Section: 5.7.1.2a Alternative QoS Profile
Content: 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[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [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. For delay-critical GBR QoS flows, an Alternative QoS Profile may also include an MDBV. NOTE 1: There is no requirement that the GFBR monotonically decreases, nor that the PDB or PER monotonically increase as the Alternative QoS Profiles become less preferred. 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 feature but cannot fulfil even the least preferred Alternative QoS Profile. NOTE 2: 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.