Network sharing is becoming more and more popular as a means to provide coverage quickly and in a cost efficient way. The high price paid for the license in some countries as well as mergers, acquisitions have raised recently high interest in this topic. For these reasons 3GPP has decided to investigate what shortcomings currently in the technical specifications may prevent a standardized approach to the deployment of shared networks. This TR is aimed to describe a wide variety of possible network sharing and highlight the expected user experience for each of the scenarios. Charging aspects, terminal aspects and security are also investigated. The purpose of this technical report is to collate in a single document the requirements, considerations and deployment scenarios that operators as well as users need to see fulfilled for a successful use of a shared network. Particular attention has been given in making possible the avoidance of proprietary solutions particularly for what concerns the terminals. Furthermore, the concepts discussed in this report may be applied to sharing a GERAN and UTRAN infrastructure, in this sense the interest in network sharing tools extends to the vast majority of the existing GSM operators who intend to deploy a UMTS Terrestrial Radio Access Network layer to complement the existing GSM/GPRS coverage.

In the current dynamic market place, as a result of partnerships, acquisitions, creative agreements among operators and so on, the need for tools that enable various degrees of network sharing is becoming more and more important. When GSM and then UMTS were specified, the possibility of sharing part or all of the network by two or more separated commercial entities was not considered and as a result the standards lack some functionalities that enable the realisation of such commercial agreements. GSM was designed under the principle "one operator, one radio access network". The GSM network has some possibilities of infrastructure sharing, but it does not support true radio access network sharing. The initial design of 3GPP system has followed the same principle. This technical report is aimed to capture the service and user requirements that must be fulfilled by the 3GPP system in order to enable network sharing in a standardised way. Section 5 describes various Network sharing includes various scenarios e.g. spanning from common radio access network connected to multiple core networks toor multiple radio access networks sharing one core network. Section 6 contains a summary of the user classification and network identities. In section 7 the user requirements are described, while section 8 deals with the network operator requirements. Section 9 describes the mobility requirements in a shared network. The rest of the document is covering security (section 10) and charging (section 11). Some conclusions can be found in section 12 and an annex with examples of practical realisation of network sharing is provided.

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.

Void

Sharing networks and network infrastructure has become a very important part of 3GPP systems. There are many network-sharing scenarios possible depending on different operator strategies but also on rules and legislation in different countries. 3GPP systems are originally not fully designed for network sharing between different operators however some limited support exists in the 3GPP Release 99.The equivalent PLMN feature in Release 99 allows operators to share a common UTRAN, with certain parts of the core networks also shared between the operators, see Figure 1.

Important to note here is that this network-sharing scenario allows operators without a UMTS license to share the network and supply its customers with 3G services. For example, a 2G operator may supply its subscribers with 3G services using another operator's allocated spectrum. A geographically split network, i.e. a scenario in which cooperating operators cover different parts of a country, is also possible in Release 99. One operator's core network may also be connected to several UTRANs, see Figure 1. Different kinds of evolution paths are essential for shared networks. For example, it is not only the sharing solution at a certain time that is important, but also how it is possible for the sharing partners to evolve either to a more dedicated network or to a more joint network. That is, the set of infrastructure sharing solutions and scenarios that is discussed in the industry cover alternatives that together include:

• solution alternatives targeting at dedicated networks in the near future,
• solutions for infrastructure sharing not targeting at immediate exit, but at exit when for example the network capacity demand so requires,
• infrastracture sharing targeting at long term sharing, which for example is the case when one of the operators lacks a frequency license.

Although these network-sharing scenarios are possible in Release 99 of 3GPP systems, the solutions are far from optimised. Identifying, changing, and adding appropriate functionality in the network will definitely lead to a better shared-network operation.

To fully support for example handover, service differentiation and access rights in shared networks it is occasionally necessary to identify to which operator that a user belongs to and possibly group the users according to this information. To avoid complicated operation and maintenance procedures, such user classification should be general for all the functions in the shared network that needs information about the user identity.

Network sharing is an agreement between network operators and is transparent to the user.

The service capabilities and requirements should not be restricted by network sharing scenarios. It should be possible for a network operator to differentiate its service offering from other network operators within shared network. The services and service capabilities offered should not be restricted by the existence of network sharing. It should be possible for a network operator to differentiate its service offering from other network operators within shared network. The provision of services and service capabilities that is possible to offer in a network should not be restricted by the existence of the network sharing It should be possible for a core network operator to differentiate its service offering from other core network operators within the shared network. It should be possible to control the access to service capabilities offered by a shared network according to the core network operator the user is subscribed to.

FFS

Charging solutions should support the shared network architecture so that both end users and network sharing partners can be correctly charged for their usage of the shared network.

This technical report has identified various scenarios, service and user requirements that should be fulfilled by 3GPP specifications in order to enable network sharing. The functionalities needed to enable network sharing in a standardized way will be added to existing or new specifications. Chapter 12.1 is a non-exhaustive list of the affected specifications. It is concluded that the further work in other groups within 3GPP on the requirements identified in this technical report is carried out.