1

Charging Management

in

3GPP SA5 SWGB

What the standards provide

Chair: Karl-Heinz Nenner (T-Mobile)

Vice Chair: Gerald Görmer (Siemens AG)

2

SA5 SWGB Rapporteur Group Structure

General Charging SessionKarl-Heinz Nenner

(T-Mobile)

Bearer Charging

SessionBenni Alexander

(Nokia)

IMS ChargingSession

Göran Andersson(Ericsson)

Service ChargingSession

Gerald Görmer(Siemens AG)

3

Table of contents

1. Motivation

2. Setting the scene for charging in 3GPP2.1 Charging Levels2.2 Charging Methods

3. Timeline

4. Release 64.1 Common Charging Architecture4.2 Common Interfaces and Applications

5. Additional Functionality5.1 The Online Charging System5.2 Flow based Bearer Charging

4

MotivationThe business principles behind

The Vendor business paradigm:– to sell equipment to Operators,– purpose of equipment is to build telecom networks

The Operator business paradigm:– build and operate a (mobile) telecom network– purpose of network is to provide end user services

The Customer– uses – and will be billed for - the end user services

Charging is the central enabler for the end user billing there will be no equipment sold, no network built and no service

offered unless the service can be billedcharging is at the core of the business for vendors and operators alike!

5

MotivationThe key terms in 3GPP

accounting: process of apportioning charges between the Home Environment, Serving Network and Subscriber.

billing: function whereby CDRs generated by the charging function(s) are transformed into bills requiring payment.

charging: a function within the telecommunications network and the associated OCS/BD components whereby information related to a chargeable event is collected, formatted, transferred and evaluated in order to make it possible to determine usage for which the charged party may be billed.

OCS: Online Charging System

BD: Billing Domain

6

Setting the scene for charging in 3GPP

Charging Levels • Bearer, Subsystem and Service charging

Charging Methods• Online versus Offline charging

7

Setting the sceneCharging Levels

1. Bearer Charging, comprising– Charging for the Circuit Switched Domain– Charging for the Packet Switched Domain (GPRS)– Charging for the I-WLAN

2. Subsystem Charging, i.e. IMS

3. Service Charging, comprising– MMS– LCS– More to come, e.g. MBMS, Push, Presence, Messaging– In future, OMA Services ?!

8

Setting the sceneCharging Methods

offline charging: Charging mechanism where charging information does not

affect, in real-time, the service rendered. The final result of this charging mechanism is the forwarding of CDR files to the Billing Domain.

online charging: Charging mechanism where charging information can

affect, in real-time, the service rendered and therefore a direct interaction of the charging mechanism with bearer/session/service control is required. The mechanism comprises the execution of credit control and subscriber account balance management on the Online Charging System.

9

Setting the scene – Bearer Charging : CS domain

CS domain charging involves:

- the GMSC- the MSC (server)- the HLR- the EIR

• Offline Charging:- CDR types for MOC, MTC,

IncGW, OutGW….

• Online charging: CAMEL– TS 03.78/09.78 (GSM)– TS 23.078 / 29.078 (3GPP)

Billing System

VMSC Server

CS Domain

CDR

CDR

MGW

GMSC Server

MGW

HLR

SCF

CDR

Mc

Mc

Billing System

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

SCF

CDR

Mc

Mc

CAP

CAP

CDR

Billing System

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

SCF

CDR

Mc

Mc

Billing System

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

SCF

CDR

Mc

Mc

CAP

CAP

CDR

C

D

IuCS A IuCS A

Billing System

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

SCF

CDR

Mc

Mc

Billing System

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

SCF

CDR

Mc

Mc

CAP

CAP

CDR

Billing System

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

CDR

Mc

Mc

PSTN

Billing Domain

VMSC Server CDR

CDR

MGW

GMSC Server

MGW

HLR

gsm SCF

CDR

Mc

Mc

CAP

CAP

CAP

CDR

C

IuCS A IuCS A

gsm SSF

gsm SSF

10

Setting the scene – Bearer Charging : CS domainBasic principles

– „call records“ per call/duration– Multiple „partial records“ for long calls– Tariff Time Change captured within CDR– All service invocation information inside CDRs

Major CS charging parameters– Origination / Destination of call– Invoked services (BS, TS, SS)– Radio resource usage for data

Special Cases– SMS (supported from the early days)

