Partial Charging Data Record

Description

A Partial CDR is a Charging Data Record (CDR) that captures charging information for a portion of a subscriber session rather than the entire session. In 3GPP charging architecture, when a session exceeds certain thresholds—such as duration, data volume, or number of charging conditions—the Charging Trigger Function (CTF) generates multiple partial CDRs instead of a single record. This mechanism is essential for long-lived sessions, such as always-on IP connectivity, streaming services, or IoT devices that remain connected for extended periods. The partial CDRs are later correlated and combined by the Charging Data Function (CDF) or billing domain to reconstruct the complete session record.

Two formats are defined for Partial CDRs: the Full Partial CDR (FQPC) and the Reduced Partial CDR (RPC). The FQPC contains all provisioned fields, including complete subscriber and session information, and is typically used for the first partial CDR of a session or when full detail is required. The RPC contains a reduced set of fields, omitting information that can be derived from previous partial CDRs, thereby reducing storage and transmission overhead. This dual-format approach optimizes network resources while maintaining data integrity.

The generation of partial CDRs is controlled by triggers configured in the CTF, such as time limits, volume limits, or specific events (e.g., QoS changes, tariff switches). Each partial CDR includes a unique record identifier and sequence number to enable correlation. The CDF receives these records via the Ga interface (for offline charging) or the Gy interface (for online charging) and may further process them before forwarding to the billing system via the Bx interface. In online charging, partial CDRs are used for quota management and real-time rating.

Partial CDRs play a critical role in ensuring that charging data is not lost due to session length or network failures. By breaking long sessions into manageable chunks, they facilitate timely billing, reduce the risk of data loss, and enable near-real-time charging. They are also essential for regulatory compliance, as they provide a detailed audit trail of subscriber activity. The 3GPP specifications 32.240 (charging architecture), 32.251 (PS charging), 32.260 (IMS charging), and others define the structure, triggers, and formats of partial CDRs across various domains.

In summary, Partial CDRs are a fundamental component of 3GPP charging, enabling scalable and reliable billing for long sessions. Their design balances completeness with efficiency, ensuring that operators can accurately charge subscribers while managing network and storage resources effectively.

Purpose & Motivation

Partial CDRs exist to address the limitations of generating a single CDR for long-lived sessions. Without them, a session lasting days or weeks would produce an enormous CDR that could overwhelm storage, delay billing, and risk data loss if transmission fails. Partial CDRs solve this by splitting the session into smaller, manageable records that can be transmitted and processed incrementally. This ensures timely charging, reduces the impact of network failures, and allows for near-real-time billing. The introduction of two formats (FQPC and RPC) further optimizes efficiency by avoiding redundant data in subsequent records. This mechanism was introduced in Release 8 and has been refined over subsequent releases to support evolving network architectures and services.