diff --git a/src/spectrum/model/three-gpp-spectrum-propagation-loss-model.cc b/src/spectrum/model/three-gpp-spectrum-propagation-loss-model.cc
index 7bba9ac89..4a47f47e7 100644
--- a/src/spectrum/model/three-gpp-spectrum-propagation-loss-model.cc
+++ b/src/spectrum/model/three-gpp-spectrum-propagation-loss-model.cc
@@ -280,49 +280,50 @@ ThreeGppSpectrumPropagationLossModel::CalcBeamformingGain(
                                                                numRxPorts,
                                                                isReverse);
 
-    // The precoding matrix is not set
+    NS_ASSERT_MSG(rxParams->psd->GetValuesN() == rxParams->spectrumChannelMatrix->GetNumPages(),
+                  "RX PSD and the spectrum channel matrix should have the same number of RBs ");
+
+    // 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)
     {
-        // Update rxParams->Psd.
-        // Compute RX PSD from the channel matrix
-        auto vit = rxParams->psd->ValuesBegin(); // psd iterator
-        size_t rbIdx = 0;
-        while (vit != rxParams->psd->ValuesEnd())
+        // When the precoding matrix P is not set, we create one with a single column
+        p = ComplexMatrixArray(rxParams->spectrumChannelMatrix->GetNumCols(), 1, 1);
+        // Initialize it to the inverse square of the number of txPorts
+        p.Elem(0, 0, 0) = 1.0 / sqrt(rxParams->spectrumChannelMatrix->GetNumCols());
+        for (size_t rowI = 0; rowI < rxParams->spectrumChannelMatrix->GetNumCols(); rowI++)
         {
-            // Calculate PSD for the first antenna port (correct for SISO)
-            *vit = std::norm(rxParams->spectrumChannelMatrix->Elem(0, 0, rbIdx));
-            vit++;
-            rbIdx++;
+            p.Elem(rowI, 0, 0) = p.Elem(0, 0, 0);
         }
+        // Replicate vector to match the number of RBGs
+        p = p.MakeNCopies(rxParams->spectrumChannelMatrix->GetNumPages());
     }
     else
     {
-        NS_ASSERT_MSG(rxParams->psd->GetValuesN() == rxParams->spectrumChannelMatrix->GetNumPages(),
-                      "RX PSD and the spectrum channel matrix should have the same number of RBs ");
-        // Calculate RX PSD from the spectrum channel matrix, H and
-        // the precoding matrix, P as:
-        // PSD = (H*P)^h * (H*P),
-        // where the dimensions are:
-        // H (rxPorts,txPorts,numRbs) x P (txPorts,txStreams, numRbs) =
-        // HxP (rxPorts,txStreams, numRbs)
-        MatrixBasedChannelModel::Complex3DVector hP =
-            *rxParams->spectrumChannelMatrix * (*rxParams->precodingMatrix);
-        // (HxP)^h dimensions are (txStreams, rxPorts, numRbs)
-        MatrixBasedChannelModel::Complex3DVector hPHerm = hP.HermitianTranspose();
+        p = *rxParams->precodingMatrix;
+    }
+    // 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();
 
-        // Finally, (HxP)^h x (HxP) = PSD (txStreams, txStreams, numRbs)
-        MatrixBasedChannelModel::Complex3DVector psd = hPHerm * hP;
-        // Update rxParams->Psd
-        for (uint32_t rbIdx = 0; rbIdx < rxParams->psd->GetValuesN(); ++rbIdx)
+    // Finally, (HxP)^h x (HxP) = PSD(txStreams, txStreams, numRbs)
+    psd = hPHerm * hP;
+
+    // Update rxParams->Psd
+    for (uint32_t rbIdx = 0; rbIdx < rxParams->psd->GetValuesN(); ++rbIdx)
+    {
+        (*rxParams->psd)[rbIdx] = 0.0;
+
+        for (size_t txStream = 0; txStream < psd.GetNumRows(); ++txStream)
         {
-            (*rxParams->psd)[rbIdx] = 0.0;
-
-            for (size_t txStream = 0; txStream < psd.GetNumRows(); ++txStream)
-            {
-                (*rxParams->psd)[rbIdx] += std::real(psd(txStream, txStream, rbIdx));
-            }
+            (*rxParams->psd)[rbIdx] += std::real(psd(txStream, txStream, rbIdx));
         }
     }
+
     return rxParams;
 }
 
diff --git a/src/spectrum/test/three-gpp-channel-test-suite.cc b/src/spectrum/test/three-gpp-channel-test-suite.cc
index 62a444e02..001510dbf 100644
--- a/src/spectrum/test/three-gpp-channel-test-suite.cc
+++ b/src/spectrum/test/three-gpp-channel-test-suite.cc
@@ -934,9 +934,18 @@ ThreeGppSpectrumPropagationLossModelTest::DoRun()
     // 1) check that the rx PSD is equal for both the direct and the reverse channel
     auto rxParamsNew =
         lossModel->DoCalcRxPowerSpectralDensity(txParams, rxMob, txMob, rxAntenna, txAntenna);
-    NS_TEST_ASSERT_MSG_EQ((*rxParamsOld->psd == *rxParamsNew->psd),
-                          true,
-                          "The long term for the direct and the reverse channel are different");
+    if ((rxParamsOld->spectrumChannelMatrix->GetNumCols() ==
+         rxParamsNew->spectrumChannelMatrix->GetNumCols()) &&
+        (rxParamsOld->spectrumChannelMatrix->GetNumRows() ==
+         rxParamsNew->spectrumChannelMatrix->GetNumRows()) &&
+        (rxParamsOld->spectrumChannelMatrix->GetNumCols() == 1) &&
+        (rxParamsOld->spectrumChannelMatrix->GetNumRows() == 1))
+    {
+        // this is only really true in case of SISO (1x1 non-polarized port array)
+        NS_TEST_ASSERT_MSG_EQ((*rxParamsOld->psd == *rxParamsNew->psd),
+                              true,
+                              "The long term for the direct and the reverse channel are different");
+    }
 
     // 2) check if the long term is updated when changing the BF vector
     // change the position of the rx device and recompute the beamforming vectors