ser equipment), 5G RAN, and UPFs. SMF should be able to determine the authorized QoS of a given QoS flow based on PCC rules that are associated with the flow, as well as to notify PCF when the QoS targets cannot be fulfilled [18]. For QoS control at the PDU session level the PCF provides a 5QI/ARP combination for the PDU session. Association of a PCC rule to a QoS flow within a PDU session is called 5.7 QoS in 5G Mobile Ultra-Broadband Application/service layer Data packets from applications QoS rules (mapping packets to QoS flows in uplink) QoS flow (packets with same QFI) AN resources AN resources session User equipment Access network AN - Access network PDR - Packet detection rule PDU - Packet data unit UPF - User plane functions Figure 5.12 QoS flow mapping in 5G. QoS flow binding. Besides the 5QI/ARP pair of parameters, if available in the PCC rule, the QoF flow binding can use the following parameters: quality of service notification control (QNC), priority level, averaging window, and maximum data burst volume. The binding of the PCC rule and the QoS flow causes the downlink transfer of the SDF to be directed toward the QoS flow. For the uplink direction the QoS rule associated with the QoS flow instructs the mobile terminal (i.e. user equipment) to direct the SDF in the uplink direction to the QoS flow in the established association. If authorized QoS from the given PCC rule is changed, the bindings are reevaluated and then the given SDF can be bound to another QoS flow. So, we have three levels of QoS control in 5G: QoS control at the SDF level; QoS control at the QoS flow level; and QoS control at the PDU session level. Figure 5.12 illustrates the mappings between the three QoS levels in 5G by 3GPP. Note that one or more SDFs can be mapped on a single QoS flow. Also, one or sev- eral QoS flows can be mapped on a given PDU session. In the downlink direction data packets (in the user plane) are classified by the UPF based on the packet filter sets of the downlink packet detection rules (PDRs), applying th