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PCRF- 3GPP Policy Charging Application

Functional Analysis

Biju M R

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Policy Charging & Management -Introduction

An intelligent policy and charging control solution helps assure the proper allocation of network resourcesbased on what subscribers have purchased and what the network can deliver.

Objectives

Network Resource Management – Traffic can be

prioritized to meet customer service expectations and

SLAs; Eg: Bandwidth congestion

Personalization Services – The value of network

assets can be maximized by offering services that meet

the individual needs of subscribers ; Eg: High

Bandwidth for a time period

New Revenue Creation and Monetization – The

ability to dynamically change the quality of service

(QoS) for an individual subscriber creates incremental

revenue and monetization opportunities; Eg: Tiered

Plans.

SGSN

SGW

BBRF/PCEF/DPI

BBFR/PCEF/DPI

BBFR/PCEF/DPI

PCRFOCS

AF

AAA

SPR

BSS

Radius Data flow

Diameter Data flow

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• The Radio Network Controller (or RNC) is a governing element in the UMTS radio access network (UTRAN) and is

responsible for controlling the Node Bs that are connected to it. There is no counterpart for BTS or NB in LTE architecture

• MME (Mobility Management Entity) is the key control-node for the LTE access-network. It is responsible for idle mode UE

(User Equipment) tracking and paging procedure including retransmissions.

• PGW (PDN Gateway) provides connectivity from the UE to external packet data networks by being the point of exit and entry

of traffic for the UE in LTE architecture.

• PCRF, PCEF, AF and BBERF are responsible for policy generation and enforcement activities. PCRF shall generate the

policy and QoS rules based on the service related information from AF and subscriber related information, provide these rules

to PCEF and BBERF.

• PCEF is located in PGW or in GGSN.PCEF will enforce the Policy rules. BBERF (Bearer Binding and Event Report Function)

is located in the SGW. BBERF is responsible for binding a set of QoS parameters to a service data flow.

• UEs are end user devices ; for eg: mobile

phones

• BTS (Base Transceiver Station) /NB(Node

B)and eNodeB facilitates the wireless

communication infrastructure part of RAN

and is responsible for establishing

connection between UE and the core

network . ENodeB (Evolved Node B) is the

counterpart for BTS in LTE architecture.

Core Network Topology

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PCC Architecture

Policy and Charging Rules Function: Key player performs:

• Identification of Service Data flow

• What should be the charging instructions for the Service Data Flow

• Quality of Service (QoS) parameters for the Service Data Flow

Policy and Charging Enforcement Function : The PCRF Rules are provided

to PCEF (Policy and Charging Enforcement Function) via the Diameter based

gx reference point which in turn enforce it in network

SPR (Subscription Profile Repository): SPR holds subscriber data along

with its QOS attributes, plan applicable etc which is referred by PCRF

Application Function – AF: The AF (Application Function) is a node that is

responsible for the service provided from a particular application. This could e.g.

be a streaming

BBERF: Bearer binding function - association of the PCC rule and the QoS

rule (if applicable) to an IP-CAN bearer within that IP-CAN session.

OCS/OFCS: These are the charging entities which will do the credit control

(OCS) and Offline charging & billing

PCRF is central entity making decisions. Decision

are based on :

• Operator configuration in the PCRF that defines

the policies applied to given services.

• Subscription information/policies for a given user,

received from the SPR.

• Information about the service received from the

AF.

• Information from the access network about what

access technology is used, etc.

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• Subscriber Information which is required for deriving the policies

• Framework required for defining different policies in terms of QoS, Gating,

charging

• Rule configuration provision for selecting appropriate policies and provision

to the network enforcement points

• PCC call flow and interface reference points from PCRF towards AF,

BBERF, PCEF and OCS

What is in Scope

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Policy Profile Representation

SPR

AF

PCEF BBERF

Sp

GxxGx

Rx

OCS OFCS

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• Location Information (Home Zone)

• Subscriber Dynamic Category

• Date of Birth

• Subscriber Plan Details

• Services allowed

• QoS allowed

• Applicable period

• Service not allowed

• Priority of service)

• Credit/Threshold Limits (against each allowed services ; if any credit of monetary present , then the details like

• threshold to keep service active

• threshold to keep service -throttled (with QoS attribute)

• threshold to keep service restricted (with QoS applicable) to wall garden services);

• Thresholds can be again

• Daily

• Monthly

• Subscriber Specific Policies (subscriber specific policies against specific service ; specific time slots in terms of blocking,

restricted usage etc; Also thresholds setting and alert /actions against subscriber own defined credit limit as well as usage limit

to be available*)

• It should also allow define plans with two thresholds together in terms of daily as well as monthly ;Say 100 MB daily and 1 GB

monthly.

