Data transmission to UE after issue in gNB NSA Option 3x

Experts, doubt: in NSA Option 3x, if I have a problem in gNB side (after SgNB Added), will I keep continue receiving data on the UE only the eNB?

SCG split bearer


Yes you can get it all the data may be directed to LTE side via sGNB split bearer.
This is what exactly happened in QCI1 in a VoLTE call in option 3X.

Humm…very strange because during a problem I have with PSCell Change (Inter SgNB change) I can’t use data on the device.
Should use 4G as you said.

If you have issue at gNB you will see data stall on device, even though there is data sent on LTE side, in typical deployment PDCP is on NR so you will see data not flowing beyond PDCP on gNB side and not reaching the Server.

I was confused, I have two different answers:
Will I have data in the UE or not? :wink:

See your Split Bearer is configured at gNB that so even though the data is coming from LTE it has to flow through gNB PDCP and most likely data stall will happen if there are missing packets from gNB.

I’m realizing this scenario with me in a place where I have a problem with PSCell Change (5G->5G) failure.
My data stops during this problem.

So, If a have a problem in 5G side I will not have data in the UE. Am I right?

What is the initial routing? Is it 5G or LTE?

You need to check PDCP config for each DRB, typically internet bearer is routed through gNB split bearer if 5G NSA is added.
VoLTE calls are usually added through LTE DRB only no split happens for VoLTE DRB.

If the gNB problem below PDCP, data will still be coming from LTE. However, if problem above PDCP, no data will be sent to UE

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