Reasons for poor UL RSSI

Hi LTE Experts.
What can be reason for poor UL RSSI value other then high overlapping or vswr issue if not there?
What can be other reasons?

Configured P0_nominal may be verified.

Ya good point dear. Do you mean open loop power control?

Yes, exactly.

PIM could be another major reason…

You may check below, some of my expert friends have already highlighted.

Do you receive close to equal power at all antenna ports on the site? If difference is significant, may indicate towards something wrong with installation.

Ponominal PUSCH and P0 nominal PUCCH and alpha.

PIM interference, that has to be considered along with all opeartors band existing over same tower.

UE Max TX power setting

While you check all above, am sure you have checked your hourly OSS statistics already, which rule out it is also higher during non traffic hours.