What is QoS?
QoS in 5G refers to the end-to-end performance guarantees applied to individual traffic flows — including guaranteed bit rate, maximum latency, packet error rate, and priority. 5G introduces a greatly enhanced, flow-based QoS model using 5QI (5G QoS Identifier) values, replacing LTE’s bearer-based QoS framework.
How Does QoS Work?
Each PDU session contains one or more QoS flows identified by a QFI (QoS Flow Identifier). Each QoS flow is associated with a 5QI value that defines its standardised characteristics (resource type: GBR or non-GBR, priority level, packet delay budget, packet error rate). The PCF configures QoS rules; the SMF enforces them at the UPF; the gNB maps QoS flows to Data Radio Bearers (DRBs) with appropriate radio scheduling priority.
Use Cases
Guaranteeing <1 ms latency for uRLLC factory control flows, minimum 100 Mbps for enterprise video conferencing, prioritising IMS voice (VoNR) over background data, network slice SLA enforcement.
3GPP / Standards Reference
3GPP TS 23.501 (5G QoS Model — Section 5.7), TS 23.503 (Policy and Charging Control Framework)
Related Terms
PCF | SMF | UPF | Network Slicing | uRLLC | QoE
Learn More
This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
