Sameh Yamany, Chief Technology Officer, VIAVI Solutions

Telecom operators worldwide are switching to open radio access network (O-RAN) architectures in an effort to simplify 5G RAN deployment and management, enabling efficient scalability to meet rising data demands. The collaborative framework of the O-RAN Alliance, TIP OpenRAN Project and Open RAN Policy Coalition is set to advance the adoption of open and interoperable solutions and widely expected to accelerate the timelines for O-RAN deployments.

O-RAN can significantly advance 5G network deployments and it is encouraging to see vendors and telecom operators working together; however, the Open RAN concept of flexible interoperability also brings challenges for test and integration. To fulfill the O-RAN promise of reduced OPEX and total cost of ownership (TCO), operators must take responsibility for multi-vendor, disaggregated elements and make sure they perform together to maintain QoE standards.

Embracing & Enabling Open RAN

Traditionally, RAN components have been built on proprietary hardware with vendor-specific protocols for communications, software functions and interfaces. Open RAN initiatives were developed to help operators evolve their infrastructure quickly to monetize new 5G business opportunities, while enabling them to better manage CAPEX and maintain OPEX.

Deployment and management of the RAN is one of the most expensive parts of wireless networks. To deliver 5G profitably, operators need to look closely at how they manage the high cost areas of network evolution, growth and maintenance. Open RAN architectures give them several new avenues to accomplish a number of goals, including:

  • An open, multi-vendor interoperable ecosystem that drives healthier competition, innovations and lower costs for RAN equipment.
  • Support for automation, which further reduces deployment and management costs.
  • Network scale and agility, as network components work as software functions that are scaled per user, network capability and capacity demand.

Challenges of an Open-ecosystem

As operators move away from proprietary vendor systems toward open networks, interoperability is of paramount concern. While considering deployment and management of Open RAN architecture, the most crucial task for both operators and equipment manufacturers is how to ensure interoperability, manageability, optimization and end-to-end performance in an O-RAN environment.

Deploying 5G RAN requires planning for a range of new features: including multiple-input, multiple-output (MIMO) antennas, large spectrum bandwidth and multi-band carrier aggregation. This presents a challenge for the growth and maintenance of the networks, which needs to support multiple generations of connectivity – 3G, 4G and 5G – at the same time scale to meet rising data demands.

Network operators and integrators need to validate technology that works together before it goes into the live network, as addressing these issues requires more than testing the interoperability of distinct vendor technology. Operators also need to see how the technology interacts with legacy 4G equipment in the network as well as responds to different user equipment (UE) environments.

Another challenge operators face with O-RAN is troubleshooting network issues, once the network has been deployed. In a multi-vendor environment it is difficult to identify product-related network performance issues, versus in traditional single-vendor networks. In an O-RAN network, operators require open standards as well as vendor-independent validation and troubleshooting to resolve network performance issues.

Accelerating O-RAN

Success of O-RAN networks will depend on the ability of operators to integrate and meet network key performance indicators (KPIs) in a multi-vendor environment. With O-RAN architecture, operators can deploy a network with an O-RAN Radio Unit (O-RU) from one vendor, O-RAN Distributed Unit (O-DU) from another and Central Unit (O-CU) from a third vendor — only if the performance meets their targets and network integration is robust. Operators need to have the confidence that all components in an O-RAN network have been validated and verified in a trusted and controlled environment and all open interfaces and components are working correctly.

Critical performance aspects to be evaluated include:

  • End-to-end network performance
  • Handover and mobility scenarios
  • Ability of the network to handle large numbers of UEs carrying different types of traffic
  • Robustness (low BER and synchronization) of the fronthaul O-RU to O-DU connection.

Use cases can help identify, isolate and resolve network performance issues, before an O-RAN multi-vendor network goes live. These include multi-vendor interoperability tests for functionality, performance, reliability, robustness and resilience; subsystem wrap-around tests; system-level tests; protocol compliance tests for open interfaces and protocols; continuous test process throughout the entire lifecycle and performance monitoring of open interfaces and protocols to ensure optimum operation and performance.

O-RAN is a powerful vision that holds tremendous promise for operators through an open ecosystem that removes vendor lock-in, while laying the foundation for virtualized network elements and enabling white-box hardware that can be quickly scaled through software-based nodes. For telecom operators to fully realize and reap the benefits of open architecture, they will need to integrate robust multi-vendor testing processes from the lab to field and beyond.


*About the Author

Sameh Yamany is Chief Technology Officer for VIAVI Solutions where he drives technology innovation in network test, assurance and automation.