RLC mode when creating the QoS flow for 5QI-5 for SIP signalling

Hi Experts.

When creating the QoS flow for 5QI-5 for SIP signalling, what kind of RLC mode needed to be selected in the CUUP bearer context setup: Ack Mode (AM) or Unack Mode (UM)?

My understanding is that we would need UM.

But need some confirmation.

What do you face?

Mean do u face any issue ?

Do you want to pump high data on 5qi 5?

I don’t. This is new arena for me. I am designing the VoNR call flow (including for IMS signaling).

I just want 5qi-5 flow for SIP signaling.

Sip signalling doesn’t needing UM.

UM generally for high data pumping.

AM is enough.

For 5QI-5, similar to CQI-5 in LTE, you would need AM as it is the SRB.

For 5QI-1, you would need UM as you need to have a GBR Bearer.


For 5QI-1 for media VoNR, my understanding is that RLC mode can be both UM and AM.

It is not mandatory to be UM.

If you keep it AM, it will not perform well as per voice qos requirements because of packet retrans and ordering.

Yes right. Many operators use AM for voice in India.

In indian networks, packet loss is major concern than pcket delay hence AM is useful.

In general any flow/ bearer with packet error rate requirement of 10^-6 should use RLC AM

1 Like