News Column

Patent Application Titled "Charging Information Transfer in the Ims" Published Online

June 5, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Dahl, Jan (Alvsjo, SE); Karlsson, Ove (Emmaboda, SE); Teppo, Patrik (Boback, SE), filed on July 5, 2011, was made available online on May 22, 2014.

The assignee for this patent application is Telefonaktiebolaget L M Ericsson (publ).

Reporters obtained the following quote from the background information supplied by the inventors: "IP Multimedia services provide a dynamic combination of voice, video, messaging, data, etc. within the same session. By growing the number of basic applications and the media which it is possible to combine, the number of services offered to the end users will grow, and the inter-personal communication experience will be enriched. This will lead to a new generation of personalised, rich multimedia communication services, including so-called 'combinational IP Multimedia' services.

"The Universal Mobile Telecommunications System (UMTS) is a third generation wireless system designed to provide higher data rates and enhanced services to users. The UMTS architecture includes a subsystem known as the IP Multimedia Subsystem (IMS) for supporting traditional telephony as well as new IP multimedia services. IMS provides key features to enrich the end-user person-to-person communication experience through the use of standardised IMS Service Enablers, which facilitate new rich person-to-person (client-to-client) communication services as well as person-to-content (client-to-server) services over IP-based networks. The IMS is able to connect to both PSTN/ISDN (Public Switched Telephone Network/Integrated Services Digital Network) as well as the Internet. It is expected that IMS will be integrated into current and future Long Term Evolution (LTE) deployments.

"The IMS makes use of the Session Initiation Protocol (SIP) to set up and control calls or sessions between user terminals (or terminals and application servers). The Session Description Protocol (SDP), carried by SIP signalling, is used to describe and negotiate the media components of the session. Whilst SIP was created as a user-to-user protocol, IMS allows operators and service providers to control user access to services and to charge users accordingly. The 3GPP has chosen SIP for signalling between a User Equipment (UE) and the IMS as well as between the components within the IMS.

"By way of example, FIG. 1 illustrates schematically how the IMS fits into the mobile network architecture in the case of a GPRS/PS access network (IMS can of course operate over other access networks). Call/Session Control Functions (CSCFs) operate as SIP proxies within the IMS. The 3GPP architecture defines three types of CSCFs: the Proxy CSCF (P-CSCF) which is the first point of contact within the IMS for a SIP terminal; the Serving CSCF (S-CSCF) which provides services to the user that the user is subscribed to; and the Interrogating CSCF (I-CSCF) whose role is to identify the correct S-CSCF and to forward to that S-CSCF a request received from a SIP terminal via a P-CSCF.

"Within the IMS service network, Application Servers (ASs) are provided for implementing IMS service functionality. Application Servers provide services to end users in an IMS system, and may be connected either as end-points over the 3GPP defined Mr interface, or 'linked in' by an S-CSCF over the 3GPP defined ISC interface. In the latter case, Initial Filter Criteria (IFC) are used by an S-CSCF to determine which Applications Servers should be 'linked in' during a SIP Session establishment (or indeed for the purpose of any SIP method, session or non-session related). The IFCs are received by the S-CSCF from an HSS during the IMS registration procedure as part of a user's Subscriber Profile.

"IMS implements flexible user charging schemes in respect of IMS services. In particular, IMS allows operators to charge for value added services over and above the mere transfer of data. For a given IMS session, it is possible that a number of IMS network elements will generate data required for offline and/or online charging. This is likely to become more common as the IMS evolves such that multiple ASs are used per session. To decrease the need for correlation at a (central) charging control function which collects data from multiple IMS charging elements, especially in the case of online charging (e.g. used for prepaid subscribers), it is useful to concentrate charging information at a single network element per session and to transfer all of this charging information from that single element to the charging control function. This will of course require that unique information available in other network elements be transported to the selected charging point.

"One method to achieve the transport of charging information between IMS network elements within SIP messages involves the use of the SIP private header P-Charging-Vector (PCV). PCV is defined in RFC3455 with the parameters: icid-value; the IMS Charging Identity Value. The icid-value is a charging value that identifies a dialogue or a transaction outside a dialogue. It is used to correlate charging records. An icid-value must be a globally unique value. icid-gen-addr, the address of the SIP proxy that creates the icid-value. orig-ioi; the originating Inter Operator Identifier. term-ioi; the terminating Inter Operator Identifier. generic-param; this parameter allows for the use of further parameters without the need to specify these individually. A network operator may define such further parameters for use within its own network domain in order to transport network specific information within the PCV.

"The treatment of these parameters in the different network elements is described in TS 24.229. This treatment is different for each parameter and also dependent on the network element. [It is noted that, as with other SIP privacy headers, the PCV header is not included in a SIP message sent between networks if no trust relationship exists between them.] An extension to the PCV is described in 3GPP TS 24.229 (access-network-charging-info).

