a functional analysis on major building blocks of PCRF from the context of 3GPP specifcations

1. 1 Confidential
PCRF- 3GPP Policy Charging Application
Functional Analysis
Biju M R

2. 2 Confidential
2
Policy Charging & Management -Introduction
An intelligent policy and charging control solution helps assure the proper allocation of network resources
based 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/PC
EF/DPI
BBFR/PC
EF/DPI
BBFR/PC
EF/DPI
PCRFOCS
AF
AAA
SPR
BSS
Radius Data flow
Diameter Data flow

3. 3 Confidential
• 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

4. 4 Confidential
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.

5. 5 Confidential
• 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

6. 6 Confidential
Policy Profile Representation
SPR
AF
PCEF BBERF
Sp
GxxGx
Rx
OCS OFCS

7. 7 Confidential
• 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)

8. 8 Confidential
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.

9. 9 Confidential
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 .

10. 10 Confidential
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

11. 11 Confidential
Control Flow – On path & Network Initiated QoS Control

12. 12 Confidential
Control Flow – On Path in Base Access

13. 13 Confidential
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

14. 14 Confidential
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:

15. 15 Confidential
Thank You
Biju M R
Telecommunication OSS/BSS Functional Architect & IT
Solution Designer
Biju.vrindavan@gmail.com|in.linkedin.com/in/bijumr
+91 7760088233|