In the past two decades, we have seen cellular networks advancements to meet different technical specifications, in the order of 2G, 3G, 4G and now 5G. The worldwide telecommunication networks are currently moving towards a new network architecture that imbibes cloud, SDN and open networking.
Like everywhere, European network operators are also adapting this at a very fast pace. They are now transcending from closed, traditional networks towards an open and virtualized radio access networks and this movement is popularly known as open RAN.
But what is Open RAN? To answer this question, we first need to grasp how networks and network functions are getting transformed throughout these years.
In this article, we will cover 7 key aspects related to Open RAN:
- What is Open RAN?
- Difference between Open RAN, O-RAN and OpenRAN
- Key components of Open RAN
- How Open RAN can add value to the network operators?
- State of Open RAN in UK
- The O-RAN Architecture
- The O-RAN Implementation
What is Open RAN?
Open RAN is an industry wide movement towards acceptance of Open, Disaggregated and Virtualized RAN (Radio Access Network) that allows for interoperability between vendors' equipment and optimise total cost of ownership with greater flexibility. The primary goal of open RAN is to establish an interoperability standard for RAN constituents, such as hardware with open standardized interfaces and software from diverse range of suppliers. Network operators that use RAN components with standard interfaces avoid being locked into proprietary hardware and software from a single vendor. The Open RAN standards are designed to alter the siloed nature of the RAN markets, where a number of RAN suppliers offer only proprietary equipment and software. This lowers interoperability and flexibility.
Difference between Open RAN, O-RAN and OpenRAN
The movement Open RAN is generally jumbled with other two similar looking terms O-RAN and OpenRAN. These three terms are widely used in the industry but in different frame of references.
Open RAN: Open RAN is the movement that we talked about in earlier section.
O-RAN: O-RAN refers to the O-RAN ALLIANCE that has been founded in February 2018 by AT&T, China Mobile, Deutsche Telekom, NTT DOCOMO and Orange. It has been established as a German entity in August 2018. O-RAN ALLIANCE’s mission is to re-shape the RAN industry towards more intelligent, open, virtualised and fully interoperable mobile networks. The new O-RAN standards will enable a more competitive and vibrant RAN supplier ecosystem with faster innovation to improve user experience. O-RAN based mobile networks will at the same time improve the efficiency of RAN deployments as well as operations by the mobile operators.
OpenRAN: The OpenRAN project group was initiated by Telecom Infra Project (TIP) to define and build mobility wireless networks based on general purpose hardware, open interfaces and software. OpenRAN’s mission is to accelerate innovation and commercialization in RAN domain with multi-vendor interoperable products and solutions that are easy to integrate in the operator’s network and are verified for different deployment scenarios. TIP’s OpenRAN program supports the development of disaggregated and interoperable 2G/3G/4G/5G NR Radio Access Network (RAN) solutions based on service provider requirements.
Key components of Open RAN:
Open RAN imbibes three key principles:
a) Open Interfaces: RAN Components with open and standardized interfaces.
b) Cloudification: Use of RAN applications as cloud-native functions. This is done via disaggregation of hardware and software.
c) Intelligence and Automation: It utilises open management and orchestration with external AI/ML capabilities.
Further an Open RAN consists of three primary components:
- Radio Unit (O-RU) - This includes macro, micro, small cells and indoor radios as per network requirement. These radio units provide for the transmission, reception, amplification and digitisation of the radio frequency signals.
- Distributed Unit (O-DU) – This component is generally deployed near to o-RU. It’s a logical node hosting RLC/MAC/High-PHY layers based on a lower layer functional split. Here he DU and RRU function includes real-time L2 functions, base band processing and radio frequency processing.
- Centralised Unit (O-CU) – This component is in general deployed near to core and can host multiple DU and RU while sitting at Datacentre or IT infra. It’s a logical node hosting the RRC and the control plane part of the PDCP protocol.
How Open RAN can add value to the network operators?
Why there is so much noise around Open RAN, you wonder? Well, in this section we will try to answer that along with the value proposition that Open RAN brings to the table. Traditional Radio Access Network vendors are limited in their offerings as they can only provide proprietary equipment and network functions. Now, these proprietary products are usually more expensive as come with their own set of complimentary equipment and software. Moreover, network operators are stuck with products from just one RAN vendor given there are no third-party RAN components available for integration into the legacy infrastructure.
To combat these issues, organizations around the world felt the need to develop standardized open RAN standards and begin a new dawn for open networking and virtualisation. Needless to say, when you have an open infrastructure where diverse set of vendors can provide the basic components of RAN, there will be a surge in innovation as well as options for the operators. In fact, this freedom also allows them to add more new services.
