Near Real Time Charging and Billing

Description

Near real time (NRT) is a timing requirement defined in 3GPP charging and billing specifications, notably TS 32.250, TS 32.273, and TS 32.295. In the context of 3GPP, near real time charging and billing information is to be generated, processed, and transported to a desired conclusion in less than one (1) minute. This definition applies across a range of charging scenarios, including offline charging, online charging, and billing domain processing, and serves as a measurable performance objective for operators and vendors implementing charging systems.

Charging in 3GPP is split into several domains: the Charging Trigger Function (CTF) in network elements such as the SMF, UPF, AMF, or P-GW generates charging events; the Charging Data Function (CDF) and Charging Gateway Function (CGF) process and store these events; and the Billing Domain (BD) consumes the resulting Charging Data Records (CDRs) for invoicing and analytics. Online charging adds the Online Charging System (OCS) with the Charging Function (CHF) and Account Balance Management Function (ABMF), where credit control must occur before or during service usage. Near real time applies to the latency with which these functions generate, process, and deliver charging information to the next stage.

The one-minute threshold is significant because it distinguishes near real time from both real-time (sub-second, required for online charging credit control) and batch processing (hours or days, typical of traditional billing cycles). Near real time charging is used for services where timely visibility of usage is important, such as postpaid data sessions, roaming, content charging, and enterprise billing, but where per-event credit authorization is not strictly necessary. It enables operators to detect fraud, apply policy adjustments, and notify subscribers with minimal delay, while avoiding the cost and complexity of fully real-time processing for every event.

Implementation of near real time charging relies on standardized interfaces such as Gy, Gz, Rf, Ro, and the service-based interfaces introduced with 5G (Nchf). The charging architecture supports both decentralized and centralized deployments, with CGFs consolidating CDRs and converting them into a format suitable for the Billing Domain (typically via FTP, SFTP, or streaming protocols). In 5G, the Charging Function (CHF) within the 5G Core plays a central role, and the convergence of offline and online charging is a key design principle. Timing requirements are typically achieved through high-throughput event processing, in-memory databases, and low-latency transport between network functions.

Compliance with the near real time requirement is verified through performance testing and considered in network dimensioning. Operators must ensure that charging elements are provisioned with sufficient processing capacity, that transport links are adequately dimensioned, and that failure recovery procedures (e.g., CDR buffering, failover) do not introduce delays beyond the one-minute threshold.

Purpose & Motivation

The near real time requirement exists to balance the conflicting demands of timeliness and cost in charging and billing systems. Real-time charging, where credit is checked and reserved before each service event, provides maximum control but imposes heavy signaling and processing overhead. Batch charging, where records are collected and processed hours later, is efficient but unsuitable for fraud detection, credit risk management, or timely customer notification. Near real time fills this gap by specifying a bounded latency — less than one minute — within which charging information must reach a usable conclusion.

Historically, as mobile networks evolved from voice-centric to data-centric services, the volume and diversity of charging events exploded. Prepaid and postpaid models became more complex, with tiered data plans, content-based charging, sponsored data, and roaming scenarios. Operators needed a way to ensure that charging systems could keep pace with service delivery without requiring per-event real-time processing. The one-minute target was chosen as a practical engineering objective that supports fraud mitigation, near-real-time balance updates, and timely subscriber notifications while remaining achievable with standard IT infrastructure.

In the 5G era, near real time charging remains relevant as networks become more service-based and dynamic. Network slicing, edge computing, and differentiated QoS require charging systems that can adapt quickly. The One Minute Target continues to guide the design of CHF, CDF, CGF, and Billing Domain systems, and it informs KPIs for charging performance in multi-vendor, multi-domain deployments.