Description
Post Event Charging (PEC) is a charging paradigm introduced in 3GPP Release 16 as part of the 5G system. It represents a shift from traditional online (OCS) and offline charging, where charging interactions occur during the session. In PEC, the network does not interact with the charging system in real-time during the service delivery. Instead, usage data is collected locally by the network function (e.g., SMF, PCF) serving the user. After the service data session or a specific service event is completed, the network function generates a Charging Data Record (CDR) or a similar usage report. This record is then forwarded to the Charging Function (CHF) for rating and billing in a post-processing manner. The architecture relies on pre-established policies and quotas agreed upon between the network and the CHF before service initiation. These policies define the charging rules, such as flat rates, event-based charges, or volume thresholds, which the network function applies locally. Key components include the PCF for policy control, the SMF for session management and CDR generation, and the CHF which acts as the billing domain. PEC is particularly managed within the Service Based Interface (SBI) framework of the 5G Core, using HTTP/2-based Nchf services. This method reduces signaling load and latency because it eliminates the need for real-time credit checks and quota updates during the session, which is ideal for machine-type communications and other services where immediate billing authorization is not critical.
Purpose & Motivation
PEC was developed to address the limitations of existing online charging systems (OCS) in handling massive numbers of low-cost, low-latency transactions expected in 5G, particularly for Internet of Things (IoT) and massive Machine-Type Communication (mMTC) scenarios. Traditional online charging requires real-time dialogue between network functions and the OCS for quota management and credit control, which introduces signaling overhead and latency that can be prohibitive for services involving billions of small, frequent events. Offline charging, while avoiding real-time interaction, still involves generating detailed records during the session and may not be flexible for new business models. PEC solves this by decoupling charging from the real-time service flow. It allows operators to implement simple, event-based charging models (e.g., per device, per transaction, or flat-rate) efficiently. The motivation stems from the need for scalable and cost-effective charging for 5G verticals like industrial IoT, where devices generate vast amounts of small data transactions. By processing charges after the fact based on pre-agreed policies, PEC reduces network signaling congestion, lowers operational costs, and enables new monetization strategies for high-volume, low-value services.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (63 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the Post Event Charging (PEC) function was enhanced to support network slice performance and analytics charging, where the Charging Enablement Function (CEF) subscribes to performance management or analytics services to determine chargeable events. This specifically introduced the capability for the CEF to report performance and analytics charging information per network slice using a PEC scenario. Additionally, corrections were made to the message content used for Post Event Charging procedures.
- Addition of Converged Charging TS 32.274CR0053
- Introduction of SMSF as a new Node for SMS charging TS 32.274CR0054
- Introduction of Message content charging SMSF TS 32.274CR0057
- Introduction of SMS information converged charging TS 32.274CR0059
- Introduction of 5GS for SMS charging via Ro Rf TS 32.274CR0060
- Introduction of offline charging for IP-SM-GW architecture and flows TS 32.274CR0061
+ 3 more changes
In Release 16, the PEC function was refined with corrections to its procedures, including updates to the Charging Enablement Function description and specific corrections to the flows for IEC, ECUR, and PEC. The release also introduced clarifications for offline charging scenarios and technical corrections regarding the sender of the Charging Data Response message and the NSPA Container Information within the Charging Data Request.
- Update description of Charging Enablement Function TS 28.201CR0004
- Correction on sender of Charging Data Response message TS 28.201CR0006
- Correction on NSPA Container Information in Charging Data Request message TS 28.201CR0007
- Correct the Event offline charging scenarios TS 32.256CR0002
- Correction on Triggers field for converged charging TS 32.274CR0077
- Correction of flows for IEC, ECUR and PEC TS 32.274CR0079
In Release 17, the PEC function was enhanced to support charging for Network Slice Performance and Analytics (NSPA). This involved defining new procedures for the Charging Enablement Function (CEF) to subscribe to and report performance metrics from management and analytics services. Additionally, corrections were made to session and charging identifiers and the content of Charging Data messages for NSPA.
In Release 18, the Post Event Charging (PEC) function was enhanced to support new network access types and charging scenarios. Specifically, it added charging support for 5G connections via satellite access and introduced charging for Private and Standalone Non-Public Networks (PNI-NPN and SNPN). Furthermore, the release extended the architecture to support slice-aware charging for roaming partners and clarified procedures for quota management and triggers within the converged charging framework.
- Add Identifier of SNPN for 5G connection and mobility charging TS 32.256CR0010
- Slice-aware charging for Roaming partners TS 32.256CR0011
- Add identifier for PNI-NPN charging TS 32.256CR0014
- Rel-18 CR 32.256 Addition of end user charging for PNI-NPN network usage of access TS 32.256CR0015
- Rel-18 CR 32.256 Addition of end user charging for SNPN network usage of access TS 32.256CR0016
- Add charging support for 5G connection via satellite access TS 32.256CR0021
+ 9 more changes
In Release 19, the Post Event Charging (PEC) function was enhanced to support new scenarios, including charging for Multi-Operator Core Network (MOCN) performance measurements and network slice performance and analytics. Specifically, the Charging Enablement Function (CEF) was extended to act as a consumer of the performance management service (MnS) for gNB performance measurements to enable MOCN performance converged charging. Additionally, support was added for new service-level charging, such as for Unmanned Aircraft Systems (UAS) and AIoT services.
- Rel-19 CR 28.201 Add charging architecture for MOCN TS 28.201CR0017
- Rel-19 CR 28.201 Add charging requirement for MOCN TS 28.201CR0018
- Rel-19 CR 28.201 Addition of charging information for MOCN TS 28.201CR0023
- Rel-19 CR 32.256 Adding use of charging characteristics for CHF Group TS 32.256CR0047
- Add UAS charging requirements TS 32.256CR0050
- Rel-19 CR 32.256 Add MVNO charging which provides satellite access service TS 32.256CR0052
+ 23 more changes
Explore further
Broader topics and technologies where PEC plays a role.
Defining Specifications
3GPP specifications that define or reference PEC, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 28.201 vj20 | 5G Network Slice Performance Analytics Charging | Rel-19 |
| TS 28.203 vi10 | Charging management | Rel-18 |
| TS 28.204 vi11 | Charging management | Rel-18 |
| TS 28.849 vj10 | CAPIF Phase2 Charging Study | Rel-19 |
| TS 32.254 vj21 | Charging for Northbound APIs | Rel-19 |
| TS 32.256 vj40 | 5G Connection & Mobility Charging Spec | Rel-19 |
| TS 32.274 vj10 | SMS Charging Management Specification | Rel-19 |
| TS 32.291 vj40 | Charging Management: Service-Based Interface Protocol | Rel-19 |