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wifi: Avoid expensive divisions

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This commit is contained in:
Gabriel Ferreira
2024-09-02 22:33:18 +02:00
parent ba6be0dbd3
commit 26b3fd9c04
1 changed files with 9 additions and 5 deletions
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14
src/wifi/model/wifi-spectrum-value-helper.cc
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@@ -184,11 +184,12 @@ WifiSpectrumValueHelper::CreateDsssTxPowerSpectralDensity(double centerFrequency
NS_ASSERT(c->GetSpectrumModel()->GetNumBands() == (nAllocatedBands + nGuardBands + 1));
// Evenly spread power across 22 MHz
double txPowerPerBand = txPowerW / nAllocatedBands;
const auto psd = txPowerPerBand / (bit->fh - bit->fl);
for (size_t i = 0; i < c->GetSpectrumModel()->GetNumBands(); i++, vit++, bit++)
{
if ((i >= (nGuardBands / 2)) && (i <= ((nGuardBands / 2) + nAllocatedBands - 1)))
{
*vit = txPowerPerBand / (bit->fh - bit->fl);
*vit = psd;
}
}
return c;
@@ -680,12 +681,13 @@ WifiSpectrumValueHelper::CreateHeMuOfdmTxPowerSpectralDensity(
});
double txPowerPerBandW = (txPowerW / numSubcarriers); // FIXME: null subcarriers
uint32_t numBands = c->GetSpectrumModel()->GetNumBands();
const auto psd = txPowerPerBandW / (bit->fh - bit->fl);
for (size_t i = 0; i < numBands; i++, vit++, bit++)
{
const auto allocated = std::any_of(ru.cbegin(), ru.cend(), [i](const auto& p) {
return (i >= p.first && i <= p.second);
});
*vit = allocated ? (txPowerPerBandW / (bit->fh - bit->fl)) : 0.0;
*vit = allocated ? psd : 0.0;
}
return c;
@@ -1073,9 +1075,10 @@ WifiSpectrumValueHelper::CreateSpectrumMaskForOfdm(
// fill in spectrum mask
auto vit = c->ValuesBegin();
auto bit = c->ConstBandsBegin();
const auto invBandwidth = 1 / (bit->fh - bit->fl);
for (auto txPowerValue : txPowerValues)
{
*vit = txPowerValue / (bit->fh - bit->fl);
*vit = txPowerValue * invBandwidth;
vit++;
bit++;
}
@@ -1093,13 +1096,14 @@ WifiSpectrumValueHelper::NormalizeSpectrumMask(Ptr<SpectrumValue> c, double txPo
NS_LOG_FUNCTION(c << txPowerW);
// Normalize power so that total signal power equals transmit power
double currentTxPowerW = Integral(*c);
double normalizationRatio = currentTxPowerW / txPowerW;
double normalizationRatio [[maybe_unused]] = currentTxPowerW / txPowerW;
double invNormalizationRatio = txPowerW / currentTxPowerW;
NS_LOG_LOGIC("Current power: " << currentTxPowerW << "W vs expected power: " << txPowerW << "W"
<< " -> ratio (C/E) = " << normalizationRatio);
auto vit = c->ValuesBegin();
for (size_t i = 0; i < c->GetSpectrumModel()->GetNumBands(); i++, vit++)
{
*vit = (*vit) / normalizationRatio;
*vit = (*vit) * invNormalizationRatio;
}
}