Hi, Recently, I have started playing with the Matlab WLAN toolbox. So far, I have managed to generate a waveform of 802.11n frame, transmit it using USPR x310 with UBX-160 daughterboard and successfully receive the frame using commercial-off-the-shelf (COTS) hardware - Intel Wireless-AC 9260 NIC. The setup also works perfectly when using USRP B205mini.
However, when I transmit the waveform using CBX-120 daughterboard (in the same x310 USRP), is not received by the COTS Intel NIC. I want to play with MIMO and I need to use CBX-120 daughterboard as we have 4 of them and only one UBX-160. I tested all of our 4 CBX-120 daughterboards with the same result. I use exactly the same command in case of CBX-120 and UBX-160 (both in same x310 USRP so I change subdev parameter), ie.: ./tx_samples_from_file --args="type=x300,addr=192.168.10.2,master_clock_rate=200e6,dboard_clock_rate=50e6" --subdev A:0 --type=short --rate=30e6 --freq 2412e6 --gain=25 --repeat --delay=1 --file 80211n_waveform.dat I have noticed that Connection Type is different in the case of CBX-120 and UBX-160, i.e. IQ vs QI, and generated waveforms accordingly in MATLAB, but without success. I connected USRP RF outputs to WiFi NIC using RF cable (with 45dB attenuation), but still, the same effect, i.e. UBX-160 works, CBX-120 does not work. In the case of UBX-160, the RSSI of the received frame equals -55dBm (as reported by NIC), so it is still a pretty good link. After running the calibration procedure (as described here https://files.ettus.com/manual/page_calibration.html), the CBX-120 started working somehow, i.e. some frames are received but not really reliably (only few out of tens transmitted frames are received). In the case of UBX-160, all frames are received correctly (of course over the cable). The frame is generated with MCS 0 (BPSK, and code rate 1/2), so it is very robust and can be received with SNR of 3dB. I have tested also a couple of the UHD versions and hence FPGA images, but with the same result. Can someone explain what is the difference between CBX-120 and UBX-160 daughterboards that cause the described behavior? Should I set some more parameters to overwrite default ones in the case of CBX-120 to achieve better results? Best Regards, Piotr Gawlowicz
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