LTE: Does the eNodeB change transmission mode per TTI for an user or it can be semi-static?

Question

On what parameter basis, eNodeB changes its current transmission mode to different transmission mode for an UE ?
What parameters are considered to take decision on transmission mode ? Does the eNodeB inform to UE about the selected TM ?

Answer 1

Based on RI indicator eNodB will take decision.
i.e if eNodB in tm4 mode and using spatial multiplexing and current TTI UE reported RI=1 then it will change transmitting mode spatial multiplexing to transmit diversity.