Does 5G always uses Closed Loop Spatial Multiplexing for PDSCH based on DMRS?

5G NR
1

Hello Experts,

  1. Is it correct to mention that 5G always uses Closed Loop Spatial Multiplexing for PDSCH based on DMRS?
  2. Have anyone seen 2 Codewords used in cases greater than 4 Layer MIMO transmission?
2

In 5G 2 codewords are needed for 5-8 layers of an UE.
There are no UEs that support this now.
Max 4 Layers per user.

3

Hello @eta004,
5G uses both precoding matix indicator (closed loop) as well as SRS based feedback to take advantage of TDD reciprocity.

As my friend also suggested, there are only max four layers SU MIMO for 5G now, only two code words allowed as of now.

Hope this helps, thank you.

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