Why RFmx Is Showing Warning 685002 When I Enable The I/Q Impairment For WLAN 802.11be MRU Analysis?

Updated Dec 22, 2023

Reported In

Software

RFmx 2023 Q2

Issue Details

When I enable the I/Q impairment in RFmx for WLAN 802.11be MRU analysis, the following warning 685002 will be shown in RFmx soft front panel:

Is the current version of RFmx 2023 Q2 does not support WLAN MRU analysis yet?

Solution

IQ Impairments Correction is not supported for partially occupied (in frequency; examples include MU PPDU 3x996 case like you've configured) signals, for all standards.

The error is thrown and that is what user will be seeing. This is an expected behavior. In general, IQ impairments estimation/correction in transceiver testing is sufficient to be done on single-user fully occupied signals. Using partially occupied signals doesn't add any value to the test per se. That is what NI have been recommending and it has been pretty standard across the industry.

Additional Information

In the use case of Frequency Dependent impairment, there are available feature (in API and RFmx SFP), namely subcarrier estimation. Configuration and result traces shown below. It also applies for fully occupied signals. This can be used to analyze the IQ impairments introduced per-subcarrier and hence any chunk of subcarriers also (thereby mimicking an RU/MRU).