Possible Bug in RSRQ Calculation

[akin soysal]

Hello,

In the main branch, in function LteUePhy::GenerateMixedCqiReport and LteUePhy::GenerateCtrlCqiReport, when calculating RSRQ:

          Values::const_iterator itIntN = m_rsInterferencePower.ConstValuesBegin ();
          Values::const_iterator itPj = m_rsReceivedPower.ConstValuesBegin ();
          for (itPj = m_rsReceivedPower.ConstValuesBegin ();
               itPj != m_rsReceivedPower.ConstValuesEnd ();
               itIntN++, itPj++)
            {
              rbNum++;
              // convert PSD [W/Hz] to linear power [W] for the single RE
              double noisePowerTxW = ((*itIntN) * 180000.0) / 12.0;
              double intPowerTxW = ((*itPj) * 180000.0) / 12.0;
              std::cout << "int power is " << intPowerTxW << " noise power is " << noisePowerTxW << std::endl;
              rsrqSum += (2 * (noisePowerTxW + intPowerTxW));
            }

          NS_ASSERT (rbNum == (*itPss).nRB);
          double rsrq_dB = 10 * log10 ((*itPss).pssPsdSum / rsrqSum);

It seems to me that intPowerTxW should have been computed from *itPj instead of *itIntN and noisePowerTxW should have been calculated from the noisePsd. These two should make up the denominator in RSRQ calculation. And m_rsReceivedPower should not be used for the denominator, since we are already including it in the numerator with (*itPss).pssPsdSum.

Could you please clarify? Thanks in advance.

Best Regards,
Akin

[Marco Miozzo]

Hi Akin,

the code has changed quite a few from last time I've seen it, let me try to clarify a bit. I guess that the names of the variables are quite misleading: noisePowerTxW seems to store the interference power (including the noise) and intPowerTxW the power of the eNB connected. Therefore rsrqSum is maintaining the RSSI, which a subsequently used for evaluating the RSRQ which is ~RSRP/RSRQ. You may find more info on the procedure we adopted for evaluating the RSRQ and the RSRP at the following link:
http://lena.cttc.es/manual/lte-design.html#ue-phy-measurements-model

Best regards,
marco.

--
You received this message because you are subscribed to the Google Groups "ns-3-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ns-3-users+...@googlegroups.com.
To post to this group, send email to ns-3-...@googlegroups.com.
Visit this group at http://groups.google.com/group/ns-3-users.
For more options, visit https://groups.google.com/d/optout.

[akin soysal]

Hi Marco,

Thanks for your reply. I went up to the LteInterference class and you are right, although the naming was a bit counterintuitive :)

Best Regards,
Akın