Description
The Auxiliary Advice of Charge Function (AACF) is a standardized network function defined within the 3GPP Telecommunication Management Network (TMN) architecture, specifically under the charging management domain. It serves as a supplementary component that works in conjunction with primary charging functions like the Charging Data Function (CDF) and Charging Gateway Function (CGF) to provide enhanced charging capabilities. The AACF operates within the framework defined in 3GPP TS 32.280, which specifies the charging management reference architecture and interfaces.
Architecturally, AACF resides in the network's management plane rather than the user plane or control plane. It interfaces with various charging-related network elements through standardized reference points, primarily the Rf reference point for offline charging and the Ro reference point for online charging systems. The function acts as an auxiliary processor that can handle specialized charging scenarios, perform additional validation on charging data records (CDRs), and support complex rating functions that may not be efficiently handled by primary charging components.
In operation, AACF receives charging events and data from network functions like the Policy and Charging Rules Function (PCRF) or directly from network elements generating charging triggers. It processes this information according to configured business rules and policies, potentially applying supplementary charging logic, performing currency conversions, applying tax calculations, or implementing customer-specific charging algorithms. The processed data is then forwarded to the appropriate charging collection or billing systems.
Key components of AACF include the charging data processing engine, rule management subsystem, and interface adapters for various charging protocols. The processing engine executes charging algorithms and business logic, while the rule management subsystem maintains and applies charging policies. Interface adapters ensure compatibility with different charging systems and protocols used across the network. AACF's role is particularly important in multi-vendor environments where charging systems from different manufacturers need to interoperate seamlessly.
The function plays a crucial role in ensuring charging accuracy and flexibility in modern telecommunications networks. By offloading specialized charging processing from primary charging functions, AACF helps maintain system performance during peak charging periods. It also enables operators to implement complex charging scenarios without modifying their core charging infrastructure, supporting innovative service offerings while maintaining billing integrity.
Purpose & Motivation
The Auxiliary Advice of Charge Function was created to address the growing complexity of charging scenarios in modern telecommunications networks. As 3GPP networks evolved from simple voice services to include data, multimedia, and value-added services, traditional charging systems faced limitations in handling diverse charging models, complex rating scenarios, and specialized billing requirements. AACF provides a standardized approach to extend charging capabilities without requiring fundamental changes to core charging infrastructure.
Historically, operators faced challenges when introducing new services with unique charging requirements. Each new service often required modifications to primary charging functions, leading to increased development cycles, testing complexity, and potential system instability. AACF addresses these limitations by providing a modular, auxiliary function that can be updated independently to support new charging scenarios. This separation of concerns allows operators to innovate with service offerings while maintaining stable core charging systems.
The creation of AACF was motivated by the need for greater flexibility in charging architectures, particularly as networks transitioned to all-IP architectures and began supporting diverse Quality of Service (QoS) levels, network slicing, and IoT services. These advanced services introduced charging requirements that were difficult to anticipate during initial network design. AACF provides a standardized mechanism to handle these evolving requirements, supporting everything from simple per-minute voice charging to complex event-based charging for IoT devices and dynamic QoS-based charging for network slices.
Key Features
- Supplementary charging data processing
- Complex rating algorithm support
- Charging data validation and enrichment
- Multi-currency and tax calculation capabilities
- Interface adaptation for heterogeneous charging systems
- Rule-based charging policy execution
Evolution Across Releases
Initial introduction of AACF as part of the enhanced charging management architecture in 3GPP Release 8. Defined the basic architecture, interfaces, and capabilities for auxiliary charging functions within the TMN framework. Established support for basic charging data processing and rule-based charging scenarios.
Defining Specifications
| Specification | Title |
|---|---|
| TS 32.280 | 3GPP TR 32.280 |