How to define the BER or BLER in LTE?

[Rafael Fernandes Lopes]

Hey guys,

I would like to evaluate the throughput of some protocols as a function of the BER or BLER in an LTE model. I have tried to set the following parameters in the simulation:

double ber = 0.01;

  Config::SetDefault ("ns3::LteAmc::Ber", DoubleValue (ber));

  Config::SetDefault ("ns3::LteAmc::AmcModel", EnumValue (LteAmc::PiroEW2010));

  Config::SetDefault ("ns3::LteSpectrumPhy::CtrlErrorModelEnabled", BooleanValue (false));

  Config::SetDefault ("ns3::LteSpectrumPhy::DataErrorModelEnabled", BooleanValue (true));

  Config::SetDefault ("ns3::RrFfMacScheduler::HarqEnabled", BooleanValue (false));

However, the BER parameter is not taking any effect in the throughput or even in the selected MCS.

There is some way to set this? Or I have to drop artificially my packets using an uniform distribution in my code?

Best regards,

-- 

Rafael Fernandes Lopes

[Tommaso Pecorella]

Hi,

I think you're understood the BER Attribute in the reverse way.

The attribute should define the minimum target BER for a MCS, i.e., the AMC will not assign a MCS if its estimated BER is higher than the attribute value.

Increasing this value will NOT increase the actual BER or BLER, which are instead dependent on the propagation models, nodes mobility, nodes positions, etc.

If you change the value, the "only" effect is that the MCS selected by the AMC will be changed "later", i.e., you'll see more packet dropped due to errors in some particular conditions.

Please study the LTE manual for more details.

T.

[Marco Miozzo]

thanks Tommaso.

Let me just add that the BER parameter only affect the Piro AMC mode selection (the default one is Vienna).

my two cents,

marco.

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[Rafael Fernandes Lopes]

Hi Tomamaso,

Thx for you help. I have read the manual but this was not cleae for me... We have increased the distance but the system continues to set the MCS = 28. I am using the Friis propagation model and ConstantPositionMobilityModel (the positions are set including the nodes in ListPosititions) - sorry if the name of the classes may be wrong, I am far way from the code, typing in my mobile.

Best regards,

Rafael.