"The generic-param may be used to carry charging related information over and above that provided for by the existing icid-value, icid-gen-addr, orig-ioi, and term-ioi parameters described above. In addition, further parameters could be specified for this purpose. However, both of these options would require that all network elements through which a message carrying the parameter can pass are updated to include appropriate behaviour, i.e. the added information must be known and understood by all of the affected network elements. This would be a complicated process particularly in a multi-vendor solution, i.e. where different vendors supply different parts of an operator's network."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "It is an object of the present invention to overcome or at least mitigate the problem discussed above. This is achieved at least in part by introducing a PCV parameter handling determinator, the purpose of which is to identify a high level action to a network element, for example whether or not the parameter needs to be processed by the element. This enables the parameter to contain non-standardised information, and in particular charging related information. The handling determinator may be a tag which points to a rule or rules for handling the parameter(s), or it may be the rule(s) itself.

"According to a first aspect of the present invention there is provided apparatus for use within an IP Multimedia Subsystem, IMS, network to handle Session Initiation Protocol, SIP, messages. The apparatus comprises a receiver for receiving a SIP message from a peer IMS node, and a SIP message inspector for inspecting a P-Charging-Vector, PCV, header within a received SIP message in order to detect the presence within the PCV header of a parameter and associated handling determinator. The apparatus further comprises a SIP message handler for determining, on the basis of a handling determinator and without reference to said associated parameter, an action or actions to be applied to said parameter and associated handling determinator.

"Embodiments of the invention allow network operators to make use of non-standardised PCV parameters to carry charging information over and above that carried by the currently standardised parameters. The only requirement placed upon nodes is that they be able to understand the handling determinator such as for example tags or rules, and implement a limited range of actions in dependence upon these determinators.

"According to a second aspect of the present invention there is provided an IP Multimedia Subsystem network comprising a plurality of apparatus according to the above first aspect of the present invention. At least one of the apparatus within the network has a SIP message handler configured to recognise and process said parameter associated with the handling determinator, and at least one of the apparatus within the network has a SIP message handler that is not configured to recognise and process said parameter associated with the handling determinator.

"According to a third aspect of the present invention there is provided apparatus for use within an IP Multimedia Subsystem, IMS, network. The apparatus comprises a charging data generator for generating charging information related to an IMS user service, and a SIP message handler for generating or receiving a SIP message related to said service, and for including within a P-Charging Vector, PCV, header of the SIP message (a) a parameter containing said charging information, and (b) a handling determinator associated with the parameter. The handling determinator defines an action or actions to be applied to said parameter and associated handling determinator by an upstream IMS node receiving the SIP message. The apparatus further comprises a SIP message sender for sending the SIP message to a peer IMS node.

"According to a fourth aspect of the present invention there is provided method of handling a Session Initiation Protocol, SIP, message within an IP Multimedia Subsystem, IMS, network. The method comprises, at a first IMS network node, generating charging information in respect of an IMS user service, generating or receiving a SIP message related to said service, including within a P-Charging Vector, PCV, header of the SIP message (a) a parameter containing said charging information, and (b) a handling determinator associated with the parameter, the handling determinator defining an action or actions to be applied to said parameter and associated handling determinator by an upstream IMS node receiving the SIP message, and sending the SIP message to a peer IMS node. The method further comprises, at a second, upstream IMS network node, receiving said SIP message, inspecting the P-Charging Vector, PCV, header within the received SIP message in order to detect the presence within the PCV header of said parameter and associated handling determinator, and determining, on the basis of a handling determinator and without reference to said associated parameter, an action or actions to be applied to said parameter and associated handling determinator.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 illustrates schematically an IMS network integrated into a communications system comprising a 3G network;

"FIG. 2 is a signalling flow associated with a first exemplary scenario involving the inclusion of a tagged PCV parameter within a SIP message;

"FIG. 3 is a signalling flow associated with a second exemplary scenario involving the inclusion of a tagged PCV parameter within a SIP message;

"FIG. 4 illustrates schematically a first, sending IMS node and a second, receiving IMS node configured to exchange and act upon a tagged PCV parameter within a SIP message; and

"FIG. 5 is a flow diagram illustrating a process for sending charging information between IMS nodes using the PCV."

For more information, see this patent application: Dahl, Jan; Karlsson, Ove; Teppo, Patrik. Charging Information Transfer in the Ims. Filed July 5, 2011 and posted May 22, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3907&p=79&f=G&l=50&d=PG01&S1=20140515.PD.&OS=PD/20140515&RS=PD/20140515

Keywords for this news article include: Telefonaktiebolaget L M Ericsson (publ).

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