PCRF-Policy Charging System-Functional Analysis

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
Anintelligentpolicyandchargingcontrolsolutionhelpsassuretheproperallocationofnetworkresources
basedonwhatsubscribershavepurchasedandwhatthenetworkcandeliver.
Objectives
NetworkResourceManagement–Trafficcanbe
prioritizedtomeetcustomerserviceexpectationsand
SLAs;Eg:Bandwidthcongestion
PersonalizationServices–Thevalueofnetwork
assetscanbemaximizedbyofferingservicesthatmeet
theindividualneedsofsubscribers;Eg:High
Bandwidthforatimeperiod
NewRevenueCreationandMonetization–The
abilitytodynamicallychangethequalityofservice
(QoS)foranindividualsubscribercreatesincremental
revenueandmonetizationopportunities;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
•TheRadioNetworkController(orRNC)isagoverningelementintheUMTSradioaccessnetwork(UTRAN)andis
responsibleforcontrollingtheNodeBsthatareconnectedtoit.ThereisnocounterpartforBTSorNBinLTEarchitecture
•MME(MobilityManagementEntity)isthekeycontrol-nodefortheLTEaccess-network.ItisresponsibleforidlemodeUE
(UserEquipment)trackingandpagingprocedureincludingretransmissions.
•PGW(PDNGateway)providesconnectivityfromtheUEtoexternalpacketdatanetworksbybeingthepointofexitandentry
oftrafficfortheUEinLTEarchitecture.
•PCRF,PCEF,AFandBBERFareresponsibleforpolicygenerationandenforcementactivities.PCRFshallgeneratethe
policyandQoSrulesbasedontheservicerelatedinformationfromAFandsubscriberrelatedinformation,providetheserules
toPCEFandBBERF.
•PCEFislocatedinPGWorinGGSN.PCEFwillenforcethePolicyrules.BBERF(BearerBindingandEventReportFunction)
islocatedintheSGW.BBERFisresponsibleforbindingasetofQoSparameterstoaservicedataflow.
•UEsareenduserdevices;foreg:mobile
phones
•BTS(BaseTransceiverStation)/NB(Node
B)andeNodeBfacilitatesthewireless
communicationinfrastructurepartofRAN
andisresponsibleforestablishing
connectionbetweenUEandthecore
network.ENodeB(EvolvedNodeB)isthe
counterpartforBTSinLTEarchitecture.
Core Network Topology

4. 4 Confidential
PCC Architecture
PolicyandChargingRulesFunction:Keyplayerperforms:
•IdentificationofServiceDataflow
•WhatshouldbethecharginginstructionsfortheServiceDataFlow
•QualityofService(QoS)parametersfortheServiceDataFlow
PolicyandChargingEnforcementFunction:ThePCRFRulesareprovided
toPCEF(PolicyandChargingEnforcementFunction)viatheDiameterbased
gxreferencepointwhichinturnenforceitinnetwork
SPR(SubscriptionProfileRepository):SPRholdssubscriberdataalong
withitsQOSattributes,planapplicableetcwhichisreferredbyPCRF
ApplicationFunction–AF:TheAF(ApplicationFunction)isanodethatis
responsiblefortheserviceprovidedfromaparticularapplication.Thiscoulde.g.
beastreaming
BBERF:Bearerbindingfunction-associationofthePCCruleandtheQoS
rule(ifapplicable)toanIP-CANbearerwithinthatIP-CANsession.
OCS/OFCS:Thesearethechargingentitieswhichwilldothecreditcontrol
(OCS)andOfflinecharging&billing
PCRFiscentralentitymakingdecisions.Decision
arebasedon:
•OperatorconfigurationinthePCRFthatdefines
thepoliciesappliedtogivenservices.
•Subscriptioninformation/policiesforagivenuser,
receivedfromtheSPR.
•Informationabouttheservicereceivedfromthe
AF.
•Informationfromtheaccessnetworkaboutwhat
accesstechnologyisused,etc.

5. 5 Confidential
•SubscriberInformationwhichisrequiredforderivingthepolicies
•FrameworkrequiredfordefiningdifferentpoliciesintermsofQoS,Gating,
charging
•Ruleconfigurationprovisionforselectingappropriatepoliciesandprovision
tothenetworkenforcementpoints
•PCCcallflowandinterfacereferencepointsfromPCRFtowardsAF,
BBERF,PCEFandOCS
What is in Scope

