Your All-in-One Guide OpenRAN

To meet the complex demands of 5G technology, RAN architectures must evolve to deliver cost-effective, low-latency networking in real-time at the edge. 

In this blog, you'll learn what OpenRAN is, how its architecture is different from the traditional RAN architecture, and how OpenRAN integrates within the 5G ecosystem.

What is OpenRAN?

OpenRAN is a type of radio access network (RAN) architecture based on interoperability, flexibility, and standardization of RAN elements with the promise to reduce operational expenditures (OPEX) and total cost of ownership (TCO). 

Operators today are increasingly demanding a more diverse ecosystem of suppliers from which to choose to construct their RAN architectures, leading them to redefine their requirements.

This is where OpenRAN comes in. The primary purpose of OpenRAN is to provide a unified interconnection and communication standard for white-box (personal) hardware and open source software by allowing a variety of vendors to supply needed equipment, improving network malleability, enhancing security, and reducing costs. 

What does an OpenRAN architecture look like?

A traditional RAN architecture is made up of a remote radio unit (RRU) and a baseband unit (BBU). A signal is received via the RRU and is sent to the BBU to be processed and forwarded to a network. 

An OpenRAN architecture, on the other hand, is separated into three main components: the RRU, the distributed unit (DU), and the centralized unit (CU). The CU and DU are disaggregated from BBU. 

Radio signals are transmitted, received, amplified, and digitized in the RRU, which is integrated into the antenna. The DU and CU are for computation, sending the digitized radio signals to the network. The DU is either physically at or near the RRU, whereas the CU is closer to the core network. 

A typical OpenRAN architecture integrates a modular base station software stack on off-the-shelf hardware to allow baseband and radio unit components from different suppliers to operate seamlessly together. 

Let's take a look at all of the components in a little more detail: 

1. Service Management and Orchestration Framework (SMO): The SMO includes an integration fabric and data services for the functions it manages; it also allows these functions to interoperate and communicate with OpenRAN. The SMO connects to RICs, the O-Cloud, the O-CU, and the O-DU. 
2. RAN Intelligence Controller (RIC): The RIC is a logical function for controlling and optimizing the elements and resources of OpenRAN. There are two types of RICs: non-real-time and near-real-time. 
   
   The non-real-time RIC is a part of the SMO framework, centrally deployed in the service provider network, which enables non-real-time--meaning greater than one second--control of RAN elements and their resources through specialized applications called rApps. Non-real-time RICs communicate with applications called xApps running on a near-real-time RIC to provide policy-based guidance for edge control of RAN elements and their resources. 
   
   The near-real-time RIC resides within the edge cloud or regional cloud and is responsible for intelligent edge control of RAN nodes and resources. The near-real-time RIC controls RAN elements and their resources with optimization that typically takes 10 milliseconds to one second to complete, receiving policy guidance from the non-real-time RIC and providing policy feedback to the non-real-time RIC though xApps. 
   
   The near-real-time RIC communicates over the E2 interface, an interface with two ends such as the near-real-time RIC and the E2 node. The E2 interface allows allows the RIC to control the processes and functionalities of the E2 node. 
3. O-Cloud: The O-Cloud is a computing platform made up of the physical infrastructure nodes using the OpenRAN architecture; it also creates and hosts the various virtual network functions that are used by the RICs and other infrastructure elements. 
4. OpenRAN central unit (O-CU): The O-CU is a logical node that hosts a handful of protocols: the radio resource control (RRC), the service data adaptation protocol (SDAP), and the packet data convergence protocol (PDCP). 
5. OpenRAN distributed unit (O-DU): The O-DU is a logical node that hosts another set of protocols: the radio link control (RLC) protocol, the service data adaption protocol (SDAP), and the physical interface (PHY). 
6. OpenRAN radio unit (O-RU): The O-RU processes radio frequencies received by the physical layer of the network. The processed radio frequencies are sent out to the O-DU through a front haul interface.

What is the O-RAN Alliance?

The O-RAN Alliance was established in 2018 by a global consortium of network operators with the stated goal of evolving RANs worldwide. To this end, the group advocates virtualizing network elements, white-box hardware, and open RAN interfaces. 

Built on openness and intelligence, the O-RAN Alliance has established eight discrete working groups with ambitious technical objectives including open frontal architecture, RAN cloudification, and software specifications for the new radio protocol stack.

What are the benefits of OpenRAN?

The primary benefit of OpenRAN is that it allows network operators to avoid being stuck with a single vendor's hardware and software. This leads to variety of other benefits such as: 

1. Innovation and competition: Previously, operational inefficiencies within RAN architectures could not be dealt with, as network operators were locked into a specific vendor. With OpenRAN, these operators benefit from an open, multi-vendor RAN ecosystem, introducing competition into the market and decreasing reliance on a single vendor for implementation and optimization. 
2. Lower equipment costs: As a result of increased competition, OpenRAN equipment costs can be driven down significantly. 
3. Improved network performance and scalability: OpenRAN requires hardware and software to be separated, or disaggregated, and it is enabled by vRAN (virtualized RAN), increasing efficiency, improving scalability, and optimizing network performance. (More on that later.)

What are the challenges of OpenRAN?

