Fully Qualified Partial CDR

Description

The Fully Qualified Partial CDR (FQPC) is a fundamental data structure in the 3GPP offline charging architecture, defined within the Charging Data Record (CDR) family. Offline charging, also known as post-paid charging, generates CDRs for later processing by the billing system. A service session (e.g., a voice call, a data session, an SMS) can generate one or more CDRs. The FQPC is a specific type of partial CDR that carries a crucial characteristic: it is 'fully qualified,' meaning it contains all the mandatory and conditional information fields required by the billing system to process it independently, without needing to reference or merge with other partial records from the same session.

The generation of FQPCs is governed by triggers within the network's Charging Trigger Function (CTF). These triggers can be event-based (e.g., end of a call, change of tariff time) or volume/duration-based (e.g., every 10 MB of data transferred, every 5 minutes of a call). When a trigger fires, the CTF in the network element (like an SGSN, GGSN, or CSCF) collects all relevant charging information up to that point, formats it according to strict specifications in TS 32.298, and creates an FQPC. This record is then transferred via the Rf or Ga reference points to the Charging Data Function (CDF), which finalizes it into a Closed CDR for the billing domain.

The 'fully qualified' nature is architecturally significant. It ensures billing reliability and robustness. If a network failure occurs after an FQPC is sent but before the session ends, the billing system can still correctly charge for the portion of the service captured in that FQPC. Other partial CDR types, like Non-Fully Qualified Partial CDRs, may lack certain fields (e.g., total session duration or volume) and require merging with a subsequent final CDR. The FQPC eliminates this dependency, simplifying the downstream billing mediation and processing logic. Its structure includes a comprehensive set of fields: record sequence number, serving network identity, subscriber identifiers (IMSI, MSISDN), service details, usage quantities (duration, data volume), timestamps, and charging identifiers that link all partial records from a single session.

Purpose & Motivation

The FQPC was developed to solve critical problems in scalability, reliability, and accuracy of offline charging in evolving 3GPP networks. Early charging systems often generated a single, monolithic CDR at the end of a potentially long session (like a multi-hour data connection). This approach risked losing all charging data if the session terminated abnormally or if the network element failed before the record could be closed and forwarded. It also created large memory burdens on network elements holding open records for extended periods.

The introduction of partial CDRs, and specifically the FQPC, addressed these limitations by enabling incremental, periodic reporting of charging events. The 'fully qualified' attribute was a key innovation to address the billing system's need for complete, actionable data. It allows the operator to realize revenue incrementally and reliably, even for ongoing sessions. This was particularly motivated by the growth of packet-switched data services in GPRS and UMTS, where sessions could be very long-lived, and the value of the data transferred up to any given point was significant. The FQPC mechanism ensured that this value could be captured and billed without waiting for the session to end, improving cash flow and financial risk management for operators.

Key Features

• Self-contained charging record with all mandatory fields for independent billing processing
• Generated based on configurable triggers (time, volume, event)
• Prevents revenue loss by capturing chargeable events periodically during a session
• Contains linking identifiers to associate all partial CDRs from a single service session
• Transferred from CTF to CDF via standardized Rf/Ga interfaces
• Defined by detailed field specifications in 3GPP TS 32.298

Evolution Across Releases

Defining Specifications