• Mobile Originated SMS CDR• Mobile Terminated SMS CDR

– LCS (supported as of Rel-4)• Mobile terminated location request CDR• Mobile originated location request CDR• Network induced location request CDR

11

Setting the scene – Bearer Charging : PS domainPS domain (GPRS) charging

involves the SGSN and the GGSN

Offline Charging:- M-CDR records MM items when

user is GPRS attached- S-CDR and G-CDR capture PDP

context charging

Online charging:• CAMEL based

– TS 03.78/09.78 (GSM)– TS 23.078 / 29.078 (3GPP)

• Diameter based– Built upon IETF DCC

12

Setting the scene – Bearer Charging : PS domainBasic principles

– There is no concept of „service invocation“, all traffic is plain IP– There is no concept of „mobile termination“, but „uplink“ and „downlink“ traffic

instead– CDRs are generated per user connection (“PDP context”)– CDRs are time and volume based– Each CDR contains one or more volume containers, characterised by QoS and

Tariff Time– Uplink and downlink volume counted separately– Non-volatile storage of CDRs on the CGF

Major GPRS charging parameters– User ID („origination“) as in CS– APN („destination“)– Time, data volume, QoS

Special Cases: SMS and LCS as in CS domain

13

Setting the scene – Bearer Charging : WLANWLAN: an interworking architecture for non-3GPP WLAN (i.e. 802.11)

with the 3GPP core network

In Rel-6, there are two relevant interworking scenarios– Scenario 2 is a SIM based authentication/authorisation, providing IP

connectivity via the WLAN – Scenario 3 with Access to 3GPP services (IMS, SMS, MMS, …) on top of

the above

Charging functionality is currently being specified in SA5– Will be similar to GPRS– Will make use of IETF AAA technology (use of Diameter)– Time and data volume to be counted

• in WLAN only in scenario 2 reported to VPLMN• in WLAN, VPLMN AAA and HPLMN AAA in scenario 3, where user traffic

traverses VPLMN and HPLMN

14

Setting the scene – Subsystem ChargingIP Multimedia Subsystem (IMS)

P-CSCF

IM Subsystem

CSCF MGCF HSS

Cx

IP Multimedia Networks

IM-MGW

PSTN

Mc

Mb

Mg

Mm

MRFP

Mb

Mr

Mb

Legacy mobile signalling Networks

CSCF

Mw

Go

PCF

Mw

Gm

BGCF Mj Mi

BGCF

Mk Mk

C, D, Gc, Gr

UE

Mb

Mb

Mb

MRFC

SLF Dx

Mp

PSTN

PSTN

15

Setting the scene – Subsystem ChargingIMS Charging : GeneralsProxy Call Session Control Function („CSCF“)

– Determines applicable I-CSCF– Routes SIP signalling between UE and S-CSCF– Resource control via embedded PCF

Serving CSCF– Responsible for session control– Interacts with service platforms– May behave as SIP proxy or user agent

• accepts requests and services them internally or translates / forwards them on • may terminate and independently generate SIP transactions

Interrogation CSCF– Determines applicable S-CSCF– Routes SIP signalling to / from „foreign“ networks (Roaming)

Application Server– Provides any kind of „service“– Services are not standardised in the 3GPP specifications– Examples: movie / music clips, news flash, soccer goals, ….

16

Setting the scene – Subsystem ChargingIMS Charging : Basic principles CDRs are generated per IMS session / duration

Tariff Time Change is captured within CDR

All media component invocation information is inside the CDRs– Each CDR contains one or more media component descriptors– AS information is captured, if AS(s) is / are involved

many similarities with CS charging, BUT– Completely different, distributed charging architecture

• ACR start / stop / interim are generated per SIP message• CDRs are generated by CCF and then sent to BD• ACRs and CDRs are asynchronous

– No transport network infomation (e.g. radio resources)– If correlation with GPRS CDRs required, this is done by cross-

correlating GPRS and IMS „Charging IDs“– Correlation between IMS CDRs is required (e.g. CSCF CDRs, AS CDRs)

– all CDRs contain the same IMS „Charging ID“

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Setting the scene – Subsystem ChargingIMS Charging : Aspects

Major IMS charging parameters– Origination / Destination of session– Invoked media components (audio, video, etc.)– AS information, if applicable

