What is open RAN?

A RAN is part of a wireless telecommunications system. It consists of base stations that have antennas, radio units, and controllers that connect devices such as a mobile phone, a computer, or any remotely controlled machine, to other parts of the network through a radio link. When a device is connected to the RAN, it is the base station’s job to transmit the device’s traffic (voice, data, video) to the service provider’s core network (CN).

A basic RAN base station consists of the following elements:

• Antennas convert electrical signals into radio waves.
• Radio units transform digital information into signals that are sent wirelessly and ensure transmissions are in the correct frequency band with the required power level.
• Controllers provide a set of signal processing functions, typically using custom electronics combined with software to enable wireless communications. Controllers connect the base station to a service provider’s CN.

As part of the ongoing development of telecommunication standards that promote stable environments, the Third Generation Partnership Project (3GPP) separated or disaggregated the RAN into three main sections as part of its Release 15 specifications:

• The Radio Unit (RU)
• The Distributed Unit (DU)
• The Centralized Unit (CU)

The RU can be integrated into the antenna or placed next to it. The DU and the CU are computational parts that send digital signals through the network. Due to the separation or disaggregation, the DU can be placed nearer to the RU, while the CU can be placed nearer to the CN. The separated or disaggregated RAN still only favors a single vendor approach.

The Open RAN model introduced by the O-RAN Alliance features, amongst other things, an open fronthaul interface between the RU and DU, allowing the potential for a multi-vendor RAN model. 

In the past, because of the way that RANs were designed, it was very difficult to find a RAN solution that took different elements from different vendors.

RAN disaggregation, cloudification, and the introduction of open RAN advocates an open source philosophy, empowering service providers to choose the different elements (RU, DU, and CU) from different vendors that fit their own unique environments and needs. As 5G networks significantly increase the complexity and scale of RANs, this type of solution flexibility is essential for the next generation of innovation in wireless telecommunication networks.

As part of RAN evolution, there are various terms used to describe the various standards, technologies, and architectures. Virtualized RAN (vRAN) and Cloud RAN are two similar, but slightly different conceptual approaches to RAN.

vRAN versus Cloud RAN

• vRAN concerns the decoupling of RAN software from the underlying hardware and is running elements of the RAN as software instead of hardware. However, this virtualization does not necessarily mean that the vRAN complies with O-RAN specifications, nor does it mean it can mix and match components from different vendors.
• Cloud RAN is a vRAN built using cloud-native technology that can include microservices and container-based technology, and a cloud platform to host DU and CU workloads. Once again, a Cloud RAN does not necessarily comply with O-RAN specifications, nor does it mean it can have mixed and matched components from different vendors.

Open RAN versus O-RAN versus OpenRAN

Open RAN, O-RAN, and OpenRAN are terms often used interchangeably, but actually mean different things:

• Open RAN is a generic term referring to an industry movement, as well as open RAN technology and architectures within service provider networks.
• O-RAN refers to the O-RAN Alliance and standards defined therein, which complement the 3GPP specifications with the definition of new open interfaces and profiles.
• OpenRAN is a project initiated by the Telecom Infra Project (TIP) that incorporates input from 3GPP and the O-RAN Alliance specifications.

The O-RAN Alliance is the primary organization that is defining open interfaces of RAN architecture. The goal of O-RAN is to define the separated or disaggregated components into different working groups (WG) that will range from WG1 to WG9. Many times when an organization says that their solution is open RAN compliant, it means that it is O-RAN compliant, and most open RAN solutions follow O-RAN standards.

vRAN and Cloud RAN issues when they aren’t open RAN

Why should you care about the difference between vRAN, Cloud RAN, and O-RAN-certified open RAN? Because getting invested in a Cloud RAN or vRAN that’s not open might mean your network isn’t flexible enough in the evolution to 5G.

Some of the biggest advantages of O-RAN-certified open RAN are that it helps promote vendor diversity, gives you tools to alleviate choke points, and allows you to find better solutions for each aspect of your network.

Vendor diversity

A single vendor approach can become a stumbling block. RAN solutions could be proprietary, non-interoperable, not O-RAN compliant, or not suitable for the network you’re looking to build.

Choke points

Some vendor vRAN and Cloud RAN systems may be built out of set pieces, and even if those pieces are disaggregated, they could be filled with choke points and inefficiencies when applied to real-world scenarios. 

Best-in-class solutions

When building a network using disaggregated components, the most efficient network will use best-in-class solutions for each RAN component. For example, the best RU solution for the network might be made by an organization that doesn’t build the best CU solution for your network or perhaps doesn’t build a CU solution at all.

With an open RAN network built to meet O-RAN specifications, you can pick and choose which solutions are best for each part of the network, and not have to take an entire package from a single vendor. 

5G networks

So why is it important to gain all of that efficiency in disaggregated network components? Because 5G networks are incredibly complex and will be built at scale, and are required to have not just incredible bandwidth, but unflagging reliability as well.

When next-generation innovations based on 5G require network response times measured by the millisecond, every part of the network needs to be functioning at peak performance.

Red Hat continues to champion the open RAN architecture and model.

The evolution of the RAN is highly dependent upon a cloud platform that can support multiple RAN functions and which spans the entire service provider network. Red Hat is focused on advancing its comprehensive enterprise Kubernetes platform, Red Hat® OpenShift®, to match the requirements of open RAN and enable the industry to build cloud-native network functions that can scale seamlessly across a network from core to edge.

Red Hat OpenShift helps service providers fully benefit from cloud economics and deliver new services faster. Through zero-touch deployment and operations using a GitOps framework, Red Hat OpenShift optimizes a service provider’s operations through simplified workflows that reduce total cost of ownership.

This works alongside Red Hat’s extensive partner ecosystem that ensures freedom of choice, so service providers can select their chosen software functions and hardware from different vendors to fit their needs.

Beyond Red Hat OpenShift, Red Hat stays involved with open RAN when participating in the organizations and projects shaping the standard. Red Hat helps monitor the progress of 6 of the 10 O-RAN Alliance working groups and works with the Telecom Infra Project (TIP) open RAN to assist efforts to accelerate the adoption of open compute hardware.