belonging to different PDU sessions to different DRBs and establishes at least one default DRB for each PDU session. The NAS-level packet filters in the UE and in the 5GC associate uplink and downlink packets with QoS flows. PDN connection 1 (EPS session 1) PGW-1 Resource type QoS parameters of EPS bearer address Dedicated EPS bearer (PDN-1) MBR (DL/UL) GBR (DL/UL) MBR (DL/UL) GBR (DL/UL) MBR (DL/UL) Dedicated EPS bearer (PDN-1) Non-GBR APN-AMBR MBR (DL/UL) (DL/UL) MBR (DL/UL) Default EPS bearer (PDN-1) Non-GBR MBR (DL/UL) UE-AMBR (DL/UL) Default EPS bearer (PDN-2) Non-GBR MBR (DL/UL) APN-AMBR (DL/UL) MBR (DL/UL) Dedicated EPS bearer (PDN-2) Non-GBR MBR (DL/UL) MBR (DL/UL) GBR (DL/UL) Dedicated EPS bearer (PDN-2) MBR (DL/UL) GBR (DL/UL) MBR (DL/UL) GBR (DL/UL) PGW-2 PDN connection 2 (EPS session 2) Figure 1.85 QoS parameters in LTE 59]. 5G Network Architecture 175 NG-RAN PDU session Radio bearer NG-U tunnel QoS flow QoS flow Radio bearer QoS flow Radio interface Figure 1.86 QoS framework in NR [16]. The AS-level mapping rules in the UE and in the NG-RAN associate uplink and downlink QoS flows with DRBs. At NAS level, the QoS flow is the finest granularity for QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QFI transferred in encapsulated format over NG-U. NG-RAN and 5GC ensure quality of service (e.g., reliability and maximum toler- able delay) by mapping packets to appropriate QoS flows and DRBs. There is a two-step mapping of IP-flows to QoS flows (NAS level) and from QoS flows to DRBs (AS level). At NAS level, a QoS flow is characterized by a QoS profile which is provided by 5GC to NG- RAN as well as a set of QoS rule(s) which are provided by 5GC to the UE. The QoS profile is used by NG-RAN to determine the treatment on the radio interface while the QoS rules define the mapping between uplink user-plane traffic and QoS flows in the UE. A QoS flow may either be GBR or non-GBR depending on its profile. The QoS profile of a QoS flow contains QoS parameters, that is, a 5G Q