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

7. 7 Confidential
•LocationInformation(HomeZone)
•SubscriberDynamicCategory
•DateofBirth
•SubscriberPlanDetails
•Servicesallowed
•QoSallowed
•Applicableperiod
•Servicenotallowed
•Priorityofservice)
•Credit/ThresholdLimits(againsteachallowedservices;ifanycreditofmonetarypresent,thenthedetailslike
•thresholdtokeepserviceactive
•thresholdtokeepservice-throttled(withQoSattribute)
•thresholdtokeepservicerestricted(withQoSapplicable)towallgardenservices);
•Thresholdscanbeagain
•Daily
•Monthly
•SubscriberSpecificPolicies(subscriberspecificpoliciesagainstspecificservice;specifictimeslotsintermsofblocking,
restrictedusageetc;Alsothresholdssettingandalert/actionsagainstsubscriberowndefinedcreditlimitaswellasusagelimit
tobeavailable*)
•Itshouldalsoallowdefineplanswithtwothresholdstogetherintermsofdailyaswellasmonthly;Say100MBdailyand1GB
monthly.
•CustomerAccountID
•CustomerAccountType
•SubscriptionID
•SubscriptionMSISDN
•SubscriptionIMSInumber
•SubscriberIMEInumber
•SubscriptionStatus
•SubscriberMaximumallowableQoS (masterQoSfor
subscriber)
•SubscriptionActiveDate
•SubscriptionInactiveDate
•SubscriberCategory
Subscriber Profile (SPR)

8. 8 Confidential
Policy Charging Framework
5.ChargingDefinitions:Respectivechargingpropertiesanddifferentiationattributesviz..Ratinggroup,Online/Offfline
charging
6.SDF(ServiceDataFlow):Responsiblefordefining,managingandhandlingthpacketfilteringinformationsagainstwhich
policy/chargingrulesareprovisioned.
7.EventTriggers:SendupdateswhencertaineventsaredetectedbynetworkelementsandreportedtoPCRF.For
example;Accessnetworkchange,locationchange;
8.RulemanagementfunctiontodefinevariousrulesorconditionswhichPCRFcanverifyandtherebyassociatethe
differentpolicyprofilesandChargingprofilestoaparticularsessionrquestreceivedfromAF/PCEF
1.Aparserresponsibleforacceptingpolicyrule
andcontrolrequestsfromPCEF,AFandOCS
andrespondbackoverDiameterprotocol
2.In--memorysessionmanagementmodule
responsibleformanagingrequestsand
controlsfromvariouselementsagainstsame
usersession(sayforexample;IP-CAN
session)
3.QoSDefinitions
4.Gatingdefinitions:HandlingtheGating
relatedinformations-whetherthepacket
gatewaytobeopenforaparticularService
DataFlow.

9. 9 Confidential
PCRF Rule Sets & Rules
ThePCRFsystemshouldhaveProcessRuleConfigurationcapabilitywherewecandefinetheprocessfor
selectingtheappropriatePolicyRule/eventtrigger,whichhastobeprovidedintheresponsetoPCEF.
•RulesshouldbedefinedasIFandELSEstatements,withthecorrespondingoperationsbyusingtheinput
valuestofetchtheappropriatePolicyRule.
•Againsteachrule,anActiontobeattachedEachactionwillhaveanargumentset.
•Anexampleforrulesetandactionisprovidedbelow
•If<age><18;Then<installpolicy><parentalcontrol18
Request & Triggers
•RequestsarevariousQoS,Sessionestablishment/modification/terminationrequestsreceivedformAF,
PCEFandBBERFtoPCRF
•TriggersarepreconfiguredinternalactionsdefinedinPCRFwhicharesupposedtogetactivatedupon
receivedcertainstatusnotificationsfromPCEF,AF.

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POLICY CHARGING –Reference Points & Control Flows
•Control Flow –On path & Network Initiated QoSControl
•Control Flow –Off Path & UE Initiated QoSControl
•Control Flow –On Path in Base Access
•Control Flow –Off Path in Base Access

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Control Flow –On path & Network Initiated QoSControl

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Control Flow –On Path in Base Access

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PCRF Gxx Interface (PCRF-BBERF)
•Provisioning,updateandremovalofQoSrulesfromthePCRF
totheBBERF
•TransmissionoftrafficplaneeventsfromtheBBERFtothe
PCRF.
•CCR-CreditControlRequest
•CCA-CreditControlAnswer
•RAR-Re-Auth-Request
•RAA–Re-Auth-Answer
PCRF GxInterface (PCRF-PCEF)
•RequestofPolicyrulesfromPCEFtoPCRF;
•ProvisionofPCCdecisionfromPCRFtoPCEFtobeapplied
onthedetectedpacketflowdata.PolicyRulesinclude:
•GatingControl–enableordisablepacketflow
•QoSControl–authorizeQoSforthepacketfloworfor
thesession
•UsageMonitoringControl–MonitorUsagefor
enforcingdynamicpolicydecisions
•TerminationofGxsession(correspondingtoanIP-CAN
session)byPCEForPCRF
•CCR-CreditControlRequest(fromPCEFtoPCRF)
•CCA-CreditControlAnswer
•RAR-Re-Auth-Request(FromPCRFtoPCEF)
•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 SyInterface (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 Syreference point is located between the Policy and Charging Rules Function (PCRF) and the Online Charging
System (OCS). The Syreference 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
BijuMR
TelecommunicationOSS/BSSFunctionalArchitect&IT
SolutionDesigner
[email protected]|in.linkedin.com/in/bijumr
[phone]|