• Customer Account ID

• Customer Account Type

• Subscription ID

• Subscription MSISDN

• Subscription IMSI number

• Subscriber IMEI number

• Subscription Status

• Subscriber Maximum allowable QoS (master QoS for

subscriber )

• Subscription Active Date

• Subscription Inactive Date

• Subscriber Category

Subscriber Profile (SPR)

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Policy Charging Framework

5. Charging Definitions: Respective charging properties and differentiation attributes viz.. Rating group , Online/Offfline

charging

6. SDF(Service Data Flow):Responsible for defining , managing and handling th packet filtering informations against which

policy /charging rules are provisioned .

7. Event Triggers: Send updates when certain events are detected by network elements and reported to PCRF . For

example ; Access network change, location change ;

8. Rule management function to define various rules or conditions which PCRF can verify and there by associate the

different policy profiles and Charging profiles to a particular session rquest received from AF/PCEF

1. A parser responsible for accepting policy rule

and control requests from PCEF , AF and OCS

and respond back over Diameter protocol

2. In--memory session management module

responsible for managing requests and

controls from various elements against same

user session(say for example ; IP-CAN

session)

3. QoS Definitions

4. Gating definitions: Handling the Gating

related informations- whether the packet

gateway to be open for a particular Service

Data Flow.

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PCRF Rule Sets & Rules

The PCRF system should have Process Rule Configuration capability where we can define the process for

selecting the appropriate Policy Rule/event trigger, which has to be provided in the response to PCEF.

• Rules should be defined as IF and ELSE statements, with the corresponding operations by using the input

values to fetch the appropriate Policy Rule.

• Against each rule , an Action to be attached Each action will have an argument set .

• An example for rule set and action is provided below

• If <age > < 18; Then <install policy> <parental control 18

Request & Triggers

• Requests are various QoS, Session establishment /modification/termination requests received form AF,

PCEF and BBERF to PCRF

• Triggers are pre configured internal actions defined in PCRF which are supposed to get activated upon

received certain status notifications from PCEF, AF .

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POLICY CHARGING –Reference Points & Control Flows

• Control Flow – On path & Network Initiated QoS Control

• Control Flow – Off Path & UE Initiated QoS Control

• Control Flow – On Path in Base Access

• Control Flow – Off Path in Base Access

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Control Flow – On path & Network Initiated QoS Control

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Control Flow – On Path in Base Access

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PCRF Gxx Interface (PCRF-BBERF)• Provisioning, update and removal of QoS rules from the PCRF

to the BBERF

• Transmission of traffic plane events from the BBERF to the

PCRF.

• CCR - Credit Control Request

• CCA - Credit Control Answer

• RAR - Re-Auth-Request

• RAA – Re-Auth-Answer

PCRF Gx Interface (PCRF- PCEF)• Request of Policy rules from PCEF to PCRF;

• Provision of PCC decision from PCRF to PCEF to be applied

on the detected packet flow data. Policy Rules include:

• Gating Control – enable or disable packet flow

• QoS Control – authorize QoS for the packet flow or for

the session

• Usage Monitoring Control – Monitor Usage for

enforcing dynamic policy decisions

• Termination of Gx session (corresponding to an IP-CAN

session) by PCEF or PCRF

• CCR- Credit Control Request(from PCEF to PCRF)

• CCA - Credit Control Answer

• RAR - Re-Auth-Request (From PCRF to PCEF)

• RAA - Re-Auth-Answer

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PCRF Rx Interface (PCRF- AF)

• IP filters information to identify the service data flow for policy

control and/or differentiated charging;

• Media/application bandwidth requirements for QoS control.

• In addition, for sponsored data connectivity:

• The sponsor's identification,

• Optionally, a usage threshold and whether the PCRF reports

these events to the AF,

• Information identifying the application service provider and

application (e.g. SDFs, Application ID, etc.).

• AA-Request -AAR

• AA-Answer -AAA

• Re-Authorization Request -RAR

• Re-Authorization Answer -RAA

PCRF Sy Interface (PCRF- OCS)

• Request of policy counter status reporting from PCRF to OCS and subscribe to or unsubscribe from spending limit

reports (i.e. notifications of policy counter status changes).

• Notification of spending limit reports from OCS to PCRF.

• Cancellation of spending limit reporting from PCRF to OCS.

The Sy reference point is located between the Policy and Charging Rules Function (PCRF) and the Online Charging

System (OCS). The Sy reference point enables transfer of policy counter status information relating to subscriber spending

from OCS to PCRF and supports the following functions:

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Thank You

Biju M R

Telecommunication OSS/BSS Functional Architect & IT

Solution Designer

Biju.vrindavan@gmail.com|in.linkedin.com/in/bijumr

+91 7760088233|