N210 MIMO

[Tarang]

Hello Kaosun, James and Erik,

I have done a setup for 2x2 MIMO using the information provided in https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x2rKCAQ&l=en-US and I am getting the same error as Kaosun.

The errors: "Invalid input symbol array; Input symbol array is empty."

Can you please help me?

Regards

Tarang

MSc. Telecom student

(Middlesex University)

[Tarang]

Sorry I forgot to mention that I am using LabView 2013 (32-bit). I hope that is not an issue.

Regards

Tarang

[kevins33]

Hi Tarang,

What USRP are you using? Has your configuration ever worked?

[Tarang]

Hi Kevin

Thank you so much for replying so quickly. I am using 4 USRP N210 r:2.0 for a 2x2 implementation. I have successfully changed the IP addresses for the USRPs. when I open the LabView file, I have tried all the possible combinations of IP addresses in the transmitters and the receivers. But everytime I get the same error. I am unable to find out where I am making an error.

And no, my configuration has never worked.

Thank you

Regards

Tarang

[ErikL]

It sounds like mathscript or another math function is not getting data.  Is the order set to 2 channel MIMO?

Do simpler examples work?

[Tarang]

Hello Erik,

Thanks for replying. I do not completely understand when you say 'simpler examples'. But I tried to run the code using only 2 N210 modules in a 1x1 MIMO implementation. But it still gives me the same error. And again forgive me for asking but how do I check whether the order is set to 2 channel MIMO or not?

Thank you

Regards

Tarang

[xavvvv]

Hi Tarang,

NI-USRP also installs a series of pre-built examples that you can access to check if you're able to run anything in the first place. You can locate these examples at Program Files\National Instruments\LabVIEW 2013\examples\instr\niUSRP. I would recommend opening niUSRP EX Tx Continuous Async and niUSRP EX Rx Continuous Async. Try running these two examples first and let's see if you're getting similar errors.

To check for 2 channels MIMO from the example 2x2 MIMO QAM Alamouti, you have to interpolate from the IP Addresses (make sure there are two) and the Per Device clusters (make sure two are defined with one MIMO for the sources). This should be properly defined by default. Does the error point to a specific VI/subVI in the example?

Have you updated images to NI-USRP for your devices? (from USRP Configuration Manager)

Hope this helps!

[Tarang]

Hello Xavier G.

Thank you so much for replying. Well I took your suggestion and tried to run the examples and found out that the examples are running fine for both the transmitters as well as the recievers. and in the examples I put in the IP addresses so this means that my hardware is working fine.

But when I try to run the main programme it gives me the same error. It directs me to the diagram. when I tried to debug the code, I found that when I reach the block TX and RX with NI USRP the input suddenly becomes zero.

And it gives  me error input array empty. I still do not know the problem. But thank you so much as now i know that the hardware is fine.

Regards

Tarang

[xavvvv]

Hi Tarang,

Thanks for the update. When you mention that the input is suddenly zero, are you referring to the TX Waveforms input to the subAsyncMulti-ChannelTransceiver(NIUSRP) function, or another function? I would try probing the inputs/outputs of that array to see what happens to the data. If you can probe it in/out of a subVI and see that the input data is valid and the output isn't, we will be able to focus on that specific subVI/function.

Which clock source are you using - are you referring to an external clock or one of the USRP's internal clocks?

Hope this helps!

[Tarang]

Hello Xavier G.

I am trying to probe how you told me to. And for the clock I am not using an external clock as I am working on a 2 by 2 MIMO. And it states that for that configuration internal MIMO clock is enough. Do you sugggest me to use an external clock?

Regards

Tarang