Best antenna position to maximize MIMO layers for FWA CPE

Hi Experts.

General 5G FWA(Fixed Wireless Access) topic:

Before installing outdoor CPE (customer premises euqipment) antenna is there any research of particular antenna location in order to maximize the MIMO layers?

I mean it would be good to try different positions till rank4 will be achieved otherwise rank 2 is more common.

But do you guys do this in reality: search for an antenna position to maximize MIMO layers for FWA CPE?

I am asking because gNodeB antenna is fixed, CPE antenna is fixed.
Once installed in a rank 4 position it will always remain rank 4 position (unless objects like people/car moving will obstruct the multipaths).