Hence, straight off the bat, increased vendor competition for innovation and customer choice along with reduced costs of equipment are the major benefits of Open RAN. Enhanced network performance is another major plus point.
Thanks to Open RAN, now third-party devices can connect with the major RAN vendor's infrastructure via Open and standardized interfaces. Network operators can alternatively use a third-party solution that is less costly and runs on generic hardware. For network operators with a switch to Open RAN architecture for 5G on their mind, can help them in optimising their total cost of ownership (TCO).
State of Open RAN in UK
Now that we have explained Open RAN value proposition, and before we deep dive into Open RAN’s core concepts, it is important to take a look at where its implementation stands in the UK.
As per the recent release by UK government, their focus is to create a more secure, future-ready and innovative Open RAN supply chain that relies less on multinational suppliers. They are also keen on making the market more accessible for new entrants.
Of course, the major objective remains the establishment of high-performance 5G Open RAN solutions to cater to the UK’s dense urban requirements by 2025. To accomplish this, the country is open to conduct R&D with the new 5G RAN suppliers.
As such, interest is high in pilots, trials and even commercial Open RAN deployments in the UK. These are being led by established operators such as Vodafone that has committed to deploying Open RAN in more than 2600 rural areas by 2027. As per forecasts, it is believed that Open RAN will account for about 10% market share by the mid-2020s – a number that could be even more as more improvements in Open RAN come to the fore.
The UK government is also looking to boost the ecosystem with timely investments in R&D and Open RAN testing. The launch of SmartRAN Open Network Interoperability Centre (SONIC) and the UK Telecoms Lab (UKTL) indicate that the country is ready to embrace the possibilities that come with the disaggregated, Open RAN future.
Now, with basics out of the way, let’s look at the Open RAN from a very granular point of view.
The O-RAN Architecture
One only needs to visit the O-RAN Alliance website as it has a well-documented version of the O-RAN architecture. Some of the major elements of O-RAN architecture include:
- SMO Framework (Service Management and Orchestration Framework): It contains an integration fabric as well as data services for the functions it oversees. Within the O-RAN architecture, it enables managed functions to communicate and interoperate. The SMO is in charge of connecting to and managing the RICs, O-Cloud, O-CU, and O-DU.
- RIC (RAN Intelligent Controller): Non-real-time and near-real-time RICs are the two major types of RICs available. Both are logical functions that govern and optimise an O-RAN's elements and resources. With granular data gathering and exchange through the E2 interface, a near-real-time RIC manages and optimises components and resources. The E2 interface connects the O-CU and O-DU to the near-real-time RIC.
- O-Cloud: A cloud computing platform that creates and host multiple virtual network functions (VNFs) used by RICs and other elements of the infrastructure. Physical infrastructure nodes make up the O-Cloud using O-RAN architecture.
- O-CU (O-RAN central unit): This is the name for the logical node that is used for hosting various protocols. These protocols include radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP).
- O-DU (O-RAN distributed unit): This is the name for the logical node that hosts a different group of protocols. These protocols include the radio link control (RLC) protocol, medium access control (MAC) protocol, and the physical interface (PHY).
- O-RU (O-RAN Radio unit): This component is used for processing radio frequencies that are received by the network’s physical layer. With the help of an O RAN fronthaul interface, these processed radio frequencies are transmitted to the O-DU.
The O-RAN Implementation
Yes, O-RAN offers intriguing new prospects in the world of radio access networks. But an argument is to be made for optimum network security considerations before operators begin implementing O-RAN architecture. A secure, safe, modern cloud-native application of Open RAN would rely on optimally securing the underlying architecture based on microservices.
The O-RAN Alliance only ensures functional compliance for the component standards and O- RAN specification. When it comes to the implementation of Open RAN, stakeholders have one major demand: Verification, integration, interoperability, and commoditized RAN components testing. All of this is necessary to support a plug-and-play paradigm. As a result, commoditization of services is insufficient; effective orchestration of the many components is the need of the hour.
In the UK as well, while Open RAN has been gaining momentum, certain challenges need to be resolved before its flawless implementation. As per the recently published UK’s Telecoms Diversification Taskforce report, certain operators consider high cost of total ownership, challenging management and unsuitability to prime-time deployment as roadblocks that must be resolved first. As such, it is likely that we won’t see the full potential of Open RAN in the UK till the time 6G comes around.For more details on STL open RAN offerings, please write to Ravi.email@example.com