MPS will enable National Security/Emergency Preparedness (NS/EP) users (herein called Service Users) to make priority calls/sessions using the public networks. This service needs to be ensured also under special conditions such as network congestion. Service Users are the government-authorized personnel, emergency management officials and/or other authorized users. Effective disaster response and management rely on the Service User's ability to communicate during congestion conditions. Service Users are expected to receive priority treatment, in support of mission critical multimedia communications. The enhancements for MPS evaluated in this document are priority aspects of EPS packet bearer services and priority related interworking between IMS and EPS packet bearer services. These enhancements enable the network to support end-to-end priority treatment for MPS call/session origination/termination, including the Non Access Stratum (NAS) and Access Stratum (AS) signalling establishment procedures at originating/terminating network side as well as resource allocation in the core and radio networks for bearers. Priority treatment will be applicable to IMS based multimedia services, priority EPS bearer services and CS Fallback. This document clarifies the architectural requirements for MPS, considers the priority service scenarios, and evaluates solution alternatives. Solutions will be proposed and evaluated based on the following three service categories: IMS based multimedia service (voice, video etc), priority EPS bearer services (PS data without IMS interaction) and CS Fallback. Common issues for multiple service categories should be resolved by single solution to limit the amount of overall functionality and to avoid complexity. The basic eMPS, i.e. priority handling of IMS based multimedia service, EPS bearer services and CS Fallback have completed in Rel 10. In Rel 11, Single Radio Voice Call Continuity (SRVCC) from LTE to UTRAN/GERAN/1xCS will be investigated based on Rel 10 SRVCC specification. The result of the analysis should be suitable as a basis for normative MPS specification work. The scope of the MPS part is to further investigate:

• The signalling and procedures for identifying priority and authorizing the usage of priority service.
• The required priority attributes used in enabling end-to-end priority marking and priority treatment during establishment, modification and release of an IMS based priority voice/video/data session.
• The scenarios and capabilities for supporting priority EPS bearer data services.
• The potential impacts on existing and relevant standard procedures in order to provide preferential treatment for MPS requests in the event of congestion.
• Inter-working with other IMS and CS networks to provide an end-to-end priority service.

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