What Is the Current Development of Open RAN?

The main challenge for network operators is the cost to deploy and maintain networks because of vendor lock-in and the complexity of networks. Open RAN is expected to deliver economic and technical benefits and improve efficiency and flexibility of the supply chain, reducing vendor lock-in and stimulating RAN innovation. Leading operators—such as Rakuten Mobile, Orange, Vodafone, Deutsche Telekom, Telefónica, TIM, and others—all support open RAN. Some have already deployed open RAN, with more deployment expected in 2022.

On January 19, 2022, Vodafone switched on its first 5G open RAN site in the United Kingdom, and on February 28, 2022, Vodafone announced at the Mobile World Congress 2022 that it will deploy open RAN in 30% of its European networks by 2030. As a result, about 30,000 sites will eventually use open RAN, starting with rural areas.

According to Parallel Wireless, RAN has always accounted for the biggest expense for network operators: 60% of Capital Expenditure (CAPEX) and 65% of Operating Expenditure (OPEX). Therefore, operators are always seeking cost-effective ways to deploy new infrastructure. Open RAN is expected to deliver the following advantages:

• Open interfaces to help realize the mix and match of RAN equipment from different vendors. This allows Centralized Unit/Distributed Unit (CU/DU) to be replaced with those that offer better performance (i.e., higher capacity and lower power consumption), without the need to swap already-deployed Radio Unit (RU). Moreover, the possibility to select RU and CU/DU from any vendor creates more competition and helps to drive down costs.
• Virtualization to disaggregate RAN equipment into software and hardware. Separating software and hardware avoids vendor lock-in, reduces CAPEX and OPEX by leveraging the most cost-effective hardware/software, and introduces cutting-edge hardware more easily and brings deployment flexibility. Also, the latest technology can be introduced by upgrading only the software. The virtualized nature means that a server can pool resources during off-peak times; some servers can be shut down or allocated to other applications until they are again required. According to a survey from the Next Generation Mobile Networks Alliance, 80% of cell sites carry only 20% of total traffic, and the busiest 10% carry 50% of the traffic. Hence, pooling RAN resources can reduce the capacity requirement of each cell site, with significant power savings.
• Intelligence to drive optimization and automation of RAN operation. Operation of RAN is getting more complex with the introduction of split architecture and virtualization; therefore, introducing more intelligence in RAN is inevitable. For operators, this intelligence helps reduce OPEX through digital transformation in the RAN operation. Improved RAN performance through automated optimization of resource management and control will also lead to higher user satisfaction. RAN intelligent controller is the key technology to offer intelligent resource management and optimization using artificial intelligence and machine learning.

At the same time, open RAN faces several challenges:

• Integration and interoperability tests. Integration with legacy systems and infrastructure can be complex, and the time needed to carry out interoperability tests until model maturity will be significant. Testing with multivendor products requires skill set and know-how. Also, when increasing end-to-end performance or fixing unexpected end-to-end issues, it is necessary to clarify and identify which component should have the responsibility to do so.
• Security issues. Mobile operators demand security, and security issues could be in the form of technology (e.g., security issues due to open-source software and off-the-shelf technology; exposed interfaces leading to increased threat surface and cloud-related security issues in the form of software and hardware split), process (e.g., operators that do not have the appropriate security process for the entire life cycle of open RAN deployment), and people (e.g., staff with insufficient resources and experience). Potential security solutions are most important in having holistic security. One key item in holistic security is the consideration of a complete life cycle where baseline security; asset, identity, and access management; and privileged access management play an important role. Interfaces can be secured by utilizing existing security protocols. With processes and resources, the Information Technology (IT) security process can form the foundation, and resource issues can be solved by utilizing IT security resources.

Just as with every new solution, open RAN brings additional challenges but also brings new opportunities. Its deployments will start with rural areas where the traffic demand is low, and it does not require Massive Multiple-Input Multiple-Output (mMIMO). When the radios are 4T4R, it is relatively simple to match baseband software to radios supplied by another vendor. With mMIMO, it is extremely difficult to match one’s baseband with another’s active antenna due to different implementation choices. Once the business case proves to be successful in rural areas, open RAN will then move to urban areas.

Open RAN has achieved success and popularity in certain markets, such as Africa, Europe, and Asia. Rakuten and MTN Group have announced that they will work together on three new proof-of-concept trials in South Africa, Liberia, and Nigeria starting later this year. Traction is picking up in Asia, with Japan being the leader, and the Indian government has plans to back development of open RAN. European operators also show great interest in this technology—for example, open RAN trials have started in rural areas of Turkey, and Vodafone has switched on its first open RAN in the United Kingdom. Despite the increased activity, open RAN is still at its infant stage. The industry needs to overcome the challenges of integration and security for open RAN to gain speed. It is expected that mass rollout may not happen until three to five years from now.