Implementing a seamless, interoperable, multi-vendor, open system presents a host of testing, management, and integration challenges that require diligence and cooperation to overcome. This is unlike the single-vendor model, where problems are dealt with through an established command structure. 

To ensure OpenRAN meets its promise of reduce expenditure and ownership costs, operators need to take responsibility for multi-vendor, disaggregated elements to make sure they perform well together and maintain quality of experience (QoE) standards. 

In addition, having various vendors supply the equipment for a single architecture can lead to finger-pointing when problems arise, which can leave management and orchestration responsibilities undefined. This, in turn, can delay launches and stunt revenue growth. 

What is the Open Test and Integration Center (OTIC)? 

With OpenRAN allowing dozens of new vendors to come into the mix, interoperability has arisen a concern. 

To address this potential challenge, the Open Test and Integration Center (OTIC) has been established in Berlin, Germany as a collaborative hub for commercial OpenRAN development and interoperability testing. 

The OTIC offers a structured environment with common test platforms and practices that enable software developers, equipment manufacturers, and system integrators to verify functional compliance to O-RAN Alliance specifications. 

The OTIC also benefits from the support of global telecom organizations with a shared commitment to verification, integration testing, and validation testing of OpenRAN components.

OpenRAN, vRAN, and FlexRAN

As mentioned earlier, in order for OpenRAN to work, hardware and software have to be disaggregated (separated). 

Disaggregation is done through network function virtualization (NFV), which turns hardware-based functions into software-based functions. This decreases costs and makes upgrades easier while increasing agility and flexibility. 

NFV is a critical component of vRAN (virtualized RAN), and both OpenRAN and vRAN are critical components of Intel® FlexRAN, a fully virtual and cloud-native vRAN architecture that streamlines resource use and separates network functions from hardware. (Read more about Intel® FlexRAN here.) 

OpenRAN and 5G

As the amount of available data increases daily, the demand for 5G technology to handle this information increases, too. 

But the implementation of 5G requires upgrading, expanding, and simplifying networks in order handle complex, demanding tasks. 

These changes take place at the cell site--in a RAN architecture, this is the BBU. 

Current RAN architectures, however, make these changes difficult, as there is one hardware-based BBU for every RRU, leading to costly, difficult maintenance; in addition, these setups are designed to only meet peak capacity and lack the flexibility needed to handle short bursts of traffic. 

OpenRAN solves these problems by creating smaller, virtual, and more numerous BBUs that are kept in a centralized location--i.e. on a single piece of hardware--sometimes called a "BBU Hotel." 

This has a number of benefits that are essential to the evolution, deployment, and flexibility of 5G networks and use cases. These benefits include: 

1. Simplified organization and management, cost reduction, increased security, less power consumption, and more efficient sharing of resources, as all BBUs are kept on the same piece of hardware
2. Increased scalability and reduced latency, as OpenRAN can easily respond to current needs or preprogrammed service level agreements (SLAs)
3. Enhanced compute power and connectivity at the edge, as all computations are on a computer that share the same CPU and memory
4. AI/ML/DL algorithms that provide deep insights and analytics that can help automate network maintenance, optimize connection paths, allocate resources appropriately, and correct over-utilization. 

Where does Trenton Systems fit in?

At Trenton, our high-performance computing solutions can support various RAN architectures, including OpenRAN, to maximize compute power and provide virtualized, low-latency connectivity at the edge. 

We can customize our solutions per our customers' technical, performance, and environmental specifications, incorporating various 5G technologies such as Intel® FlexRAN and Intel® SmartEdge, to deliver peak performance in real-time. 

Our IES 5G solution, for example, enhances networking with virtualized, open RAN architectures to accelerate mission-critical applications with complex, constantly expanding requirements. 

Each server within this system supports Intel® 3rd Gen Xeon® Scalable Processors and DDR4-3200 DIMM slots to increase throughput and provide maximum memory support to the CPU, so multiple vRANs can run simultaneously. To accelerate vRAN applications, each server can support Intel® vRAN Accelerator ACC100 adapters. 

The IES 5G helps reduce the amount of costly hardware needed while accelerating processing and networking capabilities, all without the loss of performance. 

Final thoughts

OpenRAN provides a clear advantage over traditional RAN architectures, making it the ideal choice for many network operators. 

By centralizing all operations on a single piece of hardware, infrastructures costs are greatly reduced, and RAN deployments are streamlined to meet varying demands with a much lower energy consumption rate. 

In addition, standardized communication and AI-powered algorithms allow for optimized information sharing and data analysis that can accelerate traffic flow to a core network, all without the need for human intervention.

This increases connectivity with surrounding networks and greatly reduces latency, enabling the delivery of actionable, real-time insights to increase situational awareness and enhance decision-making capabilities. 

With OpenRAN, our warfighters can reap the benefits of 5G technology in an agile, scalable, and cost-effective manner to tackle all missions across the modern, multi-domain battlespace with complete confidence. 

Interested in learning more about 5G? Check out some other key 5G technologies that enhance compute architectures here.

• "O-RAN" - Viavi Solutions 
• "O-RAN Explained: Architecture, Benefits, and Components" - STL Blog