PDCCH downlink blocking after enabling DSS

5G NR
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1

Hi All,
Anyone have observed PDCCH downlink blocking after enabling DSS? (5G NSA)

2

I also heard that DSS activation has a very bad impact on LTE, and MNOs are not happy with it.

3

PDCCH blocking and DL Throughput affected…
Throughput we can understand, but why blocking?
Is it because we can only use 2 PDCCH symbols in a subframe allocated for NR?

4

Do you have PDCCH rate matching enabled in NSA?

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There’s a good DSS that explains how to avoid colission between NR PDSCH and LTE PDCCH:

5G NR Dynamic Spectrum Sharing Drivers & Test Implications - Project Manager / Keysight Technologies - Alex Liang

5

Do you have LTE PDCCH symbol allocation static (3 symbols) or dynamically allocated?

6

Dynamically allocated.
But what I know is: in the subframe assigned for NR, we can still use LTE PDCCH, but limited only to 2 symbols not 3.
Do you agree with above satatement?
If yes then can this be the reason for increase in blocking?

7

This might be the issue: when dynamic allocation of LTE PDCCH uses 3 symbols it may get in conflict with NR PDCCH or NR PDSCH.
This would not happen if 2 symbols or 1 symbol is used for LTE PDCCH static.

8

No, but by specificatin we can use only 2 symbols for LTE PDCCH in MBSFN subframe.