5.7.2.5 Flow Bit Rates

For GBR QoS Flows only, the following additional QoS parameters exist:

• Guaranteed Flow Bit Rate (GFBR) - UL and DL;
• Maximum Flow Bit Rate (MFBR) -- UL and DL.

The GFBR denotes the bit rate that is guaranteed to be provided by the network to the QoS Flow over the Averaging Time Window. The MFBR limits the bit rate to the highest bit rate that is expected by the QoS Flow (e.g. excess traffic may get discarded or delayed by a rate shaping or policing function at the UE, RAN, UPF). Bit rates above the GFBR value and up to the MFBR value, may be provided with relative priority determined by the Priority Level of the QoS Flows (see clause 5.7.3.3).

GFBR and MFBR are signalled to the (R)AN in the QoS Profile and signalled to the UE as QoS Flow level QoS parameter (as specified in TS 24.501 [47]) for each individual QoS Flow.

NOTE 1: The GFBR is recommended as the lowest acceptable service bitrate where the service will survive.

NOTE 2: For each QoS Flow of Delay-critical GBR resource type, the SMF can ensure that the GFBR of the QoS Flow can be achieved with the MDBV of the QoS Flow using the QoS Flow binding functionality described in clause 6.1.3.2.4 of TS 23.503 [45].

NOTE 3: The network can set MFBR larger than GFBR for a particular QoS Flow based on operator policy and the knowledge of the end point capability, i.e. support of rate adaptation at application / service level.