[USRP-users] Overflow with B210 for 2by2 MIMO design

Ayaz Mahmud ayazmahmud at hotmail.com
Sun Mar 10 13:57:47 EDT 2019

Trying to develop 802.11n (a 2 by 2 MIMO) standard by using two B210s. Initially started with the existing flow of GnuRadio/examples/digital/OFDM/tx.ofdm.grc. Lets take only the transmitter side for this question.

Things that are changed in OFDM.grc:

  1.  The OFDM allocator block: The sync word. It is changed as per the rule of 802.11n. That is, we use preambles (STF/LTF…)
  2.  Made two exact same chains (just copying one flow), which previously was one, and fed into USRP-2 input ports.
  3.  Sampling rate : 20 MSPS

Problem :

  1.  Overflow occurs. (I am using USB 3.0 interface, on MAC). Two of the interfaces connected with this same laptop. Max sample rate it can handle is about 4MSPS.

I have tried saving the files in the RAM and then transmit. Does not improve the situation much.

Need suggestions on where should I look for the fix.

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