Offline Charging with 7 CDR types: 1 each per IMS node type– P-CSCF captures session related information– S-CSCF captures similar information as the P-CSCF, but

• only S-CSCF CDR has AS related information• only P-CSCF CDR has information on authorised QoS

– I-CSCF captures user registration events– AS captures service invocation information– Others (more details in „special cases“ below):

• interworking with CS services• Conferencing

Online charging only in S-CSCF, AS and MRFC

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Setting the scene – Subsystem ChargingIMS Charging : Special cases

SIP Events create ACR Events instead of start/interim/stop messages– SIP NOTIFY– SIP MESSAGE– SIP REGISTER– SIP SUBSCRIBE– SIP Final Response indicating an unsuccessful SIP session set-up– SIP Final Response indicating an unsuccessful session-unrelated procedure– SIP CANCEL, indicating abortion of a SIP session set-up– I-CSCF completing a HSS Query that was issued for a SIP INVITE– AS service invocation events

CS interworking– Several nodes support CS interworking, i.e. MGCF, MGW, BGCF– MGCF and BGCF can generate call related CDRs

Conferencing– MRFC and MRFP provide conferencing capabilities (H.248)– MRFC can generate related CDRs

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Setting the scene – Service ChargingMultimedia Messaging Service (MMS)

MM1

MM6 MM7

MM4

MM1

MM3

...

Relay

MMS User Agent A

External Server #1

(e.g. E-Mail)

External Server #2 (e.g. Fax)

External Server #N

“Foreign” MMS

Relay/Server

MMS User Agent B

Server

MMS Relay/Server

MM2

External Server #3

(e.g. UMS)

MM5

MMS User Databases

HLR

MMS VAS Applications

MM9

Online Charging System

MM8

Post-processing

System

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Setting the scene – Service ChargingMMS Charging : Generals

Multimedia Messaging Service (MMS) is based on a specific service node called the MMS Relay / Server (MMS R/S)

Originator MMS R/S serves the MM „originator“

Recipient MMS R/S serves the MM „recipient“

Inter-MMS R/S traffic uses SMTP (email)

Differences to SMS:– Only one MMS R/S involved for intra-PLMN MM transfer, e.g. T-D1 to T-

D1– 2 MMS R/S involved if originator and recipient are subscribed to

different networks (e.g. T-D1 to Vodafone)– In SMS, only one SMSC is involved– In contrast to SMS, MMS charging is standardised in the service area

(i.e. the MMS R/S), not the bearer domain (MSC/SGSN)

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Setting the scene – Service ChargingMMS Charging : Basic principles The MMS R/S collects charging information such as:

– destination / source addresses used by the “User Agent” (UA)– identification of the MMS R/S(s) involved in the MM transaction– the size of the MM and its components – storage duration, i.e. the time interval when a MM is saved on a non-

volatile memory media– identification of the bearer resources used for the transport of the MM,

i.e. the identity of the network and the network nodes In scenarios involving a VASP, the charging information describes

the identification of the VASP and the amount of user data sent and received between the MMS R/S and the VASP.

The information listed above is captured for use cases in relation to:

– MM submission, retrieval and forwarding– transactions involving the MMbox– transactions involving a VASP

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Setting the scene – Service ChargingMMS Charging : AspectsMajor charging parameters

– Originator and Recipient (user agent & network)– MM volume (size)

Offline Charging – MM1 CDR types to enable end user billing

• MM submission, retrieval and forwarding• Read reply, delivery report, notification, deletion• Upload, download, removal from / to MMBox

– MM4 CDR types intended for inter-network accounting• MM exchange between MMS R/S in different networks• Read-reply and delivery reports

– MM7 CDR types for VASP transactions• Submission and cancellation• Read-reply, delivery reports

Online Charging with Diameter Credit Control

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Setting the scene – Service ChargingLoCation Service (LCS)

VGMLC

2G- MSC

3G- SGSN

2G- SGSN

MSC server

GERAN

UTRAN

UE

gsmSCF

Lg Gb

A

Lg

Lc Le

Iu

HSS/HLR

Iu

Iu

Lg

Um

Uu

Lg Lh

OSA-LCS External LCS

Client

Iu HGMLC RGMLC Lr Lr

Lh

VPMLN

PPR

Lpp

PMD

Lid

Lid

PMD

24

Setting the scene – Service ChargingLCS Charging : Generals

Charging information in the Service domain (GMLC) is collected for inter-operator accounting purposes; a network requesting location info may be charged by the network providing the location info

