Implementing 1x2 SIMO system with LabVIEW and NI USRP 2930

[fatielb]

Hello everyone,

I am just new with USRP, that's why I need your help. I have two ni USRP 2930 and I want to implement a 1x2 SIMO system. Is it possible to do it using only two USRPs ? I am thinking about configuring the transmitter in one USRP (TX1) , and configuring two receivers using the MIMO cable (as shown in the attached figure).

Thank you for your help.

[Shalini.M]

Hi,

You should be able to use the 2 USRP 2930s in your picture plus the MIMO cable and modifying an existing 2x2 MIMO example to implement a 1x2 SIMO system. We have a white paper that explains how to build a 2x2 MIMO system using 2 USRPs: http://www.ni.com/white-paper/13878/en/

[fatielb]

Thank you for your reply.

According to the white paper you sent to me, in order to be able to implement a 1x2 SIMO system, I have to have 3 USRPs, unfortunately I only have two, could it be possible to do it with only two USRPs ? (using the implementation in the attached figure above). 

[psisterhen · Accepted solution]

In theory  you could use 2 USRPs, with one doing both Tx and Rx simultaneously, and the other just doing Rx.  You would have to modify the code from that white paper a bit.

Some issues you might face, though:

• The Tx and the first Rx would be right next to each other (same device) and the Tx and the second Rx would also be close (separated only by the MIMO cable distance).  So you may not get the spatial diversity (the benefit of MIMO) you are looking for.
• Since you will be sharing Tx and Rx bandwidth on the same bus, you may not be able to keep up at the IQ/streaming rates you want.
• I think there was a minor bug where you would have to add both devices to the Tx session, even though you are only using one.  So open the sesssion with both IP addresses, but only enable one channel and it should work fine.

[psisterhen]

Also, that example assumes two Tx channels in order to perform Alamouti encoding.  You would need to remove the Alamouti part from this example if you had only 1 Tx channel.

[fatielb]

Thank you for your help.