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Open RAN’s (O-RAN) pioneering approach that seeks to diversify monolithic RAN supply chains represents an entirely new way of building networks. O-RAN’s objectives are game changing:
Increase competition and lower costs through open, standardized interfaces and software-defined RAN architectures
Drive more innovation and new use cases via intelligent, data-driven closed-loop RAN control
Power new service models with flexible, disaggregated, and virtualized RAN technology
O-RAN’s success will be largely driven by whether it performs at least as well as traditional radio, close feature gaps, achieve simple plug-and-play interoperability, and realize anticipated cost savings.
O-RAN deployments also typically include additional next-gen network elements like cloud and automation. This is creating new dynamics in testing that must be considered and accommodated.
O-RAN architecture introduces new interfaces and interoperability challenges
The complexity of O-RAN and the high-performing 5G network in which it resides demand new, automated testing methodologies that continuously validate real-world performance and robustness, ensure interoperability, collaboration, and support open ecosystems, to realize cost efficiencies and innovation benefits.
The Open RAN Environment
Assessment areas
O-RAN must ensure it is robust, interoperable, performant, scalable, provides technical parity with traditional RAN, and is efficient to deploy, operate, and manage. Supply chains must be secure, as regulatory requirements for emergency services are met and new cost overheads are counteracted.
O-RAN assessment areas
All nodal functions in an O-RAN architecture must be conformant to 3GPP standards and new O-RAN Alliance requirements that focus on interfaces between O-RAN elements. In addition to standard conformance testing of the nodal functions, the test methodology should be extended to cover factors such as:
Multivendor interoperability
Mobility scenarios and handovers
Synchronization and timing
Feature functionality and conformance
Security
Application and service validation
Performance and robustness
Capacity and scalability
Spirent’s recommended O-RAN test methodology
O-RAN expands test considerations with a range of test considerations that must be addressed before an end-to-end system is ready to go live, with additional O-RAN testing strategy insights found here. These considerations span user equipment and disaggregated functions to the radios themselves.
Nodal testing: Nodal testing ensures that a specific O-RAN component is validated for performance, scalability, and conformance with 3GPP standards and O-RAN Alliance requirements. In this phase, a nodal network function, such as an open central unit (O-CU) or radio unit (RU), is wrapped with emulated network functions and traffic, representing a range of real-world conditions that might exist in the field. The goal is to confirm that individual components can handle the expected traffic and functionality. These components must also be tested at peak performance and capacity levels to ensure they are robust and do not become a weak link out in the field.
Adjacent testing: Once individual nodal functions are validated in the lab for conformance, they must be tested with combinations of adjacent network functions from the same or different vendors to ensure interoperability. Adjacent testing should not only validate interoperability, but interoperability at scale. As open standards can be subject to interpretation, adjacent testing is key to ensure that the critical components of the deployment will perform together in the field.
End-to-end testing: The entire O-RAN environment must be tested at capacity and scale to ensure the end-to-end system meets specifications and should be validated for delivered services such as voice, data, video, and emergency services.
Security: O-RAN involves more elements, more interfaces, more points of entry and therefore more attack surfaces. Security testing should encompass not just the traditional security tests, but should also consider:
Network functions
Underlying cloud infrastructure
RIC algorithms
Security protocols used across different interfaces (e.g., fronthaul interface)
The safest posture is to assume the worst, with Zero Trust, and conduct continuous testing for security vulnerabilities, evidence of intrusions or attacks.
The automation imperative. The multitude of validation requirements and test combinations that must be addressed call for automation and continuous testing (CT), supported by continuous integration and deployment/development (CI/CD). Manual testing in such a complex environment is a non-starter. Without automation and repeatability, the complexity of validating O-RAN would negate any agility and efficiency benefits. Spirent’s approach leverages our single user interface to completely automate test workflows, making it possible to keep up with O-RAN’s radically expansive set of multi-vendor releases.
Learn more how Spirent’s approach to O-RAN testing and read the eBook How to Test Open RAN and our solution brief: Advanced Open RAN Test as a Service.