The main charging parameters collected by the GMLCs are:– Identity of the mobile subscriber to be located– Identity of the entity requesting the location– Identity of the GMLC or PLMN serving the LCS client– the quality of the location requested by / delivered to the client– date / time the location procedure was requested by the client– Usage of continuous/periodic tracking– LBS information, describing the service specific parameters in

addition to the above location resource information The information listed above is captured for all BC use cases:

– Mobile Originated Location Request– Mobile Terminated Location Request– Network Induced Location Request

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Timeline of charging TS

• Bearer, Subsystem and Service charging Releases

• Online & Offline charging

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Timeline of charging TSCS and PS domains

CS Offline Charging– TS 12.05 (GSM until Rel-98)– TS 32.005 (3GPP Rel-99)– TS 32.205 (3GPP Rel 4/5)– TS 32.250 (3GPP Rel-6)

PS Offline Charging– TS 12.15 (GSM Rel-97/98)– TS 32.015 (3GPP Rel-99)– TS 32.215 (3GPP Rel 4/5)– TS 32.251 (3GPP Rel-6)

CS & PS Online charging: CAMEL– TS 03.78/09.78 (GSM)– TS 23.078 / 29.078 (3GPP)

PS Online Charging: based on IETF DCC– TS 32.251 (Rel-6)

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Timeline of charging TS IMS and Service Charging

IMS: Offline & Online Charging• TS 32.225 (3GPP Rel-4/5) -> TS 32.260 (3GPP Rel-6)• S-CSCF uses ISC interface for online charging

MMS: Offline Charging• TS 32.235 (3GPP Rel-4/5) -> TS 32.270 (3GPP Rel-6)

Online Charging• TS 32.270 (3GPP Rel-6)

LCS Offline & Online Charging• TS 32.271 (3GPP Rel-6)

As a major change, Rel-6 sees the introduction of common charging architecture, interfaces and applications for all 3GPP charging

28

3GPP Release 6

• Common Charging Architecture

• Common Interfaces and Applications

29

Charging Standards Rel-6Getting more organised

Every new technology came with its own charging solution– Each domain was done independently– Each domain has its own functional description and interfaces

Result: Too many different architectures and solutions

However

From an abstract viewpoint, it‘s always the same functionality, regardless of system / technology

– Chargeable / billable items (events)• Calls / Sessions• Service Events

– The same basic tasks• Collect charging relevant information (usually from signalling parameters)• Create CDRs / perform online credit control• Forward CDRs to billing domain

– Identical information flow from network to Billing Domain / OCS according to the above basic tasks

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Charging Standards Rel-6Charging Architecture

Billing Domain

ONLINE CHARGINGOFFLINE CHARGING

WLAN

BGCF

MGCF

MRFC

SIP AS

CRF

AF

CDF

TPF

CS - NE

SGSN

GGSN

CGF

OCSIMS GWF

P - CSCF

I - CSCF

S - CSCF

Service - NE

31

Charging Standards Rel-6 Common offline charging architecture

CN Domain

Service nodes

Sub - system

Billing Domain

R f G a B x

C

T

F

C

D

F

C

G

F

3GPP network

32

Charging Standards Rel-6 Common offline charging architecture

Charging Trigger Function– Collects „Metrics“ from the core system, based on system specific

triggers (e.g. signalling events)– Formats these metrics into charging events– forwards charging events to the CDF via Rf reference point

Charging Data Function– Collects charging events and formats them into CDRs according to

system specific rules– Forwards CDRs to CGF via Ga reference point

Charging Gateway Function– Provides non-volatile CDR file store– Uses Bx reference point for CDR file transfer to Billing Domain

Billing domain– Receives CDR files from CGF– No further standardisation

33

Charging Standards Rel-6 Common online charging architecture

CN Domain

Service element

Sub - system

Ro

C

T

F

3GPP network

CAP

O

C

F

ABMF

RF

OCS

Rc

Re

34

Charging Standards Rel-6 Common online charging architecture

Common approach for online charging– Same Diameter based interface (IETF Diameter CCA)– Same source collection (building on CTF)

CS and GPRS will retain CAMEL

GPRS will also see the addition of the Diameter interface to GGSN; same as WLAN

All new Rel-6 services (MBMS, Push, Presence, Messaging, …) will use same offline and online charging functions

