As stated in TS 22.261 the increased density of access nodes needed to meet future performance objectives pose considerable challenges in deployment and acquiring spectrum and antenna locations. RAN sharing is seen as a technical solution to these issues. Sharing access networks and network infrastructure has become more important part of 3GPP systems. When two or more operators have respectively deployed or plan to deploy 5G access networks and core networks, a MOCN configuration can be considered for network sharing between these operators, i.e., a Multi-Operator Core Network (MOCN) in which multiple CN nodes are connected to the same radio access and the CN nodes are operated by different operators. One of the challenges for the partners' network operators is the maintenance generated by the interconnection (e.g., number of network interfaces) between the shared RAN and two or more core networks, especially for a large number of shared base stations. For these reasons, it is suggested investigating other types of network sharing scenarios, where a 5G RAN is shared among multiple operators without necessarily assuming a direct connection between shared access and the core networks of the participating operators.

Two (or more) operators provide coverage with their respective radio access networks in different parts of a country but together cover the entire country. There is an agreement between all the operators to work together and to build a shared network, but utilizing the different operator's allocated spectrum appropriately in different parts of the coverage area (for example, Low Traffic Areas, LTA and High Traffic Areas, HTA). The hosting operator 1, as illustrated below, can share its NG-RAN with the participating operators with or without direct connections between the shared access and the core networks of the participating operators. The following preconditions apply,

1. OP1 owns the NG-RAN to be shared with three other operators; OP2, OP3, and OP4.
2. NG-RAN is shared with certain conditions, e.g., within a specific 5G frequency band or within specific area.
3. NG-RAN does not have direct connections between the shared access and the core networks of the participating operators OP2 and OP3.
4. OP4 has a MOCN arrangement with OP1.
5. In this example UE 1 is subscribed to OP1, UE 2 is subscribed to OP 2, UE 3 is subscribed to OP3, and UE 4 is subscribed to OP4.

Both options of direct and indirect connections between the shared access and the core networks of the participating operators are illustrated in Figure 5.1.2-1 below. Figure 5.1.2-2 shows the option of Indirect Network Sharing involving core network of hosting operator, as indirect connection between the shared access and the core networks of the participating operators.

1. UE1 can successfully attach to NG-RAN, and the display of the network operator name is the name of OP1.
2. UE2 can successfully attach to NG-RAN, and the display of the network operator name is the name of OP2.
3. UE3 can successfully attach to NG-RAN, and the display of the network operator name is the name of OP3.
4. UE4 can successfully attach to NG-RAN, and the display of the network operator name is the name of OP4.
5. The service provider of UE 1 is OP1.
6. The service provider of UE 2 is OP2.
7. The service provider of UE 3 is OP3.
8. The service provider of UE 4 is OP4.

For UEs accessing the Shared NG-RAN, the network of the hosting operator needs to know which participating operator a UE is registered to and what type of network sharing (e.g., MOCN or otherwise) is in place for that participating operator. The inter-connection between participating operators' core networks and Shared NG-RAN of the Hosting Operator can be supported via an element of the Hosting Operator.

The hosting network will be able to provide accessing to all participating operators' users.

Network sharing has been studied in previous releases, where related normative stage 1 requirements are introduced in TS 22.101 and TS 22.261. 3GPP TS 22.101 introduces general requirements of network sharing, stated as follows: The provisioning of services and service capabilities is described in TS 22.101. The selection of 3GPP access network is described in clause 6.19 of TS 22.261:

[PR 5.1.6-001] [PR 5.1.6-002]