Radio access network

The external interfaces of the radio access network (RAN) domain are standardized under 3GPP, as is the functional behavior of the RAN domain as a whole. Below the high-level specification, 3GPP leaves room for innovation to enhance the network with RAN-internal value-add features — a flexibility that has resulted in continuous improvement in many areas, including spectrum efficiency, energy efficiency, and enhancements to service characteristics.

To determine the optimal architectural split, the RAN architecture needs to be examined with a finer level of granularity than that offered by 3GPP. Based on function and interface characteristics, preferred execution environment, and spectrum efficiency, a target functional composition is defined by several RAN nodes.

Components and characteristics

Radio access networks graphic

RAN architecture is enhanced with the following nodes to achieve an optimal split:

Radio function (RF)

  • includes functions such as modulation, D/A conversion, filtering, and signal amplification
  • requires special radio hardware

Radio processing function (RPF)

  • contains the fast radio scheduler
  • responsible for the coordinated multi point, the selection of the MIMO scheme, and beam and antenna elements

Packet processing function (PPF)

  • includes the PDCP layer — such as encryption — and the multipath handling function for the dual connectivity anchor point and data scheduling
  • suitable for virtualization

Radio control function (RCF)

  • handles load sharing among system areas and different radio technologies
  • controls the overall RAN performance
  • suitable for virtualization

RAN in action

Block 1 graphic

In this example, the radio unit hardware is located at the antenna site. The BPF in the C-RAN deployment holds a more centralized position, and each instance of the BPF covers more antenna locations. This results in high spectrum efficiency, as the BPF can use the complete set of fast RRM features — including joint combining, multipoint transmission, and coordinated scheduling — across all the antenna points in the system area covered.

Bock 2 graphic

The flexible C-RAN architecture supports more centralized deployments, enabling smooth, dual connectivity.

Flexible architecture

The architecture has a flexible and a modular approach. It supports different usage scenarios: high to low capacity, widespread to small area, very dense coverage to spotty coverage, indoor and outdoor etc. Evolved virtualization, network programmability and 5G use cases will change everything about network design – from planning and construction, through to deployment.

Discover more about mobile access:

Related architecture articles:

4G/5G RAN architecture: how a split can make the difference

Related Ericsson portfolio:

Radio System

More reading in Future network architecture document:

Access - Mobility - Network applications