< Mode most recently used to the remote station
uint16_t
m_lastChannelWidth; //!< Channel width (in MHz) most recently used to the remote station
};
/// To avoid using the cache before a valid value has been cached
static const double CACHE_INITIAL_VALUE = -100;
NS_OBJECT_ENSURE_REGISTERED(AutoMcsWifiManager);
NS_LOG_COMPONENT_DEFINE("AutoMcsWifiManager");
TypeId
AutoMcsWifiManager::GetTypeId()
{
static TypeId tid =
TypeId("ns3::AutoMcsWifiManager")
.SetParent<WifiRemoteStationManager>()
.SetGroupName("Wifi")
.AddConstructor<AutoMcsWifiManager>()
.AddAttribute("BerThreshold",
"The maximum Bit Error Rate acceptable at any transmission mode",
DoubleValue(1e-7), // This default value was modified
MakeDoubleAccessor(&AutoMcsWifiManager::m_ber),
MakeDoubleChecker<double>())
.AddAttribute("autoMCS",
"If enabled, select the best MCS for each STA-AP pair given the SNR.",
BooleanValue(false),
MakeBooleanAccessor(&AutoMcsWifiManager::m_autoMCS),
MakeBooleanChecker())
.AddTraceSource("Rate",
"Traced value for rate changes (b/s)",
MakeTraceSourceAccessor(&AutoMcsWifiManager::m_currentRate),
"ns3::TracedValueCallback::Uint64");
return tid;
}
AutoMcsWifiManager::AutoMcsWifiManager()
: m_currentRate(0)
{
NS_LOG_FUNCTION(this);
}
AutoMcsWifiManager::~AutoMcsWifiManager()
{
NS_LOG_FUNCTION(this);
}
void
AutoMcsWifiManager::SetupPhy(const Ptr<WifiPhy> phy)
{
NS_LOG_FUNCTION(this << phy);
WifiRemoteStationManager::SetupPhy(phy);
}
uint16_t
AutoMcsWifiManager::GetChannelWidthForNonHtMode(WifiMode mode) const
{
NS_ASSERT(mode.GetModulationClass() != WIFI_MOD_CLASS_HT &&
mode.GetModulationClass() != WIFI_MOD_CLASS_VHT &&
mode.GetModulationClass() != WIFI_MOD_CLASS_HE);
if (mode.GetModulationClass() == WIFI_MOD_CLASS_DSSS ||
mode.GetModulationClass() == WIFI_MOD_CLASS_HR_DSSS)
{
return 22;
}
else
{
return 20;
}
}
void
AutoMcsWifiManager::DoInitialize()
{
NS_LOG_FUNCTION(this);
BuildSnrThresholds();
}
// void
// IdealWifiManager::PrintOutPer(double snr, WifiTxVector txVector)
// {
// }
void
AutoMcsWifiManager::BuildSnrThresholds()
{
m_thresholds.clear();
WifiTxVector txVector;
uint8_t nss = 1;
for (const auto& mode : GetPhy()->GetModeList())
{
txVector.SetChannelWidth(GetChannelWidthForNonHtMode(mode));
txVector.SetNss(nss);
txVector.SetMode(mode);
NS_LOG_DEBUG("Adding mode = " << mode.GetUniqueName());
AddSnrThreshold(txVector, GetPhy()->CalculateSnr(txVector, m_ber));
}
// Add all MCSes
if (GetHtSupported())
{
for (const auto& mode : GetPhy()->GetMcsList())
{
for (uint16_t j = 20; j <= GetPhy()->GetChannelWidth(); j *= 2)
{
txVector.SetChannelWidth(j);
if (mode.GetModulationClass() == WIFI_MOD_CLASS_HT)
{
uint16_t guardInterval = GetShortGuardIntervalSupported() ? 400 : 800;
txVector.SetGuardInterval(guardInterval);
// derive NSS from the MCS index
nss = (mode.GetMcsValue() / 8) + 1;
NS_LOG_DEBUG("Adding mode = " << mode.GetUniqueName() << " channel width " << j
<< " nss " << +nss << " GI " << guardInterval);
txVector.SetNss(nss);
txVector.SetMode(mode);
