In what situation does a UE go through closed loop MIMO and when does it go through open loop MIMO?

RAN
1

Guys, in which situation UE goes through closed loop MIMO, and in which goes through open loop MIMO ?

2

Open loop (TM3) and closed loop (TM4) can’t be configured on the same cell at the same time.

A cell can either be configured with TM2+TM3 or with TM2+TM4.

UE goes to TM3 or TM4 (depends on cells configuration) if:
SINR is greater than 15 AND Signal orthogonality has been achieved

3

Ok, as I know the main difference between TM3 and TM4 is PMI, what is the added advantage of PMI to the performance or throughput

4

The PMI contains several values, each on to instruct the eNodeB to change the phase of one of the TX signal to achieve signal orthogonality.
The UE helps the eNodeB to achieve signal orthogonality and thought the throughput.

It’s suppose to get higher throughput in DL but in the UL there’s a high signalling over head…so resources in UL is decreased.

5

Nice explanation bro, thanks :+1::+1:

6

High over head in UL why? Due to closed loop ?

7

does it contain several value even in mimo2×2?

8

Because you need to report the PMI in UL beside the other controls

9

Yes, due to closed loop

10

I am not sure, let me check.

11

OK. thanks😘