LTE policy and charging components

Question 1

PCRF

Answer 1

Policy and Charging Rules Function (PCRF) — A centralized policy decision point that deploys business policy and charging rules to allocate broadband network resources and manages flow-based charges for subscribers and services. PCRF pushes the rules down to the Policy and Charging Enforcement Function (PCEF) using the 3GPP Gx protocol and online policy interface.

Question 2

PCEF

Answer 2

Policy and Charging Enforcement Function (PCEF) — A function (contained in PGW) that provides user traffic handling and QoS at the gateway, provides service data flow detection, and applies the rules received from the PCRF. PCEF optionally interacts with the Online Charging Function (OCF) within the Online Charging System (OCS) using the 3GPP Gy protocol to retrieve policy and charging authorization for quotas and credit control.

Question 3

OCS

Answer 3

Online Charging System (OCS)—The charging control component responsible for interacting with the PCEF. The PCEF optionally reports usage and receives additional authorizations from the OCS using the 3GPP Gy protocol. Broadband PCEF (BPCEF) interactions with the OCS use online session charging with centralized unit determination and centralized rating.

Question 4

OFCS

Answer 4

Offline Charging System (OFCS)—A process where charging information for network resource usage is collected concurrently with that resource usage. If credit-based authorization is not required, the PCEF applies policies and report usage to the OFCS using the 3GPP Gz protocol. You can also use the OCS as the primary accounting destination and use the OFCS as a backup.

Question 5

AP

Answer 5

Application Function (AP)—The Application Function interacts with applications or services that require dynamic PCC. The Application Function extracts session information from the application signalling and provides application session-related information to the PCRF using the Rx protocol.

Question 6

SPR

Answer 6

Subscription Profile Repository (SPR)—SPR contains subscriber and subscription information on a per-packet data network (PDN) basis. The Sp protocol enables the PCRF to request subscription information related to a subscriber’s service or session.

Question 7

BBERF

Answer 7

Bearer Binding and Event Reporting Function (BBERF)—The PCC rule needs to be mapped to a particular IP bearer to ensure the packets receive the appropriate QoS treatment. The association between a PCC rule and a bearer is referred to as bearer binding. The BBERF location depends on the access technology. For 3GPP, the BBERF is located in the serving gateway and uses the Gxx protocol.