Open RAN (O-RAN) stakeholders promise to transform radio access networks (RANs) from groups of centralized signal processing units with proprietary interfaces to plug-and-play, virtual architectures with open APIs. If successful, operators anticipate diversified supply chains and lower costs through multivendor, flexible, software-defined RAN architectures.
However, service providers are concerned about O-RAN’s lack of maturity. Will its distributed, multivendor approach really be practical in the real network? Will it deliver the performance and robustness required by 5G use cases? Will it introduce new security risks? Most importantly, will a more complex supply chain actually reduce costs?
The answers to those questions lie in O-RAN end-to-end emulation and testing.
O-RAN challenges piling up
The RAN protocol stack consists of multiple layers, from the physical RF layer and link control to radio resource control at the upper layer. These functions have traditionally resided in a single unit at the cell site.
In contrast, O-RAN separates and distributes these functions geographically as it aims for increased scalability, improved 5G use case performance, and reduced costs:
The Open RU (radio unit) performs RF signal processing, amplification, and digitization.
The Open DU (distributed unit) is the brain of the RAN. It performs real-time scheduling and baseband processing, and handles the lower layers of the protocol stack.
The Open CU (centralized unit) orchestrates many underlying DUs, RUs, and subscribers.
The Open RIC (RAN intelligent controller) provides intelligence and algorithms, such as optimizing resources and improving efficiency.
The Open RU resides near or in the antenna, the Open DU and CU are typically in an edge cloud, while the Open RIC is in a regional cloud.
The multivendor openness of O-RAN presents significant and new challenges versus single-vendor, integrated RANs. O-RAN demands units from multiple vendors interoperate with adjacent units physically (across the network) as well as virtually (up the protocol stack).
Three essentials for end-to-end Open RAN testing
Service providers know they must implement test solutions that validate individual vendor network functions and adjacent functions, too. They need to know whether O-RAN—from end to end—will perform as well as or better than a traditional, monolithic RAN. Will units from different vendors interoperate at a physical and electrical level? Will features work seamlessly from one unit to another? What is the impact on latency? Have security risks increased?
Integrated end-to-end testing can help remove doubt by introducing:
Real-world emulation to test the end-to-end network’s performance under realistic “rainy day” and “sunny day” scenarios to ensure they will behave as expected in normal and unexpected traffic situations. End-to-end testing surrounds the O-RAN units with emulation of the core at one end and the user equipment and RF channels at the other. Emulations test the activity across the lower layers of the network, as well as up the protocol stacks and applications. Important factors to address include latency, scalability, and user experience.
An integrated UI/UX emulator interface that wraps around the domain-specific emulators, gathering and managing test results from each emulator. While experts in each domain may be needed to analyze the end-to-end emulation results, they should work from the same UI/UX, and access the same test data, instead of huddling over each node emulator’s log files.
Automation to integrate vendor updates and test workflows from multiple emulators. Pre-built automated compliance, performance, and capacity test packs save test development time and enable rapid, reproducible tests
Automated, integrated end-to-end testing alleviates service provider concerns about the nascent, multivendor O-RAN architecture while, at the same time, reducing costs and live network performance risks. It also speeds time to market for new services and vendor product updates.
A comprehensive O-RAN test system
Spirent offers a comprehensive testing solution with a single UI/UX with built-in automation. The solution provides real-time, end-to-end, wraparound Open RAN emulation that ensures functions deployed in the live network will perform as expected.
The result is a multivendor, O-RAN network that has the performance and robustness of a reaggregated RAN network. Risk is managed and costs are reduced substantially through advanced test automation.
Download our eBook to learn more about the nuances to testing open RAN components and systems.