Policy control in epc

• 1. Policy and Charging in Telecom NetworksInam Ullah Director Product Development EMI Networks

2. Agenda What is Policy Control Why Policy Control in EPC/SAE/LTE? Business Requirements for Policy & Charging Control Policy Charging and Rule Function(PCRF) Policy in 2G/3G networks Migration to IMS & EPC Policy and Charging Control in 3GPP Network Conclusion 3. What is a Policy Control?Process of Defining and Enforcing configurable business rules to enable wide range of intelligent, real-time controls, quality of service (QoS) changes, optimizing high bandwidth traffic, and enforcing usage quotas. 4. Levels of Policy Control Local Policy Local Policy is defined and administered at the entity which enforces it. For example, both QoS and Charging Local Policy may be defined at PDSN. Generally, these policies will have broad system wide applications. Static Policy Static Policy is defined on a per subscriber basis and stored on a Static Policy Server. Static Policy can be defined for both QoS as well Charging. It is downloaded into PDSN where it is enforced. Dynamic Policy Dynamic Policy is defined on a per application per session basis. It is determined by a combination of information stored at Policy Decision Function (PDF), the information provided by the subscriber during a session initiation and the application itself. It is provided by PDF to PDSN (PEF) during a session and enforced by PDSN. 5. Why Policy Control? Business requirements as how services are delivered endto-end in accordance to subscriber preferences, service agreement and network consideration covering: Authorization / Denial Charging Rule Quality of Service (e.g. Priority, Latency, Class, Route) Dialogue Redirection Bandwidth & Resource Allocation (e.g. Allocated, Shaping and Throttling) Quota Rules Routing & Location Sensitive Monitoring & Service Triggers 6. Policy Control Policy control comprises functionalities for: Binding, i.e. the generation of an association between a service data flow and the IP-CAN bearer transporting that service data flow; Gating control, i.e. the blocking or allowing of packets, belonging to a service data flow or specified by an Application Identifier, to pass through to the desired endpoint; Event reporting, i.e. the notification of and reaction to application events to trigger new behaviour in the user plane as well as the reporting of events related to the resources in the GW(PCEF); QoS control, i.e. the authorisation and enforcement of the maximum QoS that is authorised for a service data flow, an Application identified by Application Identifier or an IP-CAN bearer; Redirection, i.e. the steering of packets, belonging to an application defined by the Application Identifier to the specified redirection address; IP-CAN bearer establishment for IP-CANs that support network initiated procedures for IP-CAN bearer establishment. 7. Business Drivers for PCC Police subscribers and service agreements to a subscriber-level and subscriber-group level for the following mobile internet and broadband business models including: Service Quota & Bandwidth Caps Subscriber Overage Throttling and Termination (including EU Bill Shock) Fair Usage Control Parental Control Time-Based, Usage and Location Based Charging / Tariff Switching Voice, Video and Application QoS Setting, Bandwidth Allocation and Prioritization On-Demand Bandwidth Turbo-Button Like functions VIP Profile and Spend based prioritization and charging (e.g. Business Class, Pre-paid vs. Post-paid vs. On-demand) Partner Service Priorities (e.g. official public internet VoIP) Peak Time Video and P2P Management Automated Service Advisory, Up-sell and Cross-sell 8. Policy Control in EPC 9. 3GPP Policy and Charging Control The 3GPP PCC functions include: PCRF (policy and charging rules function) provides policy control and flow based charging control decisions. PCEF (policy and charging enforcement function) implemented in the serving gateway, this enforces gating and QoS for individual IP flows on the behalf of the PCRF. It also provides usage measurement to support charging OCS (online charging system) provides credit management and grants credit to the PCEF based on time, traffic volume or chargeable events. OFCS (off-line charging system) receives events from the PCEF and generates charging data records (CDRs) for the billing system. 10. Policy Control is the Key 11. Policy Charging and Rule Function(PCRF) The PCRF interfaces with the main packet gateway and takes charging enforcement decisions on its behalf. Dedicated policy equipment standardized in 3GPP that enables the policy function for bandwidth and charging on multimedia networks. The PCRF function is part of the larger PCC architecture, which also includes the Proxy Call Session Control Function (P-CSCF) and the Policy and Charging Enforcement Function (PCEF). Combined, the elements of the PCC provide access, resource, and quality-of-service (QoS) control. PCRF is an important part of IMS architectures, although it is not exclusive to the 3GPP-based network in which it was certified. It works across wireless networks and can come pre-integrated in a standard IT server. PCRF is often referred to as policy server or -- formerly -- a Policy Decision Function (PDF). 