22.3 Study on ims Application Server Service Data Descriptions for as interoperability uid_360030

Resources: C4

References

Document	Title/Contents
WID(s)
CP-070685	SID on IMS Application Server Service Data Descriptions for AS interoperability
Impacted Specifications
-	-
New Dedicated Specifications/Reports
TR 29.864	Study on IMS Application Server Service Data Descriptions for AS interoperability

Supporting Individual Members: Alcatel-Lucent, Verizon Wireless, Motorola, Nortel, Nokia-Siemens Networks, ZTE.

This work is linked to the CT4 Study on Restoration Procedures (FS_IMS_RP) UID_320006.

Application data for IMS is defined as being "Transparent". Transparency means that HSS and Sh interface do not semantically understand the data but just syntactically how to deal with its entirety. Application Servers (AS) are free to store data without an openly distributed definition of the stored content. However, because the data is transparent (the format is not standardized) it is potentially an issue for one AS to make use of data defined for another AS (e.g. ASs are supplied by different vendors).

Standardizing the data formats would facilitate interoperation among ASs supplied by the same or different vendors. These AS vendors may be primary and secondary suppliers of the same Service Provider (SP) within an SP's IMS network. This is especially true of mature services, such as the features provided in basic voice subscriptions, and is likely to be true of any future services that achieve a wide deployment.

There has already been work incorporated into 3GPP from TISPAN that point towards the need for definition of common data. The UE may update a service setting (e.g. a forward-to number) in an AS via Ut. The AS may store this information in transparent data in the HSS, but unless the data is defined it cannot be shared with other AS's. TISPAN defined data structures associated with multimedia telephony services which have been copied into TS 24.173. For example, 24173-ETSI-TS-183-004 provides the XML schema for the call diversion service..

Benefits of standardizing the data formats for services:

• Multi-vendor AS support. Today's telecom SPs regularly use two or more vendors to provide identical capabilities. Standardization has facilitated this, as products must conform to the defined interfaces. SPs use this to build competition among vendors and to build business contingencies. The AS market, especially for high-penetration services, is expected to follow a similar path.

• Data Synchronization In defining IMS centralized services, interworking between the HLR/HSS and the Telephony AS may occur to exchange data that is administered in CS domain and IMS. Definition of IMS AS service data descriptions facilitate this exchange.

• Feature Interaction Advertising and defining data for each application is expected to increase communication regarding features within applications. This makes integration of complex features more likely to succeed, as the information is available to examine for interactions.

• User re-homing and load balancing To facilitate re-homing of users to ASs and load balancing, the definition of IMS AS service data descriptions increases the opportunity for hosting services on alternative ASs.

This work studied the necessary components of an AS subscriber data definition and the procedures necessary to follow in enabling other applications to define, extend and publish data definitions.

• Clarify the requirements for defining application specific data descriptions

• Study mechanisms for the transfer of service data descriptions to AS.

• Provide solutions to defining data for the Telephony Application Server (TAS).

• Provide recommendations for how the framework defined for the service data schema can be reused and extended for future service definitions.

TR 29.864 identifies an AS service data representation specific to an IMS Telephony Application Server. It studies requirements for AS service data definition and transfer of defined service data between AS and HSS. Further, it exposes a service data definition for a TAS for services defined in TS 22.173 (IMS Multimedia Telephony Service and supplementary services; Stage 1). It provides recommendations for how the framework can be reused and extended for future IMS service definitions.

TR 29.864 Recommendations

• provide a definition of the IMS Telephony Supplementary service (MMTel) data understood by a variety of TASs;

• define a binary format for these service data in the context of Rel-8;

• define an XML format based on the one defined for Supplementary Services in TS 24.6xy in the context of Rel-8;

• for the binary format, include a service description specifying the services and impacts on the IMS Telephony Supplementary Services for which this approach enables interoperability. For the binary approach, describe how an optional extension mechanism works that supports more complex features for some of the services, or introduces new services;

• for the XML format, include a possibility for compression, based on either gzip or EXI;

• this be complemented by the necessary mechanism for transmission over the Sh interface;

• insert this data into the Sh User Data AVP in such a manner that additional transparent data can also be transmitted.

Genealogy of this spec:

this spec	descendant(s)
29.864	29.364

Spin-off Feature UID_410003 (IMS_ASIO) IMS Application Server Service Data Descriptions for AS interoperability.