Open RAN explained: A modern approach to mobile networks

An open radio access network, or Open RAN, is a new approach to building RANs. Examples include the 4G and 5G networks we use for calls and the internet. It operates like a traditional RAN by using radio waves to connect our devices to the network through antennas. The key difference with Open RAN is its open design, which allows parts made by one company to work seamlessly with parts made by other companies. This makes it easier and more flexible for network operators to build and upgrade networks.

The design of Open RAN isn't in the hands of just one vendor. Instead, large groups that set industry standards, such as 3GPP and the O-RAN ALLIANCE, specify how Open RAN can be built and how its parts need to communicate. AT&T, along with five other leading mobile operators, founded the O-RAN ALLIANCE in 2018, aiming to create a more flexible and open network architecture.

Let’s look at how Open RAN differs from a traditional RAN.

Traditional radio access networks depend on a closely integrated setup of specialized hardware and software, usually made and provided by a single company. This arrangement makes it challenging and costly for mobile network operators (MNOs) to switch to a different hardware or software provider or to use equipment from multiple companies that are not part of the traditional RAN in their networks.

In a traditional RAN, making a single change is complicated. Because all components are tightly interconnected and coupled, updating just one part often requires replacing other components, even if those parts aren't directly affected. This process can become prohibitively expensive. Even when there's an opportunity to make the network better or add new functionalities, an MNO may choose to keep things as they are to avoid these expensive and complicated changes.

Open RAN offers a new approach through two key concepts: disaggregation and interoperability.

Disaggregation involves separating the hardware from the software, making sure they no longer depend on each other.

Interoperability makes sure that the hardware, software, and their connecting interfaces adhere to open standards, allowing them to seamlessly communicate and function together, no matter who the vendor may be. This strategy simplifies and reduces the costs associated with updating or expanding the network. It also opens up new possibilities for innovation by making it easier to add new features or improve the network without being tied to a single supplier. This can result in faster innovation and a better experience for end users.

Open RAN replaces the traditional RAN in the overall architecture and adds layers: common off-the-shelf hardware also known as Open HW, a container-as-a-service (CaaS) or cloud layer, and Open RAN software that includes interfaces built using open industry standards. It’s also important to remember that Cloud RAN will likely interoperate with classical RANs for years.

Replacing key parts of the traditional RAN with open components and open interfaces gives mobile network operators access to data that was once only available to vendors. By combining this data with the agility and flexibility of virtualized functions, operators can use apps to tune the network for better performance or to meet subscribers’ needs. For example, the operator could use artificial intelligence (AI) or other data analysis techniques to understand its network performance. They can use apps to dynamically power parts of it up or down in real time to match demand. This can improve customer service and reduce energy use.

Disaggregating components and creating open standards enables development of any of the components and APIs that help them function. Open RAN offers incentives for hardware and software developers to enter the market with niche products. This can encourage competition and as a result, help to lower end-product pricing.

Developers, whether they’re a single person or a large corporation, can create solutions for personal use or the wider marketplace. They’re motivated to innovate and continuously improve their products to gain market share.

Freed from vendor lock-in, Open RAN operators can be more resilient and able to adapt to disruptions. For example, a natural disaster could shut down a manufacturing operation for weeks or months and lead to an inventory shortage. Transportation routes might be disrupted, resulting in higher costs. Labor strikes, cyberattacks, and widespread health emergencies like the Covid-19 pandemic could cause similar disruptions. In an Open RAN system, the impact to the operator would be minimized because parts can be substituted with interoperable parts from another supplier.

Finally, Open RAN’s flexible and agile architecture speeds innovation by reducing the time it takes to bring new solutions to market.

Since the O-RAN Alliance formed in 2018 to develop and govern Open RAN standards¹, there have been several large greenfield projects–projects created from scratch–built from the ground up. Japanese telecom company Rakuten Mobil launched a fully-virtualized, cloud-native Open RAN network to Japan in 2020. The company says it reduced customer activation times from hours to minutes and cell deployments from months to days.

So far, greenfield projects have proven less complex and larger than brownfield ones. This disparity may level out—along with research and developments costs—as standards are developed, tested, and proven. Meanwhile the benefits will become more tangible.

As a founding member of the O-RAN Alliance, AT&T has made a significant commitment to developing Open RAN. We believe Open RAN will help unlock the full potential of 5G to enable greater flexibility, efficiency, and innovation in our mobile network and deliver next-generation connectivity. Our leadership and investment in this important technology is one way we’re working to keep customers ahead of change and ready to compete in the global marketplace.

Learn more about our networking solutions for business. Contact your AT&T Business representative to connect with an expert who knows business.

See how ultra-fast, reliable fiber and 5G connectivity protected by built-in security give you a new level of confidence in the possibilities of your network. Let our experts work with you to solve your challenges and accelerate outcomes. Your business deserves the AT&T Business difference—a new standard for networking.

¹ O-RAN ALLIANCE. Accessed July 1, 2024, https://www.o-ran.org/