USRP B210 communication using OFDM

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Giti Dimrov
Giti Dimrov on 9 May 2022
Commented: Giti Dimrov on 11 May 2022
Hi,
I am trying to have an OFDM communication using 2 USRPs B210.
When I run the code using a channel model, it works perfectly, once I try it using the USRPs I face problems. Sometimes the packets are received and decoded correctly by the receiver, but not all the packets and it is only happening a few times. I am constantly transmitting 802.11a packets using OFDM. My packet length is 480, sampling rate is 20e6 and the configuration of the transmitted and receiver usrp are as follows:
Transmitter:
SimParams.StopTime = 1000;
SimParams.ChannelMapping = 1;
SimParams.USRPFrameLength = 480;
SimParams.USRPCenterFrequency = 2.415e9;
SimParams.USRPGain = 50;
SimParams.MasterClockRate = 60e6;
SimParams.USRPInterpolationFactor = 3;
Receiver:
SimParams.MasterClockRate = 60e6;
SimParams.USRPCenterFrequency = 2.415e9;
SimParams.USRPGain = 45;
SimParams.StopTime = 1;
SimParams.USRPDecimationFactor = 3;
SimParams.SamplesPerFrame = 48000;
SimParams.ChannelMapping = 1;
Can please someone help me understand what am I doing wrong??

Answers (1)

Karunya Choppara
Karunya Choppara on 10 May 2022
Hi
As the sample rate is 20e6, the packet errors could be due underruns and overruns during transmit and receive https://in.mathworks.com/help/supportpkg/usrpradio/ug/detect-underruns-and-overruns.html
To avoid underruns and overruns you can try using burst mode with USRP
Also for R2021b, there are performance improvements with USRP Support Package. Please take a look into the release notes for R2021b https://in.mathworks.com/help/supportpkg/usrpradio/release-notes.html
Thanks
Karunya
  2 Comments
Giti Dimrov
Giti Dimrov on 11 May 2022
Hi Karunya,
Thank you for your answer.
I checked and apparently overrun==1 sometimes. I would not like to switch to burst mode. To overcome the overrun, should I reduce the SampleRate = MasterClockRate/DecimationFactor??
Thank you
Sigrid
Giti Dimrov
Giti Dimrov on 11 May 2022
I also tried to switch to burst mode, and overrun is always 0, but I can not decode anymore my packets. Can you please help me?

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