AddSnrThreshold(txVector, GetPhy()->CalculateSnr(txVector, m_ber));
}
else // VHT or HE
{
uint16_t guardInterval;
if (mode.GetModulationClass() == WIFI_MOD_CLASS_VHT)
{
guardInterval = GetShortGuardIntervalSupported() ? 400 : 800;
}
else
{
guardInterval = GetGuardInterval();
}
txVector.SetGuardInterval(guardInterval);
for (uint8_t k = 1; k <= GetPhy()->GetMaxSupportedTxSpatialStreams(); k++)
{
if (mode.IsAllowed(j, k))
{
NS_LOG_DEBUG("Adding mode = " << mode.GetUniqueName()
<< " channel width " << j << " nss " << +k
<< " GI " << guardInterval);
txVector.SetNss(k);
txVector.SetMode(mode);
AddSnrThreshold(txVector, GetPhy()->CalculateSnr(txVector, m_ber));
std::vector<double> berThreshold{8.37e-7};
// std::vector<double> berThreshold{1e-6, 1e-7, 1e-8};
// std::vector<double> berThreshold{1.0 - std::pow((1.0 - 0.1),
// 12000.0),
// 1.0 - std::pow((1.0 - 0.01),
// 12000.0), 1.0 -
// std::pow((1.0 - 0.001),
// 12000.0)};
// for (auto ber : berThreshold)
// {
// std::cout << "Mode " << mode << " Requires an SNR of "
// << RatioToDb(GetPhy()->CalculateSnr(txVector, ber))
// << " for a ber " << ber << std::endl;
// }
}
else
{
NS_LOG_DEBUG("Mode = " << mode.GetUniqueName() << " disallowed");
}
}
}
}
}
}
}
double
AutoMcsWifiManager::GetSnrThreshold(WifiTxVector txVector)
{
NS_LOG_FUNCTION(this << txVector);
auto it = std::find_if(m_thresholds.begin(),
m_thresholds.end(),
[&txVector](const std::pair<double, WifiTxVector>& p) -> bool {
return ((txVector.GetMode() == p.second.GetMode()) &&
(txVector.GetNss() == p.second.GetNss()) &&
(txVector.GetChannelWidth() == p.second.GetChannelWidth()));
});
if (it == m_thresholds.end())
{
// This means capabilities have changed in runtime, hence rebuild SNR thresholds
BuildSnrThresholds();
it = std::find_if(m_thresholds.begin(),
m_thresholds.end(),
[&txVector](const std::pair<double, WifiTxVector>& p) -> bool {
return ((txVector.GetMode() == p.second.GetMode()) &&
(txVector.GetNss() == p.second.GetNss()) &&
(txVector.GetChannelWidth() == p.second.GetChannelWidth()));
});
NS_ASSERT_MSG(it != m_thresholds.end(), "SNR threshold not found");
}
return it->first;
}
void
AutoMcsWifiManager::AddSnrThreshold(WifiTxVector txVector, double snr)
{
NS_LOG_FUNCTION(this << txVector.GetMode().GetUniqueName() << txVector.GetChannelWidth()
<< snr);
m_thresholds.emplace_back(snr, txVector);
}
WifiRemoteStation*
AutoMcsWifiManager::DoCreateStation() const
{
NS_LOG_FUNCTION(this);
AutoMcsWifiRemoteStation* station = new AutoMcsWifiRemoteStation();
Reset(station);
return station;
}
void
AutoMcsWifiManager::Reset(WifiRemoteStation* station) const
{
NS_LOG_FUNCTION(this << station);
AutoMcsWifiRemoteStation* st = static_cast<AutoMcsWifiRemoteStation*>(station);
st->m_lastSnrObserved = 0.0;
st->m_lastChannelWidthObserved = 0;
st->m_lastNssObserved = 1;
st->m_lastSnrCached = CACHE_INITIAL_VALUE;
st->m_lastMode = GetDefaultMode();
st->m_lastChannelWidth = 0;
st->m_lastNss = 1;
}
void
