5.7.1.2a Alternative QoS Profile

The Alternative QoS Profile(s) can be optionally provided for a GBR QoS Flow with Notification control enabled. If the corresponding PCC rule contains the related information (as described in TS 23.503 [45]), the SMF shall provide, in addition to the QoS profile, a prioritized list of Alternative QoS Profile(s) to the NG-RAN. If the SMF provides a new prioritized list of Alternative QoS Profile(s) to the NG-RAN (if the corresponding PCC rule information changes), the NG-RAN shall replace any previously stored list with it.

An Alternative QoS Profile represents a combination of QoS parameters PDB, PER, Averaging Window and GFBR to which the application traffic is able to adapt. If the QoS Profile contains PDU Set QoS parameters PSDB and PSER in UL and/or DL (described in clause 5.7.7), the Alternative QoS Profile(s) shall also contain the PDU Set QoS parameters PSDB and PSER in the respective direction(s); otherwise, the corresponding Alternative QoS Profile(s) shall not contain the PDU Set QoS parameters PSDB and PSER.

NOTE 1: There is no requirement that the GFBR monotonically decreases, nor that the PDB or PER (or PSDB or PSER) monotonically increase as the Alternative QoS Profiles become less preferred.

For a GBR QoS Flow using the Delay-critical resource type, an Alternative QoS Profile may also include the QoS parameter MDBV.

For the NG-RAN determination whether the GFBR, the PDB and the PER can be fulfilled (i.e. for all Notification control scenarios described in clause 5.7.2.4), the NG-RAN shall also apply the value of the optional QoS parameter present in an Alternative QoS Profile instead of the corresponding QoS parameter's value in the QoS Profile (which is either provided explicitly or implicitly via the standardized 5QI QoS characteristics defined in clause 5.7.4) for every optional QoS parameter present in an Alternative QoS Profile (e.g. MDBV).

NOTE 2: For the NG-RAN behaviour related to the mandatory QoS parameters in the Alternative QoS Profile (i.e. GFBR, PDB, PER), see clause 5.7.2.4.

When the NG-RAN sends a notification to the SMF that the QoS profile is not fulfilled, the NG-RAN shall, if the currently fulfilled values match an Alternative QoS Profile, include also the reference to the Alternative QoS Profile to indicate the QoS that the NG-RAN currently fulfils (see clause 5.7.2.4). The NG-RAN shall enable the SMF to determine when an NG-RAN node supports the Alternative QoS Profile feature but cannot fulfil even the least preferred Alternative QoS Profile.

NOTE 3: To reduce the risk that GBR QoS Flows are released in case of RAN resource limitations (and then experience difficulties in being re-established), Application Functions can set the least preferred Alternative Service Requirement to an undemanding level.