I have query: without CSI-RS config IE in RRC connection reconfiguration message any impact on tm9?
Will it work or not?
there are 2 configurations related to TM9 (PMI feedback independent and feedback dependant on PMI)
1- TM7, TM8, or PMI feedback-independent TM9 (like an open loop), the eNodeB determines the downlink channel characteristics based on sounding reference signals (SRSs).
2- In PMI feedback-dependent TM9 (like a closed loop), the UE estimates channel quality based on channel state information-reference signals (CSI-RS), and then provides channel state information (CSI) feedback to the eNodeB.
in your query, you are referring to case 1 where SRS is sent by UE and the EnodeB assigns the beamforming to UE by weighting channel quality.
however, in both cases, TM9 can still be used.