AutoMcsWifiManager::DoReportRxOk(WifiRemoteStation* station, double rxSnr, WifiMode txMode)
{
NS_LOG_FUNCTION(this << station << rxSnr << txMode);
// choosenMCS.emplace_back(txMode.GetMcsValue());
}
void
AutoMcsWifiManager::DoReportRtsFailed(WifiRemoteStation* station)
{
NS_LOG_FUNCTION(this << station);
}
void
AutoMcsWifiManager::DoReportDataFailed(WifiRemoteStation* station)
{
NS_LOG_FUNCTION(this << station);
}
void
AutoMcsWifiManager::DoReportRtsOk(WifiRemoteStation* st,
double ctsSnr,
WifiMode ctsMode,
double rtsSnr)
{
NS_LOG_FUNCTION(this << st << ctsSnr << ctsMode.GetUniqueName() << rtsSnr);
AutoMcsWifiRemoteStation* station = static_cast<AutoMcsWifiRemoteStation*>(st);
station->m_lastSnrObserved = rtsSnr;
station->m_lastChannelWidthObserved =
GetPhy()->GetChannelWidth() >= 40 ? 20 : GetPhy()->GetChannelWidth();
station->m_lastNssObserved = 1;
}
void
AutoMcsWifiManager::DoReportDataOk(WifiRemoteStation* st,
double ackSnr,
WifiMode ackMode,
double dataSnr,
uint16_t dataChannelWidth,
uint8_t dataNss)
{
NS_LOG_FUNCTION(this << st << ackSnr << ackMode.GetUniqueName() << dataSnr << dataChannelWidth
<< +dataNss);
AutoMcsWifiRemoteStation* station = static_cast<AutoMcsWifiRemoteStation*>(st);
if (dataSnr == 0)
{
NS_LOG_WARN("DataSnr reported to be zero; not saving this report.");
return;
}
station->m_lastSnrObserved = dataSnr;
station->m_lastChannelWidthObserved = dataChannelWidth;
station->m_lastNssObserved = dataNss;
// The default value of m_lastMode is non-HT, thus invalid for GetMcsValue
if (station->m_lastMode != GetDefaultMode())
{
choosenMCS.emplace_back(station->m_lastMode.GetMcsValue());
}
}
void
AutoMcsWifiManager::DoReportAmpduTxStatus(WifiRemoteStation* st,
uint16_t nSuccessfulMpdus,
uint16_t nFailedMpdus,
double rxSnr,
double dataSnr,
uint16_t dataChannelWidth,
uint8_t dataNss)
{
NS_LOG_FUNCTION(this << st << nSuccessfulMpdus << nFailedMpdus << rxSnr << dataSnr
<< dataChannelWidth << +dataNss);
AutoMcsWifiRemoteStation* station = static_cast<AutoMcsWifiRemoteStation*>(st);
if (dataSnr == 0)
{
NS_LOG_WARN("DataSnr reported to be zero; not saving this report.");
return;
}
for (int i = 0; i < nSuccessfulMpdus; i++)
{
choosenMCS.emplace_back(station->m_lastMode.GetMcsValue());
}
station->m_lastSnrObserved = dataSnr;
station->m_lastChannelWidthObserved = dataChannelWidth;
station->m_lastNssObserved = dataNss;
}
void
AutoMcsWifiManager::DoReportFinalRtsFailed(WifiRemoteStation* station)
{
NS_LOG_FUNCTION(this << station);
Reset(station);
}
void
AutoMcsWifiManager::DoReportFinalDataFailed(WifiRemoteStation* station)
{
NS_LOG_FUNCTION(this << station);
Reset(station);
}
WifiTxVector
AutoMcsWifiManager::DoGetDataTxVector(WifiRemoteStation* st, uint16_t allowedWidth)
{
NS_LOG_FUNCTION(this << st << allowedWidth);
AutoMcsWifiRemoteStation* station = static_cast<AutoMcsWifiRemoteStation*>(st);
// We search within the Supported rate set the mode with the
// highest data rate for which the SNR threshold is smaller than m_lastSnr
// to ensure correct packet delivery.
