January 17, 2021
Open Radio Access Network (O-RAN) utilizes open interfaces, commercial off-the-shelf (COTS) hardware, and possibly open source software to guide and foster a more efficient open RAN ecosystem. The flexible architecture can help mobile operators more effectively deploy and operate 4G and 5G networks. To ensure an improved network environment is created, engineers need to integrate new testing approaches to verify O-RAN elements are compatible and networks meet key performance indicators (KPIs).
Innovation is one cornerstone of O-RAN. Increased competition is another. Both help create three core benefits:
Lower Cost – CAPEX is reduced by the multi-vendor ecosystem created by O-RAN. OPEX is less because RAN automation leverages new learning-based technologies to reduce operational actions. Considering the high expenses associated with 5G RAN, economic benefits are a main advantage of O-RAN.
Improved Efficiency and Performance – O-RAN could enhance network operation and the user experience because it aims to offer efficient and optimized radio resource management via near real-time and non-real-time RAN Intelligent Controllers (RIC).
Seamless Upgrades – Network expansion is simplified through O-RAN, due to its cloud native infrastructures and utilization of continuous integration, test, and deployment methods (CI/CT/CD).
Open Architecture Configuration
O-RAN architecture (figure 1) utilizes COTS hardware and virtualized software to provide multiple hierarchical cloud deployment options for operators.
The open architecture divides conventional monolithic BTS into the functional splits of an O-CU, O-DU, and O-RU. Engineers must understand the impact of such a split, particularly at the radio unit (RU) and distributed unit (DU) layers.
By breaking the RAN monolithic structure, new vendors have an easier path to enter the network market. Added competition will reduce costs. Such a scenario allows mobile operators to better service more cost-sensitive 5G network use cases, such as rural markets or private commercial 5G networks.
Another benefit of the open environment is that it stimulates innovation, including moving wireless networks to the edge. With the service-based approach of 5G, edge networking is essential for networks to meet KPIs.
O-RAN ALLIANCE Provides Roadmap
An open environment with many vendors may create advantages for network design and operation but only if testing is conducted reliably, repeatedly, and efficiently. The O-RAN ALLIANCE has provided guidance to create effective test environments, focusing on two key initiatives.
Open Testing and Integration Centres (OTICs) – Established by the Alliance, OTICs conduct myriad of activities, including plugfests and Proofs of Concepts (PoC). Anritsu has participated in these events as part of its collaborative approach to developing test solutions for O-RAN verification.
Certification and Badging – The Alliance has also created procedures to ensure vendor equipment is within the conformance, interoperability, and performance specifications established by the industry.
Certification is applied on conformance tests. It serves as a transparent verification that an individual device-under-test (DUT) behaves according to an O-RAN technical specification.
Two badges - interoperability tests (IOT) and end-to-end (E2E) tests – designate that test equipment has been approved by the O-RAN ALLIANCE. Both badges involve multiple DUTs from different vendors.
IOT is an assessment of interoperability of DUT pairs using O-RAN Interoperability Test specifications. E2E system integration badging is an assessment of end-to-end system integration of DUT groups that are implemented according to O-RAN interfaces. It is based on O-RAN E2E test specifications.
An O-RAN E2E test configuration for O-RU and O-DU subsystems is shown in figure 2. Test requirements and methods are the same as a monolithic base station. The RF interface has the same verification as 3GPP BTS test specifications.
The test set-up includes a vector signal generator/spectrum analyzer/vector signal analyzer to conduct RF measurements and a UE simulator for functional/load test. Emulated network functions provide a testing framework for comprehensive evaluation and testing prior to E2E system testing.
O-RAN Testing Aspects
A comprehensive testing strategy must be developed for successful O-RAN implementation. Anritsu has leveraged its vast 3G/4G/5G experience and active membership in the O-RAN ALLIANCE to collaborate with customers to create effective verification processes. Key tests that Anritsu-based solutions conduct are listed in table 1.
Need for Test Automation
O-RAN architecture expands across different verticals that require levels of customization. There is also an influx of new companies entering the market, as mentioned previously. Such a scenario places even greater importance on the need to ensure elements work seamlessly. To reduce complexity, as well as control cost-of-test and speed time-to-market, test automation is a necessity.
A successful test process will have automated testing and comprehensive test suites defined and developed in advance and run before any component is released. The same approach is used to validate the deployment of an O-RAN solution, so the testing runs automatically each time a new component is released. Automated tests are particularly beneficial for O-Cloud verification.
Test solutions that are completely integrated with standards and can perform the tests in a few keystrokes provide the accuracy, repeatability, and speed necessary. Flexible platforms that allow for updates as specifications evolve are also beneficial for O-RAN. For production test environments, a software-based solution that automatically updates 3GPP test cases saves time and money.
One way for test companies to develop these test solutions is through collaboration. Anritsu’s membership in the O-RAN ALLIANCE and involvement in the association’s plugfests have forged advantageous relationships. Anritsu is also an active member of the Telecom Infra Project (TIP), a diverse community that includes hundreds of participating companies, from service providers and technology partners to system integrators and other connectivity stakeholders. The result is a unique ability to develop flexible test solutions that meet existing needs and can be easily upgraded as new requirements arise, helping bring O-RAN solutions to market more efficiently and with greater confidence.
To learn more about the impact O-RAN is having on network design and how to test it, download this testing O-RAN literature. You can also listen to this Fierce Wireless virtual event entitled Open RAN and The Evolution of Telecommunications Infrastructure featuring Sundara Venkatesh of Anritsu.