For a low DL Throughput case - UE is reporting rank 1/2 mostly, in 4x4 environment but only in ENDC Enabled case - while ENDC Disabled it is fine.
Other parameters such as PUSCH SINR, CQI and MCS is fine and perfect.
Does anyone know under what circumstances UE can report lower rank?
With real UE or simulator?
Check your PDCCH DL grants count & PDSCH RB numbers per slot // RANK issue mainly due to scheduling issue (for example, multiple users available for scheduling at that particular time or scheduling error etc) or the transmission have packets loss cause the upriver data not coming enough.
Also check your handset capability issue for example few handset not support multiple LTE 2/3xCC combination with in ENDC scenario. Few handset face issue in SRS switching for particular NR band
These you can check in RRC UE CAP info during gNB addition req.
Another thing to check as you mentioned thp is fine after ENDC disable, this may also suggest, your LTE side could be congested can cause issue in NR split/SCG suspension. Check your DLSplitTraffic also.
Also check flag switch mode, this parameter sets the TM mode on the basis of UE’s channel characteristics and antenna configuration of eNB, check if it is set as TM3 or TM4 intra transmode adaption or fixed RI, it will also cause in excessive attempts of RI1.
The per TTI PRB Allocation for 20 MHz BW is very good approx. 96 on average. Also, there is only one UE (One Plus 8) that we are trying with our eNB Software in lab environment. So congestion and traffic rules out.
I can see RRM setting the TM4 but I have doubt since max Layer MIMO (which should come as Four Layers) is not being configured by RRM. I think this is the root cause of this issue. Will check it further. Thanks for replying.
If you have n41 band. OnePlus8T only supports 22 with band combination with n41. Though its supports 44 in n78. Your band might be n41 i believe in this situation.
The scenario that I speak of here is for LTE, 5G NR channel is attenuated or the UE setting is chosen to “4G LTE Only” mode so that UE falls back to LTE in NSA scenario. I will need to find out the LTE Band but it is certainly for 20 MHz BW in 4x4 scenario.