WifiMode maxMode = GetDefaultModeForSta(st);
WifiTxVector txVector;
WifiMode mode;
uint64_t bestRate = 0;
uint8_t selectedNss = 1;
uint16_t guardInterval;
uint16_t channelWidth = std::min(GetChannelWidth(station), allowedWidth);
txVector.SetChannelWidth(channelWidth);
if ((Simulator::Now().GetSeconds() < 10))
{
if ((station->m_lastSnrCached != CACHE_INITIAL_VALUE) &&
(station->m_lastSnrObserved == station->m_lastSnrCached) &&
(channelWidth == station->m_lastChannelWidth))
{
// SNR has not changed, so skip the search and use the last mode selected
maxMode = station->m_lastMode;
selectedNss = station->m_lastNss;
NS_LOG_DEBUG("Using cached mode = " << maxMode.GetUniqueName() << " last snr observed "
<< station->m_lastSnrObserved << " cached "
<< station->m_lastSnrCached << " channel width "
<< station->m_lastChannelWidth << " nss "
<< +selectedNss);
}
else
{
if (GetHtSupported() && GetHtSupported(st))
{
for (uint8_t i = 0; i < GetNMcsSupported(station); i++)
{
mode = GetMcsSupported(station, i);
txVector.SetMode(mode);
if (mode.GetModulationClass() == WIFI_MOD_CLASS_HT)
{
guardInterval = static_cast<uint16_t>(
std::max(GetShortGuardIntervalSupported(station) ? 400 : 800,
GetShortGuardIntervalSupported() ? 400 : 800));
txVector.SetGuardInterval(guardInterval);
// If the node and peer are both VHT capable, only search VHT modes
if (GetVhtSupported() && GetVhtSupported(station))
{
continue;
}
// If the node and peer are both HE capable, only search HE modes
if (GetHeSupported() && GetHeSupported(station))
{
continue;
}
// Derive NSS from the MCS index. There is a different mode for each
// possible NSS value.
uint8_t nss = (mode.GetMcsValue() / 8) + 1;
txVector.SetNss(nss);
if (!txVector.IsValid() || nss > std::min(GetMaxNumberOfTransmitStreams(),
GetNumberOfSupportedStreams(st)))
{
NS_LOG_DEBUG("Skipping mode " << mode.GetUniqueName() << " nss " << +nss
<< " width "
<< txVector.GetChannelWidth());
continue;
}
double threshold = GetSnrThreshold(txVector);
uint64_t dataRate = mode.GetDataRate(txVector.GetChannelWidth(),
txVector.GetGuardInterval(),
nss);
NS_LOG_DEBUG("Testing mode " << mode.GetUniqueName() << " data rate "
<< dataRate << " threshold " << threshold
<< " last snr observed "
<< station->m_lastSnrObserved << " cached "
<< station->m_lastSnrCached);
double snr = GetLastObservedSnr(station, channelWidth, nss);
if (dataRate > bestRate && threshold < snr)
{
NS_LOG_DEBUG("Candidate mode = "
<< mode.GetUniqueName() << " data rate " << dataRate
<< " threshold " << threshold << " channel width "
<< channelWidth << " snr " << snr);
bestRate = dataRate;
maxMode = mode;
selectedNss = nss;
}
}
else if (mode.GetModulationClass() == WIFI_MOD_CLASS_VHT)
{
guardInterval = static_cast<uint16_t>(
std::max(GetShortGuardIntervalSupported(station) ? 400 : 800,
GetShortGuardIntervalSupported() ? 400 : 800));
txVector.SetGuardInterval(guardInterval);
// If the node and peer are both HE capable, only search HE modes
if (GetHeSupported() && GetHeSupported(station))
{
continue;
}
// If the node and peer are not both VHT capable, only search HT modes
if (!GetVhtSupported() || !GetVhtSupported(station))
{
continue;
}
for (uint8_t nss = 1; nss <= std::min(GetMaxNumberOfTransmitStreams(),
GetNumberOfSupportedStreams(station));
nss++)
{
txVector.SetNss(nss);
if (!txVector.IsValid())
{
NS_LOG_DEBUG("Skipping mode " << mode.GetUniqueName() << " nss "
