The Telecom ecosystem has evolved through generations of mobile technology and it is experiencing a paradigm shift with 5G connecting nearly everything, which makes real-time data available at high speeds and near zero latency.

Open Radio Access Networks (O-RAN) is one of the progressing shifts in the telecom industry today. It refers to a disaggregated RAN functionality approach to deploy mobile networks, built using open interfaces and protocols that operate on commercial off-the-shelf hardware (COTS) with open interfaces.

Open RAN is applicable to all generations of mobile technology such as 2G, 3G, 4G, 5G and other future generations. Mobile network operators are reconstructing their network environment by leveraging the Open RAN concept, to cut down the cost of network deployment and maintenance.

O-RAN allows more flexibility compared to traditional Radio Access Networks (RAN). O-RAN is actualized by using vendor neutral hardware and SDN technology, which is dependent on open interfaces, protocols and industry developed standards.

Before we understand how O-RAN differs from Conventional or Traditional RAN, let us look at the three essential components of RAN:

• Radio Unit (RU): Here the transmission and reception of radio frequency signals occur which are amplified to a desired level and digitized. Radio Unit (RU) is located near the antenna.
• Distributed Unit (DU): It is where the lower layer packet processing functions dwell. The DU is located close to the cell site or it can be centralized.
• Centralized Unit (CU): Here higher layer packet processing functions dwell.

Open RAN vs. Conventional or Traditional RAN

• In Conventional RAN, mobile networks are constructed on a closed network using proprietary radio unit, hardware, and software. Here, almost all the hardware equipment is supplied by a single vendor and hence network operators cannot deploy mobile network by using radios from one vendor with hardware and software from different vendor. Having different vendors at different cell sites leads to a performance issue, hence network operators opt for a single vendor to deploy mobile network. This leads to vendor lock-in, which, in turn, limits the entry for new vendors.
• Open RAN is not an innovation, but a rather progressing shift in mobile network architecture which permits networks to be built using elements and components from a variety of vendors. Open RAN concept is successfully achieved by opening the protocols and interfaces between the radio unit, hardware, and software in the RAN. The advantages of this approach are increased flexibility of networks, high speeds, and cost reduction.

Open RAN mainly focus on the interfaces between Radio Unit, Distributed Unit, and Centralized Unit. O-RAN allows network operators to standardize and by opening interfaces, the operators can move to a diverse ecosystem where multivendor solutions can be deployed without relying on a single vendor. By implementing these changes, the Distributed Unit and Centralized Unit can be run as virtualized software functions on vendor-neutral hardware.

Market reports suggest that by 2024, the global Open RAN market is likely to generate about $3.2 billion in annual revenues, giving it about 9.4% of the total 4G and 5G market.

Open RAN Ecosystem
The two main Standards Development Organizations include:

1. The OpenRAN Group which is a part of the Telecom Infra Group (TIP) formed by Facebook in 2016. Members of this group include operators, developers, system integrators, and vendors. The main objective of this group is to deploy 2G, 3G, and 4G RAN solutions based on COTS hardware and disaggregated software so that operator and vendors will have benefit from this flexibility.
2. The O-RAN Alliance is an operator founded organization which was founded in 2018. The O-RAN Alliance’s focus is to standardize the next-gen RAN Architecture and open interfaces, which fully hold O-RAN’s core principles of openness and intelligence. It is mainly focused on operator deployment needs.

Operators Benefits of Open RAN

• Cost savings both CapEx and OpEx due to the use of standard equipment and quick time to market
• Deployment time is less since virtualized RAN are used. With the addition of RAN Intelligent Controller (RIC) nodes, Artificial intelligence and automation benefit is achieved which will reduce the average time for deploying a site and OPEX. Optimizing networks for each network environment and use case is achieved using RIC. Network virtualization creates software app infrastructure for RIC. Software Defined Networking allows apps to orchestrate and configure networks to deliver network automation for deployment.
• Eliminates ‘Vendor Lock-In’ because of standardization which allows operator to move to a diverse ecosystem where multivendor solutions can be deployed and operators can choose best of breed options for their deployment, without relying on a single vendor.
• A simple software update can all be handled remotely, hence there is no need to rip and replace infrastructure.
• Rapid 5G deployment since Open RAN architecture will support more innovative use cases by keeping the next-gen 5G networks open and disaggregated.

Open Test and Integration Center (OTIC) initiative
In 2019, operators from across the globe had initiated the Open Test and Integration Centre (OTIC), to collaborate with industry partners, equipment manufacturers, and other opensource products and solutions. This was formed to be in line with O-RAN Alliance specifications, through integration and testing of disaggregated RAN segments and to deliver the flawless architecture design which supports plug and play model. The OTIC initiative will expedite multi-vendor, open and disaggregated wireless Network infrastructure.

Examples of Open RAN Use cases

• Low-Cost Radio Access Network White-box Hardware: 5G deployment expenses can be reduced by promoting white-box hardware. O-RAN releases a reference design of a high-performance white-box base station. By utilizing the reference designs of white-box hardware a cost reduction is achieved.
• Traffic Steering: By using RAN Intelligent Controller (RIC), human intervention is reduced, saving OPEX. It is quick and more efficient in handling traffic problems and can predict the user equipment performance and network condition, thus improving user experiences. By adapting AI/ML to RIC module, intelligent and proactive traffic steering control is achieved.
• RAN Slice SLA Assurance: To create and manage RAN slices, O-RAN Alliance uses SMO (Service Management and Orchestration) and RIC (RAN Intelligent Controller). O-RAN’s open interfaces are linked with its AI/ML based architecture, which will allow RAN SLA assurance process.
• Context Based Dynamic Handover Management for V2X: Here O-RAN architecture is used for assortment of data, maintenance and to have access to actual traffic and navigation information. The deployment and assessment of AI/ML based applications identify and foresee any irregularities on a user equipment.

Sasken has more than 25 years of expertise in working with NEMs to develop and test 2G, 3G, 4G, 5G virtual RAN (vRAN), GSM-R and GMR2P. It is also working actively on developing and testing O-RAN compliant interfaces between Radio Unit and Distributed Unit. We are also working with Network Equipment Manufacturers (NEMs) to offer Open and Virtualized Radio Access Network, which are in line with 3GPP.