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spectrum: Reduce PSD complexity by computing only the main matrix diagonal

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This commit is contained in:
Gabriel Ferreira
2025-01-07 17:28:41 +01:00
parent e299ddba3a
commit 1a5957d9d0
1 changed files with 11 additions and 8 deletions
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19
src/spectrum/model/three-gpp-spectrum-propagation-loss-model.cc
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@@ -285,7 +285,6 @@ ThreeGppSpectrumPropagationLossModel::CalcBeamformingGain(
// Calculate RX PSD from the spectrum channel matrix H and
// the precoding matrix P as: PSD = (H*P)^h * (H*P)
MatrixBasedChannelModel::Complex3DVector psd;
MatrixBasedChannelModel::Complex3DVector p;
if (!rxParams->precodingMatrix)
{
@@ -307,23 +306,27 @@ ThreeGppSpectrumPropagationLossModel::CalcBeamformingGain(
// When we have the precoding matrix P, we first do
// H(rxPorts,txPorts,numRbs) x P(txPorts,txStreams,numRbs) = HxP(rxPorts,txStreams,numRbs)
MatrixBasedChannelModel::Complex3DVector hP = *rxParams->spectrumChannelMatrix * p;
// Then (HxP)^h dimensions are (txStreams, rxPorts, numRbs)
MatrixBasedChannelModel::Complex3DVector hPHerm = hP.HermitianTranspose();
// MatrixBasedChannelModel::Complex3DVector hPHerm = hP.HermitianTranspose();
// Finally, (HxP)^h x (HxP) = PSD(txStreams, txStreams, numRbs)
psd = hPHerm * hP;
// MatrixBasedChannelModel::Complex3DVector psd = hPHerm * hP;
// Update rxParams->Psd
// And the received psd is the Trace(PSD).
// To avoid wasting computations, we only compute the main diagonal of hPHerm*hP
for (uint32_t rbIdx = 0; rbIdx < rxParams->psd->GetValuesN(); ++rbIdx)
{
(*rxParams->psd)[rbIdx] = 0.0;
for (size_t txStream = 0; txStream < psd.GetNumRows(); ++txStream)
for (size_t rxPort = 0; rxPort < hP.GetNumRows(); ++rxPort)
{
(*rxParams->psd)[rbIdx] += std::real(psd(txStream, txStream, rbIdx));
for (size_t txStream = 0; txStream < hP.GetNumCols(); ++txStream)
{
(*rxParams->psd)[rbIdx] +=
std::real(std::conj(hP(rxPort, txStream, rbIdx)) * hP(rxPort, txStream, rbIdx));
}
}
}
return rxParams;
}