Check PMI value reported by UE from logs or counter at eNodeB end

4G LTE
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1

Hi LTE Experts.

Is there any way to check PMI value reported by UE from logs or counter at eNodeB end?

For 4x4 MIMO UE will report RI = 4 if radio conditions is good, i.e. each layer having good SINR measured by UE.

Please tell for 4x4 will UE report CQI for each layer individually?

As per understanding for LTE we have 2 CW Max so need more clarity

2

Consider CQI as something like saying that for codeword 0 I am expecting to be able to decode transport block of size X at MCS Y within a bler of 10 percent.

Hence CQI is not reported for individual antennas as transport block is basically coded via the Codewords.

We have only 2 defined so CQI is reporter for max 2 CW no matter you use 4 layers or 8 in the downlink (Tm9 like BF).

3

Thanks!

So for 4x4 it’s like cw0, cw1, copy of cw0, copy of cw1 on 4 layers.

Now RI reported by UE, i.e. RI = 4 depends on radio conditions and data to be scheduled in buffer of eNodeB …is it correct?

Also please can you tell how can we check PMI reported by UE considering closed loop MIMO used?

4

Check the UCI message, there you can find the CQI, PMI, RI values, since data is ongoing you can first check PUSCH message then check PUCCH message.

5

No, if we just do an exact copy of the cw0 and cw1 and map it to 4 layers, then essentially we are using only 2 layers in a sort of transmit diversity arrangements.

For 4 layer transmission, we have 2 Codewords which should be mapped to 4 layers so we essentially take some data from each cw and map it to individual layers. This is why 4 layer transmission can increase the data rate.

The equations for this mapping is defined in 36.211 section 6.