In order to check MIMO mode in use during a DT which parameters do I should inspect?
Transmission Mode + rank + Antenna ports?
The need is to verify operation in MIMO 4x4, 2x4, 4x2, etc
It is depend on your Mimo configuration but usually the Rank + CQi is enought
If closed loop mimo are used you can use the PMI also
In RRC reconfig message check TX antenna ( for number of DL antennas)
You can check rank indicator, but as far as I know during DT you can only check how much your UE is receiving from downlink. We can assume the MIMO config but we also need to be familiarized in the configs that are existing in the network and we can conclude like for example, 1; = SIMO, 1< 2; = 2x2, 2<=4; =4x4. The upper-mentioned values are concluded as per the existing MIMO config based in the network Im working with. We dont have 3x3 MIMO here so the range 2<=4; =4x4. You can also check in L3 messages.