nterface. The value of the PDB is the same in downlink and uplink for a certain 5QI. The PDB is used to support the configuration of scheduling and link layer functions (e.g., configuration of schedul- ing priority weights and HARQ target operating points). For a delay-sensitive GBR flow, a packet delayed more than PDB is considered as a lost packet, if the data burst is not exceeding the MDBV within the period of PDB and the QoS flow is not exceeding the GFBR. For GBR QoS flows with GBR resource type, the PDB is interpreted as a maximum delay with a confidence interval of 98%. The packet error rate defines an upper bound for the rate of PDUs or IP packets that have been processed by the sender of a link layer protocol, but are not successfully delivered by the corresponding receiver to the upper layers. Therefore, the PER defines an upper bound for non-congestion related packet losses. The purpose of the PER is to find appro- priate link layer protocol configurations. For some 5QI values, the target PER is the same in the downlink and uplink. For QoS flows with delay-sensitive GBR resource type, a packet which is delayed more than PDB is dropped and included in the PER calculation, unless the data burst is exceeding the MDBV within the period of PDB or the QoS flow is exceeding the GFBR. 184 Chapter 1 Averaging window is defined only for GBR QoS flows and denotes the time interval over which the GFBR and MFBR are calculated. The averaging window may be sig- naled with 5QIs to the AN and the UPF and if it is not received a predefined value is used. The maximum data burst volume (MDBV) is associated with each GBR QoS flow with delay-sensitive resource type. The MDBV denotes the largest amount of data that a 5G-AN is required to serve within a period of 5G-AN PDB (i.e., 5G-AN part of the PDB). Each standardized 5QI of delay-sensitive GBR resource type is associated with a default value for the MDBV. The MDBV may also be signaled together with a stan- dardized or pre-configured 5QI to the AN. Reflective QoS enables 