12. Policy in Action: Video Streaming Example customer has requested a streaming video that will be paid for by the included advertising. We will assume the customer likes the video and decides after five minutes to pay for a higher data rate with no advertising from her pre-paid video account. This requires specific QoS treatment to the requested and modified by the streaming video controller during the session. It does this by appearing as an application function to the PCRF. The PCRF and PCEF work together to ensure the correct QoS is provided. The charging aspects are managed by the OCS. When the customer switches to the non-advertising stream the PCEF will request credit from the OCS. The OCS will check the customers video balance and provide the appropriate credit for the IP flow. The OCS has the job of correlating charging events to ensure the customer is not charged for the data stream, but only the video. This sufficiently powerful to provide dynamic control of charging and QoS on a per flow and per subscriber basis. 13. Policy in 2G/3G networks Policy control, charging and billing mediation are already complex functions. IN pre-paid platform: originally deployed to provide simple pre-paid voice services, has been continuously extended to include roaming, messaging, data and content services to pre-paid customers. Active mediation platforms: have been deployed as adjunct platforms to the IN pre-paid platform to support control and usage measurement for messaging, data and contents services. Complex real-time rating platforms: have been deployed as adjunct platforms to the IN pre-paid platform to support more complex tariff models and subscriber models. Policy control is already implemented to support existing data services. This includes some PCRF type functionality, but not the full dynamic control of policy that the EPC will provide. GGSN and dedicated deep packet inspection (DPI) platforms support active mediation by enabling very detailed usage measurements and control of IP flows. 14. Migration path from IMS LTE This real-time infrastructure is being integrated with offline billing to support a hybrid model; where a customer can choose to have individual services billed on a pre-paid or post-paid basis. The fundamental issue operators will face is how this already complex policy control, charging and billing infrastructure will evolve to accommodate the needs of LTE. A migration path is required from the legacy environment shown previously to include the LTE/SAE architecture . The growth in transaction rates that the PCC will be required to support will drive the replacement of most legacy components during the migration. The IN pre-paid platform in particular will be gradually eliminated as balance management migrates to the online billing platform and the circuit switched infrastructure is eventually replaced. 15. Policy in IMS Networks VoIP delivered over LTE will require the full dynamic QoS controls standardized in the EPC. To ensure appropriate QoS for voice calls and use a similar mechanism to the video streaming example The PCRF capability should be the focus for any enhancements to policy control. Implementation on the PCRF enables policy control to be used for both pre-paid, post-paid and hybrid billing. IP network for transport, signaling and control based on IMS, EPC and LTE standards There is likely to be a proliferation of application and content servers that will use the AF to manage quality of service and charging requirements. T This will generate a much higher load on the policy and charging control platform. Operators should factor in the scalability requirements of these future needs when selecting solutions to the current data only scenario. 16. PCRF requirements for LTE Active mediation systems and complex real-time rating adjuncts must evolve to support the requirements of the 3GPP to find OCS. Rapidly growing usage will put a significant load on the systems and they will need to be scaled accordingly. The migration of functionality away from legacy IN pre-paid platforms will continue. Operators are already moving in this direction to support more complex hierarchical accounts and enable subscribers to choose how individual services are charged (pre-paid or post-paid). The PCRF capability should be the focus for any enhancements to policy control. Implementation on the PCRF enables policy control to be used for both pre-paid, post-paid and hybrid billing. Existing billing mediation platforms will need to be extended to support the EPC elements. With rapidly increased data traffic these will need significant scaling to meet demand. Existing off-line post-paid billing systems are complex and expensive to upgrade. Where possible operators should insulate billing systems from the changes in the network by focusing on enhancements to the PCC. 17. LTE Billing and charging requirements 18. Full LTE with IMS Service Control 19. 3GPP Policy Control Architecture 20. 