Hi experts,
Could anyone provide insights on how the gNB applies the PMI in the case of 3-layer transmission (RI = 3)?
Additionally, if the PMI is not applied correctly, could it lead to increased BLER in the system?
In this case, the gNB applies the CSI report (RI, PMI, CQI) as received.
However, for PDSCH requiring retransmission, it should use layer 4 (RI = 4) specifically for the retransmission. Meanwhile, any new data on the PDSCH will utilize RI = 3 as per the latest report.
So, let’s say during Link Adaptation (LA), after a certain RSRP level, if the CSI indicates RI = 3 instead of RI = 4, will the gNB adjust its matrix calculation accordingly?
Are there ways to analyze in detail whether the gNB is behaving correctly based on the PMI reported by the UE?
As per my understanding, the CSI bits can help identify this.
For example, in a CSI report with a total of 12 bits:
- The first 3 bits represent the RI (for up to 8x8 MIMO).
- The next 5 bits represent the PMI.
- The last 4 bits represent the CQI.
Based on the RI value, the PMI value will change, which means the corresponding bits in the CSI report will also change accordingly.
Yes, that’s correct.
However, for RI = 3 or 4, does the gNB use the Type 2 Enhanced Codebook system for PMI computation, or is there a specific system in place for PMI computation when RI = 3?
I’m not sure about that either.
I’ll check and let you know if I find any relevant information.