5G introduces a new Core Network called the 5G Core (5GC) for the 5G System (5GS). This is an evolution of the Evolved Packet Core (EPC) in the 4G Evolved Packet System (EPS).

In many instances today, 5G is implemented only in the Radio Access Network (RAN) and used in conjunction with 4G RAN and EPC. This deployment is called 5G Non-Standalone (NSA).

As operators start to deploy 5G Cores, they may decide to transition to 5G Standalone (SA), either fully, or running alongside 5G NSA networks.. A number of factors will influence this choice, including – but not limited to - the kind of architecture selected, the amount of spectrum held, planned services, and target use cases and sectors.

Most operators will also support different types of private networks and may offer end-to-end solutions as part of their portfolio. These private networks can be based on 4G or 5G and typically contain the radio access and core network. A lightweight solution can contain all the core functionality in a single small server, often referred to as a network-in-a-box (NIB).

These private networks require a high level of privacy and security regardless of whether data is stored on premise or in the cloud.

3GPP specifies security as mutual authentication of nodes, identity protection, integrity protection and ciphering, but with the transition to Open RAN and cloud, additional levels of security are required to ensure that networks perform reliably and securely.

One approach widely supported in the industry is Zero Trust Architecture (ZTA), which is rooted in the principle of “never trust, always verify”. The ZTA approach is of particular value if an intruder manages to get in the network; it limits damage by blocking unauthorised access to network resources while at the same time limiting internal lateral movement of data.

With the frequent introduction of new architecture, approaches and infrastructure, security should be always a top priority during planning, design, deployment, configuration and testing.

For core networks, end-to-end solutions and security therefore, the key issues for Open RAN are:

• Reliability and security
• Ownership and resolution of network faults
• Interoperability across public and private networks
• Interoperability across domains like terrestrial and non-terrestrial
• Business model for new deployment models