Can anyone tell me what does PMI i(2, 1) indicates for 5G beams?
This PMI i(2, 1) indicates or mapped to the EL(elevation) axis in AODheatmap(AZ & EL).
There is calculation for this and have several vales for EL based on the N2O2 antenna ports(CSI-RS).
Note: PMI i(1, 2) actually… if I am not wrong.
My 50 cents…
PMI (together with CQI and RI) in LTE and 5G are used in link adaptation to update the modulation and the coding scheme and the format of each transport block TB:
CQI is Channel Quality Indicator.
PMI stands for Pre-coding Matrix Indicator.
And RI is Rank Indicator.
These three values are computed on the fly in LTE/5G NR systems and used to try to optimize resource allocation among the various user end devices (UEs) that are requesting service.
More efficient use of resources means that a system can serve more users at once. Therefore, it is highly desirable that the values reflect as accurately as possible the quality of the LTE access channel, that is, the accuracy of the transfer of bits in each direction over the wireless (RF) channel.
Constraints on the processor power available to compute these values and constraints on the length of time the values remain accurate (ie, limits to the delay in getting a value) make it difficult to optimize resource allocation.
The computation becomes more complex if the UE is moving, since the RF conditions will change as the user moves and will changes faster the faster the user moves (walking vs driving, say).
There are different proposals for computing these values, and you should refer to the appropriate LTE/5G NR standard or one of the various papers that describe methods of computation for more information.
No i am talking about PMI i(2 ,1).