LTE-U Frame Timing

[ctarver]

In the LTE-U/LAA Application Example, "LTE_WIFI_coex_2_0_1_RC1_20170629," I have been running tests using an oscilloscope. In particular, I watch the RF signal with the "Start of Frame" pulse on the AUX I/O port. 

I've noticed that in the LTE-U mode, a new frame starts every 12 ms instead of every 10 ms. Is there a reason for this? 

This change seams to be in the host VI. Inside the "LTE Setup TX.gvi" block, the TX start trigger count is changed from floor(DataClockRate/100) to 1200000 (which seams to align with the 12 ms I measured on the oscilloscope.

Also, the "processing delay" port to the "LTE Compute TX Trigger Offset" block is changed from 17230 to 17250. Any explanation for the addition of 20 cycles? Is there an extra 20 cycles in the TX IQ path for the LTE-U/LAA FPGA design? 

Any insight on the frame timing/TX triggering mechanism for the LTE design and LAA design is appreciated. 

Thanks!

-ctarver

[AirFrantz]

Hey ctarver,

I'm an Applications Engineer here at NI, and I'm currently looking into this issue for you.  I'll let you know what I can find out after consulting some of my resources.

Jon

Applications Engineer

National Instruments

[AirFrantz · Accepted solution]

ctarver,

Sorry for the wait on this.  Our team for this app framework made some changes to the 'LTE Setup TX.gvi' that should fix this behavior.  If you implement this, the frame rate should be 10ms.  There are a few other updates that were unrelated that should also increase the performance.

Let us know if you have any questions!

Jon

Applications Engineering

National Instruments

[melahi]

Hi,

I am trying to test the LTE/Wi-Fi Coexistence from the following link. I can't seem to find the edits suggested in the LTE framework. Can I have the code that implements the LTE LAA?

https://www.ni.com/en-us/innovations/white-papers/16/real-time-lte-wi-fi-coexistence-testbed.html