Figure 1: Network slices use dedicated or shared network functions across multiple network domains.

The new 5G RAN (aka NG-RAN) architecture, which was specified in 3GPP Release 15, supports slicing and flexible deployment of the RAN building blocks. The NG-RAN radio base stations (known as gNBs) incorporate three main functional modules – the centralized unit (CU), the distributed unit (DU), and the radio unit (RU) or active antenna unit (AAU) – which can be deployed in multiple combinations, according to the mobile operator’s requirements and preferences. The CU can be further disaggregated into CU user plane (CU-UP) and CU data plane (CU-DU), accommodating the separation between the control plane and the user plane.

The 5G service-oriented virtualized and fragmented core network, together with the NG-RAN, can realize on-demand orchestration and rapid deployment of network functions and sub-slices, while meeting the elasticity, low latency and high availability requirements, laying a solid foundation for network slicing and monetization of 5G network assets.

As network slices span across the RAN, transport and core network domains, it will become a necessity for mobile network operators to manage their lifecycle and performance from end to end, while ensuring the required network cloud resources are correctly allocated, in a timely fashion, to all VNFs, PNFs and CNFs that serve the network slice across the different network domains.

For this reason, mobile network operators will require an end-to-end network slice manager to fulfil customer orders into efficient and effective network-oriented service implementation plans using predefined workflows and deployment optimization across the distributed 5G network and cloud environments. The network slice manager controls the end-to-end lifecycle of network slices and the NFs used by them by applying end-to-end network slicing management across multiple layers of the architecture (including design, configuration, instantiation, configuration, scaling, termination, updates and decommissioning of numerous NFs deployed in multiple, different virtual and physical environments).

Finally, to gain maximum operational efficiency, NFs will be instantiated and scaled in an automated, zero-touch operations mode so that 5G networks can deliver their promise of dynamic flexibility, agility and scalability, which in turn will allow service providers to provision network slices so as to meet the needs of a variety of use cases and customer requirements. The new virtualized 5G Core and RAN will indeed provide the foundation that operators need for service innovation and monetization of their network investments.