5G VONR configuration parameters

5G NR
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1

Hi, any one having 5g Voice over what are the parameter need to be configured and how do VONR work

2

Hi,

Voice service triggered by the PDU Session Modification procedure, that is handled with EPS Fallback feature, which sends the UE requesting for a voice QoS flow with 5QI=1 to LTE from NR.

New parameter introduced to handle this, called “EpsFallbackOperation” to control the EPS Fallback operation on cell level.
The gNB checks this parameter after receiving the NGAP: PDU Session Resource Modify Request message with the request to set up a new QoS Flow with 5QI = 1.

EpsFallbackOperation (NRCellCU in GNBCUCPFunction)
:black_small_square: 0 – Inactive (always use VoNR)
:black_small_square: 1 – Active (EPS Fallback available for UE not supporting VoNR)
:black_small_square: 2 – Forced (always use EPS Fallback, default value for E//)

Few details to remember always.
- VoNR triggered if (EpsFallbackOperation = 0) or (EpsFallbackOperation = 1 and UE capable of VoNR)
- Otherwise, EPS fallback is triggered
all these depends on the UE Capability and MOM configuration in NR RAN.

However It’s possible to monitor the success rate of this procedure for the support of voice call setup in NR RAN, below are the KPIs to be monitored for the same.

  1. PDU Session Modification SR
  2. DRB Retainability Percentage Lost per mapped 5QI
  3. DRB Retainability Percentage Lost per mapped 5QI, gNodeB triggered only

PDU Session Modification SR :
pmPduSessionModifySucc / pmPduSessionModifyAtt * 100 [%]

DRB Retainability Percentage Lost per mapped 5QI:
(pmDrbRelAbnormalGnb5qi + pmDrbRelAbnormalAmf5qi / (pmDrbRelNormal5qi + pmDrbRelAbnormalGnb5qi + pmDrbRelAbnormalAmf5qi)) * 100 [%]

DRB Retainability Percentage Lost per mapped 5QI, gNodeB triggered only:
(pmDrbRelAbnormalGnb5qi / (pmDrbRelNormal5qi + pmDrbRelAbnormalGnb5qi + pmDrbRelAbnormalAmf5qi)) * 100 [%]