3GPP2 IMS Charging Infrastructure

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3GPP2 IMS Charging Infrastructure

Presented for 3GPP2 TSG-X

by Nick Mazzarella

of Lucent Technologies

September 25, 2004

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3GPP2 IMS Charging InfrastructureContents

Scope3GPP2 Organization3GPP2 IP Networking ModelCurrent Rev 0 Charging Structure

Architecture Charging Functions and Correlations Basic Flows

Evolution to Rev A Charging Adding On-Line Charging New Charging Functions Possible Additional Enhancements Harmonization between 3GPP and 3GPP2 Abbreviations and References

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ScopeProvide architecture and flows for charging for IMS services. Objectives

Define principles of charging in an IMS network Provide a description of the charging architecture Provide the descriptions of events and triggers for the next

generation of charging data. Provide charging message flows along with charging data triggers,

message content and format along with the transport of these messages using the Diameter protocol.

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Charging functions exist in several areas within TSG-X

CSN Work Group – Circuit Domain Charging

PDS Work Group – Packet Data Subsystem Charging

MMD Work Group - IMS Charging

This Presentation will focus on Charging in IMS

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3GPP2 Organizational Context

TSG-X TSG-S TSG-C TSG-A

SCOP

CSN PSN

PDS

MMS MMD

CHARGING

PRESENCE

GoGq

MMD Work

Activities

BAN

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3GPP2 IP Networking ModelAll IP Network Architecture Model

(NAM)Offline Data Bases

LocationServices

Radio Access

AAA

AccessGateway

OSAAS

PDF

MRFP

MRCF

MGCF

MGW

CSCF

Legacy MS Domain TIA-41

TIA-41

IP Networ

k

IP Networ

k

PSTN

PSTN

SIPAS

OSACS

IMS

PDS

Charging

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Current Rev 0 Charging Structure

Home(B) = Visited(B)

ASAS

MRFCMRFC

S-CSCFS-CSCF

I-CSCFI-CSCF

P-CSCFP-CSCF

BGCFBGCF

BS

Rf

Home(A) = Visited(A)

ASAS

AAA

MRFCMRFC

S-CSCFS-CSCF

I-CSCFI-CSCF

P-CSCFP-CSCF

BGCFBGCF

BS

RfAAA

BGCFPDSNPDSN

1. Off-line IMS Charging architecture for non-roaming scenario

Basic Architecture

MGCF

MGCF

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AS AS

MRFC MRFC

S - CSCF S - CSCF

I - CSCF I - CSCF

P - CSCF P - CSCF

BGCF BGCF

BS

Rf

AS AS

AAA

MRFC MRFC

S - CSCF S - CSCF

I - CSCF I - CSCF

P - CSCF P - CSCF

BGCF BGCF

BS

Rf AAA

Visited(A)

BS P - CSCF P - CSCF AAA

Rf

PDSN

Visited(B)

AAA BS

P - CSCF P - CSCF Rf

PDSN

2. Off-line IMS Charging architecture for roaming scenario

Basic Architecture

MGCF MGCF

Home(B) Home(A)

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Current Rev 0 Charging Structure Charging Functions-

AAA

AAA provides the mechanism to transfer charging (i.e. Accounting) information from the IMS nodes to the network operator's chosen Billing System(s). *Does not define actual end user billing records.

• Main functions:

The collection of Session charging information from the IMS node Intermediate data storage buffering

The transfer of the charging data to the off-line billing systems

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Charging Correlation Levels -

Correlation between the session and the media records

The IMS Charging ID may be used to correlate session level charging records with media records.

Correlation at media component level

For a session comprising several media components (such as audio and video), charging data is generated for each media component and needs to be correlated between network elements and between media component records.

Correlation within a session

The IMS Charging ID may be used to correlate the charging data between network elements.

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Charging Correlation CapabilitiesTo support the correlation of charging information, the following capabilities apply to:

The correlation of charging information for an IMS session is based on the use of IMS Charging Identifiers (ICIDs).

The first IMS network entity within the SIP signalling path is responsible for assigning an ICID.

The ICID is passed to all IMS network entities in the SIP signalling path. This is performed using SIP signalling.

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The charging correlation identifiers (ICIDs, TCIDs) will not be passed to the UE.

Charging Correlation Capabilities- For the charging correlation between the ICN and the IMS,

one or more Transport Charging IDs, which identify the channels of the session, may be passed from the ICN to the IMS.

The Transport Charging IDs (TCIDs) are passed by the P-CSCF to the S-CSCF and the AS using SIP signalling. Along with the ICID, the S-CSCF includes the TCIDs in the off-line charging record.

The ICID applies for the duration of the event with which it is associated.

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Supported Off-line Interface Types Rf Offline (Post Paid) Charging Reference Point between

an IMS Network Entity or an AAA

Rf and ISC Interfaces All other IMS nodes (S-CSCF, P-CSCF, I-CSCF, BGCF

and MGCF) apply offline charging via the Rf interface using the AAA address as received via SIP signaling or the locally configured AAA address.