3GPP Policy Control Architecture SpSubscription Profile Repository (SPR)AF Online Charging System (OCS)RxPolicy and Charging Rules Function (PCRF) SyGxxSdGxGy BBERFTDFPCEFPCEF GzGatewayOffline Charging System (OFCS) 21. Functional Elements of PCC ArchitectureThe PCC functionality is comprised by the functions of the Policy and Charging Enforcement Function (PCEF) Bearer Binding and Event Reporting Function (BBERF) Policy and Charging Rules Function (PCRF) Application Function (AF) Traffic Detection Function (TDF) Online Charging System (OCS) Offline Charging System (OFCS) Subscription Profile Repository (SPR) or the User Data Repository (UDR) 22. Policy Control and Charging Rules Function (PCRF) The PCRF encompasses policy control decision and flow based charging control functionalities. The PCRF provides network control regarding the service data flow detection, gating, QoS and flow based charging (except credit management) towards the PCEF. The PCRF shall apply the security procedures, as required by the operator, before accepting service information from the AF. The PCRF shall decide whether application traffic detection is applicable, as per operator policies, based on user profile configuration, received within subscription information. The PCRF shall decide how certain service data flow/detected application traffic shall be treated in the PCEF and in the TDF, if applicable, and ensure that the PCEF user plane traffic mapping and treatment is in accordance with the user's subscription profile. 23. Policy and Charging Enforcement Function (PCEF) The PCEF encompasses service data flow detection, policy enforcement and flow based charging functionalities. This functional entity is located at the Gateway (e.g. GGSN in the GPRS case, and PDG in the WLAN case). It provides service data flow detection, user plane traffic handling, triggering control plane session management (where the IP-CAN permits), QoS handling, and service data flow measurement as well as online and offline charging interactions. A PCEF shall ensure that an IP packet, which is discarded at the PCEF as a result from policy enforcement or flow based charging, is neither reported for offline charging nor cause credit consumption for online charging. 24. Application Function (AF) The Application Function (AF) is an element offering applications that require dynamic policy and/or charging control over the IP-CAN user plane behaviour. The AF shall communicate with the PCRF to transfer dynamic session information, required for PCRF decisions as well as to receive IP-CAN specific information and notifications about IP-CAN bearer level events. One example of an AF is the P-CSCF of the IM CN subsystem. The AF may receive an indication that the service information is not accepted by the PCRF together with service information that the PCRF would accept. In that case, the AF rejects the service establishment towards the UE. If possible the AF forwards the service information to the UE that the PCRF would accept. 25. Traffic Detection Function The TDF is a functional entity that performs application detection and reporting of detected application and its service data flow description to the PCRF. For those cases where service data flow description is not possible to be provided by the TDF to the PCRF, the TDF performs: - Gating; - Redirection; - Bandwidth limitation. for the detected applications. 26. Subscription Profile Repository (SPR) The SPR logical entity contains all subscriber/subscription related information needed for subscription-based policies and IP-CAN bearer level PCC rules by the PCRF. Subscriber's allowed services; For each allowed service, a pre-emption priority; Information on subscriber's allowed QoS, including the Subscribed Guaranteed Bandwidth QoS; Subscriber's charging related information (e.g. location information relevant for charging); Subscriber's User CSG Information reporting rules; Subscriber category; Subscriber's usage monitoring related information; MPS EPS Priority and MPS Priority Level; IMS Signalling Priority; Subscriber's profile configuration indicating whether application detection and control should be enabled. Spending limits profile containing an indication that policy decisions are based on policy counters available at OCS that has a spending limit associated with it and optionally the list of policy counters. 27. Online Charging System Covered in Charging and Billing Part 28. Offline Charging System (OFCS) Covered in Charging and Billing Part 29. Bearer Binding and Event Reporting Function (BBERF) The BBERF includes the following functionalities: Bearer binding. Uplink bearer binding verification. Event reporting to the PCRF. Sending or receiving IP-CAN-specific parameters, to or from the PCRF. 30. Policy and charging control rule The Policy and charging control rule (PCC rule) comprises the information that is required to enable the user plane detection of, the policy control and proper charging for a service data flow. The packets detected by applying the service data flow template of a PCC rule are designated a service data flow. Two different types of PCC rules exist: Dynamic rules and predefined rules. The dynamic PCC rules are provisioned by the PCRF via the Gx reference point, while the predefined PCC rules are directly provisioned into the PCEF and only referenced by the PCRF. The usage of pre-defined PCC rules for QoS control is possible if the BBF remains in the PCEF during the lifetime of an IP-CAN session. In addition, pre-defined PCC rules may be used in a non-roaming situation and if it can be guaranteed that corresponding pre-defined QoS rules are configured in the BBF and activated along with the pre-defined PCC rules. 