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I use wl_example_siso_ofdm_txrx and wl_example_mimo_ofdm_txrx to run experiments on WARP nodes v3 with 7.7 bitstreams.
When I use node 1 as tx and node 2 as rx, I can run it successfully. Just when I swap the tx and rx, I got error
No LTS Correlation Peaks Found!
Again, when I iterate the code for 30 runs, for example, some iterations succeed some do not. This is a simple code I use.
% Set the number of experiments you want to do
exp_num = 30;
%final_results = zeros(1,exp_num);
for (i=1:exp_num)
% put function to loop here
pause(1);
wl_example_mimo_ofdm_txrx;
end
Note that I can do all of these (swaps and iterations) on wl_example_basic_txrx without any error.
I appreciate any help. Thank you.
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By default the wl_example_mimo_ofdm.m uses channel 11. Depending on your wireless environment (i.e. if there is a lot of wireless traffic on channel 11), this could be an issue. The example does not do any medium sensing before transmitting, so it could easily transmit while the medium is "busy". Try a different channel and see if you still have the same issue. Also, you could use the spectrogram example, or another spectrum analyzer (such as wi-spy) to get a sense of how busy the medium is.
The other thing to look at would be the individual paths between your antennas. You can modify the wl_example_basic_txrx example to use the different RF interfaces. Start with RF_A --> RF_A and get a sense of the signal magnitude and RSSI from the plots, then test the other combinations of both TX/RX and RF interface to see of one of the paths is very different (note, wl_example_basic_txrx uses fixed RX gains which might need to be adjust so that you get a good baseline):
Node 1 TX Node 2 RX RF_A RF_A RF_A RF_B RF_B RF_A RF_B RF_B Node 1 RX Node 2 TX RF_A RF_A RF_A RF_B RF_B RF_A RF_B RF_B
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Thank you. When I changed channel from 1 to 11, it worked fine, although I still occasionally found No LTS Correlation Peaks Found!
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