During the definition of MBMS enhancement requirements, IMS support of media delivery over multicast bearers has been identified in TS 22.228 as follows: Initial understanding of the architectural implications would base on the regional services to grouped IMS users provided at hot spots such as a football stadium. From such a requirement point towards the feasibility analysis and more IMS services should be investigated for the better understanding of the use and applicability of multicast bearers (e.g. MBMS) in the context of IMS.

This study analyzes the feasibility and applicability of using multicast bearers (e.g. MBMS) in the context of IMS-based applications. This study item captures the results of the technical considerations and solutions for transporting IMS services over multicast bearers with a focus on the possible enhancements to IMS functionalities and relevant charging, security and service provision procedures. A brief summary of considerations include:

• Signalling procedures of multicast enabled IMS services should be analyzed based on the grouped communication scenarios and possible optimisations to the delivery mechanisms should be investigated.
• Charging and policy control procedures according to the PCC architecture.
• Service provision procedures both in network elements and UEs.
• Possible security requirements to multicast enabled IMS functionalities and bearer service entities.
• Real-time QoS requirements e.g. delay , interruption.
• UE capability requirements.

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When looking at the current requirements of IMS services, the multicast bearer based applications on the market is obvious and will developing from a minor role to a larger extent. This is especially valid in the lights of the deployment of the grouped real-time multimedia services. The profit of IMS service media delivery optimization based on multicast bearer services is not restricted to traditional IMS services as PoC and conference only, but the emergence of new value-added services. In general, it can be expected if there is a technical guidance to enable IMS service functionalities to utilize the efficient multicast bearer service that IMS offer hundreds of combined real-time multimedia applications one never would have thought of before. The general issues as the additional enhancements and the alignments with relative architectural requirements as charging and policy control, security should be investigated and identified.