<< +nss << " width "
<< txVector.GetChannelWidth());
continue;
}
double threshold = GetSnrThreshold(txVector);
uint64_t dataRate = mode.GetDataRate(txVector.GetChannelWidth(),
txVector.GetGuardInterval(),
nss);
NS_LOG_DEBUG("Testing mode = "
<< mode.GetUniqueName() << " data rate " << dataRate
<< " threshold " << threshold << " last snr observed "
<< station->m_lastSnrObserved << " cached "
<< station->m_lastSnrCached);
double snr = GetLastObservedSnr(station, channelWidth, nss);
if (dataRate > bestRate && threshold < snr)
{
NS_LOG_DEBUG("Candidate mode = " << mode.GetUniqueName()
<< " data rate " << dataRate
<< " channel width "
<< channelWidth << " snr " << snr);
bestRate = dataRate;
maxMode = mode;
selectedNss = nss;
}
}
}
else // HE
{
guardInterval = std::max(GetGuardInterval(station), GetGuardInterval());
txVector.SetGuardInterval(guardInterval);
// If the node and peer are not both HE capable, only search (V)HT modes
if (!GetHeSupported() || !GetHeSupported(station))
{
continue;
}
for (uint8_t nss = 1; nss <= std::min(GetMaxNumberOfTransmitStreams(),
GetNumberOfSupportedStreams(station));
nss++)
{
txVector.SetNss(nss);
if (!txVector.IsValid())
{
NS_LOG_DEBUG("Skipping mode " << mode.GetUniqueName() << " nss "
<< +nss << " width "
<< +txVector.GetChannelWidth());
continue;
}
double threshold = GetSnrThreshold(txVector);
uint64_t dataRate = mode.GetDataRate(txVector.GetChannelWidth(),
txVector.GetGuardInterval(),
nss);
NS_LOG_DEBUG("Testing mode = "
<< mode.GetUniqueName() << " data rate " << dataRate
<< " threshold " << threshold << " last snr observed "
<< station->m_lastSnrObserved << " cached "
<< station->m_lastSnrCached);
double snr = GetLastObservedSnr(station, channelWidth, nss);
if (dataRate > bestRate && threshold < snr)
{
NS_LOG_DEBUG("Candidate mode = "
<< mode.GetUniqueName() << " data rate " << dataRate
<< " threshold " << threshold << " channel width "
<< channelWidth << " snr " << snr);
bestRate = dataRate;
maxMode = mode;
selectedNss = nss;
}
}
}
}
}
else
{
// Non-HT selection
selectedNss = 1;
for (uint8_t i = 0; i < GetNSupported(station); i++)
{
mode = GetSupported(station, i);
txVector.SetMode(mode);
txVector.SetNss(selectedNss);
uint16_t width = GetChannelWidthForNonHtMode(mode);
txVector.SetChannelWidth(width);
double threshold = GetSnrThreshold(txVector);
uint64_t dataRate = mode.GetDataRate(txVector.GetChannelWidth(),
txVector.GetGuardInterval(),
txVector.GetNss());
NS_LOG_DEBUG("mode = " << mode.GetUniqueName() << " threshold " << threshold
<< " last snr observed " << station->m_lastSnrObserved);
double snr = GetLastObservedSnr(station, width, 1);
if (dataRate > bestRate && threshold < snr)
{
NS_LOG_DEBUG("Candidate mode = " << mode.GetUniqueName() << " data rate "
<< dataRate << " threshold " << threshold
<< " snr " << snr);
bestRate = dataRate;
maxMode = mode;
}
}
}
NS_LOG_DEBUG("Updating cached values for station to "
<< maxMode.GetUniqueName() << " snr " << station->m_lastSnrObserved);
station->m_lastSnrCached = station->m_lastSnrObserved;
station->m_lastMode = maxMode;
station->m_lastNss = selectedNss;
}
}
else
{
double average = 0;
for (auto it : choosenMCS)
{
average += it;
}
// std::cout << " raw value " << average / choosenMCS.size() << std::endl;
average = std::ceil(average / choosenMCS.size());
std::string mcs = "HeMcs" + std::to_string(int(average));