31. Reference Points 32. Rx reference point The Rx reference point resides between the AF and the PCRF. This reference point enables transport of application level session information from AF to PCRF. Such information includes, but is not limited to: IP filter 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.).The Rx reference point enables the AF subscription to notifications on IP-CAN bearer level events (e.g. signalling path status of AF session) in the IP-CAN. 33. Gx reference point The Gx reference point resides between the PCEF and the PCRF. The Gx reference point enables a PCRF to have dynamic control over the PCC behaviour at a PCEF. The Gx reference point enables the signalling of PCC decision, which governs the PCC behaviour, and it supports the following functions: Request for PCC decision from PCEF to PCRF; Provision of IP flow mobility routing information from PCEF to PCRF; this applies only when IP flow mobility as defined in TS 23.261 [23] is supported; Provision of PCC decision from PCRF to PCEF; Reporting of the start and the stop of a detected applications and transfer of service data flow descriptions for detected applications, if available, from the PCEF to the PCRF; Delivery of IP-CAN-specific parameters from PCRF to PCEF or from PCEF to PCRF; this applies only when Gxx is deployed. Negotiation of IP-CAN bearer establishment mode (UE-only or UE/NW); Termination of Gx session (corresponding to an IP-CAN session) by PCEF or PCRF. 34. Subscriber Databases Sp reference point The Sp reference point lies between the SPR and the PCRF. The Sp reference point allows the PCRF to request subscription information related to the IP-CAN transport level policies from the SPR based on a subscriber ID, a PDN identifier and possible further IP-CAN session attributes, see Annex A and Annex D. For example, the subscriber ID can be IMSI. The reference point allows the SPR to notify the PCRF when the subscription information has been changed if the PCRF has requested such notifications. The SPR shall stop sending the updated subscription information when a cancellation notification request has been received from the PCRF. Ud reference point The Ud reference point resides between the UDR and the PCRF, acting as an Application Frontend as defined in TS 23.335 [25]. It is used by the PCRF to access PCC related subscription data when stored in the UDR. 35. Gy reference point The Gy reference point resides between the OCS and the PCEF. The Gy reference point allows online credit control for service data flow based charging Gy reference point are defined in TS 32.251 36. Gz reference point The Gz reference point resides between the PCEF and the OFCS. The Gz reference point enables transport of service data flow based offline charging information. The Gz interface is specified in TS 32.240 37. Sd reference point The Sd reference point resides between the PCRF and the TDF. The Sd reference point enables a PCRF to have dynamic control over the application detection and control behaviour at a TDF. The Sd reference point enables the communication between TDF and PCRF for the purpose of: Establishment of TDF session between PCRF and TDF; Termination of TDF session between PCRF and TDF; Provision of Application Detection and Control decision from the PCRF for the purpose of traffic detection and enforcement at the TDF; Reporting of the start and the stop of a detected applications and transfer of service data flow descriptions for detected applications, if deducible, from the TDF to the PCRF, 38. Sy reference point The Sy reference point resides between the PCRF and the OCS. The Sy reference point enables transfer of information relating to subscriber spending from OCS to PCRF and supports the following functions: - Request of charging status reporting from PCRF to OCS. - Notification of policy counter status change from OCS to PCRF. - Cancellation of charging status reporting from PCRF to OCS. Since the Sy reference point resides between the PCRF and OCS in the HPLMN, roaming with home routed or visited access as well as non-roaming scenarios are supported in the same manner. 39. Conclusion The end user experience, with the appropriate charging and billing infrastructure, can be translated into increased revenue and customer loyalty. PCC capabilities will be an enabler for new differentiated services and new business models. Moving beyond a simple flat rate to offering customers the choice of bandwidth, QoS, advertising funded services and the like will be important in monetizing the LTE investment. LTE/SAE supported data services can deliver significant new value to the end customer with increased bandwidth, reduced latency and fine-grained control over QoS. The value can only be realized by flexible charging, policy management and billing solutions. The ability to rapidly deploy new charging models and integrate QoS policies will be critical to competing and succeeding with LTE. Operators must include these requirements in their LTE/SAE rollout plan. Billing systems have proved to be costly and time-consuming to upgrade. Operators can minimize the impact of this by using the mediation and charging platforms to hide major changes from the billing system. These tend to be more modern platforms and therefore less costly to upgrade. 40. Conclusion Providing voice over LTE with IMS support for rich communication services can add significant value to the services offered. Deployment of more powerful DPI capabilities, either standalone or as part of the PDN gateway will be important in supporting some of the more sophisticated new service opportunities. Policy and online charging will become increasingly connected as the network evolves towards full LTE/IMS. The final choice of how to balance revenue and cost will depend on a particular operators situation, but the discussed issues should be considered with relation to charging, policy control and billing systems;