EN-DC and DSS

5G NR
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1

Hello!

Anyone know the difference between EN-DC and Coexistence (DSS)?

I know EN-DC is when you have a MCG which is LTE and SCG which is 5GNR. While DSS allows the LTE and NR to share the spectrum. Anyone have further insights?’

Thank you

2

ENDC is a user-based concept. There are 2 nodes (Lte Master node and secondary NR node) and at least 2 cells: min 1 LTE cell (Pcell) and min 1 NR(PScell). In order for the user to access the NR cells (SCG), the user must first connect to the LTE cell (MCG)

DSS is a cell-based concept. At least 2 cells from 2 different technologies use the same spectrum ( typically 1 LTE cell and 1 NR cell). Each cell has its own users. The schedulers are designerd to ensure no collision between the traffic of each cell.

The 2 concepts can exist together.

3

Thank you! A couple of more questions come to mind.

Question 1 for ENDC does RACH have to occur on the secondary NR node?
Question 2 Can the two cells in DSS use the same time frequency resources and possibly interfere with each other? ?

Appreciate your insights

4

  1. Yes, RACH to PSCell must occur

  2. No, each cell uses separate time frequency
    resources.

DSS is completely transparent to LTE users but NR uses must support some optional capabilities ( e.g. rate matching around LTE CRS)