The Nuances of 5G RAN, Cloud RAN, ORAN

In late 2023, AT&T announced a new deal with Ericsson to use the Swedish vendor’s cloud Radio Access Network (RAN) architecture and to start moving to Open RAN (ORAN). In December 2024, AT&T announced additional radio deals with Fujitsu and Mavenir to deploy their radios with Ericsson’s Intelligent Automation Platform (EIAP).

Dish built its new 5G network entirely on ORAN architectures using RAN solutions from Fujitsu, Samsung, CommScope and Mavenir.

AT&T, Dish and many other operators across the world are demonstrating how RAN equipment from different vendors can be mixed and matched using ORAN. Proponents of ORAN highlight this increased vendor competition from an expanded RAN ecosystem and the resulting reduction in RAN deployment and operational costs as a major benefit.

But what is ORAN? How is it different from Cloud RAN? And are both required for 5G deployments? As the wireless world has moved from 4G to 5G, the RAN has also evolved to include Cloud RAN and Open RAN. These terms are often misunderstood.

What is Cloud RAN?

In a cloud network, network functions are typically virtualized – that is, the hardware and software are split. Instead of having dedicated hardware for each component, the network software can run on off-the-shelf hardware, (also called commercial, off-the-shelf equipment) which is usually less expensive. Starting with the 4G LTE deployments, most components in the mobile network have been virtualized to some degree, with the exception of the radio.

For the newest 5G networks, many of the RAN components are virtualized and distributed. For example, the baseband unit is split into a centralized unit (CU) and distributed units (DU), each of which uses commercial off-the-shelf hardware. Typically, the DU is located at the cell site or a local data center, while the CU is usually in a local data center. Note that the radios are provided by the same vendor as the DU and CU.

Many names are given to this software-based, commercial off-the-shelf, distributed, virtualized network architecture. Some refer to the virtualized DU and CU as Cloud RAN. Others call the whole architecture Cloud 5G or Cloud networking. Virtualized RAN or vRAN is also a common term.

One advantage of a virtualized cloud RAN architecture is less equipment at the base of the tower, which results in lower power requirements and smaller cabinets. Since the CU and DU use off-the-shelf hardware, initial deployment and replacement costs are potentially lowered. Additionally, because the CU may be in a centralized data center, cloud data center resources can be leveraged and the CU can be hosted by hyperscalers.

Between the radio and the DU, a Common Public Radio Interface (CPRI) is used. This was also the case in 3G and 4G networks. However, over the years, vendors have added specific functions to CPRI to support network management functions and address specific operator requests.

As a result, radios from one vendor can only be used with a DU or baseband unit from the same vendor. For example, an Ericsson radio can only be used with an Ericsson DU, and a Nokia radio will only work with a Nokia DU. Thus, while CPRI is technically an industry standard, customization over the years means that CPRI is not an open standard and the RAN is not ”open.”

It should be noted that significant benefits have resulted from this CPRI customization. Power efficiency, performance and capacity improvements in 4G and 5G networks can, in part, be attributed to expansion of CPRI and closer integration between the radio and DU or baseband.

What is Open RAN?

Open RAN is not the same as Cloud RAN. A traditional mobile architecture can be deployed “in the cloud” with the same vendor providing the radio and BBU/DUs.

In its most general sense, the word “open” refers to the intentional capability of software, hardware and/or interfaces to comply with an agreed-upon standard so that equipment and software from multiple vendors all work together and can be interchanged.

Applying the open concept to the RAN results in having an architecture that opens up the interfaces in the traditional RAN and enables different vendors to be supported by the radio and DU. Open RAN uses RAN software on commercial off-the-shelf hardware.

In this case, being “open” means that there are reference designs and standards for hardware and software such that there are open interfaces exposed, enabling ORAN-compliant software/hardware from different vendors to work together. For example, an open remote radio from Vendor A will be able to talk via open interfaces to software running on commercial off-the-shelf server with (virtualized) network functions from Vendor B.

Not all ORAN networks are 5G and 5G does not have to use ORAN. In fact, the first ORAN networks were 4G LTE deployments. And some ORAN vendors offer 3G and even 2G RANs to provide cost-effective replacements for older networks.

What is the potential impact of ORAN on the wireless infrastructure ecosystem?

While the goal is to increase the number of RAN vendor options and lower the overall cost of RAN, the same basic components will still be deployed on the tower or small cell. Antennas, radios, DU/CUs, backhaul and power supplies are still required.

Construction and engineering companies will still put RAN components on the tower or small cell, but with ORAN, vendors supplying components may be more varied.

One important area that will change is RAN integration. In a traditional RAN, the integration between the radio and the DU is done by the RAN vendor – after all, both components come from the same company. But with ORAN, someone still needs to do all the integration between the various vendors. In the major deployments to date, the ORAN integration has been done by the MNO. But increasingly, other vendors (such as Ericsson) are taking on more responsibility in this important role.

Want to learn more?

You can learn more about the direction the RAN is taking at Connect (X) 2025 in Chicago, May 12 – 14, 2025. Leading vendors, integrators and mobile operators will be discussing the latest RAN developments and the implications for the industry.

Register Today