By WG SA5, Authors: Chen Shan, Gerald Goermer, Mirko Cano Soveri

3GPP SA5 specifies network slicing charging per UE and per tenant based on the charging requirements from NGMN, GSMA (NG.116), 3GPP SA1 and SA2 (TS 23.501 and TS 23.502) for different business models (e.g. B2B Services, NSaaS):

• In Rel-15: Basic Network Slice (NS) instance charging is supported. The charging information collected per PDU session includes the network slice instance the PDU session belongs to, which is then reported to the Converged Charging System (CCS).
• In Rel-16: The Charging management is extended into Network Slicing (NS) through the introduction of NS lifecycle management (NSM) and NS Performance and Analytics (NSPA). The NSPA Charging information (e.g. Latency, Throughput and Load level) and the NSM charging information (e.g. List of Service profile charging information for the Network Slice Instance (NSI) Creation, Modification and Termination) are reported to the CCS. The NS instance charging is also enhanced by the collected per UE Registration and connection (e.g. Allowed NSSAI) reported to the CCS.
• In Rel-17: The enhancement of charging of Network Slicing (NS) charging based on 5G data connectivity is introduced for informative, describing how to realise Network Slice usage charging, with the CHF hosted by CCS extended for NS Tenant,  when the N S is identified by an S-NSSAI (Single Network Slice Selection Assistance Information), and the NS usage is considered under 5G data connectivity by individual UEs. 

NS Performance and Analytics charging:

Based on the converged charging architecture specified in Rel-15 TS 32.290, including the CHF (Charging Function) as the NF producer and the NF Consumers (CTF), a new NF for Network Slice charging, CEF (Charging Enablement Function), is introduced.

The Charging Enablement Function (CEF) is a consumer of Nchf charging services, and for the purpose of performance and analytics charging information collection may consume management services (MnS), services exposed by other Network Functions (NF) (i.e. Network Data Analytics service (Nnwdaf) from NWDAF) or both, as specified in TS 28.201.

Figure 1, extracted from TS 28.201 , shows the interaction between CEF and CHF and the interaction between CEF and NWDAF/MnS:

Figure 1: Network slice performance and analytics converged charging architecture

NS management charging:

Network Slice Management charging specified in TS 28.202 covers Network Slice Instance (NSI) Creation, modification and termination and relies on two alternative architectures:

• with CEF as the consumer of Nchf charging service, consuming provisioning service (MnS) for the purpose of NS management charging information collection;
• with CTF as the consumer of Nchf charging service, responsible for NS management charging information collection. Figure 2, extracted from TS 28.202 , shows the alternative with CTF:

Figure 2: Network Slice Management converged charging architecture (CTF)

Network Slicing Charging SID/WIDs

An overview and summary of network slicing charging related SID/WIDs are provided in the TR 21.91x series of specifications: TR 21.915 [15] for Rel-15, TR 21.916 [16] for Rel-16 and TR 21.917 [17] for Rel-17.

Rel-15

Rel-16

Rel-17

Rel-18

Specifications and Releases

A series of specifications cover Network slicing charging across several releases. The common charging specifications for all 5G services are also used for the network slicing charging.

• TS 32.240: "Charging architecture and principles"
• TS 32.290: " 5G system; Services, operations and procedures of charging using Service Based Interface (SBI)."
• TS 32.291: " 5G system, charging service; Stage 3"
• TS 32.298: "Charging Data Record (CDR) parameter description"

Specific charging specifications for Network slicing are the following:

From Rel-15 onwards:

• TS 32.255, "5G Data connectivity domain charging; stage 2".

And then, in Rel-16:

• TR 32.845: " Study on charging aspects of network slicing"
• TS 28.201: "Network slice performance and analytics charging in the 5G System (5GS); Stage 2"
• TS 28.202: "Network slice management charging in the 5G System (5GS); Stage 2"

In Rel-17:

• TS 32.255: "5G Data connectivity domain charging; stage 2"--- Annex D (informative):

Network slice charging based on 5G data connectivity

In Rel-18:

• TR 32.847: "Study on Charging Aspects for Network Slicing Phase 2"