[Discuss-gnuradio] How to implement MIMO transmissions

[Lara Deek]

Hello,

I have a question about the details of transmitting using gnuradio. I
have set up a 2x2 MIMO transmitter using 2 USRP2's (or N200's) that
are connected via a MIMO cable. In C++, I initialize a single USRP
sink, and set the # channels to 2 (excluding the other settings).

I am currently using the uhd send() function to transmit data, and my
first question is: Does issuing a single send() function transmit
samples on both USRP2's simultaneously, to achieve MIMO spatial
diversity?

I also want to send different samples on each USRP2, to achieve MIMO
spatial multiplexing. Since the buffer that is passed to the send()
function is a vector, does specifying a vector of size 2, with each
vector holding different data, do the trick? In that case, to achieve
MIMO diversity, the 2 vectors would have to carry the same data,
correct?

Thanks,
Lara