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wifi: Handle creation of wifi spectrum model for non-contiguous channels

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This commit is contained in:
Sébastien Deronne
2023-04-10 14:23:26 +02:00
parent a53ff7ab6e
commit 05cc8d8910
1 changed files with 28 additions and 11 deletions
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39
src/wifi/model/wifi-spectrum-value-helper.cc
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@@ -27,6 +27,7 @@
#include "ns3/fatal-error.h"
#include "ns3/log.h"
#include <algorithm>
#include <cmath>
#include <map>
#include <sstream>
@@ -90,22 +91,32 @@ WifiSpectrumValueHelper::GetSpectrumModel(const std::vector<uint16_t>& centerFre
uint32_t carrierSpacing,
ChannelWidthMhz guardBandwidth)
{
NS_ASSERT_MSG(centerFrequencies.size() == 1,
"There is no support for HE OFDM PSD for non-contiguous channels");
NS_LOG_FUNCTION(printFrequencies(centerFrequencies)
<< channelWidth << carrierSpacing << guardBandwidth);
NS_ASSERT_MSG(centerFrequencies.size() <= 2,
"Spectrum model does not support more than 2 segments");
if (centerFrequencies.size() != 1)
{
NS_ASSERT_MSG(centerFrequencies.front() != centerFrequencies.back(),
"Center frequency of each segment shall be different");
}
Ptr<SpectrumModel> ret;
WifiSpectrumModelId key{centerFrequencies, channelWidth, carrierSpacing, guardBandwidth};
auto it = g_wifiSpectrumModelMap.find(key);
if (it != g_wifiSpectrumModelMap.end())
if (const auto it = g_wifiSpectrumModelMap.find(key); it != g_wifiSpectrumModelMap.cend())
{
ret = it->second;
}
else
{
Bands bands;
double centerFrequencyHz = centerFrequencies.front() * 1e6;
double bandwidth = (channelWidth + (2.0 * guardBandwidth)) * 1e6;
const auto [minCenterFrequency, maxCenterFrequency] =
std::minmax_element(centerFrequencies.cbegin(), centerFrequencies.cend());
const auto separationWidth =
(minCenterFrequency == maxCenterFrequency)
? 0
: (*maxCenterFrequency - *minCenterFrequency - (channelWidth / 2));
NS_ASSERT(separationWidth == 0 || centerFrequencies.size() == 2);
double bandwidth = (channelWidth + (2 * guardBandwidth) + separationWidth) * 1e6;
// For OFDM, the center subcarrier is null (at center frequency)
auto numBands = static_cast<uint32_t>((bandwidth / carrierSpacing) + 0.5);
NS_ASSERT(numBands > 0);
@@ -117,10 +128,16 @@ WifiSpectrumValueHelper::GetSpectrumModel(const std::vector<uint16_t>& centerFre
}
NS_ASSERT_MSG(numBands % 2 == 1, "Number of bands should be odd");
NS_LOG_DEBUG("Num bands " << numBands << " band bandwidth " << carrierSpacing);
// lay down numBands/2 bands symmetrically around center frequency
// and place an additional band at center frequency
double startingFrequencyHz =
centerFrequencyHz - (numBands / 2 * carrierSpacing) - carrierSpacing / 2;
// The lowest frequency is obtained from the minimum center frequency among the segment(s).
// Then, we subtract half the channel width to retrieve the starting frequency of the
// operating channel. If the channel is made of 2 segments, since the channel width is the
// total width, only a quarter of the channel width has to be subtracted. Finally, we
// remove the guard band width to get the center frequency of the first band and half the
// carrier spacing to get the effective starting frequency of the first band.
const auto startingFrequencyHz = *minCenterFrequency * 1e6 -
((channelWidth * 1e6) / (2 * centerFrequencies.size())) -
(guardBandwidth * 1e6) - (carrierSpacing / 2);
for (size_t i = 0; i < numBands; i++)
{
BandInfo info;
@@ -303,7 +320,7 @@ WifiSpectrumValueHelper::CreateDuplicated20MhzTxPowerSpectralDensity(
(2e6 / carrierSpacing) +
0.5); // size in number of subcarriers of the 0dBr<->20dBr slope (2MHz for HT/VHT)
WifiSpectrumBandIndices maskBand(0, nAllocatedBands + nGuardBands);
uint32_t puncturedSlopeWidth =
const auto puncturedSlopeWidth =
static_cast<uint32_t>((500e3 / carrierSpacing) +
0.5); // size in number of subcarriers of the punctured slope band