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Dileep Karwa Kumar
Posts: 7
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testing 802.16a using PXI 5660 and 5670

I am trying to implement 802.16a on PXI modular instruments. The code was developed on labview by a Research group in University of Texas Austin.

http://zone.ni.com/devzone/cda/epd/p/id/3954

I want to modify this code so that it works on PXI modular instruments. I am using 5660 as RFSA and 5670 as RFSG on PXI 1045 chasis. I have studied the help of RFSG and 5660 that comes with the instruments and I have also studied examples. However the problem I am facing is that in this code after applying pulse shaping to the symbols I dont know how to transmit and receive them. I ll be very grateful if someone tells me the programming flow and what exactly I have to do to make this code work on hardware.

 

I plan to do research on latest WIMAX standards after this.

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Sarah_Y
Posts: 242
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Re: testing 802.16a using PXI 5660 and 5670

Hi Dileep,

 

To receive this, you will need to work through the examples for the 5660 and the OFDM modulation scheme to write code that will downconvert this signal and demodulate it.  Unfortunately, I have not found an example that does OFDM demodulation.  This process will be very tedious without the Modulation Toolkit.  Do you know if you have the Modulation Toolkit?  If not I recommend that you see if purchasing a copy of it is feasible.  In the long run it will save you a significant amount of time.  We also have a WIMAX toolkit that could be helpful if you are doing a lot of work with WIMAX.

 

As far as sending the OFDM signal out of the RFSG device, you will need to go through the example and change the array of data into real and imaginary parts, which will be your I and your Q data.  You can find this data by looking at the OFDMModulator0423 subVI.  Then you should see this:

2012-03-12_164058.png

You need to take the orange wire coming out of the QAM Map subVI and change it to real and imaginary parts.  That will be the data that you want to send to your RFSG device.  However, if you have Modulation Toolkit, there is another example online that already has the data in the correct format to be output to a VSG.  You can find that example here:

 

http://zone.ni.com/devzone/cda/epd/p/id/5152

 

Another important thing to remember is that the 5660 and 5670 only work up to 2.7 GHz.  I'm not sure what your frequency range will be, but that is a limitation of that hardware.

 

Hope that helps and let me know if you have any more questions.

Sarah Y

Test Engineer
Ettus Research
Member
Dileep Karwa Kumar
Posts: 7
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Re: testing 802.16a using PXI 5660 and 5670

i have made the code that transmits complex waveform. The problem that I am facing is that when complex waveform is transmitted, the receiver is not synchronised and it also takes empty samples. I just dont know how to synchronize them .

Active Participant
Sarah_Y
Posts: 242
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Re: testing 802.16a using PXI 5660 and 5670

Hi Dileep,

 

I am a bit confused as to why you would want to synchronize the transmit and the receive.  If you are trying to do real world testing, the transmitter and receiver typically aren't synchronized.  There are usually sync bits that are sent out as the first few bits of the data that is being transmitted, and this is what the receiver uses to help it lock to the signal before demodulating it.

 

If you do want to synchronize these devices, sharing a sample clock and a trigger will be the best option.  

Sarah Y

Test Engineer
Ettus Research