35

Charging Standards Rel-6Structure of TS series

32.240

Charging Architecture and Principles

32.250

CS- domain Charging

32.251

PS- domain Charging

32.252

WLAN Charging

32.260

IM Subsystem Charging

32.270

MMS Charging

32.271

LCS Charging

32.295

Charging Data

Record (CDR) transfer

32.297

Charging Data

Record (CDR) file

format and transfer

32.298

Charging Data

Record (CDR)

parameter description

32.299

Diameter

Charging Application

32.27x

x Service Charging

32.296

Online Charging

System (OCS)

applications and interfaces

36

Charging Standards Rel-6Structure of TS series

TS 32.240 Architecture and Principles– Common online and offline charging architecture– General principles of Charging

One „Middle Tier“ TS per domain / subsystem / service– Mapping of common architecture onto specific domain– Domain / subsystem / service specific charging functionality,

especially type and content of CDRs and ACRs Common interfaces and applications between the entities

of the common architecture– Rf and Ro Diameter application (TS 32.299)– Bx interface to Billing Domain (TS 32.297)– Ga interface between CDF and CGF (TS 32.295)– CDR Parameter and ASN.1 Syntax Description (TS 32.298)

Special case: Online Charging System (OCS) (TS 32.296)

37

Additional functionality

• The Online Charging System

• Flow based Bearer Charging

38

The Online Charging System

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The Online Charging SystemThe following components of an „OCS“ have been identified

– „Charging functions“ for• Session based charging• Event based charging

– Account Balance Management Function (ABMF)• Holds subscriber account• Controls addition / deduction of monetary amounts from account• Performs credit reservation on the account• Management of counters applicable for the account

– Rating Function (RF)• unit determination: calculation of a number of non-monetary units

(“service units”, data volume, time and events);• price determination: calculation of monetary units (price) for a

given number of non-monetary units;• tariff determination: determination of tariff information based on

the subscribers contractual terms and service being requested;• Management of counters applicable for rating

40

The Online Charging SystemTS 32.296: OCS applications and interfaces

Confined to Re (Rating) interface in Rel-6 Two approaches are being standardised

1. Rating engine model (Class A)• Charging function fetches data from the Account Balance

Management Function • Charging function issues rating request towards the Rating

Function• Charging function triggers counter / account update on the

Account Balance Management Function• Design goal: allow common Rating Function for online & offline

charging 2. Extended rating engine model (Class B)

• Similar to the above, but the rating function also stores and manages some of the counters needed for the rate calculation

• Requires additional scenario on Re to acknowledge service delivery and counter update

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Flow based Bearer ChargingProblem Statement

The problem:• Charging for bearer resources does not take into account the

value of services accessed via these bearer resources• Integrated service pricing: when the tariff model calls for

subscribers paying for the service (e.g. MMS), the charges for bearer usage must be removed

• Due to different bearer charges in roaming and non-roaming cases, the service price must depend on whether the customer is on the HPLMN or roaming on a foreign network

The solution:• Make bearer charging “service aware”• Make service charging “access aware”• Make bearer and service charging “roaming aware”

42

Flow based Bearer ChargingFunctionality• Differentiate between different service data flows for the

purpose of charging, e.g.• Web browsing• IP Video Telephony• MMS versus WAP traffic• …….

• Applicable to GPRS (GGSN – TS 32.251) and WLAN (PDG) charging

• Charging rules for online / offline charging are predefined or provided from a CRF (TS 29.210)

• Charging rules determine the CDR generation (offline charging) and credit control procedure (online charging)

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Backup

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Service Based Local Policy (SBLP) : Introduction

• SBLP was defined in Rel-5 to enable the IMS to control the QoS provided by the GPRS bearer service based on the requirements of the negotiated application services.

• This is based on particular interest if the bearer uses a high QoS and/or if an operator uses IMS network entities to charge application services.

• In Rel-6 the concept was extended for non-IMS application functions.

45

Service Based Local Policy (SBLP) : Architecture UE

AF (e.g P-CSCF)

GGSN

PDF

Gq

Go PEP

User Plane

AF session signalling e. g SIP

GPRS bearers

46

Service Based Local Policy (SBLP) : Functions

• Policy Enforcement Point (PEP)

• Policy Decision Function (PDF)

• Application Function (AF)