The 3GPP system currently supports GERAN and UTRAN based Access Networks in conjunction with Circuit-Switched and Packet-Switched Core Network domains and IP Multimedia CN subsystem. The All-IP concept was initially introduced within 3GPP in Rel-4 with the standardisation of the MSC Server - MGW split core network architecture for the CS domain and extended from Rel-5 by the standardisation of the IP Multimedia CN sub-system. WLAN as an alternative access system to access services of the mobile core network is recognized from Rel-6 onwards. In order for 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. It is anticipated that the progression towards an All-IP Network (AIPN) may enable leverage of information technology (IT) hardware and software with general-purpose, and mobile network specific software that should provide cost reduction (CAPEX and OPEX) for infrastructure equipment and applications of 3GPP based mobile networks. Moreover, it is important to ensure compliance with Internet protocols within future developments of the 3GPP system. Additionally, the following aspects identified within TR 21.902 [2] "Evolution of 3GPP System"are considered relevant to the long-term evolution of the 3GPP system:

• A seamless integrated network comprising a variety of networking access systems connected to a common IP based network supported by a centralised mobility manager
• A similarity of services and applications across the different systems is beneficial to users
• 3GPP should focus on the inter-working between 3GPP Mobile Networks and other Networks considering mobility, high security, charging and QoS management

Taking the above into consideration it is necessary to further define the All-IP Network (AIPN) concept, explore user, business and technological drivers and evaluate the feasibility of evolving the 3GPP system towards an All-IP Network (AIPN). Furthermore, aspects of the 3GPP system requiring enhancement need to be identified and developed in accordance with this common vision. This report discusses the concept of an "All-IP" network. In the context of this report the term "All-IP" does not just refer to the transport protocol used within the 3GPP network. 3GPP Release 5 and Release 6 network can already be implemented just using IP transport and could in that sense be said to be "All-IP". In this report the term "All-IP" refers to the general concept of a network based on IP and associated technologies which provide an enhanced, integrated service set independent as far as possible to the access system used.

The present document studies the feasibility of the progression of the 3GPP system to an AIPN. More specifically, this document:

1. Identifies and describes the objectives and user, business and technological drivers for progression of the 3GPP system to an AIPN:
   1. Investigates the High Level Objectives
   2. Investigates Motivations and Drivers
   3. Investigates impacts upon current models (e.g. business/charging/service models)
2. Defines and develops the end-user and AIPN operator aspects of an AIPN:
   1. Produces an AIPN vision, taking into account the special requirements for the mobile community e.g. carrier grade, optimisation for the radio environment, recognizing support of multiple access system scenarios.
   2. Investigates needs and requirements associated with the evolution of the 3GPP System to an AIPN.
   3. Investigates requirements associated with the reuse of legacy infrastructure and support of legacy terminals
   4. Investigates migration and cost effective introduction of new technology.
3. Identifies the capability expansion required to introduce the AIPN concept into the 3GPP system (migration and co-existence)
4. Evaluates whether an AIPN should be standardised within 3GPP, and in the case of a positive conclusion identifies the subsequent steps to be taken to achieve this by defining the scope, target, and roadmap for work to be undertaken within Rel-7 and future 3GPP releases.