Policy and charging rules function

Policy charging and rules function (PCRF) is the node designated in real-time to determine policy rules. PCRF evolved out of the 3GPP (‘third generation partnership product’ for 3G mobile networks) specification as a component for IP Multimedia Subsystem networks (IMS), an architectural framework for delivering multimedia services using Internet Protocol (IP), a common transport protocol that allows for access independence and enables a single-core multimedia network. Today, PCRF is not exclusively tied to IMS networks but is applicable across many network types. To better understand how PCRF fits into a network, it might be helpful to take a step back and gain a basic understanding of IMS and policy itself.

History and Background IMS is a network infrastructure that was specifically designed to handle detailed, real-time multimedia services that incorporate audio and video components. IMS uses the session initiation protocol (SIP), which was developed for Internet traffic, to enable session setup and teardown. In addition, IMS typically uses the Diameter protocol (which was derived from the RADIUS protocol)for policy and charging control (PCC). An important contribution of IMS is that it introduced the concept of ‘access technology independence,’ meaning that various wireless and wireline access networks and interfaces could come together in a single core network.

Originally introduced as part of the 3GPP IMS standardization effort in order to dynamically authorize and link IMS sessions with mobile packet access resources, today policy plays a key role in the functionality of an IMS, 3G, or Long Term Evolution (LTE) network (regardless of the access technology or air interface). Policy encompasses the business and technological rules that govern which network services a subscriber can access, at what bandwidth level, when, and for how long. Generally speaking, the policy function queries, coordinates, and adjusts all of the network resources to provide the required services to individual, authorized subscribers. It identifies the appropriate policy rules for the situation and enforces them.

PCRF Today Despite its inception as part of the 3GPP initiative, the PCRF concept has evolved along its own path. While not necessarily tied to GSM, 3GPP, IMS, or LTE networks exclusively, the PCRF is typically compatible with them. Most importantly, PCRF enables the policy function for multimedia networks.

As a policy tool, the PCRF plays a central role in next-generation networks. Unlike earlier policy engines that were added on to an existing network to enforce policy, the PCRF is a software component that operates at the network core and efficiently accesses subscriber databases and other specialized functions, such as a charging systems, in a scalable, reliable, and centralized manner.

Think of the PCRF as the part of the network architecture that aggregates information to and from the network, operational support systems, and other sources (such as portals) in real time, supporting the creation of rules and then automatically making intelligent policy decisions for each subscriber active on the network. Such a network might offer multiple services, quality of service (QoS) levels, and charging rules.

Available PCRF Solutions There are a number of policy solution options available, and several PCRF ones. The basics available with any PCRF solution include: redundancy and carrier-grade performance, multi-handset-vendor support, multi-standard support. Advanced PCRF solutions also include service velocity and flexibility, open policy development frameworks, two-way interaction between service provider and subscriber, support for multiple access technologies, and the ability to scale.

External links

• example.com