A.24 Monitoring of DRB Setup in NG-RAN

28.5523GPP5G performance measurementsManagement and orchestrationRelease 18TS

The DRB setup procedure in NG-RAN is to assign resources in gNB and on the air interface (Uu) for one or several DRBs that will handle the QoS flows requested to setup by the core network. The gNB may map several QoS flows to the same DRB so there is no one-to-one mapping between the flows and DRBs.

At DRB setup, the gNB will handle all QoS flows mapped to one DRB the same (mapped 5QI). A QoS flow that is at a later stage mapped to an already setup existing DRB will not increment the DRB setup counters.

The DRB setup is one of the most key procedures to allocate resources in the NG-RAN to the UE per the QoS requirements. Whether or not the DRB is successfully setup has direct impact to the user experience. A failed DRB setup may directly cause service failure or degradation for an end user. So, the performance related to the DRB setup for the gNB needs to be monitored per supported mapped 5QI and per S-NSSAI.