Description
The QoS Rule Identifier (QRI) is a fundamental element in the 5G Quality of Service (QoS) model defined from 3GPP Release 15 onwards. A QoS Rule is a set of parameters that defines how a specific Service Data Flow (SDF) or aggregate of SDFs should be treated regarding packet forwarding (e.g., priority, packet delay budget, packet error rate). Each QoS Rule configured in the User Equipment (UE) or applied by the network is associated with a unique QRI. The QRI is an integer value that serves as a handle to reference that particular rule within QoS-related signaling and operations.
Architecturally, the QRI operates within the Protocol Data Unit (PDU) Session context. During PDU Session Establishment or Modification, the Session Management Function (SMF) may create QoS Rules and assign QRIs. These rules, along with their identifiers, are then provided to the UE via the NAS SM protocol (specified in TS 24.501) and to the (R)AN via the N2 interface. The UE uses the QRI to map uplink user plane packets to the appropriate QoS Flow (identified by a QFI - QoS Flow Identifier) based on the packet filters and precedence defined in the corresponding QoS Rule. In the downlink, the UPF marks packets with a QFI, and the (R)AN uses the binding between QFI and the QoS profile (which is associated with the QoS Rules via the QRI) to apply the correct radio resource treatment.
How it works: When the SMF decides to install, modify, or remove a QoS Rule for a PDU Session, it includes the QRI in the relevant N1 (to UE) and N2 (to (R)AN) messages. For example, in a PDU Session Modification Command, the SMF may send a QoS rule operation (e.g., 'add') with a new QRI value. The UE stores this rule locally in its QoS Rules container. During uplink transmission, the UE's uplink classifier evaluates packet headers against the packet filters of all QoS Rules in order of precedence. When a match is found, the UE tags the packet with the QFI corresponding to the matched rule's QRI (via a binding known from the QoS rule). This allows consistent end-to-end QoS enforcement. The QRI's role is thus to provide a stable reference point for managing the potentially dynamic set of QoS rules per PDU Session, enabling efficient updates without ambiguity.
Purpose & Motivation
The QRI was introduced with the new 5G QoS model in Release 15 to address limitations in the EPS (4G) bearer-based QoS mechanism. In EPS, QoS was tightly coupled with EPS bearers, and rules were implicitly associated with a bearer's Traffic Flow Template (TFT). This made dynamic QoS adjustments cumbersome, as modifying filters often required bearer modification. The 5G system decouples QoS rules from the transport layer (QoS Flows), allowing more flexible and granular QoS control. The QRI exists to uniquely identify each independent QoS rule within this decoupled architecture.
The motivation stems from the need to support diverse 5G use cases—from enhanced mobile broadband (eMBB) to ultra-reliable low-latency communications (URLLC) and massive IoT—each with distinct QoS requirements. A system was needed where the network could swiftly add, modify, or remove packet detection and treatment rules without disrupting ongoing flows. The QRI provides the necessary handle for such operations. It solves the problem of unambiguous reference in signaling: when the SMF instructs the UE to update a specific rule, it uses the QRI to pinpoint exactly which rule to change. This enables fine-grained, service-driven QoS management, which is essential for network slicing and efficient resource utilization in 5G's service-based architecture.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (23 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the QRI (QoS Rule Identifier) was newly introduced alongside the QFI (QoS Flow Identifier) for inclusion within 5GSM messages. This function specifically enables QoS differentiation of traffic for non-3GPP devices connecting through a UE by binding a non-3GPP device identifier to the device's traffic that requires differentiated QoS.
In Release 16, the QRI function was enhanced with a semantic error check to prevent duplicate QRI or QFI values, ensuring unique QoS rule identification. Additionally, updates were made to the packet filter identifier setting procedure when requesting new packet filters.
- Correction of certain erroneous Information Element Identifiers TS 24.501CR2033
- Semantic error check for duplicate QRI or QFI TS 24.501CR2364
- Packet filter identifier setting when requesting new packet filters TS 24.501CR2536
- Alignment of the 5G ciphering and integrity algorithm identifiers TS 24.501CR1219
In Release 17, the QRI function was enhanced with specific error handling procedures for cases where the network sets the QoS Rule Identifier or QoS Flow Identifier to zero. Furthermore, clarifications were provided on how to set the packet filter identifier value within QoS rules. These updates improved the robustness and precision of QoS rule management in PDU sessions.
- Avoid including both PAP/CHAP and EAP identifiers in PDU session establishment request TS 24.501CR2941
- Clarification on the setting of packet filter identifier value TS 24.501CR3300
- Network identifier is not specified TS 24.501CR3389
- Error handling for QRI and QFI set to zero by the network TS 24.501CR3695
- Access Technology Identifier satellite NG-RAN TS 24.501CR3636
In Release 18, the QRI (QoS Rule Identifier) function was enhanced to support QoS differentiation for traffic from non-3GPP devices connected through a UE. This allows a non-3GPP device identifier to be bound to a specific device, enabling the 5GS to distinguish and apply differentiated QoS to traffic from different non-3GPP devices sharing the same UE's PDU session. Furthermore, the UE gained the capability to request the suspension of previously applied QoS differentiation for specific non-3GPP device identifiers via the UE-requested PDU session modification procedure.
In Release 19, the QRI function was enhanced to support QoS differentiation for traffic from non-3GPP devices connecting through a UE. The new capabilities include supporting multiple non-3GPP device identifiers for this differentiation and allowing the UE to request the suspension of previously requested QoS differentiation for such identifiers via the UE-requested PDU session modification procedure.
- Support of reject QoS differentiation for non-3GPP device identifier(s) TS 24.501CR6926
- Procedure update for QoS differentiation of non-3GPP device identifiers TS 24.501CR6994
- Suspending QoS differentiation for non-3GPP device identifier TS 24.501CR7087
- Correction to the inconsistent LCS correlation identifier TS 24.501CR6380
- Support of multiple Non-3GPP device identifiers for QoS differentiation TS 24.501CR6925
- QoS differentiation for non-3GPP device identifiers clean up TS 24.501CR6993
+ 2 more changes
Explore further
Broader topics and technologies where QRI plays a role.
Defining Specifications
3GPP specifications that define or reference QRI, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 24.890 vg00 | 5G NAS Protocol for 5GS Stage 3 | Rel-16 |