How do I know the matrix of a pmi index?

Specs & Protocol Testing
1

Hi All.

I see pmi index is 1540 with 4x4 mimo layers and ri 4.
What does that pmi index mean?
How do I know the matrix of that pmi index?

2

It also depends on codebooktype 1 or 2, on number of csi-rs ports.

Only then you will know what PMI means based on 3GPP tables.