Cloud RAN mobile architecture: 6 questions answered

The volume of mobile data traffic has been steadily increasing over recent years and shows no signs of ever decreasing. This can be attributed to growth in end-user devices such as smartphones, smart home and office devices, and especially the advent of 5G.

[ Learn why open source and 5G are a perfect partnership. ]

In its 2022 mobile data traffic outlook report, Ericsson predicted total global mobile data traffic, including fixed wireless access (FWA), would hit around 115 EB (exabytes, or 1 billion gigabytes) per month by the end of 2022 and 453 exabytes per month by the end of 2028, with video traffic estimated to account for 70% of all mobile data traffic. To help meet this growing need for data, telco operators are turning to the cloud (or centralized) radio access network (RAN) architecture (C-RAN).

If you'd like to know more about Cloud RAN, read on to learn about this architecture and the power it holds. This summary is based on an excellent four-article series by telco architects Kashif Islam and Syed Hassan, which is linked at the end of this article.

How will changes in RAN architecture impact 5G and beyond?

If you have a cellphone, you've probably heard of 5G (or fifth-generation) mobile technology. It's the most advanced mobile network technology currently available and offers faster data speeds, lower latency, and more support for real-time applications than previous technologies.

RAN plays a pivotal role in delivering on the promises of 5G. Compared with its predecessors, 5G RAN brings significant and revolutionary changes. 5G is transforming the entire RAN deployment model and architecture. A clear and deep understanding of the new, innovative RAN architecture is essential to designing and deploying 5G and advanced networks. Explore 5G RAN architecture and its foundational concepts in The road to Cloud RAN from 1G to 5G.

What are the key radio access network concepts and terms to know?

The number of acronyms in the world of wireless communications can feel overwhelming. Here are three foundational RAN concepts to help you understand 5G RAN:

• Distributed RAN (D-RAN) and Centralized RAN (C-RAN): These are dueling architectures that refer to the placement of the radio processing equipment.
• RAN disaggregation and RAN decomposition: Although disaggregation and decomposition sound similar, they describe how RAN functions are decoupled from proprietary hardware and broken down into smaller chunks using different split options.
• Virtual RAN (vRAN), Cloud RAN, and Open RAN: These refer to the characteristics of the disaggregated and decomposed RAN function and how various RAN functions interact.

The RAN word soup is extensive, however 20 radio access network (RAN) terms to know describes commonly used RAN concepts and terminologies to add to your RAN vocabulary.

What are Distributed and Centralized RAN architectures?

RAN architectures can be broadly classified into two categories: Distributed RAN (D-RAN) and Centralized RAN (C-RAN).

In D-RAN, a typical cell site operates as an independent entity with radio antennas and the required radio processing equipment (a baseband unit) colocated at the site. In other words, the RAN equipment is distributed across the network.

C-RAN refers to an architecture where the radio processing equipment for multiple cell sites is pooled together in a location central to those sites.

The radio antennas are located at the cell site in both the D-RAN and C-RAN architectures. The placement of radio signal processing equipment defines whether a deployment is classified as D-RAN or C-RAN.

D-RAN is the dominant architecture for most 4G and current 5G implementations. However, with RAN disaggregation and decomposition, C-RAN deployments are growing in use.

[ Check out Red Hat Portfolio Architecture Center for a wide variety of reference architectures you can use. ]

What are RAN decomposition and disaggregation?

Though used simultaneously in 5G RAN, disaggregation and decomposition are independent concepts. Disaggregation refers to separating the RAN software from customized hardware and running it on generic hardware. The generic hardware may be in privately hosted infrastructure (a private cloud) or implemented in a public cloud environment.

Decomposition refers to splitting the RAN's function performed by the radio and baseband units and implementing them as three separate functions: Radio, Distributed, and Centralized Units (RU, DU, and CU). The distribution of RAN functions between RU, DU, and CU is defined by the Lower Layer Split and Higher Layer Split.

While RAN decomposition and disaggregation are distinct concepts, they are used in conjunction to provide flexibility and usability.

What is the relationship between vRAN, Cloud RAN, and Open RAN?

Cloud RAN and virtualized RAN (vRAN) are used in RAN virtualization. vRAN is a RAN implementation where the CU and DU RAN functions are virtualized and implemented on general-purpose hardware. This increases flexibility, cost savings, and the ability to scale the network more efficiently.

Despite being virtualized, the vRAN components may not always be cloud native. If the virtualized functions (vDU and vCU) are implemented in a true cloud-native fashion, the vRAN implementation is called Cloud RAN.

Open RAN (Open Radio Access Network) facilitates interoperability and vendor neutrality. Primarily driven by telecom service providers, Open RAN advocates for standardization and open interfaces between RAN devices. A multivendor approach fosters competition, helping to reduce costs and increase innovation in the industry.

Learn about the effort to open RAN interfaces to eliminate vendor lock-in and the organizations defining the standards around Open RAN in What is Open RAN?

What is the best way to get started with RAN?

Cloud RAN is designed to take advantage of cloud-native technologies and principles, such as microservices, automation, containerization, and hybrid cloud environments. Containers are isolated and portable units of software that package an application and its dependencies together. Container platforms are software environments that enable the deployment and management of applications in containers.

Container platforms are essential to Cloud RAN mobile networks and drive innovation in the mobile network space. By leveraging the benefits of containers and cloud computing while utilizing an Open RAN ecosystem, mobile network operators can build more flexible, scalable, and efficient networks that can meet the needs of mobile users today and tomorrow.

Red Hat OpenShift provides tools for managing containerized applications, including the vCU and the vDU used in RAN architectures. What does Red Hat OpenShift have to do with Cloud RAN? outlines a few deployment options to fit hybrid cloud deployment scenarios for different telco needs.

[ Do you know the difference between Red Hat OpenShift and Kubernetes? ]

Wrapping up

I hope this summary has provided some insight into Cloud RAN and some of its key concepts. To learn more, please read the four articles in this series by Kashif Islam and Syed Hassan:

• The road to Cloud RAN from 1G to 5G
• 20 radio access network (RAN) terms to know
• What is Open RAN?
• What does Red Hat OpenShift have to do with Cloud RAN?