Dropped samples error in Over the air LTE transmission

I am trying to implement over the air LTE transmission by following this link: https://in.mathworks.com/help/supportpkg/xilinxzynqbasedradio/examples/lte-transmitter-using-analog-devices-ad9361-ad9364.html

In, Transmission using SDR Hardware(code in above link),

bufferUnderflow = sdrTransmitter(txFrame(:,n));

if bufferUnderflow~=0

warning('Dropped samples')

bufferUnderflow's value is 1 always. Therefore, transmission is not happening due to dropped samples. Some problem is happening with sdrTransmitter object I think.

New to wireless communication and SDR.

Answer 1

[Neil MacEwen]

Hi Mughda,

Underflows are not surprising when trying to stream data in real-time from MATLAB/Simulink to the SDR hardware. Either MATLAB may not keep up with the required sample rate on the hardware, or the Ethernet link between your host PC and the board may not be fast enough. Make sure you use a dedicated network card, or USB3 dongle on your PC.

You can use the transmitRepeat method to work around these limitations. This loads a set of samples onto the board and transmits it repeatedly onto the air. Please see this answer for futher details.

Thanks,

Neil

[Mugdha Jadhao]

Hi Neil,

Thanks for your response. We tried using TransmitRepeat function for transmission of single frame(we did not reshape eNodeOutput in 8 frames) (Can transmitRepeat be used for multiple frames?-doesn't seem logical). The transmitter code now works properly.

Facing error in receiving from another sdr platform(https://in.mathworks.com/help/supportpkg/xilinxzynqbasedradio/examples/lte-receiver-using-analog-devices-ad9361-ad9364.html): No PBCH detected. Any suggestions?

Regards,

Mugdha.

[Neil MacEwen]

There could be lots of reasons you are not receiving the data, so it's hard for me to advise I'm afraid. I would start by double checking the data you are transmitting is good. When you use transmit repeat you repeatedly send the same vector of data over and over, so you may want to check that the beginning and end of your signal is going to loop nicely. I would recommend you send as many frames as you can, so that your receiver has as much chance as possible of grabbing a full frame.

[Mugdha Jadhao]

Hi Neil,

Thanks for your respnse.

Regards,

Mugdha.

[Yaser Abdallah]

Hello Mr MacEwen,

I face the same problem (dropped samples), even though my USRP B210 is connected through USB 3.0!

I am trying to send and receive from two USRP-B210, following the example given from mathworks, but it is not possible at the moment. Any suggestion or idea please??

thanks