How CQI affects throughput

[taqi raza]

Hi,

My goal is to see throughout variation based on CQI feedback from UE to eNodeB. Because CQI is generated from SINR, therefore, I am directly changing SINR values at UE Phy layer.

I have changed the code in "lte-ue-phy.cc" as follow

LteUePhy::CreateDlCqiFeedbackMessage (const SpectrumValue& sinr)
{
  NS_LOG_FUNCTION (this);
  // apply transmission mode gain
  NS_ASSERT (m_transmissionMode < m_txModeGain.size ());
  SpectrumValue newSinr = sinr;
  newSinr = 5.02728e+11; //my custom SINR value
  newSinr *= m_txModeGain.at (m_transmissionMode);
.
.
}
But, I have noticed that DLPDCP throughput varies when the  SINR value is in the range of 0 to 1. Such as when I set "newSinr = 5.02728e-1" or "newSinr = 3.02728e-1" etc.
But I did not notice any DL-PDCP throughput variation when SINR is changed to some other value, which is > 1

Can someone help where I am getting things wrong? (i.e. why SINR values >1 has no affect on throughput)

Thank you.

[Tommaso Pecorella]

Hi,

are you sure that this is a good place to discuss about it ?

I mean, it's not a question about ns-3, it's "just" a totally normal behavior of digital communications. The answer is in any text book. Do you want a link to one ?

T.