4x4 MIMO USRP-rio

[yglee1096]

Hello

I'm trying to simulate transmit signals with 4 antennas in two USRP-rio devices.

But I don't know what should I do to synchronize with the 4 transmit antennas.

(labview, cable connection and related examples ... )

If you have any idea for the issue, please tell me anything.

Thank you for your kindness in advance.

Best regard,

Lee

[Victor.F]

Hello there

You can start by launching the NI-USRP Multi-Device Synchronized Simple Streaming sample project via New>Project in LabVIEW

Then once the project opens, have a look on the provided documentation. Make sure you set it up as described, especially:
"If synchronizing with PPS Trig, wire the PPS TRIG OUT from one device, the master, to the PPS TRIG IN of all the devices (including the master). An Ettus Research OctoClock-G is the recommended solution to connect the PPS TRIG lines.

Note   Due to the output voltage levels, an additional amplifier is required to connect the PPS TRIG OUT of the master NI 294x/295x to the OctoClock or other NI 294x/295x devices."

Also, you'll be able to get +-1/2 sample clock sync. If you want less than that, then you'll need to calibrate your setup.

Let us know how it goes.

Bye

[muffin.vi]

yglee1096,

As Victor.F mentioned, you'll need some hardware that will let you distribute a 10 MHz reference clock and a Pulse Per Second (PPS) signal. The Octoclock-G or the CDA-2990 with GPSDO will work for this. It's important to have the GPSDO because it will allow you to generate a 10 MHz and PPS signal internally in the clock distribution accessory. That way, you simply need to use match-length SMA cables to connect the 10 MHz and PPS outputs to the respective inputs on the USRP RIO. Then, you will need to set the software to reference these signals rather than the clock internal to the USRP RIO. 

[True_Boombo]

Hi Victor,

It is goog to know that an amplifier is required between PPS out and OctClock.

Could you further point out which amplifier is recommend here?

Thanks a lot. 

Cheers,

Bo

[brooksprumo]

I answered a similar question to this, Bo. See if my reply helps you.

http://forums.ni.com/t5/USRP-Software-Radio/how-to-synchronize-multiple-usrp-rio-294x-devices/m-p/31...

[True_Boombo]

Cheers, Victor 

I am using the clock configuration as described in the link. 

Thank you. 

[Patricioa1]

Hello my friend, did the  4x4 MIMO ?
I can help with the Labview software or the parameters I use because I am doing a 4x4 MIMO system with OFDM but at the reception I only get noise at the reception.

[figther92]

anyone share with me a VI with Implementing 2x1 MISO system with LabVIEW and NI USRP 2921?? I need problem with the estimation channel in the receptor, i used the alamouti code with 2 antennas trnasmitter and one antenna receiver.

[True_Boombo]

Glad to help, rather sending you a VI code directly. Because any USRP related VI code corresponding to specific hardware configuration. The "ready meal" works for other people may not work in your case.

So, I think the first step for moving on is to confirm the hardware configuration:

1. how many 2921s you are going to build your 2X1 system?

2. what sync method you are using?

3. Is your sync only for 2 transmitting channels, or for all channels (2 transmitting and 1 receiving)  

You said that you have the problem on channel estimation? Does it mean that you already sort you the USRP related hardware problem, not focus on pure signal processing problem? As far as I know, either alamouti decoding or channel estimation is pure software problem, is not related to hardware. 

I think you need to describe your situation in detail (very detail), otherwise, it is very difficult for other people to help.

Cheers,

Bo 

Cheers,

Bo