Description
QoS flow Based Charging (QBC) is a charging architecture defined within the 3GPP 5G Core network, specified primarily in the 32-series (Charging) specifications. It represents a paradigm shift from bearer-based charging in 4G EPS to a more granular, flow-based model aligned with the 5G Core's service-based architecture and QoS model. In 5G, user plane traffic is organized into QoS Flows, each with a unique QoS Flow Identifier (QFI) and a specific QoS profile defining parameters like 5G QoS Identifier (5QI), Guaranteed Flow Bit Rate (GFBR), and Maximum Flow Bit Rate (MFBR). QBC operates by generating Charging Data Records (CDRs) or Charging Events that are correlated to these individual QoS Flows.
The architecture involves several key network functions. The Session Management Function (SMF) is central, as it establishes, modifies, and releases QoS Flows within a PDU Session. The SMF interacts with the Policy Control Function (PCF) to receive policy and charging control (PCC) rules. These PCC rules include charging instructions that dictate how a specific service data flow, mapped to a QoS Flow, should be charged. When charging is triggered, the SMF, acting as a Charging Trigger Function (CTF), collects relevant charging information such as QoS Flow identifiers, data volumes, duration, and associated network slice information. It then forwards this information to the Charging Data Function (CDF) or Online Charging System (OCS) via the Nchf service-based interface.
How QBC works is intrinsically linked to the 5G QoS model. A single PDU Session can contain multiple QoS Flows—for example, one for high-priority voice traffic, one for best-effort internet browsing, and another for a low-latency gaming service. QBC allows the operator to apply distinct charging rates, quotas, or billing models to each of these flows independently. The charging data records can capture not just volume and time, but also the specific 5QI value, the network slice instance (S-NSSAI) serving the flow, and the data network name (DNN). This enables highly detailed billing reports and facilitates service-differentiated pricing, such as charging a premium for guaranteed low-latency flows or offering zero-rating for specific application flows.
Purpose & Motivation
QBC was created to address the limitations of the EPS bearer-based charging model, which was not granular enough for the diverse service landscape envisioned for 5G. In 4G, charging was typically associated with an EPS bearer, which aggregated traffic with similar QoS requirements. This made it difficult to implement fine-grained, service-specific charging policies, especially as networks evolved to support network slicing and a wide variety of vertical industry services with distinct QoS profiles.
The primary problem QBC solves is enabling monetization models that match the technical capabilities of 5G. With network slicing, IoT services, ultra-reliable low-latency communication (URLLC), and enhanced mobile broadband (eMBB) all coexisting on the same infrastructure, a one-size-fits-all charging approach is inadequate. QBC provides the mechanism to charge based on the actual value or cost of delivering a specific QoS level. This allows operators to create innovative tariff plans, offer service level agreement (SLA)-based billing to enterprise customers, and implement fair usage policies that consider the quality of service consumed, not just the raw data volume. Its introduction was motivated by the business need to monetize 5G's advanced capabilities beyond simple data buckets.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (247 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the QBC function was introduced as part of the new converged charging architecture for the 5G System. This architecture, based on the stage 2 description in TS 23.501, specifies that the SMF generates charging events towards the Charging Function (CHF) for QoS flow-based data connectivity charging. The CHF, acting as a Charging Data Function (CDF), then creates Charging Data Records (CDRs) for offline charging and handles charging events for converged online and offline charging via the Nchf service-based interface.
- Charging enhancement for eFMSS TS 32.298CR0643
- Add CDR parameter for WLAN-based ProSe direct discovery TS 32.298CR0654
- Introduce the NAPS API Charging TS 32.298CR0657
- Enhance UE location description for IMS charging when over WLAN TS 32.298CR0662
- Introduce new Charging Function record type TS 32.298CR0669
- Addition of SMS Charging to CHF CDR TS 32.298CR0680
+ 10 more changes
In Release 16, the QBC function was enhanced to introduce comprehensive support for offline-only charging, including the generation of offline charging data records (CDRs) by the SMF and CHF. This release added specific charging procedures and information definitions for interworking with EPC and for scenarios involving an Intermediate SMF (I-SMF). Furthermore, it detailed the message formats and trigger conditions required for these new offline charging capabilities.