maxMode = WifiMode(mcs);
}
NS_LOG_DEBUG("Found maxMode: " << maxMode << " channelWidth: " << channelWidth
<< " nss: " << +selectedNss);
station->m_lastChannelWidth = channelWidth;
if (maxMode.GetModulationClass() == WIFI_MOD_CLASS_HE)
{
guardInterval = std::max(GetGuardInterval(station), GetGuardInterval());
}
else if ((maxMode.GetModulationClass() == WIFI_MOD_CLASS_HT) ||
(maxMode.GetModulationClass() == WIFI_MOD_CLASS_VHT))
{
guardInterval =
static_cast<uint16_t>(std::max(GetShortGuardIntervalSupported(station) ? 400 : 800,
GetShortGuardIntervalSupported() ? 400 : 800));
}
else
{
guardInterval = 800;
}
WifiTxVector bestTxVector{
maxMode,
GetDefaultTxPowerLevel(),
GetPreambleForTransmission(maxMode.GetModulationClass(), GetShortPreambleEnabled()),
guardInterval,
GetNumberOfAntennas(),
selectedNss,
0,
GetPhy()->GetTxBandwidth(maxMode, channelWidth),
GetAggregation(station)};
uint64_t maxDataRate = maxMode.GetDataRate(bestTxVector);
if (m_currentRate != maxDataRate)
{
// std::cout << "New datarate: " << maxMode << std::endl;
m_currentRate = maxDataRate;
}
return bestTxVector;
}
WifiTxVector
AutoMcsWifiManager::DoGetRtsTxVector(WifiRemoteStation* st)
{
NS_LOG_FUNCTION(this << st);
if (!m_autoMCS)
{
AutoMcsWifiRemoteStation* station = static_cast<AutoMcsWifiRemoteStation*>(st);
// We search within the Basic rate set the mode with the highest
// SNR threshold possible which is smaller than m_lastSnr to
// ensure correct packet delivery.
double maxThreshold = 0.0;
WifiTxVector txVector;
WifiMode mode;
uint8_t nss = 1;
WifiMode maxMode = GetDefaultMode();
// RTS is sent in a non-HT frame
for (uint8_t i = 0; i < GetNBasicModes(); i++)
{
mode = GetBasicMode(i);
txVector.SetMode(mode);
txVector.SetNss(nss);
txVector.SetChannelWidth(GetChannelWidthForNonHtMode(mode));
double threshold = GetSnrThreshold(txVector);
if (threshold > maxThreshold && threshold < station->m_lastSnrObserved)
{
maxThreshold = threshold;
maxMode = mode;
}
}
return WifiTxVector(
maxMode,
GetDefaultTxPowerLevel(),
GetPreambleForTransmission(maxMode.GetModulationClass(), GetShortPreambleEnabled()),
800,
GetNumberOfAntennas(),
nss,
0,
GetChannelWidthForNonHtMode(maxMode),
GetAggregation(station));
}
else
{
return WifiTxVector(
WifiMode("OfdmRate6Mbps"),
GetDefaultTxPowerLevel(),
GetPreambleForTransmission(WifiMode("OfdmRate6Mbps").GetModulationClass(),
GetShortPreambleEnabled()),
ConvertGuardIntervalToNanoSeconds(WifiMode("OfdmRate6Mbps"),
GetShortGuardIntervalSupported(st),
NanoSeconds(GetGuardInterval(st))),
1,
1,
0,
GetPhy()->GetTxBandwidth(WifiMode("OfdmRate6Mbps"), GetChannelWidth(st)),
GetAggregation(st));
}
}
double
AutoMcsWifiManager::GetLastObservedSnr(AutoMcsWifiRemoteStation* station,
uint16_t channelWidth,
uint8_t nss) const
{
double snr = station->m_lastSnrObserved;
if (channelWidth != station->m_lastChannelWidthObserved)
{
snr /= (static_cast<double>(channelWidth) / station->m_lastChannelWidthObserved);
}
if (nss != station->m_lastNssObserved)
{
snr /= (static_cast<double>(nss) / station->m_lastNssObserved);
}
NS_LOG_DEBUG("Last observed SNR is " << station->m_lastSnrObserved << " for channel width "
<< station->m_lastChannelWidthObserved << " and nss "
<< +station->m_lastNssObserved << "; computed SNR is "
<< snr << " for channel width " << channelWidth
<< " and nss " << +nss);
return snr;
}
} // namespace ns3