Did anyone succeed in building MIMO with USRP2?

Hi, all

I have read a lot from the mailing list. And I know that we can use the
reference clock to lock the clock on the USRP2, then use the command
config_mimo() and sync_to_pps() to synchronize the USRP2s.
I want to ask that how to use the timestamps to synchronize the data
since the m-block is discarded.
Would anyone succeed in building a 2*2 MIMO with USRP2 using the
reference clock?
Would you give me some details of building that?

Thanks a lot.