Radio Environment Map problem

[Yared Zerihun]

Hello dears,

I put the script that produces REM just above Simulator::Run() . I also have a script that will calculate simulation results above the REM code.

here is the script to produce REM,

Ptr<RadioEnvironmentMapHelper> remHelper = CreateObject<RadioEnvironmentMapHelper> ();
   remHelper->SetAttribute ("ChannelPath", StringValue ("/ChannelList/1"));
   remHelper->SetAttribute ("OutputFile", StringValue ("rem.out"));
   remHelper->SetAttribute ("XMin", DoubleValue (-400.0));
   remHelper->SetAttribute ("XMax", DoubleValue (400.0));
   remHelper->SetAttribute ("XRes", UintegerValue (100));
   remHelper->SetAttribute ("YMin", DoubleValue (-300.0));
   remHelper->SetAttribute ("YMax", DoubleValue (300.0));
   remHelper->SetAttribute ("YRes", UintegerValue (75));
   remHelper->SetAttribute ("Z", DoubleValue (0.0));
   remHelper->SetAttribute ("UseDataChannel", BooleanValue (true));
   remHelper->SetAttribute ("RbId", IntegerValue (10));
   remHelper->SetAttribute("StopWhenDone", BooleanValue(true));
   remHelper->Install ();

But the third column of the output file (rem.out) ,which is the SNR value is always zero.

I don't understand why this is the case.

[Tommaso Pecorella]

Hi,

are you sure that the 3rd column is the SNR ?

I mean, couldn't be something different like... the z axis position ?

Check the code before having doubts, it's way faster than posting a question and waiting for an answer.

T.

[Yared Zerihun]

Hello Tommaso,

I am really sorry. I mean to say the fourth column.

I've searched the forum, and anywhere else, but I couldn't find the solution.

[Tommaso Pecorella]

Hi,

well, if the 4th column is zero, then there IS a problem. Check your script against the two in src/lte/examples, probably you missed some bits (these two works).

Have fun,

T.

[Yared Zerihun]

commenting out the following line of code corrected everything,

remHelper->SetAttribute ("UseDataChannel", BooleanValue (true));

My script couldn't generate REM for a data channel as it is described in the models document about REM.

Further more, I checked how SNR values are calculated, and it turns out that it uses the power of the
reference signal in the calculation, and this value is always zero if I use the above line of code. I think the reference signal is a control 
signal that operates only in the physical layer (with no mapping in higher layers unlike other channels), I am not 
sure though.