Open RAN is an Indicator of More Than Just Open Architectures
With the advent of 5G, our industry is rethinking the radio access network—the RAN. Every new generation of mobile has seen significant changes in the RAN. These include profound changes from how—and how much—spectrum is used, to how the radio system is connected to the core network.
Perhaps the most profound change in the RAN for 5G is the rethinking of the architecture and the move to Open RAN systems. The most visible work is happening in the O-RAN Alliance.
Keysight started working with the Open RAN community in early 2018 as part of the xRAN Forum, which later joined forces with the CRAN Alliance to form the O-RAN Alliance.
The O-RAN Alliance is not the only group working on open RAN architectures, but it is perhaps the best example of this overhaul of the RAN. While the continual reformulation of industry consortia can be confusing, these two bodies merging just a few short years ago underscores the importance of two critical aspects of this change.
Perhaps the most profound change in the RAN for 5G is the rethinking of the architecture and the move to Open RAN systems. The most visible work is happening in the O-RAN Alliance.
The "O" refers to "open" standard interfaces. Interfaces between what? In the days of 1G and 2G deployments, analogue signals were routed from radios at the base of cell towers to the antennas above. Now that most of the network is digital, we integrate the radio units with the antenna systems and use digital means to get information to those radio units. This migration drove massive improvements in system performance, and the interfaces between the radio and digital units evolved as proprietary standards. The base station is thus no longer a single physical entity but is distributed across two or three different physical locations.
Those organizations and technologists driving Open RAN systems are pushing the industry to a standardized architecture involving central, digital and radio units, each with standard definitions. This also involves open and standardized definitions of the interfaces between them.
But "open" is only part of the picture. What the "C" in C-RAN brought to the merger of the groups was the "centralized" or "cloud" aspect.
Not only would the architecture and interfaces be standardized and open, but because they are purely digital, almost everything except the radio unit could be virtualized as scalable software entities. Thus, the early 5G visions of C-RAN can be implemented in a set of common architectures with common interfaces.
Not only would the architecture and interfaces be standardized and open, but because they are purely digital, almost everything except the radio unit could be virtualized as scalable software entities.
And the work does not stop there. The complex functionality of the RAN must now include advanced MIMO techniques; capacity management (scheduling); managing power consumption; managing mobility and handovers; and leveraging location information. In addition, it is also an essential part of implementing network slicing, low-latency, and high-reliability networks.
Virtualizing the digital parts of what we used to call a base station means all this advanced functionality requires real-time coordination through what the O-RAN Alliance calls the RAN Intelligent Controller (RIC).
A simple way to think of the RIC is it is a cloud-native network function that enables intelligent orchestration of RAN resources through modular microservices and open interfaces.
The Open RAN community is driving a rethink of network architecture, not just disaggregating base stations with open interfaces. This is a major part of the cloud-native thought process for every part of the network that is in the digital domain.
How is it working out?
As in all major changes, the devil is in the details. Open standards mean multiple vendors contributing to a single network and thus system integration ownership is more complex. Standardized interfaces, especially those between network elements from different companies, mean the establishment of validation and conformance specifications and procedures. The software controlling these resulting complex networks is now responsible for ensuring even more performance, including increasing demands on capacity management, latency, and reliability. This requires sophisticated development and configuration management systems, along with rigorous trials and ongoing testing as updates and enhancements are applied. And open interface standards and architectures change the nature of how security and privacy need to be managed in the network.
Download The Essential Guide for Understanding O-RAN to learn more about O-RAN architecture and the insights to help you assess if this model is right for your company.