USRP B210 communication using OFDM

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??

Answer 1

[Karunya Choppara]

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

https://in.mathworks.com/help/supportpkg/usrpradio/ug/burst-mode-buffering.html

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

[Giti Dimrov]

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]

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?