5G PDCP used even after 5G SCG Failure

[eta004]

HI Experts,

Any idea about the logic for PDCP entity selection ie 5G PDCP or 4G PDCP in ENDC network?
I can see cases where even after 5G RLC/MAC/PHY layer is failed due to SCG failure still the PDCP entity used after the failure is 5G NR PDCP .
Any thoughts on the same?

Rgrds
eta004

[liana]

Hi,

Option 3x network which is having X2-U between MCG & SCG can support that.

BR

[eta004]

Hi,

Option 3x network which is having X2-U between MCG & SCG can support that.

BR

Hi Liana

Yes I agree in option 3x we can have 5G PDCP and in Lower layer can be LTE or 5G.
My question is Will 5G PDCP be used even if the 5G Physical link is failed and the gNB knows it.

Or in another sense, is the PDCP allotment truly independent of the underlying condition of the Lower Physical layer?

BR
eta004

[ghoulhades]

PDCP probably reporting commonly for NR and LTE. Do the values align with LTE other layers?

[Ping]

HI Experts,

Any idea about the logic for PDCP entity selection ie 5G PDCP or 4G PDCP in ENDC network?
I can see cases where even after 5G RLC/MAC/PHY layer is failed due to SCG failure still the PDCP entity used after the failure is 5G NR PDCP .
Any thoughts on the same?

Rgrds
eta004

Hi eta004,

You should check Chapter 7.7: SCG/MCG Failure handling, 3GPP TS37.340
After UE detected that it losts connection with SCG 5G Cell, it will notify to MCG 4G Cell via message "SCG Failure Information". In this message, UE will send measurement information of SCG 5G Cell and other beams of neighbour 5G Cells.
>>> Base on the measurement report, MCG 4G Cell could request UE to:

[1] Re-establishment connection and sync with SCG 5G Cell
>>> In this case, PDCP and RLC must be re-establishment. You could check PDCP entity re-establishment in Chapter 5.1, 3GPP TS38.323

[2] Release connection with SCG

[3] Change SCG, UE will leave the connection with old SCG 5G Cell and add a neighbour 5G cell to be new SCG.

I think the case that you talk to, is case No 1: Re-establishment connection and sync with SCG 5G Cell. In this case, PDCP entity is kept, but must be refresh in re-establishment procedure.