Re: [Discuss-gnuradio] How to implement MIMO transmissions

[Lara Deek]

Thank you Josh for your reply!

> Well in gnuradio, you dont have access to the send function.

I created a usrp sink using uhd_make_usrp_sink(), and using the pointer to
the multi_usrp that is returned from calling get_device() on the usrp sink
variable, I access send() (ofcourse including the necessary uhd libraries).
In fact, the method I use to access the send() function is the same as that
used in the gr_uhd_usrp_sink.cc work() and start() functions.

> The 
> scheduler will deliver two streams of equal length (from 2 ports). 

I use the uhd send() function to transmit data, as shown in
rx_multi_samples.cpp for the receiver, and I actually referred to
tx_bursts.cpp to implement the transmitter. Then I guess to control the data
[source] in the streams, I would have to transmit samples from a .dat file
(as done in tx_samples_from_file.cpp) using an ifstream, correct? Can I
avoid the gnuradio usrp_sink scheduler by doing this?

I also want to control when to use MIMO vs SISO, sometimes I only want to
use a single antenna/transmitter. I can't find a method to specify which
usrp/channel to use in send(). Is there a way to transmit on a single
antenna/channel in a MIMO setting? There's set_antenna() in gr-uhd
(set_tx_antenna() in UHD multi_usrp.hpp), can it be used to implement this?

Thanks again,
Lara



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