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3GPP Core Rx Interface Evolution

Policy and Charging Control Access for Internet Application Developers

By Xia Haitao and Horst Brinkmann, 3GPP CT3

Policy and charging management allows operators to define the rules for Quality of Service (QoS), network usage and charging control. In the All-IP era it is assumed that web application developers will now work on telecom services in the same way they have been working on computer based services until now. For this purpose, the 3GPP Policy and Charging Control (PCC) system is acting as an entry point for end-to-end service control - based on PCC functionality.

The 3GPP way to fulfil this new demand is to adapt the Diameter based Rx interface to be incorporated in standards and protocols used by Internet application developers. The evolution of the Rx interface will enable them to smoothly access the 3GPP PCC architecture and to use the PCC functionality for the creation of value-added services. The upshot of this is a better business model for the operator, providing the right QoS and charging possibilities for mobile applications.

3GPP CT3 has started a feasibility study - Technical Report 29.817 - describing an eXtensible Markup Language (XML) based access of the Application Function (AF) to the Policy and Charging Rule Function (PCRF) for the case of non IP Multimedia Subsystem (IMS) applications. RESTful HTTP concepts will be used on the new interface whereby the XML documents are embedded in the HTTP commands. This study aims to provide an XML based equivalent to the Diameter based signalling that is specified in 3GPP Technical Specification 29.214.  

Session management, PCRF addressing and the transport of PCC information were key issues of the study. The feasibility study resulted in the introduction of a new logical functional entity between the Application Function and the PCRF.

rx image policy3GPP Technical Specification 29.201 will specify the Rx interface evolution based on XML documents and HTTP, whereby the Application Function session can be addressed as a resource with the Uniform Resource Identifier (URI). This will allow using the existing Rx interface to IMS based applications with the Diameter protocol and to other web applications with the new RESTful HTTP/XML approach.

The normative work is expected to be finialized by end of 2014.

Further Reading:

  • 3GPP Technical Report 29.817 - Study on XML-based access of the Application Function (AF) to the Policy and Charging Rules Function (PCRF)
  • 3GPP Technical Specification 29.214 - Policy and charging control over Rx reference point
  • 3GPP Technical Specification 29.201 - Representational State Transfer (REST) reference point between Application Function (AF) and Protocol Converter (PC)

About 3GPP CT3:

The TSG Core Network and Terminals WG3 (CT WG3) specifies the bearer capabilities for circuit and packet switched data services, and the necessary interworking functions towards both, the user equipment in the UMTS PLMN and the terminal equipment in the external network. In addition CT3 works on end-to-end QoS for the UMTS core network in Release 5 and beyond.

CT3 is responsible for:

  • Interworking between a 3GPP PLMN and external nodes or networks, interworking between PLMNs as well as interworking between PLMN domains.
  • Policy and charging control, end-to-end QoS mechanisms.


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