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Current Rev 0 Charging StructureBasic Off-Line Charging Message Flows

UE P-CSCF S-CSCF AAA (visited)

Visited Network

AAA (home)

Home Network

1. INVITE

Service Control

More SIP signalling

2. 200 OK (Invite)

3. Accounting Request [Start]

4. Accounting Answer

2. 200 OK (Invite)



Open a P-CSCF AIR

2. 200 OK (Invite)

1. INVITE 1. INVITE

Service Control

Open a S-CSCF AIR

SIP Session established

More SIP signalling

1. Message Sequence Chart for Session Establishment (Mobile Origination)

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Current Rev 0 Charging StructureBasic Off-Line Charging Message Flows-

UE P- CSCF S-CSCF AAA (visited)

Visited Network

AAA (home)

Home Network

I- CSCF

1. INVITE

Cx Query with the HSS

2. Accounting Request [Event]


Open I- CSCF AIR

Service Control

1. INVITE

1. INVITE 1. INVITE

4. 200 OK

4. 200 OK



Open P- CSCF AIR

4. 200 OK



Open S- CSCF AIR

4. 200 OK

SIP Session established

More SIP signalling

More SIP signalling

2. Message Sequence Chart for Session Establishment (Mobile Termination)

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Current Rev 0 Charging StructureBasic Off-Line Charging Message Flows-

3. Message Sequence Chart for Session Release – Mobile Initiated

UE P-CSCF S-CSCF AAA (visited)

Visited Network

AAA (home)

Home Network

1. BYE

Service Control

6. 200 OK 6. 200 OK

6. 200 OK

1. BYE 1. BYE

2. Accounting Request [Stop]


Close the P-CSCF AIR

4. Accounting Request [Stop]


Close the S-CSCF AIR

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Evolution to Rev A Charging

Where applicable, 3GPP2 will adapt some IMS charging functionality from 3GPP

Revision A Charging will provide standardized functionality for On-line Charging. On-line Charging Architecture has already been defined

in 3GPP2 documentation New on-line charging stage 3 flows will have to be

developed

3GPP2 wishes to maintain harmonization with 3GPP Release 6 Charging functionality.

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Charging information

flow

ISC

ITSITS

Online Charging System

Home(A) + Visited(A)

Re

Rb

Ro

Ro

Re

Rc

MRFCMRFC

AS(s)AS(s)

ISC

ITSITS

Online Charging System

Home(B) + Visited(B)

Re

Rb

Ro

Ro

Re

Rc

Account

Correlation FunctionBearer

Charging FunctionAccount

Correlation Function Bearer

Charging Function

RatingFunction

RatingFunction

S-CSCFS-CSCF S-CSCFS-CSCF

AS(s)AS(s)

MRFCMRFC SCCF

CPCF

SCCF

CPCF

SessionCharging Function

SessionCharging Function

EventCharging Function

EventCharging Function

On-line IMS Charging architecture

* In

3GPP Rel 5 and 6, a Media Gateway has been

added with an

Ro interface.

3GPP2 may

consider this as a revision to Rev 0

Architecture.

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The Event Charging Function (ECF) performs event-based charging (content charging). It makes use of the rating function in order to determine the value of the service rendered. The ECF may correlate several event-based charging requests.

Added Functions for On-line Charging Session Charging Function (SCF)

Responsible for Session Charging including the session control such as e.g. session termination.

Bearer Charging Function (BCF) The Bearer Charging Function performs the Bearer

Charging

Event Charging Function (ECF)

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The CPCF manages the account that is maintained for the content provider. Upon receipt of a charging request from the AS/MRFC, the CPCF processes the request and relays it to the SCCF.

Added Functions for On-line Charging Subscriber Content Charging Function (SCCF)

The SCCF is always located in the same operator network as the account of the subscriber, and handles content charging requests that are made when the subscriber accesses the content.

Content Provider Charging Function (CPCF)

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e.g. Call Data Records (CDRs)

Additional Enhancements

3GPP2 TSG-X MMD will evaluate additional charging functions and decide which to include.

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Current 3GPP Rel. 5 to 3GPP2 Rev. 0

Correlation

3GPP TS 32.200 V5.5.0

3GPP Ts 32.225 V5.5.0

3GPP2 X.P0013-007-0

3GPP2 X.P0013-008-0

Possible Correlation for 3GPP Rel. 6 to 3GPP2 Rev. A *

3GPP TS 32.260 V6.0

3GPP TS 32.296 V6.0

3GPP TS 32.299 V6.0

3GPP2 X.P0013- 008-A

3GPP2 X.P0013-012-A

3GPP2 X.P0013-013-A

May be enhanced by….

*Currently under study in TSG-X MMD Group

Harmonization between 3GPP and 3GPP2

Harmonization

Harmonization

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Symbols and AbbreviationsAbbreviations

AAA Authentication, Authorization, and Accounting

ACA Accounting-Answer

ACR Accounting-Request

AIR Audit Information Record

AS Application Server

AVP Attribute Value Pair

BCF Billing Control Function

BS Billing System

CPCF Content Provider Charging Function

CSCF Call Session Control Function

(I-Interrogating; P-Proxy; and S-Serving)

ECF Event Charging Function

IAM Initial Address Message

ICN IP Connectivity Network

IEC Immediate Event Charging

IMS IP Multimedia Subsystem

ISC IMS Service Control

MGCF Media Gateway Control Function

MRFC Media Resource Function Controller

MRFP Multimedia Resource Function Processor

OCS Online Charging System

REL Release Message

SCCF Subscriber Content Charging Function

SDP Session Description Protocol

SIP Session Initiation Protocol

UE User Equipment

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References

3GPP2 X.S0013-008-0 v1.0 IP Multimedia Subsystem - Accounting Information Flows and Protocol

3GPP2 X.S0013-007-0 v1.0 IP Multimedia Subsystem - Charging Architecture

Documents

3GPP2 IMS Charging Infrastructure