What is Switching Mode in LTE?

Dear Experts,
What is Switching Mode in LTE?
What is difference between TM3 Intra-TransMode Adaption & TM4 Intra-TransMode Adaption?

TM3 is open loop, TM4 is closed loop.

What is the difference between them?
And what is best for LTE in term of payload and throughput?

In TM3 UE do not report PMI.
For TM4 UE report PMI and its better in terms of throughput.

Basically eNodeB having more accuracy about channel conditions with PMI in TM4.
Apaart from CQI, RI.

Also to add, TM4 is recommended in normal/low mobility areas.
TM3 is recommended in high speed areas (highways).

Yes, true.

Fast MIMO Switch can be used.

I think no such parameter in ZTE.

Can payload increase to activate TM4?

Not sure for payload increase (as not seen).
But throughput gain there.

Payload in the packet is not affected, the change is mainly on the physical layer, upper layers are not affected in term of traffic increase related to the change.
Throughput increase.
Same traffic (video download for example) is downloaded but in less time (higher Throughput).