Tariff Sequence

Description

The Tariff Sequence is a concept in 3GPP charging management that defines an ordered list of consecutive subtariffs that must be applied for the charging of a communication event. It is used when a single communication event requires the application of multiple tariffs in a specific order, such as when a session spans multiple tariff periods or when different portions of a service are charged at different rates. The Tariff Sequence is defined in 3GPP specifications TS 29.458 and TS 29.658, which cover charging management and the charging architecture for various network domains. Each subtariff within the sequence represents a specific tariff that applies to a portion of the communication event, and the sequence ensures that these subtariffs are applied in the correct order.

In practice, a Tariff Sequence is used by the charging system to handle complex charging scenarios. For example, consider a voice call that starts during an off-peak period and continues into a peak period. The charging system may define a Tariff Sequence with two subtariffs: the first subtariff applies to the off-peak portion of the call, and the second subtariff applies to the peak portion. The sequence ensures that the correct tariff is applied to each portion based on the time of day. Similarly, a data session may involve multiple service components, each with its own tariff, and the Tariff Sequence defines the order in which these tariffs are applied. The sequence is typically evaluated by the charging functions, such as the Charging Trigger Function (CTF) or the Charging Data Function (CDF), which apply the subtariffs sequentially as the communication event progresses.

The Tariff Sequence is closely related to other charging concepts such as the Tariff Period and the Tariff Determination Instance. The Tariff Period defines the time intervals during which specific tariffs apply, while the Tariff Sequence defines the order in which these tariffs are applied when a communication event spans multiple periods. The Tariff Determination Instance represents the overall process of determining and applying the tariff, and the Tariff Sequence is a specific mechanism used within that process. Together, these concepts provide a comprehensive framework for flexible and accurate charging in mobile networks. The Tariff Sequence is particularly important for online charging, where the charging system must authorize and rate the service usage in real-time, and for offline charging, where the sequence is used to generate accurate Charging Data Records (CDRs).

The implementation of Tariff Sequences requires the charging system to maintain state information about the communication event, including the current position in the sequence and the time spent in each subtariff. This state information is used to apply the correct subtariff at each stage of the event. The 3GPP specifications provide guidelines for the management of Tariff Sequences, including the handling of transitions between subtariffs and the generation of partial CDRs when a subtariff changes. The Tariff Sequence also supports the use of multiple subtariffs within a single tariff period, allowing for fine-grained charging based on factors such as data volume or service type. This flexibility enables operators to create sophisticated pricing models that can be tailored to different services and subscriber segments.

In summary, the Tariff Sequence is a key component of 3GPP charging management that enables the application of multiple tariffs in a specific order for a single communication event. It provides a standardized way to handle complex charging scenarios, ensuring that charging is accurate and consistent across the network. Its definition in TS 29.458 and TS 29.658 and its continued presence from Release 8 to Release 19 highlight its importance in both traditional and advanced mobile networks.

Purpose & Motivation

The Tariff Sequence exists to enable the application of multiple tariffs in a specific order for a single communication event, addressing the need for complex charging scenarios that cannot be handled by a single tariff. In traditional charging systems, a communication event was often charged using a single tariff, which limited the ability to apply different rates to different portions of the event. As mobile services became more diverse and pricing models more sophisticated, operators needed a way to apply multiple tariffs sequentially, such as when a session spans multiple tariff periods or when different service components have different rates. The Tariff Sequence was introduced in Release 8 to provide a standardized mechanism for this purpose.

The primary problem it solves is the need to handle charging for communication events that cross tariff boundaries or involve multiple service components. For example, a video streaming session may start during an off-peak period and continue into a peak period, requiring the application of two different tariffs. Without a Tariff Sequence, the charging system would have to apply a single tariff to the entire session, which would be inaccurate and unfair to the subscriber. The Tariff Sequence allows the charging system to apply the correct tariff to each portion of the session, ensuring accurate billing. It also supports scenarios where a single event includes multiple services, each with its own tariff, by defining the order in which the tariffs are applied.

Historically, the Tariff Sequence was developed as part of the broader 3GPP charging framework to support the increasing complexity of mobile services and pricing models. Its introduction in Release 8 coincided with the rise of data-centric services and the need for more flexible charging. The Tariff Sequence has been maintained and refined in subsequent releases, and its continued presence in Release 19 demonstrates its enduring relevance. As networks evolve towards 5G and support new services such as IoT and network slicing, the Tariff Sequence remains a valuable tool for implementing sophisticated charging strategies that can adapt to diverse business models.