Strange CSI.Rank with Exynos

Hi Experts,

I’ve found that Exynos based phones are reporting rank with strange behavior in clean rf channels. I’m testing with 4t4r gnb with csi-rs configured as 4t4r,
We are typically testing with type1-SinglePanel-riRestriction = ‘00000011’
However, with this setting the handsets report rank1 when DL traffic is minimal. Then it reports a steady rank2 when full-buffer traffic is present. CQI remains 15 the entire time. (other chipsets are not doing this)

When testing with type1-SinglePanel-riRestriction = ‘00001111’ in the same channel,
regardless of DL-traffic, the handset reports mostly (rank, CQI) = (2, 15) with a flickering of (4,15). The CQI never changes but the rank flickers.

These results have been verified by NEMO.

Has anyone seen this bevavior?

Maybe it’s too close to the antenna. If the antenna of the gNB is in line of sight with the phone and very close, there is interference between ports, which causes low rank. Try to move away from the antenna or get some obstacles between the antenna and the phone.

I’ll watch for this, thanks. It could explain some sensitivites, but shouldn’t explain the difference between the ri-restriction settings, or the difference between DL traffic types. Also, the behavior I’m seeing is very repeatable even after swapping phones in and out it and only seen on S21 and M33 Exynos (not observed on qcom phones). I’ll pay closer attention to orientation and proximity to antennas.

Just want to add a data point here. The channel in this case is expected be rank 2 with CQI 15. Qcomm phones are reporting this consistantly regardless of ri-restriction or DL traffic type.