When a handful of vendors dominates a market, it generally bodes ill for customer choice and customer economics. This is most certainly the case for the Mobile 4G/5G Radio Access Network (RAN) equipment market, where, by some accounts, three vendors control almost 80% of the market and five account for nearly 95% of the market.
Open Radio Access Network (Open RAN) standards confront this problem by supporting interoperability between equipment and software from different RAN vendors. RANs have traditionally been proprietary systems, with a given RAN being built entirely using equipment and software from a single supplier. Open RAN provides an alternative to being locked into a single vendor when building a RAN, enabling network operators and enterprises to mix-and-match best-of-breed RAN elements using open white box hardware and software from different vendors.
A diagram showing Open RAN’s architecture and interfaces is shown in Figure 1, below.
Figure 1: Open RAN Architecture
Components of this architecture include:
- Open RAN Radio Unit (RU) which includes the low-physical (PHY) layer and radio frequency (RF) components.
- Open RAN Distributed Unit (DU) which hosts the Radio Link Control (RLC), the Media Access Control (MAC) and the high-PHY layers.
- Open RAN Central Unit-Control Plane (CU-C) that is composed of the Radio Resource Control (RRC) and the Control Plane (CP) part of the Packet Data Convergence Protocol (PDCP).
- Open RAN Central Unit-User Plane (CU-U) comprising the Service Data Adaptation Protocol (SDAP) and the User Plane (UP) part of PDCP.
- Near Real-Time RAN Intelligent Controller (near-RT-RIC or nRT-RIC) that enables near-real-time control/optimization of RAN elements and resources. The nRT-RIC may include artificial intelligence/machine learning (AI/ML) capabilities.
- Non-Real-Time RAN Intelligent Controller (Non-RT-RIC or NRT-RIC) that enables non-RT control/optimization of RAN elements and resources and policy-based guidance of the nRT-RIC. The NRT-RIC may also include an AI/ML component.
- A software-defined RIC that decouples the RAN’s CP from its UP, supporting a more cost-effective and scalable UP while enabling more advanced control functionality leveraging machine learning (ML) and artificial intelligence (AI).
- RAN virtualization that enables network functionality to be implemented in software running on white box hardware.
- Open interfaces that allow interoperability between decoupled RAN components from different vendors.
- Operation on white box hardware that offers the full advantage of economies of scale.
- Use of open source software to deliver the best value to network operators.
With these advances, Open RAN will enable the RAN to scale in a manner similar to the way hyperscalers implemented scaling in the cloud. According to the O-RAN Alliance, “[O-RAN aims] to bring cloud scale economics to the RAN.”
Open RAN Benefits for Private 5G Networks
While Open RAN was initially targeted at mobile carriers, it is now starting to be leveraged by more disruptive and innovative approaches for enterprise 5G networks. In private 5G networks, Open RAN can bring significant cost and performance advantages by enabling:
- Choice of radio vendors and ability to mix-and-match equipment and software from multiple vendors. Vendor choice enables the use of best-of-breed solutions and avoids the economic penalties that typically come with vendor lock-in.
- Use of the enterprise’s spectrum band(s) of choice. Enterprises can use unlicensed/lightly licensed spectrum, such as Citizens Broadband Radio Service (CBRS) spectrum in the U.S., or opt to pay for licenses to secure exclusive legal access to the spectrum they choose, potentially gaining lower interference, higher performance and better security.
- Choice of preferred radio architecture. With Open RAN, the baseband unit (BBU) of the traditional mobile network architecture can be divided into a distributed unit (DU) and centralized unit (CU). Further, the functionality of the RU and DU, as well as the DU and CU, can be split in a way that optimizes cost and performance based on parameters such as number and density of connected devices, need to provide Quality of Service (QoS), geography, use case, and networking technology available to connect the RU and DU, as well as the DU and CU. In addition to enabling the CU–DU-RU split, Open RAN allows for realizing the base stations as i) two disaggregated components: CU and DU+RU, and/or CU+DU and RU, or ii) all in-one: CU+DU+RU.
- Use of an nRT-RIC that enables the network to optimally allocate radio resources, implement handovers, manage interference and balance load between cells in dense 5G networks that can operate using a number of different spectrum bands, and enable better network performance via more efficient use of available spectrum. It contains AI/ML capabilities that can provide faster reaction and optimization when RF conditions or user needs change. The nRT-RIC also fosters innovation in the RAN by providing open interfaces for third-party developers, enables holistic radio resource management and allows for use case-based management of the RAN.
- Scaling network capacity as needed. Open RAN supports cloud native implementations, allowing the RAN to leverage cloud infrastructure and to be scaled out rather than scaled up.
- Tuning network performance and parameters for Quality of Experience (QoE) optimization, QoS-based resource optimization and massive MIMO optimization.
- Evolving functionality of RAN components as applications and use cases evolve. An additional benefit of Open RAN’s cloud native nature is that it facilitates use of continuous integration and continuous delivery (CI/CD) software development and deployment practices. As a result, new software features can be rolled out more quickly than possible using traditional software development and release methodologies, enabling faster support for new applications and use cases.
In sum, Open RAN provides significant value to enterprises for their private 5G networks as well as to traditional mobile network operators.
Open RAN brings big economic and technical benefits to enterprise private 5G networks by fostering vendor choice, enabling use of white box hardware and open source software, providing flexibility in choosing spectrum and RAN architecture, and supporting functional evolution as users’ requirements change.
This post, the fourth in a series, is an expanded excerpt from the Ananki white paper “Enabling Digital Transformation and Industry 4.0 with Private 5G”. Register to view the complete white paper.
“What Are the Open RAN Standards?” SDX Central
“O-RAN Architecture, Nodes, and Interfaces” Rimedo Labs
“O-RAN: Towards an Open and Smart RAN” O-RAN Alliance
“Open RAN Functional Splits, Explained” 5G Technology World
“SD-RAN: ONF’s Software-Defined RAN Platform Consistent with the O-RAN Architecture” Open Networking Foundation
“O-RAN Use Cases and Deployment Scenarios” O-RAN Alliance
“CI/CD in O-RAN” Rimedo Labs