To ensure competitiveness of the 3GPP systems in a time frame of the next 10 years and beyond, a long-term evolution of the 3GPP access technology needs to be considered. In particular, to enhance the capability of the 3GPP system to cope with the rapid growth in IP data traffic, the packet-switched technology utilised within 3G mobile networks requires further enhancement. A continued evolution and optimisation of the system concept is also necessary in order to maintain a competitive edge in terms of both performance and cost. Important parts of such a long-term evolution include reduced latency, higher user data rates, improved system capacity and coverage, and reduced overall cost for the operator. Additionally, it is expected that IP based 3GPP services will be provided through various access technologies. A mechanism to support seamless mobility between heterogeneous access networks, e.g. I-WLAN and 3GPP access systems, is a useful feature for future network evolution. In order to achieve this, an evolution or migration of the network architecture, as well as an evolution of the radio interface, partly addressed already by individual WIDs, should be considered. Architectural considerations will include end-to-end systems aspects, including core network aspects and the study of a variety of IP connectivity access networks (e.g. fixed broadband access).

The objective of this feasibility study is to develop a framework for an evolution or migration of the 3GPP system to a higher-data-rate, lower-latency, packet-optimized system that supports, multiple RATs. The focus of this work will be on the PS domain with the assumption that voice services are supported in this domain. The main objectives are to address the following aspects:

1. Overall architecture impacts stemming from requirements coming out from TSG-RAN's Study Item on Radio Evolution (see SP 040915). The architectural developments should take into account the targets for the evolution of the radio-interface, e.g.:
   1. whether there is a need for a modified network architecture and/or different functional split between network nodes (compared to the current 3GPP architecture);
   2. how to provide a very low latency (including C-plane) for the overall network (including core network, radio access network and radio access technology);
   3. how to provide the efficient support of the various types of services, especially from the PS domain (e.g. Voice over IP, Presence).
2. Overall architecture impacts stemming from the work in SA1 on an All-IP Network (AIPN) (see TS 22.258 [4]), e.g.:
   1. support of a variety of different access systems (existing and future) and access selection based on combinations of operator policies, user preferences and access network conditions;
   2. how to realize improvements in basic system performance e.g. communication delay, communication quality, connection set-up time, etc.;
   3. how to maintain the negotiated QoS across the whole system; in particular to address inter-domain and inter-network interworking, and, QoS on the network link to the Base Station site.
3. Overall architecture aspects of supporting mobility between heterogeneous access networks, including service continuity. E.g.:
   1. service continuity between I-WLAN and the 3GPP PS domain;
   2. how to support multiple radio access technologies and terminal mobility between different radio access technologies;
   3. how to maintain and support the same capabilities of access control (authentication, authorization), privacy and charging when moving between different radio access technologies.

Migration aspects should be taken into account for the above, i.e. how to migrate from the existing architecture. In the course of conducting this feasibility study additional individual Work Items may be identified and prepared to address certain aspects and to take care of the respective specification work. The timelines of those Work Items may or may not concur with the timeline of this feasibility study.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

• References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.