Network sharing enables operators to maximize rollout and improve overall network quality. The 3GPP system supports different types of network sharing since Rel-5, most of which are inherited by 5G (Rel-15 onward). With the expanding of 5G deployments more network sharing scenarios can arise, depending on different operators' strategies, commercial agreements, and specific rules/legislation in different countries. One of the challenges for the operators is the maintenance of the interconnections (e.g., number of network interfaces) between the shared NG-RAN and participating operators' core networks, especially in the case of a large number of the shared base stations. It is therefore suggested to investigate other type of network sharing scenarios, where a NG-RAN is shared among multiple operators without necessarily assuming a direct connection between the shared radio access network and the participating operator's core network.

The present document investigates use cases and potential new requirements related to 3GPP system enhanced support of specific 5G network sharing deployment scenarios, in particular where there is no direct interconnection between the shared NG-RAN and participating operators' core networks. It includes the following aspects:

• Mobility and service continuity, e.g., when moving from a non-shared 4G/5G network to a shared 5G network and vice versa, with focus on CN aspects.
• Potential security requirements.
• Charging requirements (e.g., based on traffic differentiation in specific network sharing geographical areas).
• User/service experience (e.g., maintain the communication latency for voice, and SMS) when accessing the shared network, including scenarios of home-routed traffic or local breakout.
• Other aspects, e.g., regulatory requirements, emergency services, PWS support.

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.

The present document introduces the newly supported network sharing scenario, where a NG-RAN is shared among multiple operators without necessarily assuming a direct connection between the shared radio access network and the participating operator's core network. Use cases including service continuity and QoS, access control and mobility, international roamers in shared network, hosted services, long-distance road transport are analyzed. This study provides alternatives for existing operators who intend to deploy a NG Radio Access Network to complement the existing market, taking into account of operators' business consideration, such as network planning, operation and other factors.