Open source powers the RAN evolution

A radio access network (RAN) is responsible for enabling and connecting devices such as smartphones or internet of things (IoT) devices to a mobile network. For communications service providers (CSPs), RAN is a significant network technology and monetary investment, needing to perform intensive and complex processing, and facing rapidly increasing demand from emerging edge and 5G use cases. 

CSPs are modernizing their mobile network with container-based and cloud-native implementations of RAN. One study indicates deployment of virtual RAN (vRAN)/Open RAN (oRAN) solutions realize network TCO savings of up to 44% compared to traditional distributed/centralized RAN configurations. In this post, we describe the application of cloud-native technologies in architecting a blueprint for an open source RAN solution.

Benefits of cloud-native and container-based RAN solutions

Through this modernization, CSPs can simplify network operations and improve flexibility, availability, and efficiency—all while serving an increasing number of use cases. Cloud-native and container-based RAN solutions provide lower costs, improved ease of upgrades and modifications, ability to scale horizontally, and with less vendor lock-in than proprietary or  VM-based solutions.

Achieving the RAN transformation will include the disaggregation of RAN by decoupling hardware and software, as well as using cloud technology for automated deployment and scaling and workload placement. 

Furthermore, this may be facilitated by the new functional splits where the real-time and non-real-time baseband functions are split into three separate functions: radio unit (RU), distributed unit (DU) and central unit (CU).  

A requirement to make this possible is a robust cloud native infrastructure that can accomodate intensive demands of the RAN evolution and new 5G use cases such as those presented in Industry 4.0—the growing reality of the fourth industrial revolution, which merges interconnectivity, automation, IoT, machine learning, and real-time data analysis in an optimized ecosystem. The cloud native infrastructure provides the flexibility and scalability to deploy DU and CU instances, scales efficiently, and provides isolation for services like network slicing. 

Logical solution view

Conceptually, the RAN solution stack deployed on an open cloud-native infrastructure like Red Hat OpenShift can be categorized into: 

• Distributed clusters across cell site, edge datacenter, regional datacenter and central datacenter.

• Control plane clusters in the aggregation points.

• Management cluster in the central datacenter.

We present Figure 1: as a means to reinforce common elements and concepts as a generalized architecture configuration.

Logical Diagram - Open Radio Access Networks

Figure 1: General architecture configuration

RAN technology stack components

We’ve decomposed the RAN solution stack into high-level logical components within a typical deployment model as follows:

1. Cell Site

2. Edge Datacenter

3. Regional Datacenter

4. Central Datacenter

5. Control plane clusters

6. Management and application orchestration clusters

Cell Site

The infrastructure for the cell site is critical for the RAN, especially for distributed deployments where the DU and the RU are collocated. A cell site has constraints on power, cooling, and space, allowing only a limited amount of resources to be hosted—including the RU, which remains a physical element.  Figure 2: Cell site

Cell site infrastructure could be enabled with remote worker nodes with a centralized cluster control plane, or with a single node with integrated cluster control plane. Both deployment models are supported by OpenShift.     

Edge datacenter

Figure 3: Edge datacenter

The Edge Datacenter (EDC), located within the access layer at the edge of the network, hosts the infrastructure providing the time synchronization required by the RU and DU distributed at the cell sites, or DU pools centralized on the edge datacenter. Depending on the size of the deployment, the EDC infrastructure can be enabled by deploying OpenShift remote worker nodes with a centralized cluster control plane, or OpenShift clusters with an integrated cluster control plane. 

Regional datacenter

Figure 4: Regional datacenter

The Regional Datacenter (RDC), located at the aggregation layers of the network, hosts the infrastructure for the CU pools and some required functions such as the images repository—allowing timely distribution of the DU and CU across the access network. 

Central datacenter

Figure 5: Central datacenter

The Central Datacenter (CDC), typically provides infrastructure for the core of the mobile network, but in this case, it hosts the Element Management System for the RAN elements (RUs, DUs, CUs). In conjunction with enabling management functions, it also supports the infrastructure at scale of those elements across the cell sites (EDCs and RDCs). 

Control plane clusters

Figure 6: Control plane clusters

When the cell site and edge site infrastructure is deployed with OpenShift remote worker nodes, the control plane clusters (CPC) provide centralized services and the life-cycle management required by those nodes on the cell sites (EDCs and RDCs). 

Supporting the RAN elements, the Red Hat Openshift platform provides a series of extensions via the Operator Framework allowing RAN elements (DUs and CUs) to access physical capabilities required to meet performance requirements of the mobile network. These platform services are managed centrally on the CPC.

Management and application orchestration clusters

Figure 7: Management cluster

Management and orchestration allows dynamic scaling of an end-to-end 5G solution, across multiple clusters with automation.

Looking ahead and more information 

Our intent was to provide an overview of the common generic elements that make up an open RAN architectural blueprint on the logical level.

As we further develop successive materials, we’ll expand our description(s) with a more detailed look at the interaction between various RAN solution components that allow the capability to adapt and distribute them for each business requirements perspective—as well as scaling the RAN components on-demand. 

To learn more about how Red Hat’s open solutions in the telecommunications sector drive infrastructure modernization and digital transformation, we invite you to explore more here.