- Add offline only charging TS 32.255CR0035
- Add offline only charging for SMF TS 32.255CR0036
- Add offline only charging CDR generation TS 32.255CR0038
- Add description of charging information for offline only charging TS 32.255CR0039
- Add offline only charging for flow based charging TS 32.255CR0040
- Add offline only charging for QoS flow based charging TS 32.255CR0041
+ 40 more changes
In Release 17, the QBC function was enhanced with new charging support for Ultra-Reliable Low Latency Communication (URLLC) services, 5G LAN-type services, and 5GS Cellular IoT. These additions introduced specific charging principles, quota management, and usage reporting procedures for URLLC, while also defining new charging information and requirements for 5G LAN and CIoT services.
- Add URLLC Charging Requirement TS 32.255CR0254
- Add Highly reliable URLLC services Charging TS 32.255CR0255
- Add Charging Principle for Usage Reporting TS 32.255CR0263
- Add PDU Modification and Release Message flow for URLLC Charging TS 32.255CR0275
- Add the Quota Management for URLLC Charging TS 32.255CR0276
- Add the Usage Reporting for URLLC Charging TS 32.255CR0277
+ 57 more changes
In Release 18, the QBC function was enhanced to support new charging architectures and principles for emerging services, including 5G Multicast/Broadcast Services (5MBS) and Time-Sensitive Communication (TSC) traffic. It also introduced new capabilities for slice-aware charging for roaming partners and expanded charging support for satellite access and backhaul. Furthermore, the release added charging procedures for Standalone Non-Public Networks (SNPN) and introduced a CHF-to-CHF architecture to support network slice charging.
- Add Identifier of SNPN for 5G data connectivity charging TS 32.255CR0418
- Slice-aware charging for Roaming partners TS 32.255CR0422
- Add charging principle of volume-based charging for IMS data channel TS 32.255CR0428
- Support of Caller and Callee Information in PDU session charging TS 32.255CR0429
- Add charging requirements for 5MBS TS 32.255CR0430
- Add charging principle for 5MBS TS 32.255CR0431
+ 68 more changes
In Release 19, the QBC function was enhanced with new charging principles and support for emerging services. Key additions included volume-based charging for the standalone IMS Data Channel and specific charging principles for satellite roaming, MOCN, and disaster roaming. The release also introduced charging support for new use cases like AIoT services, UAS (Unmanned Aircraft Systems), and UE-to-UE satellite communication.
- Rel-19 CR 32.255 Adding use of charging characteristics for CHF Group TS 32.255CR0566
- Rel-19 CR 32.255 Support volume-based charging for standalone IMS data channel TS 32.255CR0573
- Rel-19 CR 32.255 Addition of the Satellite Roaming Charging Principle TS 32.255CR0574
- Rel-19 CR 32.255 Add volume based charging principle for DC application download and usage TS 32.255CR0575
- Rel-19 CR 32.255 Add volume based charging principle to support IMS DC as a PS Data Off Exempt Service TS 32.255CR0576
- Rel-19 CR 32.255 Addition of charging principles for MOCN TS 32.255CR0590
+ 38 more changes
In Release 20, the QBC function was enhanced to support charging for multi-modality services and to address the charging impacts from enhanced QoS handling in XRM through new information elements. The release also included corrections to the technical descriptions of QoS flow Based Charging itself. Furthermore, it provided a correction for PDU Session ID handling specific to V-SMF charging in EPS–5GS interworking scenarios.
- Add informatin elements to support charging aspects of multi-modality service TS 32.255CR0606
- Rel-20 TS 32.255 Add information elements to address charging impacts from enhanced QoS handling in XRM TS 32.255CR0616
- Rel-20 CR 32.255 Correct some descriptions on QoS flow Based Charging TS 32.255CR0619
- Rel-20 CR 32.255 Correction on PDU Session ID Handling for V-SMF Charging in EPS–5GS Interworking TS 32.255CR0622
Explore further
Broader topics and technologies where QBC plays a role.
Defining Specifications
3GPP specifications that define or reference QBC, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 32.255 vk10 | Telecom Management; Charging for 5G Data Connectivity | Rel-20 |
| TS 32.291 vj40 | Charging Management: Service-Based Interface Protocol | Rel-19 |
| TS 32.298 vj30 | Charging Data Record (CDR) Parameter Specification | Rel-19 |